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Sample records for theoretical infrared spectra

  1. Theoretical study of NMR, infrared and Raman spectra on triple-decker phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Atsushi; Oku, Takeo [Department of Materials Science, The University of Shiga Prefecture 2500 Hassaka, Hikone, Shiga, 522-8533 (Japan)

    2016-02-01

    Electronic structures and magnetic properties of multi-decker phthalocyanines were studied by theoretical calculation. Electronic structures, excited processes at multi-states, isotropic chemical shifts of {sup 13}C, {sup 14}N and {sup 1}H-nuclear magnetic resonance (NMR), principle V-tensor in electronic field gradient (EFG) tensor and asymmetry parameters (η), vibration mode in infrared (IR) and Raman spectra of triple-decker phthalocyanines were calculated by density functional theory (DFT) and time-dependent DFT using B3LYP as basis function. Electron density distribution was delocalized on the phthalocyanine rings with electron static potential. Considerable separation of chemical shifts in {sup 13}C, {sup 14}N and {sup 1}H-NMR was originated from nuclear spin interaction between nitrogen and carbon atoms, nuclear quadrupole interaction based on EFG and η of central metal under crystal field. Calculated optical absorption at multi-excited process was derived from overlapping π-orbital on the phthalocyanine rings. The vibration modes in IR and Raman spectra were based on in-plane deformation and stretching vibrations of metal-ligand coordination bond on the deformed structure.

  2. Theoretical modeling of infrared spectra of the hydrogen and deuterium bond in aspirin crystal

    Science.gov (United States)

    Ghalla, Houcine; Rekik, Najeh; Michta, Anna; Oujia, Brahim; Flakus, Henryk T.

    2010-01-01

    An extended quantum theoretical approach of the ν IR lineshape of cyclic dimers of weakly H-bonded species is proposed. We have extended a previous approach [M.E.-A. Benmalti, P. Blaise, H.T. Flakus, O. Henri-Rousseau, Chem. Phys. 320 (2006) 267] by accounting for the anharmonicity of the slow mode which is described by a "Morse" potential in order to reproduce the polarized infrared spectra of the hydrogen and deuterium bond in acetylsalicylic acid (aspirin) crystals. From comparison of polarized IR spectra of isotopically neat and isotopically diluted aspirin crystals it resulted that centrosymmetric aspirin dimer was the bearer of the crystal main spectral properties. In this approach, the adiabatic approximation is performed for each separate H-bond bridge of the dimer and a strong non-adiabatic correction is introduced into the model via the resonant exchange between the fast mode excited states of the two moieties. Within the strong anharmonic coupling theory, according to which the X-H→⋯Y high-frequency mode is anharmonically coupled to the H-bond bridge, this model incorporated the Davydov coupling between the excited states of the two moieties, the quantum direct and indirect dampings and the anharmonicity for the H-bond bridge. The spectral density is obtained within the linear response theory by Fourier transform of the damped autocorrelation functions. The evaluated spectra are in fairly good agreement with the experimental ones by using a minimum number of independent parameters. The effect of deuteration has been well reproduced by reducing simply the angular frequency of the fast mode and the anharmonic coupling parameter.

  3. Theoretical Study of Infrared and Raman Spectra of Hydrated Magnesium Sulfate Salts

    Science.gov (United States)

    Chaban, Galina M.; Huo, Winifred M.; Lee, Timothy J.; Kwak, Dochan (Technical Monitor)

    2002-01-01

    Harmonic and anharmonic vibrational frequencies, as well as infrared and Raman intensities, are calculated for MgSO4.nH20 (n=1-3). Electronic structure theory at the second order Moller-Plesset perturbation theory (MP2) level with a triple-zeta + polarization (TZP) basis set is used to determine the geometry, properties, and vibrational spectra of pure and hydrated MgSO4 salts. The direct vibrational self-consistent field (VSCF) method and its correlation corrected (CC-VSCF) extension are used to determine anharmonic corrections to vibrational frequencies and intensities for the pure MgSO4 and its complex with one water molecule. Very significant differences are found between vibrational of water molecules in complexes with MgSO4 and pure water. Some of the O-H stretching frequencies are shifted to the red very significantly (by up to 1500-2000/cm) upon complexation with magnesium sulfate. They should be observed between 1700 and 3000/cm in a region very different from the corresponding O-H stretch frequency region of pure water (3700-3800/cm). In addition, the SO2 stretching vibrations are found at lower frequency regions than the water vibrations. They can serve as unique identifiers for the presence of sulfate salts. The predicted infrared and Raman spectra should be of valuable help in the design of future missions and analysis of observed data from the ice surface of Jupiter's moon Europa that possibly contains hydrated MgSO4 salts.

  4. Theoretical emission line ratios for [Fe III] and [Fe VII] applicable to the optical and infrared spectra of gaseous nebulae.

    Science.gov (United States)

    Keenan, F P; Aller, L H; Ryans, R S; Hyung, S

    2001-08-14

    Recent calculations of electron impact excitation rates and Einstein A-coefficients for transitions among the 3d(6) levels of Fe III and among the 3d(2) levels of Fe VII are used to derive theoretical emission line ratios applicable to the optical and infrared spectra of gaseous nebulae. Results for [Fe III] are generated for electron temperatures T(e) = 7,000-20,000 K and densities N(e) = 10(2)-10(8) cm(-3), whereas those for [Fe VII] are provided for T(e) = 10,000-30,000 K and N(e) = 10(2)-10(8) cm(-3). The theoretical line ratios are significantly different in some instances from earlier calculations and resolve discrepancies between theory and observation found for the planetary nebulae IC 4997 and NGC 7027.

  5. Rotational structure in molecular infrared spectra

    CERN Document Server

    di Lauro, Carlo

    2013-01-01

    Recent advances in infrared molecular spectroscopy have resulted in sophisticated theoretical and laboratory methods that are difficult to grasp without a solid understanding of the basic principles and underlying theory of vibration-rotation absorption spectroscopy. Rotational Structure in Molecular Infrared Spectra fills the gap between these recent, complex topics and the most elementary methods in the field of rotational structure in the infrared spectra of gaseous molecules. There is an increasing need for people with the skills and knowledge to interpret vibration-rotation spectra in many scientific disciplines, including applications in atmospheric and planetary research. Consequently, the basic principles of vibration-rotation absorption spectroscopy are addressed for contemporary applications. In addition to covering operational quantum mechanical methods, spherical tensor algebra, and group theoretical methods applied to molecular symmetry, attention is also given to phase conventions and their effe...

  6. Experimental and Theoretical Investigations of Infrared Multiple Photon Dissociation Spectra of Aspartic Acid Complexes with Zn2+ and Cd2.

    Science.gov (United States)

    Boles, Georgia C; Hightower, Randy L; Coates, Rebecca A; McNary, Christopher P; Berden, Giel; Oomens, Jos; Armentrout, P B

    2018-04-12

    Complexes of aspartic acid (Asp) cationized with Zn 2+ : Zn(Asp-H) + , Zn(Asp-H) + (ACN) where ACN = acetonitrile, and Zn(Asp-H) + (Asp); as well as with Cd 2+ , CdCl + (Asp), were examined by infrared multiple photon dissociation (IRMPD) action spectroscopy using light generated from a free electron laser. A series of low-energy conformers for each complex was found using quantum chemical calculations to identify the structures formed experimentally. The main binding motif observed for the heavy-metal complex, CdCl + (Asp)[N,CO,CO s ], is a charge-solvated, tridentate structure, where the metal center binds to the backbone amino group and carbonyl oxygens of the backbone and side-chain carboxylic acids. Likewise, the deprotonated Zn(Asp-H) + (ACN) and Zn(Asp-H) + (Asp) complexes show comparable [N,CO - ,CO s ](ACN) and [N,CO - ,CO s ][N,CO,CO s ] coordinations, respectively. Interestingly, there was only minor spectral evidence for the analogous Zn(Asp-H) + [N,CO - ,CO s ] binding motif, even though this species is predicted to be the lowest-energy conformer. Instead, rearrangement and partial dissociation of the amino acid are observed, as spectral features most consistent with the experimental spectrum are exhibited by a four-coordinate Zn(Asp-NH 4 ) + [CO 2 - ,CO s ](NH 3 ) complex. Analysis of the mechanistic pathway leading from the predicted lowest-energy conformer to the isobaric deaminated complex is explored theoretically. Further, comparison of the current work to that of Zn 2+ and Cd 2+ complexes of asparagine (Asn) allows additional conclusions regarding populated conformers and effects of carboxamide versus carboxylic acid binding to be drawn.

  7. Infrared Model Spectra for Evolving Red Supergiants

    Directory of Open Access Journals (Sweden)

    Kyung-Won Suh

    1993-06-01

    Full Text Available The space and ground based infrared spectra of red supergiants are modeled and arranged in order of their evolutionary status with their theoretical model parameters. The chemical compositions of the dust shells around red supergiants are affected by the nuclear reaction and dredge-up processes of the cental stars. The processes are sensitively dependent on the initial mass, the initial chemical composition, and the evolutionary status. Miras, infrared carbon stars, and OH/IR stars have close link in their evolution in manu aspects, i,e., the chemical composition, the optical depths and the mass loss rates. The evolutionary tracks for the three classes of red supergiants on infrared two-color diagrams have been made from model calculations and IRAS observational data.

  8. Infrared spectra of mineral species

    CERN Document Server

    Chukanov, Nikita V

    2014-01-01

    This book details more than 3,000 IR spectra of more than 2,000 mineral species collected during last 30 years. It features full descriptions and analytical data of each sample for which IR spectrum was obtained.

  9. Far-infrared spectra of acetanilide revisited

    Science.gov (United States)

    Spire, A.; Barthes, M.; Kellouai, H.; De Nunzio, G.

    2000-03-01

    A new investigation of the temperature dependence of the far-infrared spectra of acetanilide and some isotopomers is presented. Four absorption bands are considered at 31, 42, 64, and 80 cm-1, and no significant change of their integrated intensity is observed when reducing the temperature. The temperature induced frequency shift values and other properties of these bands are consistent with an assignment as anharmonic lattice phonons. These results rule out the assignment of the 64, 80, and 106 cm-1 bands as normal modes of the polaronic excitation, as previously suggested.

  10. Machine learning molecular dynamics for the simulation of infrared spectra.

    Science.gov (United States)

    Gastegger, Michael; Behler, Jörg; Marquetand, Philipp

    2017-10-01

    Machine learning has emerged as an invaluable tool in many research areas. In the present work, we harness this power to predict highly accurate molecular infrared spectra with unprecedented computational efficiency. To account for vibrational anharmonic and dynamical effects - typically neglected by conventional quantum chemistry approaches - we base our machine learning strategy on ab initio molecular dynamics simulations. While these simulations are usually extremely time consuming even for small molecules, we overcome these limitations by leveraging the power of a variety of machine learning techniques, not only accelerating simulations by several orders of magnitude, but also greatly extending the size of systems that can be treated. To this end, we develop a molecular dipole moment model based on environment dependent neural network charges and combine it with the neural network potential approach of Behler and Parrinello. Contrary to the prevalent big data philosophy, we are able to obtain very accurate machine learning models for the prediction of infrared spectra based on only a few hundreds of electronic structure reference points. This is made possible through the use of molecular forces during neural network potential training and the introduction of a fully automated sampling scheme. We demonstrate the power of our machine learning approach by applying it to model the infrared spectra of a methanol molecule, n -alkanes containing up to 200 atoms and the protonated alanine tripeptide, which at the same time represents the first application of machine learning techniques to simulate the dynamics of a peptide. In all of these case studies we find an excellent agreement between the infrared spectra predicted via machine learning models and the respective theoretical and experimental spectra.

  11. Observational and theoretical spectra of supernovae

    Science.gov (United States)

    Wheeler, J. Craig; Swartz, Douglas A.; Harkness, Robert P.

    1993-05-01

    Progress in nuclear astrophysics by means of quantitative supernova spectroscopy is discussed with special concentration on type Ia, Ib and Ic and on SN 1987A. Spectral calculations continue to support an exploding C/O white dwarf as the best model of a SN Ia. Deflagration model W7 produces good maximum light spectra of SN Ia and seems to have a better composition distribution compared to delayed detonation models, but proper treatment of opacity remains a problem and the physical basis of SN Ia explosions is still not completely understood. All models for SN Ia predict large quantities of 56Co in the ejecta, but it is not clear that observations confirm this. Although the evolutionary origin of SN Ia remains uncertain, there is recent evidence that transfer of hydrogen in a binary system may be involved, as long suspected. There has been progress in comparing dynamical models with the optical/IR spectra of SN 1987A. The evolution of the [OI] λλ6300, 6364 feature and the presence of strong persistent HeI λ10 830 indicate that both the envelope and core material contribute substantially to the formation of emission lines in the nebular phase and that neither the core nor the envelope can be neglected. Blending with nearby hydrogen lines may affect both of these spectral features, thereby complicating the analysis of the lines. The effects of continuum transfer and photoionization have been included and are under study. The discrepancies between theoretical and observed spectra are due primarily to the one-dimensional hydrodynamic models. The spectral data are not consistent with the high density ``spike'' (in radial coordinate) of the core material that is predicted by all such models. Analysis of the light curves of SN Ib and SN Ic supernovae implies that there are significant differences in their physical properties. Some SN Ib have considerably more ejecta mass than SN Ic events. SN Ib require He-rich atmospheres to produce the observed strong optical lines of

  12. Low resolution infrared spectra of quasars

    International Nuclear Information System (INIS)

    Soifer, B.T.; Neugebauer, G.; Oke, J.B.; Matthews, K.

    1980-01-01

    Low resolution spectra of a significant sample of quasars show that the Paschen α and Balmer line ratios do not agree with the radiative recombination case B result and vary widely within the quasars sampled. The range in Pα:Hβ ratios is a factor of approximately 6, while the range in Lyα:Hα ratios is a factor of approximately 5. For the Pα:Balmer series, the deviations from case B recombination are not consistent with reddening, but appear, within large dispersions, to be consistent with optical depth effects in the Balmer lines affecting the line ratios. The Lyα:Hα ratio is, however, correlated with the continuum spectral index, and can be explained as due to reddening affecting both the lines and continuum. Recent observational results based on a joint infrared/optical survey of the hydrogen line spectra of a significant number of the brightest low and high redshift quasars are summarised. This survey includes 12 quasars in the redshift range 0.07 1.5, where Hα and/or Hβ is redshifted into the 1.65μm or 2.2μm atmospheric windows. (Auth.)

  13. Theoretical modelling of actinide spectra in solution

    International Nuclear Information System (INIS)

    Danilo, Cecile

    2009-01-01

    The framework of this PhD is the interpretation of Nuclear Magnetic Relaxation Dispersion experiments performed on solvated U"4"+, NpO_2"+ and PuO_2"2"+, which all have a f"2 configuration. Unexpectedly the two actinyl ions have a much higher relaxivity than U"4"+,. One possible explanation is that the electronic relaxation rate is faster for Uranium(IV) than for the actinyl ions. We address this problem by exploring the electronic spectrum of the three compounds in gas phase and in solution with a two-step SOCI (Spin-Orbit Configuration-Interaction) method. The influence of electron correlation (treated in the first step) and spin-orbit relaxation effects (considered in the second step) has been discussed thoroughly. Solvent effects have been investigated as well. Another issue that has been questioned is the accuracy of Density Functional Theory for the study of actinide species. This matter has been discussed by comparing its performance to wave-function based correlated methods. The chemical problem chosen was the water exchange in [UO_2"2"+ (H_2O)_5]. We looked at the associative and at the dissociative mechanisms using a model with one additional water in the second hydration sphere. The last part of the thesis dealt with the spectroscopy of coordinated Uranyl(V). Absorption spectrum of Uranyl(V) with various ligands has been recorded. The first sharp absorption bands in the Near-Infrared region were assigned to the Uranium centered 5f-5f transitions, but uncertainties remained for the assignment of transitions observed in the Visible region. We computed the spectra of naked UO_2"+ and [UO_2(CO_3)_3]"5"- to elucidate the spectral changes induced by the carbonate ligands. (author) [fr

  14. Theoretical microcontact spectra of metal electron-phonon coupling

    International Nuclear Information System (INIS)

    Kulagina, T.N.; Zhernov, A.P.

    1987-01-01

    Theoretical and experimental microcontact spectra of simple and certain transition metals are discussed. The Eliashberg thermodynamic functions for the metals are considered, as well as correlations between spectra peculiarities and parameters of metals and microbridge models

  15. Synthesis and infrared spectra of alkaline earth metal carbonates ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The metal carbonate, MCO3 (M = Ca, Sr and Ba), was synthesized by a novel method of reacting aqueous solution of each of Ca2+, Sr2+ and Ba2+ salts with urea at high temperature, ~ 80°C. The reaction products were characterized through elemental analysis and infrared spectra. The infrared spectra of the.

  16. Synthesis and infrared spectra of alkaline earth metal carbonates

    Indian Academy of Sciences (India)

    The metal carbonate, MCO3 (M = Ca, Sr and Ba), was synthesized by a novel method of reacting aqueous solution of each of Ca2+, Sr2+ and Ba2+ salts with urea at high temperature, ∼ 80°C. The reaction products were characterized through elemental analysis and infrared spectra. The infrared spectra of the products are ...

  17. EFFECTS OF FORSTERITE GRAIN SHAPE ON INFRARED SPECTRA

    International Nuclear Information System (INIS)

    Koike, C.; Imai, Y.; Chihara, H.; Murata, K.; Tsuchiyama, A.; Suto, H.; Tachibana, S.; Ohara, S.

    2010-01-01

    The Infrared Space Observatory (ISO) detected several sharp infrared features around young stars, comets, and evolved stars. These sharp features were identified as Mg-rich crystalline silicates of forsterite and enstatite by comparison with spectra from laboratory data. However, certain infrared emission bands in the observed spectra cannot be identified because they appear at slightly shorter wavelengths than the peaks in forsterite laboratory spectra, where the shapes of forsterite particles are irregular. To solve this problem, we measured infrared spectra of forsterite grains of various shapes (irregular, plate-like with no sharp edges, elliptical, cauliflower, and spherical) in the infrared spectral region between 5 and 100 μm. The spectra depend on particle shape. The spectra of the 11, 19, 23, and 33 μm bands, in particular, are extremely sensitive to particle shape, whereas some peaks such as the 11.9, 49, and 69 μm bands remained almost unchanged despite different particle shapes. This becomes most evident from the spectra of near-spherical particles produced by annealing an originally amorphous silicate sample at temperature from 600 to 1150 deg. C. The spectra of these samples differ strongly from those of other ones, showing peaks at much shorter wavelengths. At a higher annealing temperature of 1200 deg. C, the particle shapes changed drastically from spherical to irregular and the spectra became similar to those of forsterite particles with irregular shapes. Based on ISO data and other observational data, the spectra of outflow sources and disk sources may correspond to differences in forsterite shape, and further some unidentified peaks, such as those at 32.8 or 32.5 μm, may be due to spherical or spherical-like forsterite.

  18. Fourier transform infrared emission spectra of atomic rubidium: g- and h-states

    Czech Academy of Sciences Publication Activity Database

    Civiš, Svatopluk; Ferus, Martin; Kubelík, Petr; Chernov, Vladislav E.; Zanozina, Ekaterina M.

    2012-01-01

    Roč. 45, č. 17 (2012), s. 175002 ISSN 0953-4075 R&D Projects: GA AV ČR IAAX00100903 Institutional support: RVO:61388955 Keywords : Fourier transform infrared emission spectra * atomic rubidium * physical chemistry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.031, year: 2012

  19. Photographic infrared spectra of symbiotic stars

    International Nuclear Information System (INIS)

    Andrillat, Y.; Houziaux, L.

    1982-01-01

    The authors have observed six symbiotic stars during the period 1962-1977 with a grating spectrograph attached to the newtonian focus of the 120-cm telescope at Observatoire de Haute Provence. The reciprocal dispersion is 230 A.mm -1 and the region 5800 to 8800 A has been covered using hypersensitized IN plates. The minimum equivalent width for an emission line to be seen is about 0.5 A. The spectra are displayed and the main spectral characteristics are reviewed briefly. (Auth.)

  20. Infrared spectra of jennite and tobermorite from first-principles

    Energy Technology Data Exchange (ETDEWEB)

    Vidmer, Alexandre, E-mail: alexandre@vidmer.com; Sclauzero, Gabriele; Pasquarello, Alfredo

    2014-06-01

    The infrared absorption spectra of jennite, tobermorite 14 Å, anomalous tobermorite 11 Å, and normal tobermorite 11 Å are simulated within a density-functional-theory scheme. The atomic coordinates and the cell parameters are optimized resulting in structures which agree with previous studies. The vibrational frequencies and modes are obtained for each mineral. The vibrational density of states is analyzed through extensive projections on silicon tetrahedra, oxygen atoms, OH groups, and water molecules. The coupling with the electric field is achieved through the use of density functional perturbation theory, which yields Born effective charges and dielectric constants. The simulated absorption spectra reproduce well the experimental spectra, thereby allowing for a detailed interpretation of the spectral features in terms of the underlying vibrational modes. In the far-infrared part of the absorption spectra, the interplay between Ca and Si related vibrations leads to differences which are sensitive to the calcium/silicon ratio of the mineral.

  1. Infrared spectra of lunar soils. [using a Michelson interferometer

    Science.gov (United States)

    Aronson, J. R.; Emslie, A. G.; Smith, E. M.

    1979-01-01

    Measured data obtained by Michelson interferometer spectrometer were stored in a computer file and smoothed by being passed forward and backward through a digital four-pole low pass filter. Infrared spectra of the 10 lunar samples are presented in the format of brightness temperature versus frequency. The mol % of feldspar, pyroxene, olivine, ilmenite and ferromagnetic silicate in each sample is presented in tables. The reflectance spectra of ilmenite and enstatite are shown in graphs.

  2. Connecting infrared spectra with plant traits to identify species

    Science.gov (United States)

    Buitrago, Maria F.; Skidmore, Andrew K.; Groen, Thomas A.; Hecker, Christoph A.

    2018-05-01

    Plant traits are used to define species, but also to evaluate the health status of forests, plantations and crops. Conventional methods of measuring plant traits (e.g. wet chemistry), although accurate, are inefficient and costly when applied over large areas or with intensive sampling. Spectroscopic methods, as used in the food industry and mineralogy, are nowadays applied to identify plant traits, however, most studies analysed visible to near infrared, while infrared spectra of longer wavelengths have been little used for identifying the spectral differences between plant species. This study measured the infrared spectra (1.4-16.0 μm) on individual, fresh leaves of 19 species (from herbaceous to woody species), as well as 14 leaf traits for each leaf. The results describe at which wavelengths in the infrared the leaves' spectra can differentiate most effectively between these plant species. A Quadratic Discrimination Analysis (QDA) shows that using five bands in the SWIR or the LWIR is enough to accurately differentiate these species (Kappa: 0.93, 0.94 respectively), while the MWIR has a lower classification accuracy (Kappa: 0.84). This study also shows that in the infrared spectra of fresh leaves, the identified species-specific features are correlated with leaf traits as well as changes in their values. Spectral features in the SWIR (1.66, 1.89 and 2.00 μm) are common to all species and match the main features of pure cellulose and lignin spectra. The depth of these features varies with changes of cellulose and leaf water content and can be used to differentiate species in this region. In the MWIR and LWIR, the absorption spectra of leaves are formed by key species-specific traits including lignin, cellulose, water, nitrogen and leaf thickness. The connection found in this study between leaf traits, features and spectral signatures are novel tools to assist when identifying plant species by spectroscopy and remote sensing.

  3. Near infrared spectra of Wolf-Rayet stars

    International Nuclear Information System (INIS)

    Bappu, M.K.V.; Ganesh, K.S.; Scaria, K.K.

    1977-01-01

    The near-infrared spectra of three Wolf-Rayet stars of the carbon sequence and five of the nitrogen sequence have been studied. Wavelength identifications and intensity scans are presented to show the emission line characteristics of these objects in the 6800 A to 8200 A domain of the spectrum. (author)

  4. Infrared spectra of interstellar deuteronated PAHs

    Science.gov (United States)

    Buragohain, Mridusmita; Pathak, Amit; Sarre, Peter

    2015-08-01

    Polycyclic Aromatic Hydrocarbon (PAH) molecules have emerged as a potential constituent of the ISM that emit strong features at 3.3, 6.2, 7.7, 8.6, 11.2 and 12.7 μm with weaker and blended features in the 3-20μm region. These features are proposed to arise from the vibrational relaxation of PAH molecules on absorption of background UV photons (Tielens 2008). These IR features have been observed towards almost all types of astronomical objects; say H II regions, photodissociation regions, reflection nebulae, planetary nebulae, young star forming regions, external galaxies, etc. A recent observation has proposed that interstellar PAHs are major reservoir for interstellar deuterium (D) (Peeters et al. 2004). According to the `deuterium depletion model' as suggested by Draine (2006), some of the Ds formed in the big bang are depleted in PAHs, which can account for the present value of D/H in the ISM. Hence, study of deuterated PAHs (PADs) is essential in order to measure D/H in the ISM.In this work, we consider another probable category of the large PAH family, i.e. Deuteronated PAHs (DPAH+). Onaka et al. have proposed a D/H ratio which is an order of magnitude smaller than the proposed value of D/H by Draine suggesting that if Ds are depleted in PAHs, they might be accommodated in large PAHs (Onaka et al. 2014). This work reports a `Density Functional Theory' calculation of large deuteronated PAHs (coronene, ovalene, circumcoronene and circumcircumcoronene) to determine the expected region of emission features and to find a D/H ratio that is comparable to the observational results. We present a detailed analysis of the IR spectra of these molecules and discuss the possible astrophysical implications.ReferencesDraine B. T. 2006, in ASP Conf. Ser. 348, Proc. Astrophysics in the Far Ultraviolet: Five Years of Discovery with FUSE, ed. G. Sonneborn, H. Moos, B-G Andersson (San Francisco, CA:ASP) 58Onaka T., Mori T. I., Sakon I., Ohsawa R., Kaneda H., Okada Y., Tanaka M

  5. Multivariate calibration applied to the quantitative analysis of infrared spectra

    Energy Technology Data Exchange (ETDEWEB)

    Haaland, D.M.

    1991-01-01

    Multivariate calibration methods are very useful for improving the precision, accuracy, and reliability of quantitative spectral analyses. Spectroscopists can more effectively use these sophisticated statistical tools if they have a qualitative understanding of the techniques involved. A qualitative picture of the factor analysis multivariate calibration methods of partial least squares (PLS) and principal component regression (PCR) is presented using infrared calibrations based upon spectra of phosphosilicate glass thin films on silicon wafers. Comparisons of the relative prediction abilities of four different multivariate calibration methods are given based on Monte Carlo simulations of spectral calibration and prediction data. The success of multivariate spectral calibrations is demonstrated for several quantitative infrared studies. The infrared absorption and emission spectra of thin-film dielectrics used in the manufacture of microelectronic devices demonstrate rapid, nondestructive at-line and in-situ analyses using PLS calibrations. Finally, the application of multivariate spectral calibrations to reagentless analysis of blood is presented. We have found that the determination of glucose in whole blood taken from diabetics can be precisely monitored from the PLS calibration of either mind- or near-infrared spectra of the blood. Progress toward the non-invasive determination of glucose levels in diabetics is an ultimate goal of this research. 13 refs., 4 figs.

  6. Improving interpretation of infrared spectra for OM characterization by subtraction of spectra from incinerated samples

    Science.gov (United States)

    Ellerbrock, Ruth H.; Gerke, Horst H.; Leue, Martin

    2017-04-01

    Non-destructive methods such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) have been applied to characterize organic matter (OM) at intact structural surfaces among others. However, it is often difficult to distinguish effects of organic components on DRIFT signal intensities from those of mineral components. The objective of this study was to re-evaluate DRIFT spectra from intact earthworm burrow walls and coated cracks to improve the interpretation of C-H and C=O bands. We compared DRIFT and transmission Fourier transform infrared (FTIR) spectra of entire samples that were from the same pedogenetic soil horizon, but different in mineral composition and texture (i.e., glacial till versus loess). Spectra of incinerated samples were subtracted from the original spectra. Transmission FTIR and DRIFT spectra were almost identical for entire soil samples. However, the DRIFT spectra were affected by the bulk mode bands (i.e., wavenumbers 2000 to 1700 cm-1) that affected spectral resolution and reproducibility. The ratios between C-H and C=O band intensities as indicator for OM quality obtained with DRIFT were smaller than those obtained from transmission FTIR. A spectral subtraction procedure was found to reduce effects of mineral absorption bands on DRIFT spectra allowing an improved interpretation. DRIFT spectroscopy as a non-destructive method for analyzing OM composition at intact surfaces in structured soils could be calibrated with information obtained with the more detailed transmission FTIR and complementary methods.

  7. Theoretical studies on core-level spectra of solids

    International Nuclear Information System (INIS)

    Kotani, Akio

    1995-01-01

    I present a review on theoretical studies of core-level spectra (CLS) in solids. In CLS, the dynamical response of outer electrons to a core hole is reflected through the screening of core hole potential. Impurity Anderson model (IAM) or cluster model is successfully applied to the analysis of X-ray photoemission spectra (XPS) and X-ray absorption spectra (XAS) in f and d electron systems, where the f and d electron states are hybridized with the other valence or conduction electron states. The effect of the core-hole potential in the final state of XPS and XAS plays an important role, as well as the solid state hybridization and intra-atomic multiplet coupling effects. As typical examples, the calculated results for XPS of rare-earth compounds and transition metal compounds are shown, and some discussions are given. As a subject of remarkable progress with high brightness synchrotron radiation sources, I discuss some theoretical aspects of X-ray emission spectra (XES) and their resonant enhancement at the X-ray absorption threshold. Some experimental data and their theoretical analysis are also given. (author)

  8. Mid-Infrared Silicate Dust Features in Seyfert 1 Spectra

    Science.gov (United States)

    Thompson, Grant D.; Levenson, N. A.; Sirocky, M. M.; Uddin, S.

    2007-12-01

    Silicate dust emission dominates the mid-infrared spectra of galaxies, and the dust produces two spectral features, at 10 and 18 μm. These features' strengths (in emission or absorption) and peak wavelengths reveal the geometry of the dust distribution, and they are sensitive to the dust composition. We examine mid-infrared spectra of 32 Seyfert 1 active galactic nuclei (AGN), observed with the Infrared Spectrograph aboard the Spitzer Space Telescope. In the spectra, we typically find the shorter-wavelength feature in emission, at an average peak wavelength of 10.0 μm, although it is known historically as the "9.7 μm" feature. In addition, peak wavelength increases with feature strength. The 10 and 18 μm feature strengths together are sensitive to the dust geometry surrounding the central heating engine. Numerical calculations of radiative transfer distinguish between clumpy and smooth distributions, and we find that the surroundings of these AGN (the obscuring "tori" of unified AGN schemes) are clumpy. Polycyclic aromatic hydrocarbon (PAH) features are associated with star formation, and we find strong PAH emission (luminosity ≥ 1042 erg/s) in only four sources, three of which show independent evidence for starbursts. We will explore the effects of luminosity on dust geometry and chemistry in a comparison sample of quasars. We acknowledge work supported by the NSF under grant number 0237291.

  9. Ultrasensitive Detection of Infrared Photon Using Microcantilever: Theoretical Analysis

    International Nuclear Information System (INIS)

    Li-Xin, Cao; Feng-Xin, Zhang; Yin-Fang, Zhu; Jin-Ling, Yang

    2010-01-01

    We present a new method for detecting near-infrared, mid-infrared, and far-infrared photons with an ultrahigh sensitivity. The infrared photon detection was carried out by monitoring the displacement change of a vibrating microcantilever under light pressure using a laser Doppler vibrometer. Ultrathin silicon cantilevers with high sensitivity were produced using micro/nano-fabrication technology. The photon detection system was set up. The response of the microcantilever to the photon illumination is theoretically estimated, and a nanowatt resolution for the infrared photon detection is expected at room temperature with this method

  10. Recommendations for the presentation of infrared absorption spectra in data collections condensed phases

    CERN Document Server

    Becker, E D

    2013-01-01

    Recommendations for the Presentation of Infrared Absorption Spectra in Data Collections-A. Condensed Phases presents the recommendations related to the infrared spectra of condensed phase materials that are proposed for permanent retention in data collections. These recommendations are based on two reports published by the Coblentz Society. This book emphasizes the three levels of quality evaluation for infrared spectra as designated by the Coblentz Society, including critically defined physical data, research quality analytical spectra, and approved analytical spectra. This text discusses the

  11. Vibronic spectra of Gd3+ in metaphosphate glasses: Comparison with Raman and infrared spectra

    International Nuclear Information System (INIS)

    Hall, D.W.; Brawer, S.A.; Weber, M.J.

    1982-01-01

    Vibronic sidebands associated with the 6 P/sub 7/2/→ 8 S/sub 7/2/ transition of Gd 3+ -doped metaphosphate glasses are observed using line-narrowed fluorescence techniques. Glasses having metal cations of different mass and charge (La,Al,Mg,Ba) are examined. Vibronic spectra, which probe vibrations about the rare-earth element site, are compared with polarized Raman scattering data and the infrared dielectric constant obtained from near-normal reflectance measurements. Results indicate that in metaphosphate glasses vibronic selection rules are similar to HV (vertical height) Raman selection rules. The wavelengths and relative intensities of peaks in the high-frequency portion of the vibronic spectra change with respect to corresponding peaks in the Raman spectra when the mass and/or charge of Gd 3+ differs significantly from that of the metal cation

  12. Infrared spectra in monitoring biochemical parameters of human blood

    International Nuclear Information System (INIS)

    Prabhakar, S; Singh, R A; Jain, N

    2012-01-01

    Infrared spectroscopy is gaining recognition as a promising method. The infrared spectra of selected regions (2000-400cm -1 ) of blood tissue samples are reported. Present study related to the role of spectral peak fitting in the study of human blood and quantitative interpretations of infrared spectra based on chemometrics. The spectral variations are interpreted in terms of the biochemical and pathological processes involved. The mean RNA/DNA ratio of fitted intensities and analytical area as calculated from the transmittance peaks at 1121cm -1 /1020cm -1 is found to be 0.911A.U and 2.00A.U. respectively. The ratio of 1659cm -1 /1544cm -1 (amide-I/amide-II) bands is found to shed light on the change in the DNA content. The ratio of amide-I/amide-II is almost unity (≅1.054) for blood spectra. The deviation from unity is an indication of DNA absorption from the RBC cells. The total phosphate content has found to be 25.09A.U. The level for glycogen/phosphate ratio (areas under peaks 1030cm -1 /1082cm -1 ) is found to be 0.286A.U. The ratio of unsaturated and saturated carbonyl compounds (C=O) in blood samples is in form of esters and the analytical areas under the spectral peaks at 1740cm -1 and 1731cm -1 for unsaturated esters and saturated esters respectively found to be 0.618A.U.

  13. Compositional stratigraphy of crustal material from near-infrared spectra

    International Nuclear Information System (INIS)

    Pieters, C.M.

    1987-01-01

    An Earth-based telescopic program to acquire near-infrared spectra of freshly exposed lunar material now contains data for 17 large impact craters with central peaks. Noritic, gabbroic, anorthositic and troctolitic rock types can be distinguished for areas within these large craters from characteristic absorptions in individual spectra of their walls and central peaks. Norites dominate the upper lunar crust while the deeper crustal zones also contain significant amounts of gabbros and anorthosites. Data for material associated with large craters indicate that not only is the lunar crust highly heterogeneous across the nearside, but that the compositional stratigraphy of the lunar crust is nonuniform. Crustal complexity should be expected for other planetary bodies, which should be studied using high spatial and spectral resolution data in and around large impact craters

  14. Compositional stratigraphy of crustal material from near-infrared spectra

    Science.gov (United States)

    Pieters, Carle M.

    1987-01-01

    An Earth-based telescopic program to acquire near-infrared spectra of freshly exposed lunar material now contains data for 17 large impact craters with central peaks. Noritic, gabbroic, anorthositic and troctolitic rock types can be distinguished for areas within these large craters from characteristic absorptions in individual spectra of their walls and central peaks. Norites dominate the upper lunar crust while the deeper crustal zones also contain significant amounts of gabbros and anorthosites. Data for material associated with large craters indicate that not only is the lunar crust highly heterogeneous across the nearside, but that the compositional stratigraphy of the lunar crust is nonuniform. Crustal complexity should be expected for other planetary bodies, which should be studied using high spatial and spectral resolution data in and around large impact craters.

  15. Infrared spectra of hexamethylbenzene—tetracyanoethylene complexes at high pressures

    Science.gov (United States)

    Yamada, Haruka; Saheki, Masao

    Infrared spectra of hexamethylbenzene(HMB)—tetracyanoethylene(TCNE), 1:1 and 2:1, complexes were measured under high pressures, 11˜4,000 bar. It was found that the CC stretching (A g) band of TCNE became much stronger at high pressures than at 1 bar and that the intensity increase of this band was especially large for both of the complexes. Based on these facts the strong appearance of the CC band at 1 bar, which is inconsistent with the symmetry consideration derived from X-ray analysis, can be discussed.

  16. Theoretical White Dwarf Spectra on Demand: TheoSSA

    Science.gov (United States)

    Ringat, E.; Rauch, T.

    2010-11-01

    In the last decades, a lot of progress was made in spectral analysis. The quality (e.g. resolution, S/N ratio) of observed spectra has improved much and several model-atmosphere codes were developed. One of these is the ``Tübingen NLTE Model-Atmosphere Package'' (TMAP), that is a highly developed program for the calculation of model atmospheres of hot, compact objects. In the framework of the German Astrophysical Virtual Observatory (GAVO), theoretical spectral energy distributions (SEDs) can be downloaded via TheoSSA. In a pilot phase, TheoSSA is based on TMAP model atmospheres. We present the current state of this VO service.

  17. Copernicus spectra and infrared photometry of 42 Orionis

    International Nuclear Information System (INIS)

    Johnson, H.M.; Snow, T.P. Jr.; Gehrz, R.D.; Hackwell, J.A.

    1977-01-01

    The Orion sword star 42 Ori is embedded in a nebula north of and separated from the Orion nebula. The B1 V star is probably normal. Other members of the multiple remain poorly defined, and the nebula may exhibit some peculiarities that may depend on them. Copernicus ultraviolet spectra of the star are described here, especially in the form of tables of wavelength identifications. The properties of the interstellar material in the line of sight are also discussed. We present infrared photometry which suggests that 3 less than or equal to R less than or equal to 3.5 for the interstellar matter in the direction of 42 Ori. The IR photometry provides no evidence for companion stellar or circumstellar components

  18. Infrared absorption spectra of selenate compounds of indium (3)

    International Nuclear Information System (INIS)

    Kharitonov, Yu.Ya.; Kadoshnikova, N.V.; Tananaev, I.V.

    1979-01-01

    Obtained and discussed are infrared absorption spectra (400-4000 cm -1 ) of the following indium selenates: In 2 (SeO 4 ) 3 x5H 2 O, In 2 (SeO 4 ) 3 x9H 2 O, NaIn(SeO 4 ) 2 x6H 2 O, NaIn(SeO 4 ) 2 xH 2 O, MIn(SeO 4 ) 2 x4H 2 O (M=NH 4 , K, Rb), CsIn(SeO 4 ) 2 x2H 2 O, Na 3 In(SeO 4 ) 3 x7H 2 O, MIn(SeO 4 ) 2 (M=NH 4 , Na, K, Rb, Cs), M 2 InOH(SeO 4 ) 2 xyH 2 O (M=NH 4 , Na, K, Rb) and K 2 InOD(SeO 4 ) 2 xyD 2 O

  19. Theoretical investigation on the molecular structure, Infrared, Raman and NMR spectra of para-halogen benzenesulfonamides, 4-X-C 6H 4SO 2NH 2 (X = Cl, Br or F)

    Science.gov (United States)

    Karabacak, Mehmet; Çınar, Mehmet; Çoruh, Ali; Kurt, Mustafa

    2009-02-01

    In the present study, the structural properties of para-halogen benzenesulfonamides, 4-XC 6H 4SO 2NH 2 (4-chlorobenzenesulfonamide (I), 4-bromobenzenesulfonamide (II) and 4-fluorobenzenesulfonamide (III)) have been studied extensively utilizing ab initio Hartree-Fock (HF) and density functional theory (DFT) employing B3LYP exchange correlation. The vibrational frequencies were calculated and scaled values were compared with experimental values. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The effects of the halogen substituent on the characteristic benzenesulfonamides bands in the spectra are discussed. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecules were calculated using the Gauge-Invariant Atomic Orbital (GIAO) method. Finally, geometric parameters, vibrational bands and chemical shifts were compared with available experimental data of the molecules. The fully optimized geometries of the molecules were found to be consistent with the X-ray crystal structures. The observed and calculated frequencies and chemical shifts were found to be in very good agreement.

  20. Infrared spectra of small molecular ions trapped in solid neon

    Energy Technology Data Exchange (ETDEWEB)

    Jacox, Marilyn E. [Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)

    2015-01-22

    The infrared spectrum of a molecular ion provides a unique signature for that species, gives information on its structure, and is amenable to remote sensing. It also serves as a comparison standard for refining ab initio calculations. Experiments in this laboratory trap molecular ions in dilute solid solution in neon at 4.2 K in sufficient concentration for observation of their infrared spectra between 450 and 4000 cm{sup !1}. Discharge-excited neon atoms produce cations by photoionization and/or Penning ionization of the parent molecule. The resulting electrons are captured by other molecules, yielding anions which provide for overall charge neutrality of the deposit. Recent observations of ions produced from C{sub 2}H{sub 4} and BF{sub 3} will be discussed. Because of their relatively large possibility of having low-lying excited electronic states, small, symmetric molecular cations are especially vulnerable to breakdown of the Born-Oppenheimer approximation. Some phenomena which can result from this breakdown will be discussed. Ion-molecule reaction rates are sufficiently high that in some systems absorptions of dimer cations and anions are also observed. When H{sub 2} is introduced into the system, the initially-formed ion may react with it. Among the species resulting from such ion-molecule reactions that have recently been studied are O{sub 4}{sup +}, NH{sub 4}{sup +}, HOCO{sup +}, and HCO{sub 2}{sup !}.

  1. Infrared Spectra and Optical Constants of Elusive Amorphous Methane

    Science.gov (United States)

    Gerakines, Perry A.; Hudson, Reggie L.

    2015-01-01

    New and accurate laboratory results are reported for amorphous methane (CH4) ice near 10 K for the study of the interstellar medium (ISM) and the outer Solar System. Near- and mid-infrared (IR) data, including spectra, band strengths, absorption coefficients, and optical constants, are presented for the first time for this seldom-studied amorphous solid. The apparent IR band strength near 1300 cm(exp -1) (7.69 micrometer) for amorphous CH4 is found to be about 33% higher than the value long used by IR astronomers to convert spectral observations of interstellar CH4 into CH4 abundances. Although CH4 is most likely to be found in an amorphous phase in the ISM, a comparison of results from various laboratory groups shows that the earlier CH4 band strength at 1300 cm(exp -1) (7.69 micrometer) was derived from IR spectra of ices that were either partially or entirely crystalline CH4 Applications of the new amorphous-CH4 results are discussed, and all optical constants are made available in electronic form.

  2. Cis- and trans-perfluorodecalin: Infrared spectra, radiative efficiency and global warming potential

    Science.gov (United States)

    Le Bris, Karine; DeZeeuw, Jasmine; Godin, Paul J.; Strong, Kimberly

    2017-12-01

    Perfluorodecalin (PFD) is a molecule used in various medical applications for its capacity to dissolve gases. This potent greenhouse gas was detected for the first time in the atmosphere in 2005. We present infrared absorption cross-section spectra of a pure vapour of cis- and trans-perfluorodecalin at a resolution of 0.1 cm-1. Measurements were performed in the 560-3000 cm-1 spectral range using Fourier transform spectroscopy. The spectra have been compared with previous experimental data and theoretical calculations by density functional theory. The new experimental absorption cross-sections have been used to calculate a lifetime-corrected radiative efficiency at 300 K of 0.62 W m-2 ppb-1 and 0.57 W.m-2.ppb-1 for the cis and trans isomers respectively. This leads to a 100-year time horizon global warming potential of 8030 for cis-PFD and 7440 for trans-PFD.

  3. Theoretical investigations of molecular wires: Electronic spectra and electron transport

    Science.gov (United States)

    Palma, Julio Leopoldo

    The results of theoretical and computational research are presented for two promising molecular wires, the Nanostar dendrimer, and a series of substituted azobenzene derivatives connected to aluminum electrodes. The electronic absorption spectra of the Nanostar (a phenylene-ethynylene dendrimer attached to an ethynylperylene chromophore) were calculated using a sequential Molecular Dynamics/Quantum Mechanics (MD/QM) method to perform an analysis of the temperature dependence of the electronic absorption process. We modeled the Nanostar as a series of connected units, and performed MD simulations for each chromophore at 10 K and 300 K to study how the temperature affected the structures and, consequently, the spectra. The absorption spectra of the Nanostar were computed using an ensemble of 8000 structures for each chromophore. Quantum Mechanical (QM) ZINDO/S calculations were performed for each conformation in the ensemble, including 16 excited states, for a total of 128,000 excitation energies. The spectral intensity was then scaled linearly with the number of conjugated units. Our calculations for both the individual chromophores and the Nanostar, are in good agreement with experiments. We explain in detail the effects of temperature and the consequences for the absorption process. The second part of this thesis presents a study of the effects of chemical substituents on the electron transport properties of the azobenzene molecule, which has been proposed recently as a component of a light-driven molecular switch. This molecule has two stable conformations (cis and trans) in its electronic ground state, with considerable differences in their conductance. The electron transport properties were calculated using first-principles methods combining non-equilibrium Green's function (NEGF) techniques with density functional theory (DFT). For the azobenzene studies, we included electron-donating groups and electron-withdrawing groups in meta- and ortho-positions with

  4. [Investigation of typical melamine urinary stones using infrared spectra].

    Science.gov (United States)

    Si, Min-Zhen; Li, Qing-Yun; Liu, Ren-Ming; Kang, Yi-Pu; Wang, Kun-Hua; Zhang, Zhi-Guo

    2010-02-01

    A typical melamine kidney stone confirmed by some medicine expert was collected from the first people's hospital of Yunnan. The kidney stone was adequately determined by PE corporation spectra 100(with resolution of 1 cm(-1)). The stone samples for FTIR analysis were prepared using the KBr pellet technique, where 2 mg of the pretreated stone powder was mixed with 200 mg of analytical grade KBr using an agate pestle and mortar. The digital spectrum was then scanned in the mid-infrared region from 4 000 to 400 cm(-1) at room temperature. The appearing bands between 4 000 and 2 000 cm(-1) were 3 487, 3 325, 3 162 and 2 788 cm(-1), those between 1 700 and 1 000 cm(-1) were 1 694, 1 555, 1 383, 1 340, 1 189 and 1 122 cm(-1), and those between 1 000 and 400 cm(-1) were 993, 782, 748, 709, 624, 585, 565 and 476 cm(-1). It was found that the main constituent of calculi showed few comparability with cat kidney stone, which was from cats that died after consuming the contaminated food, and confirmed that these deposits were primarily composed of melamine and cyanuric acid compared to the IR spectra of calculi in literature. It was also found that the main constituent of calculi showed few comparability with popular kidney stone by comparison with the IR spectra of calculi in literature. The spectrum of calculi was 50% respectively similar with melamine and uric acid as compared with the IR spectrum. It was found that the main constituent of calculi was melamine itself and uric acid as compared with the IR spectra of calculi and melamine: (1 : 1), because the spectrum of calculi was 83. 3% similar to melamine and uric acid (1 : 1). The appearing bands of melamine and uric acid (1 : 1) between 4 000 and 2 000 cm(-1) were 3 469, 3 419, 3 333, 3 132, 3 026, 2 827 cm(-1), those between 1 700 and 1 000 cm(-1) were 1 696, 1 656, 1 555, 1 489, 1 439, 1 350, 1 311, 1 198, 1 124 and 1 028 cm(-1), and those between 1 000 and 400 cm(-1) were 993, 878, 814, 784, 745, 708, 619, 577 and

  5. Using Molecular Modeling in Teaching Group Theory Analysis of the Infrared Spectra of Organometallic Compounds

    Science.gov (United States)

    Wang, Lihua

    2012-01-01

    A new method is introduced for teaching group theory analysis of the infrared spectra of organometallic compounds using molecular modeling. The main focus of this method is to enhance student understanding of the symmetry properties of vibrational modes and of the group theory analysis of infrared (IR) spectra by using visual aids provided by…

  6. Gas-Phase Infrared Spectra of Vinyl Selenol and Vinyl Tellurol

    Science.gov (United States)

    Benidar, Abdessamad; Khater, Brahim; Guillemin, Jean-Claude; Gámez, José A.; Yáñez, Manuel

    2009-10-01

    The infrared spectra (3500-500 cm-1) of gaseous vinyl selenol and vinyl tellurol have been recorded at 0.1 cm-1 resolution. For the latter the spectra were obtained at room temperature, but for the former a temperature of -40 °C was required because of the chemical instability of vinyl selenol at room temperature. To compensate the very weak vapor pressure of vinyl tellurol at room temperature, a long optical path up to 136 m was necessary to record its spectrum. B3LYP density functional theory (DFT) calculations have been performed to assign the different absorption bands. Since an unambiguous assignment of the absorption bands requires a precise knowledge on the relative abundance of the syn and gauche rotamers of these compounds, their relative energies and their anharmonic vibrational frequencies were obtained using a very extended Def2-QZVP basis set. Two rotamers, the syn, which is planar, and a nonplanar gauche, were found to be local minima for both compounds. The gauche rotamer presents two degenerate conformers, which differ by the position of the SeH (TeH) hydrogen atom above or below the molecular plane. Our theoretical results are in good agreement with the main features of the experimental spectra. Fundamental bands and some combination bands of vinyl selenol and vinyl tellurol were assigned and compared with those of vinyl alcohol and vinyl thiol, whose spectra had been reported previously in the literature.

  7. Theoretical modeling of infrared spectra of twinned lead zirconate

    Czech Academy of Sciences Publication Activity Database

    Dočekalová, Zuzana; Pasciak, Marek; Hlinka, Jiří

    2017-01-01

    Roč. 90, č. 1 (2017), s. 17-23 ISSN 0141-1594 R&D Projects: GA ČR GA15-04121S Institutional support: RVO:68378271 Keywords : domains * IR spectroscopy * dielectric permittivity * lead zirconate * shell model * Born effective charge Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.060, year: 2016

  8. Laboratory-based grain-shape models for simulating dust infrared spectra

    NARCIS (Netherlands)

    Mutschke, H.; Min, M.; Tamanai, A.

    2009-01-01

    Context. Analysis of thermal dust emission spectra for dust mineralogy and physical grain properties depends on comparison spectra, which are either laboratory-measured infrared extinction spectra or calculated extinction cross sections based on certain grain models. Often, the agreement between

  9. Matrix infrared spectra and electronic structure calculations of the first actinide borylene: FB=ThF(2).

    Science.gov (United States)

    Wang, Xuefeng; Roos, Björn O; Andrews, Lester

    2010-03-14

    Laser-ablated Th atoms react with BF(3) during condensation in excess argon at 6 K to form the first actinide borylene (FB=ThF(2)) and actinide-boron multiple bond. Three new product absorptions in the B-F and Th-F stretching regions of matrix infrared spectra are assigned to FB=ThF(2) from comparison to theoretically predicted vibrational frequencies.

  10. Update from the Analysis of High Resolution Propane Spectra and the Interpretation of Titan's Infrared Spectra

    Science.gov (United States)

    Klavans, V.; Nixon, C.; Hewagama, T.; Jennings, D. E.

    2012-01-01

    Titan has an extremely thick atmosphere dominated by nitrogen, but includes a range of trace species such as hydrocarbons and nitriles. One such hydrocarbon is propane (C3H8). Propane has 21 active IR bands covering broad regions of the mid-infrared. Therefore, its ubiquitous signature may potentially mask weaker signatures of other undetected species with important roles in Titan's chemistry. Cassini's Composite Infrared Spectrometer (CIRS) observations of Titan's atmosphere hint at the presence of such molecules. Unfortunately, C3H8 line atlases for the vibration bands V(sub 8), V(sub 21), V(sub 20), and V(sub 7) (869, 922, 1054, and 1157 per centimeter, respectively) are not currently available for subtracting the C3H8 signal to reveal, or constrain, the signature of underlying chemical species. Using spectra previously obtained by Jennings, D. E., et al. at the McMath-Pierce FTIR at Kitt Peak, AZ, as the source and automated analysis utilities developed for this application, we are compiling an atlas of spectroscopic parameters for propane that characterize the ro-vibrational transitions in the above bands. In this paper, we will discuss our efforts for inspecting and fitting the aforementioned bands, present updated results for spectroscopic parameters including absolute line intensities and transition frequencies in HITRAN and GEISA formats, and show how these optical constants will be used in searching for other trace chemical species in Titan's atmosphere. Our line atlas for the V(sub 21) band contains a total number of 2971 lines. The band integrated strength calculated for the V(sub 21) band is 1.003 per centimeter per (centimeter-atm).

  11. Comet Mineralogy as Inferred from Infrared Spectra of Comets

    Science.gov (United States)

    Wooden, Diane H.

    2006-01-01

    For most comets, infrared (IR) spectroscopy (remote sensing) is the method through which we diagnose the mineralogy and size distribution of dust in their comae. The shape and contrast of the IR spectral features depend on the particle size: optically active minerals (absorbing of visible and near-IR solar photons) and submicron solid grains or highly porous (> 90% vacuum) grains primarily contribute to the shapes of the observed resonances. Comet mineralogies typically are determined by fitting thermal emission models of ensembles of discrete mineral grains to observed IR spectral energy distributions. The absorptivities (Q-abs) and scattering efficiencies (Q-scat) of the discrete mineral grains are computed using Mie scattering, Maxwell-Garnet mixing, Discrete Dipole Approximation, and Multi-Layered Sphere codes. These techniques when applied to crystalline minerals, specifically olivine (Mg_x, Fe_1-x)2 Si04, x>0.9, require the use of ellipsoidal shaped particles with elongated axial ratios or hollow spheres to produce the shapes of the resonances observed both from comet comae and laboratory samples. The wavelength positions of the distinct resonances from submicron-radii crystalline silicates, as well as their thermal equilibrium temperatures, constrain the crystalline olivine to have a relatively high Mg-content (x>0.9, or Fo>90). Only resonances computed for submicron Mg-rich crystalline olivine and crystalline orthopyroxene match the observed IR spectral features. However, this has led to the interpretation that micron-radii and larger crystals are absent from comet comae. Furthermore, the mass fraction of silicate crystals is dependent upon whether just the submicron portion of the size distribution is being compared or the submicron crystals compare to the aggregates of porous amorphous silicates that are computationally tractable as porous spheres. We will discuss the Deep Impact results as examples of these challenges to interpreting mid-IR spectra of

  12. Gas-phase infrared spectrum of phosphorus (III) oxycyanide, OPCN: Experimental and theoretical and theoretical investigations

    International Nuclear Information System (INIS)

    Allaf, A.W.; Kassem, M.; Alibrahim, M.

    1999-01-01

    An attempt was made to observe the gas-phase infrared spectrum of phosphorus (III) oxycyanide, OPCN for the first time. This molecule was produced by on-line process using phosphorus (III) oxychloride, OPCI as precursor passed over heated Ag CN. The products were characterised by the infrared spectra of their vapours. The low resolution gas-phase Fourier transform infrared spectrum shows two bands at 2165 and 1385 cm -1 . These bands are assigned to ν 1 (C≡N stretch) and ν 2 (O=P stretch), respectively. Ab initio self-consistent-field (SCF) molecular orbital (MO) and Moeller - Plesset second order perturbation theory (MP2) calculations were performed to determine the geometry, total energy and vibrational frequencies of OPCN. (authors)

  13. Quantum Calculation for Musk Molecules Infrared Spectra towards the Understanding of Odor

    Directory of Open Access Journals (Sweden)

    Elaine Rose Maia

    2014-01-01

    Full Text Available It is not clear so far how humans can recognize odor. One of the theories regarding structure-odor relationship is vibrational theory, which claims that odors can be recognized by their modes of vibration. In this sense, this paper brings a novel comparison made between musky and nonmusky molecules, as to check the existence of correlation between their modes on the infrared spectra and odor. For this purpose, sixteen musky odorants were chosen, as well as seven other molecules that are structurally similar to them, but with no musk odor. All of them were submitted to solid theoretical methodology (using molecular mechanics/molecular dynamics and Neglect of Diatomic Differential Overlap Austin Model 1 methods to optimize geometries as to achieve density functional theory spectra information, with both Gradient Corrected Functional Perdew-Wang generalized-gradient approximation (GGA/PW91 and hybrid Becke, three-parameter, Lee-Yang-Parr (B3LYP functional. For a proper analysis over spectral data, a mathematical method was designed, generating weighted averages for theoretical frequencies and computing deviations from these averages. It was then devised that musky odorants satisfied demands of the vibrational theory, while nonmusk compounds belonging either to nitro group or to acyclic group failed to fulfill the same criteria.

  14. LOCAL LUMINOUS INFRARED GALAXIES. II. ACTIVE GALACTIC NUCLEUS ACTIVITY FROM SPITZER/INFRARED SPECTROGRAPH SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Alonso-Herrero, Almudena; Pereira-Santaella, Miguel [Centro de Astrobiologia, INTA-CSIC, E-28850 Torrejon de Ardoz, Madrid (Spain); Rieke, George H. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Rigopoulou, Dimitra [Astrophysics Department, University of Oxford, Oxford OX1 3RH (United Kingdom)

    2012-01-01

    We quantify the active galactic nucleus (AGN) contribution to the mid-infrared (mid-IR) and the total infrared (IR, 8-1000 {mu}m) emission in a complete volume-limited sample of 53 local luminous infrared galaxies (LIRGs, L{sub IR} = 10{sup 11}-10{sup 12} L{sub Sun }). We decompose the Spitzer Infrared Spectrograph low-resolution 5-38 {mu}m spectra of the LIRGs into AGN and starburst components using clumpy torus models and star-forming galaxy templates, respectively. We find that 50% (25/50) of local LIRGs have an AGN component detected with this method. There is good agreement between these AGN detections through mid-IR spectral decomposition and other AGN indicators, such as the optical spectral class, mid-IR spectral features, and X-ray properties. Taking all the AGN indicators together, the AGN detection rate in the individual nuclei of LIRGs is {approx}62%. The derived AGN bolometric luminosities are in the range L{sub bol}(AGN) = (0.4-50) Multiplication-Sign 10{sup 43} erg s{sup -1}. The AGN bolometric contribution to the IR luminosities of the galaxies is generally small, with 70% of LIRGs having L{sub bol}[AGN]/L{sub IR} {<=} 0.05. Only {approx_equal} 8% of local LIRGs have a significant AGN bolometric contribution L{sub bol}[AGN]/L{sub IR} > 0.25. From the comparison of our results with literature results of ultraluminous infrared galaxies (L{sub IR} = 10{sup 12}-10{sup 13} L{sub Sun }), we confirm that in the local universe the AGN bolometric contribution to the IR luminosity increases with the IR luminosity of the galaxy/system. If we add up the AGN bolometric luminosities we find that AGNs only account for 5%{sub -3%}{sup +8%} of the total IR luminosity produced by local LIRGs (with and without AGN detections). This proves that the bulk of the IR luminosity of local LIRGs is due to star formation activity. Taking the newly determined IR luminosity density of LIRGs in the local universe, we then estimate an AGN IR luminosity density of {Omega}{sup AGN

  15. Thermal Infrared Spectra of a Suite of Forsterite Samples and Ab-initio Modelling of theirs Spectra

    Science.gov (United States)

    Maturilli, A.; Stangarone, C.; Helbert, J.; Tribaudino, M.; Prencipe, M.

    2017-12-01

    Forsterite is the dominating component in olivine, a major constituent in ultrafemic rocks, as well as planetary bodies. Messenger X-ray spectrometer has shown that Mg-rich silicate minerals, such as enstatite and forsterite, dominate Mercury's surface (Weider et al 2012). A careful and detailed acquaintance with the forsterite spectral features and their dependence wrt environmental conditions on Mercury is needed to interpret the remote sensing data from previous and forthcoming missions. We propose an experimental vs calculation approach to reproduce and describe the spectral features of forsterite. TIR emissivity measurements are performed by the Planetary Spectroscopy Laboratory (PSL) of DLR. PSL offers the unique capability to measure the emissivity of samples at temperature up to 1000K under vacuum conditions. TIR emissivity and reflectance measurements are performed on 11 olivine samples having a different composition within the forsterite-fayalite series. When available, the sample has been measured in 2 different grain sizes (chameleon-like effects of Mercury surface already observed (Helbert et al. 2013), this study wants to point out the main spectral features due to the composition and temperature. Our results are used to create a theoretical background to interpret the high temperature infrared emissivity spectra from MERTIS onboard the ESA BepiColombo mission to Mercury (Helbert et al. 2010).

  16. Experimental and theoretical investigation of vibrational spectra of coordination polymers based on TCE-TTF.

    Science.gov (United States)

    Olejniczak, Iwona; Lapiński, Andrzej; Swietlik, Roman; Olivier, Jean; Golhen, Stéphane; Ouahab, Lahcène

    2011-08-01

    The room-temperature infrared and Raman spectra of a series of four isostructural polymeric salts of 2,3,6,7-tetrakis(2-cyanoethylthio)-tetrathiafulvalene (TCE-TTF) with paramagnetic (Co(II), Mn(II)) and diamagnetic (Zn(II), Cd(II)) ions, together with BF(4)(-) or ClO(4)(-) anions are reported. Infrared and Raman-active modes are identified and assigned based on theoretical calculations for neutral and ionized TCE-TTF using density functional theory (DFT) methods. It is confirmed that the TCE-TTF molecules in all the materials investigated are fully ionized and interact in the crystal structure through cyanoethylthio groups. The vibrational modes related to the C=C stretching vibrations of TCE-TTF are analyzed assuming the occurrence of electron-molecular vibration coupling (EMV). The presence of the antisymmetric C=C dimeric mode provides evidence that charge transfer takes place between TCE-TTF molecules belonging to neighboring polymeric networks. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Thermal Infrared Spectra of Microcrystalline Sedimentary Phases: Effects of Natural Surface Roughness on Spectral Feature Shape

    Science.gov (United States)

    Hardgrove, C.; Rogers, A. D.

    2012-03-01

    Thermal infrared spectral features of common microcrystalline phases (chert, alabaster, micrite) are presented. Spectra are sensitive to mineralogy and micron-scale (~1-25 µm) surface roughness. Roughness is on the scale of the average crystal size.

  18. Estimation of leaf water content from far infrared (2.5-14µm) spectra using continuous wavelet analysis

    NARCIS (Netherlands)

    Ullah, S.; Skidmore, A.K.; Naeem, M.; Schlerf, M.

    2012-01-01

    The objective of this study was to estimate leaf water content based on continuous wavelet analysis from the far infrared (2.5 - 14.0 μm) spectra. The entire dataset comprised of 394 far infrared spectra which were divided into calibration (262 spectra) and validation (132 spectra) subsets. The far

  19. Observed and theoretical spectra in the 10-100 A interval. [of solar spectra

    Science.gov (United States)

    Brown, W. A.; Bruner, M. E.; Acton, L. W.

    1988-01-01

    The soft X-ray spectra recorded in two sounding-rocket flights in 1982 and 1985 are compared with predicted spectra. The processed densitometer trace of the full spectrum is presented, together with the new spectrum from the 1985 experiment. The intensities of the lines are then compared with predictions.

  20. Infrared Spectroscopic and Theoretical Study of the HC_nO^+(N=5-12) Cations

    Science.gov (United States)

    Li, Wei; Jin, Jiaye; Wang, Guanjun; Zhou, Mingfei

    2017-06-01

    Carbon chains and derivatives are highly active species, which are widely existed as reactive intermediates in many chemical processes including atmospheric chemistry, hydrocarbon combustion, as well as interstellar chemistry. The carbon chain cations, HC_nO^+ (n = 5-12) are produced via pulsed laser vaporization of a graphite target in supersonic expansions containing carbon monoxide and hydrogen. The infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of the CO "tagged" [HC_nO.CO] cation complexes in the 1600-3500 \\wn region. The geometries and electronic ground states of these cation complexes are determined by their infrared spectra in conjunction with theoretical calculations. All the HC_nO^+ (n = 5-12) core cations are characterized to be linear carbon chain derivatives terminated by hydrogen and oxygen. The HC_nO^+ cations with odd n have closed-shell singlet ground states with polyyne-like structures, while those with even n have triplet ground states with allene-like structures.

  1. Theoretical Analysis of Rydberg and Autoionizing State Spectra of Antimony

    Institute of Scientific and Technical Information of China (English)

    Shuang-Fei Lv; Ruohong Li; Feng-Dong Jia; Xiao-Kang Li; Jens Lassen; Zhi-Ping Zhong

    2017-01-01

    We calculate the Rydberg and autoionization Rydberg spectra of antimony (Sb) from first principles by relativistic multichannel theory within the framework of multichannel quantum defect theory.Our calculation can be used to classify and assign the atomic states described in recently reported three Rydberg series and four autoionizing states.The perturbation effects on line intensity,variation and line profile are discussed.Assignments of the perturber states and autoionizing states are presented.

  2. Spitzer mid-infrared spectra of cool-core galaxy clusters

    NARCIS (Netherlands)

    de Messières, G.E.; O'Connell, R.W.; McNamara, B.R.; Donahue, M.; Nulsen, P.E.J.; Voit, G.M.; Wise, M.W.; Smith, B.; Higdon, J.; Higdon, S.; Bastian, N.

    2010-01-01

    We have obtained mid-infrared spectra of nine cool-core galaxy clusters with the Infrared Spectrograph aboard the Spitzer Space Telescope. X-ray, ultraviolet and optical observations have demonstrated that each of these clusters hosts a cooling flow which seems to be fueling vigorous star formation

  3. Infrared and near infrared emission spectra of TeH and TeD

    Science.gov (United States)

    Yu, Shanshan; Shayesteh, Alireza; Fu, Dejian; Bernath, Peter F.

    2005-04-01

    The vibration-rotation emission spectra for the X2Π ground state and the near infrared emission spectra of the X2Π 1/2- X2Π 3/2 system of the TeH and TeD free radicals have been measured at high resolution using a Fourier transform spectrometer. TeH and TeD were generated in a tube furnace with a DC discharge of a flowing mixture of argon, hydrogen (or deuterium), and tellurium vapor. In the infrared region, for the X2Π 3/2 spin component we observed the 1-0, 2-1, and 3-2 vibrational bands for most of the eight isotopologues of TeH and the 1-0 and 2-1 bands for three isotopologues of TeD. For the X2Π 1/2- X2Π 3/2 transition, we observed the 0-0 and 1-1 bands for TeH and the 0-0, 1-1, and 2-2 bands for TeD. Except for a few lines, the tellurium isotopic shift was not resolved for the X2Π 1/2- X2Π 3/2 transitions of TeH and TeD. Local perturbations with Δ v = 2 between the two spin components of the X2Π state of TeH were found: X2Π 1/2, v = 0 with X2Π 3/2, v = 2; X2Π 1/2, v = 1 with X2Π 3/2, v = 3. The new data were combined with the previous data from the literature and two kinds of fits (Hund's case (a) and Hund's case (c)) were carried out for each of the 10 observed isotopologues: 130TeD, 128TeD, 126TeD, 130TeH, 128TeH, 126TeH, 125TeH, 124TeH, 123TeH, and 122TeH.

  4. Theoretical and Experimental Analysis of Fast Neutron Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Van Dam, H.; Kleijn, H. R. [Reactor Instituut, Delft (Netherlands)

    1968-04-15

    The reactor physics division of the Inter-Academic Reactor Institute at Delft is concentrating its efforts in the field of fast reactor physics on problems of a more fundamental nature. The object of the programme is to determine experimentally a number of microscopic reactor physics parameters such as conversion potentials, fission ratios and Doppler coefficients for simple geometries and material compositions. Because of the extreme importance of knowledge of the neutron spectrum for the interpretation of the results, attention has initially been concentrated on both the measurement and the calculation of fast neutron spectra. The transport of neutrons in absorbing and non-absorbing heavy atom materials is studied by solving the Boltzmann equation. Both isotropic and anisotropic scattering are considered. Anisotropic scattering is treated by the P{sub n}-approximation, while flux-anisotropy is handled with the S{sub N}-method. In the code FAST-DELFT, scattering is treated up to the P{sub 4} component, a further extension of which is useless because of the lack of available cross-section data. By using this method, the effect of scattering anisotropy on the spectrum formation has been studied. In addition the influence of group cross-section inaccuracies was determined. The experimental work has been concentrated on methods to determine in-core spectra. Using home-made proportional counters with gamma-ray discrimination provisions fast neutron spectra have been measured in simple geometries. These experiments were complemented by foil measurements in the lower energy region. The results of this work are presented in this paper. (author)

  5. Quantitative infrared and near-infrared gas-phase spectra for pyridine: Absolute intensities and vibrational assignments

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, T. J.; Aker, P. M.; Scharko, N. K.; Williams, S. D.

    2018-02-01

    Using vetted methods for generating quantitative absorption reference data, broadband infrared and near-infrared spectra (total range 11,000 – 600 cm-1) of pyridine vapor were recorded at 0.1 cm-1 spectral resolution, with the analyte thermostatted at 298 K and pressure-broadened to 1 atmosphere using N2 ballast gas. The quantitative spectrum is reported for the first time, and we have re-assigned some of the 27 fundamental modes. Fundamental assignments were confirmed by IR vapor phase band shapes, FT-Raman measurements and comparison with previous analyses. For the 760-Torr vapor-phase IR data several bands show resolved peaks (Q-branches). We have also assigned for the first time hundreds of combination and overtone bands in the mid- and near-IR. All assignments were made via comparison to theoretically calculated frequencies and intensities: The frequencies were computed with Gaussian03 with the anharmonic option, using MP2 and the ccpvtz basis set. The intensities were taken from a VSCF calculation in GAMESS using Hartree-Fock (for overtones and combination bands) or from the harmonic MP2 for fundamentals. Overtone and combination band harmonic and anharmonic frequencies, as well as intensities were also calculated using the CFOUR program. It is seen in the NIR spectrum near 6000 cm-1 that the very strong bands arise from the C-H first overtones, whereas only much weaker bands are observed for combination bands of C-H stretching modes. Certain features are discussed for their potential utility for atmospheric monitoring.

  6. Overview of the use of theory to understand infrared and Raman spectra and images of biomolecules: colorectal cancer as an example

    DEFF Research Database (Denmark)

    Piva, J. A. A. C.; Silva, J. L. R.; Raniero, L.

    2011-01-01

    In this work, we present the state of the art in the use of theory (first principles, molecular dynamics, and statistical methods) for interpreting and understanding the infrared (vibrational) absorption and Raman scattering spectra. It is discussed how they can be used in combination with purely...... of biomolecules are very sensitive to their environment and aggregation state, the combined use of infrared and Raman spectroscopy and imaging and theoretical simulations are clearly fields, which can benefit from their joint and mutual development....

  7. Infrared spectra of the gaseous iodides of chromium, iron and nickel

    International Nuclear Information System (INIS)

    Konings, R.J.M.; Booij, A.S.

    1991-11-01

    The infrared spectra of the vapours over chromium, iron and nickel di-iodide have been studied by high-temperature infrared spectroscopy. The gaseous molecules CrI 2 , FeI 2 and NiI 2 were all identified and the interpretation of the spectra is in agreement with a linear structure. Additional strong absorption bands in the spectra of the vapour phase above liquid CrI 2 and FeI 2 were assigned to dimeric (MI 2 ) 2 molecules. Valence force constants and thermodynamic quantities have been calculated. (author). 41 refs.; 4 figs.; 5 tabs

  8. Fourier transform infrared spectra applications to chemical systems

    CERN Document Server

    Ferraro, John R

    1978-01-01

    Fourier Transform Infrared Spectroscopy: Applications to Chemical Systems presents the chemical applications of the Fourier transform interferometry (FT-IR).The book contains discussions on the applications of FT-IR in the fields of chromatography FT-IR, polymers and biological macromolecules, emission spectroscopy, matrix isolation, high-pressure interferometry, and far infrared interferometry. The final chapter is devoted to the presentation of the use of FT-IR in solving national technical problems such as air pollution, space exploration, and energy related subjects.Researc

  9. Infrared spectroscopic and theoretical study of the HC2n+1O+ (n = 2-5) cations

    Science.gov (United States)

    Jin, Jiaye; Li, Wei; Liu, Yuhong; Wang, Guanjun; Zhou, Mingfei

    2017-06-01

    The carbon chain cations, HC2n+1O+ (n = 2-5), are produced via pulsed laser vaporization of a graphite target in supersonic expansions containing carbon monoxide and hydrogen. The infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of the CO "tagged" [HC2n+1O.CO]+ cation complexes in the 1600-3500 cm-1 region. The geometries and electronic ground states of these cation complexes are determined by their infrared spectra compared to the predications of theoretical calculations. All of the HC2n+1O+ (n = 2-5) core cations are characterized to be linear carbon chain derivatives terminated by hydrogen and oxygen, which have the closed-shell singlet ground states with polyyne-like carbon chain structures.

  10. Preparation, thermogravimetric study and infrared spectra of rare earth acetates

    International Nuclear Information System (INIS)

    Graehlert, X.; Starke, M.

    1992-01-01

    The anhydrous and the hydrated acetates of Ho, Er, Tm, Yb and Lu have been prepared. The compounds obtained have been investigated by thermogravimetric analysis and infrared spectroscopy. The thermal decomposition of the rare earth acetates may proceed via various steps. It depends on both the number of crystal water molecules in the acetates and the rare earth element's behaviour. (orig.)

  11. Infrared spectra of peculiar emission-line stars

    International Nuclear Information System (INIS)

    Andrillat, Yvette; Houziaux, Leo

    1975-01-01

    230A/mm spectra of HD51585, V1016Cyg, HBV475 and XXOph between 8,000 and 11,000A are described. Important spectral variations have been noted between 1974 and 1975. Satisfactory identifications cannot be proposed for lines at 9,180 and 9,204A [fr

  12. BinMag: Widget for comparing stellar observed with theoretical spectra

    Science.gov (United States)

    Kochukhov, O.

    2018-05-01

    BinMag examines theoretical stellar spectra computed with Synth/SynthMag/Synmast/Synth3/SME spectrum synthesis codes and compare them to observations. An IDL widget program, BinMag applies radial velocity shift and broadening to the theoretical spectra to account for the effects of stellar rotation, radial-tangential macroturbulence, instrumental smearing. The code can also simulate spectra of spectroscopic binary stars by appropriate coaddition of two synthetic spectra. Additionally, BinMag can be used to measure equivalent width, fit line profile shapes with analytical functions, and to automatically determine radial velocity and broadening parameters. BinMag interfaces with the Synth3 (ascl:1212.010) and SME (ascl:1202.013) codes, allowing the user to determine chemical abundances and stellar atmospheric parameters from the observed spectra.

  13. Fourier transform infrared spectra applications to chemical systems

    CERN Document Server

    Ferraro, John R

    1985-01-01

    The final and largest volume to complete this four-volume treatise is published in response to the intense commercial and research interest in Fourier Transform Interferometry.Presenting current information from leading experts in the field, Volume 4 introduces new information on, for example, applications of Diffuse Reflectance Spectroscopy in the Far-Infrared Region. The editors place emphasis on surface studies and address advances in Capillary Gas Chromatography - Fourier Transform Interferometry.Volume 4 especially benefits spectroscopists and physicists, as well as researchers

  14. Prebiotic polymers and infrared spectra of galactic sources

    International Nuclear Information System (INIS)

    Wickramasinghe, N.C.; Hoyle, F.; Brooks, J.; Shaw, G.

    1977-01-01

    It is stated that infrared absorption features characteristic of molecular dust clouds in the Galaxy may be assigned to complex organic polymers or prebiotic polymers. It could be argued that such highly stable, complex polymers evolve due to radiation processing of molecular mantles on interstellar grains - essentially by a type of natural selection which operates in the interstellar medium. A large fraction of all C, N, O elements in the interstellar medium could be condensed in the form of these stable polymers. Such interstellar material may also account for a significant fraction of the 'insoluble organic matter' which is found in carbonaceous chondrites. (author)

  15. Quantitative mid-infrared spectra of allene and propyne from room to high temperatures

    KAUST Repository

    Es-sebbar, Et-touhami

    2014-11-01

    Allene (a-C3H4; CH2CCH2) and propyne (p-C3H4; CH3C2H) have attracted much interest because of their relevance to the photochemistry in astrophysical environments as well as in combustion processes. Both allene and propyne have strong absorption in the infrared region. In the present work, infrared spectra of a-C3H4 and p-C3H4 are measured in the gas phase at temperatures ranging from 296 to 510 K. The spectra are measured over the 580-3400 cm-1 spectral region at resolutions of 0.08 and 0.25 cm-1 using Fourier Transform Infrared spectroscopy. Absolute integrated intensities of the main infrared bands are determined at room temperature and compared with values derived from literature for both molecules. Integrated band intensities are also determined as a function of temperature in various spectral regions.

  16. Quantitative mid-infrared spectra of allene and propyne from room to high temperatures

    KAUST Repository

    Es-sebbar, Et-touhami; Jolly, A.; Benilan, Y.; Farooq, Aamir

    2014-01-01

    Allene (a-C3H4; CH2CCH2) and propyne (p-C3H4; CH3C2H) have attracted much interest because of their relevance to the photochemistry in astrophysical environments as well as in combustion processes. Both allene and propyne have strong absorption in the infrared region. In the present work, infrared spectra of a-C3H4 and p-C3H4 are measured in the gas phase at temperatures ranging from 296 to 510 K. The spectra are measured over the 580-3400 cm-1 spectral region at resolutions of 0.08 and 0.25 cm-1 using Fourier Transform Infrared spectroscopy. Absolute integrated intensities of the main infrared bands are determined at room temperature and compared with values derived from literature for both molecules. Integrated band intensities are also determined as a function of temperature in various spectral regions.

  17. Structural properties of maize hybrids established by infrared spectra

    Directory of Open Access Journals (Sweden)

    Radenović Čedomir N.

    2015-01-01

    Full Text Available This paper discusses the application of the infrared (IR spectroscopy method for determination of structural properties of maize hybrid grains. The IR spectrum of maize grain has been registered in the following hybrids: ZP 341, ZP 434 and ZP 505. The existence of spectral bands varying in both number and intensity, as well as their shape, frequency and kinetics have been determined. They have been determined by valence oscillations and deformation oscillations of the following organic compounds: alkanes, alkenes, alkynes, amides, alcohols, ethers, carboxylic acids, esters and aldehydes and ketones, characteristic for biogenic compounds such as carbohydrates, proteins and lipids. In this way, possible changes in the grain structure of observed maize hybrids could be detected.

  18. Dual stacked partial least squares for analysis of near-infrared spectra

    Energy Technology Data Exchange (ETDEWEB)

    Bi, Yiming [Institute of Automation, Chinese Academy of Sciences, 100190 Beijing (China); Xie, Qiong, E-mail: yimbi@163.com [Institute of Automation, Chinese Academy of Sciences, 100190 Beijing (China); Peng, Silong; Tang, Liang; Hu, Yong; Tan, Jie [Institute of Automation, Chinese Academy of Sciences, 100190 Beijing (China); Zhao, Yuhui [School of Economics and Business, Northeastern University at Qinhuangdao, 066000 Qinhuangdao City (China); Li, Changwen [Food Research Institute of Tianjin Tasly Group, 300410 Tianjin (China)

    2013-08-20

    Graphical abstract: -- Highlights: •Dual stacking steps are used for multivariate calibration of near-infrared spectra. •A selective weighting strategy is introduced that only a subset of all available sub-models is used for model fusion. •Using two public near-infrared datasets, the proposed method achieved competitive results. •The method can be widely applied in many fields, such as Mid-infrared spectra data and Raman spectra data. -- Abstract: A new ensemble learning algorithm is presented for quantitative analysis of near-infrared spectra. The algorithm contains two steps of stacked regression and Partial Least Squares (PLS), termed Dual Stacked Partial Least Squares (DSPLS) algorithm. First, several sub-models were generated from the whole calibration set. The inner-stack step was implemented on sub-intervals of the spectrum. Then the outer-stack step was used to combine these sub-models. Several combination rules of the outer-stack step were analyzed for the proposed DSPLS algorithm. In addition, a novel selective weighting rule was also involved to select a subset of all available sub-models. Experiments on two public near-infrared datasets demonstrate that the proposed DSPLS with selective weighting rule provided superior prediction performance and outperformed the conventional PLS algorithm. Compared with the single model, the new ensemble model can provide more robust prediction result and can be considered an alternative choice for quantitative analytical applications.

  19. Dual stacked partial least squares for analysis of near-infrared spectra

    International Nuclear Information System (INIS)

    Bi, Yiming; Xie, Qiong; Peng, Silong; Tang, Liang; Hu, Yong; Tan, Jie; Zhao, Yuhui; Li, Changwen

    2013-01-01

    Graphical abstract: -- Highlights: •Dual stacking steps are used for multivariate calibration of near-infrared spectra. •A selective weighting strategy is introduced that only a subset of all available sub-models is used for model fusion. •Using two public near-infrared datasets, the proposed method achieved competitive results. •The method can be widely applied in many fields, such as Mid-infrared spectra data and Raman spectra data. -- Abstract: A new ensemble learning algorithm is presented for quantitative analysis of near-infrared spectra. The algorithm contains two steps of stacked regression and Partial Least Squares (PLS), termed Dual Stacked Partial Least Squares (DSPLS) algorithm. First, several sub-models were generated from the whole calibration set. The inner-stack step was implemented on sub-intervals of the spectrum. Then the outer-stack step was used to combine these sub-models. Several combination rules of the outer-stack step were analyzed for the proposed DSPLS algorithm. In addition, a novel selective weighting rule was also involved to select a subset of all available sub-models. Experiments on two public near-infrared datasets demonstrate that the proposed DSPLS with selective weighting rule provided superior prediction performance and outperformed the conventional PLS algorithm. Compared with the single model, the new ensemble model can provide more robust prediction result and can be considered an alternative choice for quantitative analytical applications

  20. Infrared spectra of volatile adduct of uranyl pivaloyltrifluoroacetonate with hexamethylphosphorotriamide

    International Nuclear Information System (INIS)

    Bukhmarina, V.N.; Dushin, R.B.; Sidorenko, G.V.; Suglobov, D.N.

    1983-01-01

    Adduct of uranyl pivaloyltrifluoroacetonate with hexamethylphosphortriamide (1), sublimated without decomposition and characterized by a high thermal stability, has been synthesized, as well as adducts of uranyl dipivaloylmethanate with hexamethylphosphortriamide (2) and dimethyl sulfoxide (3), sublimated with partial dissociation. IR spectra of crystalline adducts 1-3, their solutions in benzene; gaseous and matrix-isolated adduct 1 have been measured. It is shown that in gaseous phase 1 exists practically completely in non-dissociated form. It is detected that uranyl group in crystalline 1 and 2 and in matrix-isolated 1 in contrast to crystalline 3 and previously studied adducts of uranyl β-diketonates has an asymmetric structure. Strength constants of uranyl group in crystalline 1-3 and matrix-isolated 1 are determined

  1. Improved assignments of the vibrational fundamental modes of ortho -, meta -, and para -xylene using gas- and liquid-phase infrared and Raman spectra combined with ab initio calculations: Quantitative gas-phase infrared spectra for detection

    Energy Technology Data Exchange (ETDEWEB)

    Lindenmaier, Rodica; Scharko, Nicole K.; Tonkyn, Russell G.; Nguyen, Kiet T.; Williams, Stephen D.; Johnson, Timothy J.

    2017-07-25

    Xylenes contain a blend of the ortho-, meta-, and para- isomers, and all are abundant contaminants in the ground, surface waters, and air. To better characterize xylene and to better enable its detection, we report high quality quantitative vapor-phase infrared spectra of all three isomers over the 540-6500 cm-1 range. All fundamental vibrational modes are assigned based on these vapor-phase infrared spectra, liquid-phase infrared and Raman spectra, along with density functional theory (DFT), ab initio MP2 and high energy-accuracy compound theoretical model (W1BD) calculations. Both MP2 and DFT predict a single conformer with C2v symmetry for ortho-xylene, and two conformers each for meta- and para-xylene, depending on the preferred orientations of the methyl groups. For meta-xylene the two conformers have Cs and C2 symmetry, and for para-xylene these conformers have C2v or C2h symmetry. Since the relative population of the two conformers is approximately 50% for both isomers and predicted frequencies and intensities are very similar for each conformer, we made an arbitrary choice to discuss the Cs conformer for meta-xylene and the C2v conformer for para-xylene. We report integrated band intensities for all isomers. Using the quantitative infrared data, we determine the global warming potential values of each isomer and discuss potential bands for atmospheric monitoring.

  2. Infrared absorption spectra of various doping states in cuprate superconductors

    International Nuclear Information System (INIS)

    Yonemitsu, K.; Bishop, A.R.; Lorenzana, J.

    1992-01-01

    Doping states in a two-dimensional three-band extended Peierls-Hubbard model was investigated within inhomogeneous Hartree-Fock and random phase approximation. They are very sensitive to small changes of interaction parameters and their distinct vibrational and optical absorption spectra can be used to identify different doping states. For electronic parameters relevant to cuprate superconductors, as intersite electron-phonon interaction strength increases, the doping state changes from a Zhang-Rice state to a covalent molecular singlet state accompanied by local quenching of the Cu magnetic moment and large local lattice distortion in an otherwise undistorted antiferromagnetic background. In a region where both intersite electron-phonon interaction and on-site electron-electron repulsion are large, we obtain new stable global phases including a bond-order-wave state and a mixed state of spin-Peierls bonds and antiferromagnetic Cu spins, as well as many metastable states. Doping in the bond-order-wave region induces separation of spin and charge. 9 refs

  3. FT-Raman and FTIR spectra of photoactive aminobenzazole derivatives in the solid state: A combined experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Rodrigo Martins [Universidade Federal do Pampa, Campus Bagé, Grupo de Pesquisa em Espectroscopia de Materiais Fotônicos, 96400-970 Bagé, RS (Brazil); Rodembusch, Fabiano Severo [Universidade Federal do Rio Grande do Sul, Grupo de Pesquisa em Fotoquímica Orgânica Aplicada, Av. Bento Gonçalves 9500, CEP 91501-970 Porto Alegre, RS (Brazil); Habis, Charles [Northern Virginia Community College, Manassas, VA (United States); Moreira, Eduardo Ceretta, E-mail: eduardomoreira@unipampa.edu.br [Universidade Federal do Pampa, Campus Bagé, Grupo de Pesquisa em Espectroscopia de Materiais Fotônicos, 96400-970 Bagé, RS (Brazil)

    2014-12-15

    This study reports the experimental investigation of two photoactive aminobenzazole derivatives in the solid state by FT-Raman and Infrared Spectroscopies (FTIR) and its comparison with theoretical models. The optimized molecular structure, vibrational frequencies, and corresponding vibrational assignments of these compounds have been investigated experimentally and theoretically using Spanish Initiative for Electronic Simulations with Thousands of Atoms (SIESTA) and Gaussian03 Software Package. The FT-Raman and FTIR spectra were acquired with high resolution and emission frequencies identified by simulating the vibrational modes. The most intense peak observed in the FT-Raman spectra is the in-plane deformation vibrational of O–H bond that could be related to the vibrational region responsible for the stabilization of the enol conformer in the ground state which undergoes ESIPT to form a keto tautomer in the excited state. Additionally, the position of the amino group played an important role on the vibrational characteristics of the studied compounds. Also, the simulations proved to be a good approach in undertaking the FTIR and FT-Raman experiments. The use of graphic correlations helps us to determine the method and basis that best fit the experimental results. - Highlights: • Structural and vibrational properties of two aminobenzazoles were reported. • Comparison between experimental techniques and theoretical models. • The position of the amino group played an important role on the vibrational characteristics of the studied compounds.

  4. Infrared and Raman spectra of uric acid and its 15N and D labelled compounds

    International Nuclear Information System (INIS)

    Majoube, Michel

    Infrared and Raman spectra of polycrystalline uric acid (2, 6, 8-trioxypurine) 1.3, 7 and 9- 15 N and deuterated analogues have been determined. Band shifts with 15 N substitution and with deuteration are discussed. An assignment of fundamental vibrations of uric acid is proposed from the comparison of the eight isotopically substituted analogues [fr

  5. The NASA Ames Polycyclic Aromatic Hydrocarbon Infrared Spectroscopic Database : The Computed Spectra

    NARCIS (Netherlands)

    Bauschlicher, C. W.; Boersma, C.; Ricca, A.; Mattioda, A. L.; Cami, J.; Peeters, E.; de Armas, F. Sanchez; Saborido, G. Puerta; Hudgins, D. M.; Allamandola, L. J.

    The astronomical emission features, formerly known as the unidentified infrared bands, are now commonly ascribed to polycyclic aromatic hydrocarbons (PAHs). The laboratory experiments and computational modeling done at the NASA Ames Research Center to create a collection of PAH IR spectra relevant

  6. Correlation of quality measurements to visible-near infrared spectra of pasteurized egg

    Science.gov (United States)

    A twelve week study was conducted on the egg albumen from both pasteurized and non-pasteurized shell eggs using visible-near infrared spectroscopy. Correlation of the chemical changes detected in the spectra to the measurement of Haugh units (measure of interior egg quality) was carried out using ch...

  7. Chemometric correlation of shelf life, quality measurements, and visible-near infrared spectra of pasteurized eggs

    Science.gov (United States)

    A twelve week study was conducted on the egg albumen from both pasteurized and non-pasteurized shell eggs using visible-near infrared spectroscopy. Correlation of the chemical changes detected in the spectra to the measurement of Haugh units (measure of interior egg quality) was carried out using pr...

  8. STELLAR POPULATIONS IN MEDIUM REDSHIFT CLUSTERS .2. OPTICAL-INFRARED PHOTOMETRY AND SPECTRA

    NARCIS (Netherlands)

    PICKLES, AJ; VANDERKRUIT, PC

    1991-01-01

    We present optical and infrared photometry (BV RI, J H K) and spectra of galaxies in 6 medium redshift clusters covering the redshift range 0.19 less-than-or-equal-to z less-than-or-equal-to 0.4. The array photometry is used to note the radial distribution of the cluster galaxies with optical and

  9. A New Indicator for Optimal Preprocessing and Wavelengths Selection of Near-Infrared Spectra

    NARCIS (Netherlands)

    Skibsted, E.; Boelens, H.F.M.; Westerhuis, J.A.; Witte, D.T.; Smilde, A.K.

    2004-01-01

    Preprocessing of near-infrared spectra to remove unwanted, i.e., non-related spectral variation and selection of informative wavelengths is considered to be a crucial step prior to the construction of a quantitative calibration model. The standard methodology when comparing various preprocessing

  10. New indicator for optimal preprocessing and wavelength selection of near-infrared spectra

    NARCIS (Netherlands)

    Skibsted, E. T. S.; Boelens, H. F. M.; Westerhuis, J. A.; Witte, D. T.; Smilde, A. K.

    2004-01-01

    Preprocessing of near-infrared spectra to remove unwanted, i.e., non-related spectral variation and selection of informative wavelengths is considered to be a crucial step prior to the construction of a quantitative calibration model. The standard methodology when comparing various preprocessing

  11. Sulfur Speciation of Crude Oils by Partial Least Squares Regression Modeling of Their Infrared Spectra

    NARCIS (Netherlands)

    de Peinder, P.; Visser, T.; Wagemans, R.W.P.; Blomberg, J.; Chaabani, H.; Soulimani, F.; Weckhuysen, B.M.

    2013-01-01

    Research has been carried out to determine the feasibility of partial least-squares regression (PLS) modeling of infrared (IR) spectra of crude oils as a tool for fast sulfur speciation. The study is a continuation of a previously developed method to predict long and short residue properties of

  12. A method for comparison of experimental and theoretical differential neutron spectra in the Zenith reactor

    International Nuclear Information System (INIS)

    Reed, D.L.; Symons, C.R.

    1965-01-01

    A method of calculation is given which assists the analyses of chopper measurements of spectra from ZENITH and enables complex multigroup theoretical calculations of the spectra to be put into a form which may be compared with experiment. In addition the theory of the cut-off function has been extended to give analytical expressions which take into account the effects of sub-collimators, off centre slits and of a rotor made of a material partially transparent to neutrons. The theoretical cut-off function suggested shows good agreement with experiment. (author)

  13. A method for comparison of experimental and theoretical differential neutron spectra in the Zenith reactor

    Energy Technology Data Exchange (ETDEWEB)

    Reed, D L; Symons, C R [General Reactor Physics Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

    1965-01-15

    A method of calculation is given which assists the analyses of chopper measurements of spectra from ZENITH and enables complex multigroup theoretical calculations of the spectra to be put into a form which may be compared with experiment. In addition the theory of the cut-off function has been extended to give analytical expressions which take into account the effects of sub-collimators, off centre slits and of a rotor made of a material partially transparent to neutrons. The theoretical cut-off function suggested shows good agreement with experiment. (author)

  14. AN ATLAS OF BRIGHT STAR SPECTRA IN THE NEAR-INFRARED FROM CASSINI-VIMS

    International Nuclear Information System (INIS)

    Stewart, Paul N.; Tuthill, Peter G.; Nicholson, Philip D.; Sloan, G. C.; Hedman, Matthew M.

    2015-01-01

    We present the Cassini Atlas Of Stellar Spectra (CAOSS), comprised of near-infrared, low-resolution spectra of bright stars recovered from space-based observations by the Cassini spacecraft. The 65 stellar targets in the atlas are predominately M, K, and S giants. However, it also contains spectra of other bright nearby stars including carbon stars and main-sequence stars from A to F. The spectra presented are free of all spectral contamination caused by the Earth's atmosphere, including the detrimental telluric molecular bands which put parts of the near-infrared spectrum out of reach of terrestrial observations. With a single instrument, a spectro-photometric data set is recovered that spans the near-infrared from 0.8 to 5.1 μm with spectral resolution ranging from R = 53.5 to R = 325. Spectra have been calibrated into absolute flux units after careful characterization of the instrumental spectral efficiency. Spectral energy distributions for most stars match closely with literature values. All final data products have been made available online

  15. AN ATLAS OF BRIGHT STAR SPECTRA IN THE NEAR-INFRARED FROM CASSINI-VIMS

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Paul N.; Tuthill, Peter G. [Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006 (Australia); Nicholson, Philip D. [Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States); Sloan, G. C. [Cornell Center for Astrophyics and Planetary Science, Cornell University, Ithaca, NY 14853 (United States); Hedman, Matthew M., E-mail: p.stewart@physics.usyd.edu.au [Department of Physics, University of Idaho, Moscow, ID 83844 (United States)

    2015-12-15

    We present the Cassini Atlas Of Stellar Spectra (CAOSS), comprised of near-infrared, low-resolution spectra of bright stars recovered from space-based observations by the Cassini spacecraft. The 65 stellar targets in the atlas are predominately M, K, and S giants. However, it also contains spectra of other bright nearby stars including carbon stars and main-sequence stars from A to F. The spectra presented are free of all spectral contamination caused by the Earth's atmosphere, including the detrimental telluric molecular bands which put parts of the near-infrared spectrum out of reach of terrestrial observations. With a single instrument, a spectro-photometric data set is recovered that spans the near-infrared from 0.8 to 5.1 μm with spectral resolution ranging from R = 53.5 to R = 325. Spectra have been calibrated into absolute flux units after careful characterization of the instrumental spectral efficiency. Spectral energy distributions for most stars match closely with literature values. All final data products have been made available online.

  16. Infrared and Raman spectra, DFT-calculations and spectral assignments of germacyclohexane

    Energy Technology Data Exchange (ETDEWEB)

    Aleksa, V., E-mail: valdemaras.aleksa@ff.vu.lt; Ozerenskis, D.; Pucetaite, M.; Sablinskas, V. [Faculty of Physics, Vilnius University, Sauletekio av. 9, block 3, Vilnius, LT-10222 (Lithuania); Cotter, C.; Guirgis, G. A. [Department of Chemistry and Biochemistry, College of Charleston, Charleston, SC 29424 (United States)

    2015-03-30

    Raman spectra of germacyclohexane in liquid and solid states were recorded and depolarization data obtained. Infrared absorption spectra of the vapor and liquid have been studied. The wavenumbers of the vibrational modes were derived in the harmonic and anharmonic approximation in B3LYP/ccpVTZ calculations. According to the calculations, germacyclohexane exists in the stable chair conformation, whereas a possible twist form should have more than 15 kJ·mol{sup -1} higher enthalpy of formation what makes this conformer experimentally not observable. The 27 A' and 21 A'' fundamentals were assigned on the basis of the calculations and infrared and Raman band intensities, contours of gas phase infrared spectral bands and Raman depolarization measurements. An average discrepancy of ca. 0.77 % was found between the observed and the calculated anharmonic wavenumbers for the 48 modes. Substitution of carbon atom with Ge atom in the cyclohexane ring is reasoning flattening of the ring.

  17. Diffuse reflectance infrared Fourier-Transform spectra of selected organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Harmon, S.H.; Caton, J.E.

    1982-05-01

    Diffuse reflectance infrared spectra of a variety of different organic compounds have been determined. Profiles of the spectra along with the location and relative intensity of the principal bands have been included for each compound studied. In addition both diffuse reflectance and transmittance infrared spectra were obtained for the same samples, and the spectral results were compared. Although some minor variations are observed between a diffuse reflectance spectrum and the corresponding transmittance spectrum, the diffuse reflectance is quite useful and may be a superior technique for the study of many samples because it possesses an inherently higher signal-to-noise response, requires less sample preparation and allows a very wide range of samples (solids, liquids of low volatility, neat sample, or sample diluted in a reflecting medium) to be studied under very similar conditions.

  18. A theoretical and experimental analysis of modulated laser fields and power spectra

    DEFF Research Database (Denmark)

    Olesen, Henning; Jacobsen, G.

    1982-01-01

    A general theoretical description of modulated laser fields and power spectra for a current modulated single-mode laser is derived, taking into account both the intensity and frequency modulation (IM and FM) of the emitted light. The theory relies on an explicit knowledge of the modulus as well...

  19. Investigating the fermentation of cocoa by correlating denaturing gradient gel electrophoresis profiles and near infrared spectra

    DEFF Research Database (Denmark)

    Nielsen, Dennis Sandris; Snitkjær, Pia; van der Berg, Franciscus Winfried J

    2008-01-01

    demonstrating the microbial succession taking place during the fermentation. Subsequently the DGGE spectra were correlated to the NIR spectra using Partial Least Squares regression models (PLS2). Correlations of 0.87 (bacterial derived DGGE spectra) and 0.81 (yeast derived DGGE spectra) were obtained indicating......Raw cocoa has an astringent, unpleasant taste and flavour, and has to be fermented, dried and roasted in order to obtain the characteristic cocoa flavour and taste. During the fermentation microbial activity outside the cocoa beans induces biochemical and physical changes inside the beans...... of the beans and the chemical processes inside the beans have been carried out previously. Recently it has been shown that Denaturing Gradient Gel Electrophoresis (DGGE) offers an efficient tool for monitoring the microbiological changes taking place during the fermentation of cocoa. Near Infrared (NIR...

  20. THE NASA AMES POLYCYCLIC AROMATIC HYDROCARBON INFRARED SPECTROSCOPIC DATABASE: THE COMPUTED SPECTRA

    International Nuclear Information System (INIS)

    Bauschlicher, C. W.; Ricca, A.; Boersma, C.; Mattioda, A. L.; Cami, J.; Peeters, E.; Allamandola, L. J.; Sanchez de Armas, F.; Puerta Saborido, G.; Hudgins, D. M.

    2010-01-01

    The astronomical emission features, formerly known as the unidentified infrared bands, are now commonly ascribed to polycyclic aromatic hydrocarbons (PAHs). The laboratory experiments and computational modeling done at the NASA Ames Research Center to create a collection of PAH IR spectra relevant to test and refine the PAH hypothesis have been assembled into a spectroscopic database. This database now contains over 800 PAH spectra spanning 2-2000 μm (5000-5 cm -1 ). These data are now available on the World Wide Web at www.astrochem.org/pahdb. This paper presents an overview of the computational spectra in the database and the tools developed to analyze and interpret astronomical spectra using the database. A description of the online and offline user tools available on the Web site is also presented.

  1. Theoretical analysis of time-dependent neutron spectra in bulk assemblies

    International Nuclear Information System (INIS)

    Akimoto, Tadashi; Ogawa, Yuichi; Togawa, Orihiko.

    1988-01-01

    Time-dependent neutron spectra in an iron assembly and in a graphite assembly are obtained with the one-dimensional S N calculation, in order an attempt to investigate the availability of these spectra to the benchmark test by the LINAC-TOF method for evaluation of nuclear data and numerical methods. The group constants are taken from the JAERI FAST SET Version 1, 2 and the ABBN SET. It was demonstrated by a sensitivity test that the time-dependent neutron spectra are sensitive to changes in the inelastic scattering cross section data in the iron assembly and to changes in the elastic scattering cross section data in the graphite assembly. Moreover, it is shown that the time-dependent spectra in the graphite assembly are sensitive to the group structure. Because some information about the neutron transport phenomena which has not been obtained in the stationary spectra is observed in the time-dependent spectra, the availability of the benchmark test based on the time-dependent spectra is indicated from the theoretical analysis. (author)

  2. Synthesis, crystal structure, vibrational spectra and theoretical calculations of quantum chemistry of a potential antimicrobial Meldrum's acid derivative

    Science.gov (United States)

    Campelo, M. J. M.; Freire, P. T. C.; Mendes Filho, J.; de Toledo, T. A.; Teixeira, A. M. R.; da Silva, L. E.; Bento, R. R. F.; Faria, J. L. B.; Pizani, P. S.; Gusmão, G. O. M.; Coutinho, H. D. M.; Oliveira, M. T. A.

    2017-10-01

    A new derivative of Meldrum's acid 5-((5-chloropyridin-2-ylamino)methylene)-2,2-dimethyl-1,3-dioxane-4,6-dione (CYMM) of molecular formula C12H11ClN2O4 was synthesized and structurally characterized using single crystal X-ray diffraction technique. The vibrational properties of the crystal were studied by Fourier Transform infrared (FT-IR), Fourier Transform Raman (FT-Raman) techniques and theoretical calculations of quantum chemistry using Density functional theory (DFT) and Density functional perturbation theory (DFPT). A comparison with experimental spectra allowed the assignment of all the normal modes. The descriptions of the normal modes were carried by means of potential energy distribution (PED). Additionally, analysis of the antimicrobial activity and antibiotic resistance modulatory activity was carried out to evaluate the antibacterial potential of the CYMM.

  3. Retrieval of leaf water content spanning the visible to thermal infrared spectra

    CSIR Research Space (South Africa)

    Ullah, S

    2014-05-01

    Full Text Available ; Hunt and Rock 1989; Sepulcre-Cantó et al. 2006). 45 Retrieving leaf water content using remote sensing data, has been widely investigated in the 46 visible near infrared (VNIR) and shortwave infrared (SWIR) spectra (Thomas et al. 1971; 47 Danson et..., USA: NASA / GSFC 400 Savitzky, A., & Golay, M.J.E. (1964). Smoothing and differentiation of data by simplified Least 401 squares procedures. Analytical Chemistry, 36, 1627-1639 402 Sepulcre-Cantó, G., Zarco-Tejada, P.J., Jiménez-Muñoz, J.C., Sobrino...

  4. Simulation of attenuated total reflection infrared absorbance spectra: applications to automotive clear coat forensic analysis.

    Science.gov (United States)

    Lavine, Barry K; Fasasi, Ayuba; Mirjankar, Nikhil; Nishikida, Koichi; Campbell, Jay

    2014-01-01

    Attenuated total reflection (ATR) is a widely used sampling technique in infrared (IR) spectroscopy because minimal sample preparation is required. Since the penetration depth of the ATR analysis beam is quite shallow, the outer layers of a laminate or multilayered paint sample can be preferentially analyzed with the entire sample intact. For this reason, forensic laboratories are taking advantage of ATR to collect IR spectra of automotive paint systems that may consist of three or more layers. However, the IR spectrum of a paint sample obtained by ATR will exhibit distortions, e.g., band broadening and lower relative intensities at higher wavenumbers, compared with its transmission counterpart. This hinders library searching because most library spectra are measured in transmission mode. Furthermore, the angle of incidence for the internal reflection element, the refractive index of the clear coat, and surface contamination due to inorganic contaminants can profoundly influence the quality of the ATR spectrum obtained for automotive paints. A correction algorithm to allow ATR spectra to be searched using IR transmission spectra of the paint data query (PDQ) automotive database is presented. The proposed correction algorithm to convert transmission spectra from the PDQ library to ATR spectra is able to address distortion issues such as the relative intensities and broadening of the bands, and the introduction of wavelength shifts at lower frequencies, which prevent library searching of ATR spectra using archived IR transmission data.

  5. MID-INFRARED ATOMIC FINE-STRUCTURE EMISSION-LINE SPECTRA OF LUMINOUS INFRARED GALAXIES: SPITZER/IRS SPECTRA OF THE GOALS SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Inami, H. [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Armus, L.; Stierwalt, S.; Díaz-Santos, T.; Surace, J.; Howell, J.; Marshall, J. [Spitzer Science Center, California Institute of Technology, CA 91125 (United States); Charmandaris, V. [Department of Physics and Institute of Theoretical and Computational Physics, University of Crete, GR-71003 Heraklion (Greece); Groves, B. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Kewley, L. [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Petric, A. [Department of Astronomy, California Institute of Technology, MS 320-47, Pasadena, CA 91125 (United States); Rich, J. [The Observatories, Carnegie Institute of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Haan, S. [CSIRO Astronomy and Space Science, Marsfield, NSW 2122 (Australia); Evans, A. S. [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Mazzarella, J.; Lord, S. [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Appleton, P. [NASA Herschel Science Center, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Spoon, H. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Frayer, D. [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944 (United States); Matsuhara, H., E-mail: inami@noao.edu [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (Japan); and others

    2013-11-10

    We present the data and our analysis of mid-infrared atomic fine-structure emission lines detected in Spitzer/Infrared Spectrograph high-resolution spectra of 202 local Luminous Infrared Galaxies (LIRGs) observed as part of the Great Observatories All-sky LIRG Survey (GOALS). We readily detect emission lines of [S IV], [Ne II], [Ne V], [Ne III], [S III]{sub 18.7{sub μm}}, [O IV], [Fe II], [S III]{sub 33.5{sub μm}}, and [Si II]. More than 75% of these galaxies are classified as starburst-dominated sources in the mid-infrared, based on the [Ne V]/[Ne II] line flux ratios and equivalent width of the 6.2 μm polycyclic aromatic hydrocarbon feature. We compare ratios of the emission-line fluxes to those predicted from stellar photo-ionization and shock-ionization models to constrain the physical and chemical properties of the gas in the starburst LIRG nuclei. Comparing the [S IV]/[Ne II] and [Ne III]/[Ne II] line ratios to the Starburst99-Mappings III models with an instantaneous burst history, the emission-line ratios suggest that the nuclear starbursts in our LIRGs have ages of 1-4.5 Myr, metallicities of 1-2 Z{sub ☉}, and ionization parameters of 2-8 × 10{sup 7} cm s{sup –1}. Based on the [S III]{sub 33.5{sub μm}}/[S III]{sub 18.7{sub μm}} ratios, the electron density in LIRG nuclei is typically one to a few hundred cm{sup –3}, with a median electron density of ∼300 cm{sup –3}, for those sources above the low density limit for these lines. We also find that strong shocks are likely present in 10 starburst-dominated sources of our sample. A significant fraction of the GOALS sources (80) have resolved neon emission-line profiles (FWHM ≥600 km s{sup –1}) and five show clear differences in the velocities of the [Ne III] or [Ne V] emission lines, relative to [Ne II], of more than 200 km s{sup –1}. Furthermore, six starburst and five active galactic nucleus dominated LIRGs show a clear trend of increasing line width with ionization potential

  6. X-ray spectra of PG quasars. I. The continuum from X-rays to infrared

    International Nuclear Information System (INIS)

    Elvis, M.; Green, R.F.; Bechtold, J.; Schmidt, M.; Neugebauer, G.; Kitt Peak National Observatory, Tucson, AZ; Steward Observatory, Tucson, AZ; Palomar Observatory, Pasadena, CA)

    1986-01-01

    Einstein IPC X-ray spectra for a sample of eight optically selected quasars from the Palomar Bright Quasar survey are presented. The quasars have a mean power law energy slope which in five individual cases is inconsistent with the value found in hard X-ray selection criterion rather than luminosity, redshift, or U-B color. New IUE and optical continuum spectra and infrared photometry are presented for these quasars. The data are combined into log vf(v) and log v distributions which support the decomposition of the overall quasar spectrum into a power law plus a superposed optical-UV big bump which may be due to an accretion disk. At least six of the quasars have vf(v)s which are roughly constant between their infrared and X-ray power laws, suggesting a strong link between the two regions. 104 references

  7. Far-infrared spectra of polycrystalline Ba2YCu3O/sub 9-//sub δ/

    International Nuclear Information System (INIS)

    Thomas, G.A.; Ng, H.K.; Millis, A.J.; Bhatt, R.N.; Cava, R.J.; Rietman, E.A.; Johnson, D.W. Jr.; Espinosa, G.P.; Vandenberg, J.M.

    1987-01-01

    We present far-infrared reflectivity spectra of seven samples of ceramic superconductors in the Ba-Y-Cu-O system with transition temperatures near 93 K. We find superconducting gap structures on the basis of which we estimate the ratio of twice the average gap to the transition temperature to be consistent with 3.5, but possibly higher. Questions of normal-state characterization preclude a definitive analysis

  8. Source brightness fluctuation correction of solar absorption fourier transform mid infrared spectra

    Directory of Open Access Journals (Sweden)

    T. Ridder

    2011-06-01

    Full Text Available The precision and accuracy of trace gas observations using solar absorption Fourier Transform infrared spectrometry depend on the stability of the light source. Fluctuations in the source brightness, however, cannot always be avoided. Current correction schemes, which calculate a corrected interferogram as the ratio of the raw DC interferogram and a smoothed DC interferogram, are applicable only to near infrared measurements. Spectra in the mid infrared spectral region below 2000 cm−1 are generally considered uncorrectable, if they are measured with a MCT detector. Such measurements introduce an unknown offset to MCT interferograms, which prevents the established source brightness fluctuation correction. This problem can be overcome by a determination of the offset using the modulation efficiency of the instrument. With known modulation efficiency the offset can be calculated, and the source brightness correction can be performed on the basis of offset-corrected interferograms. We present a source brightness fluctuation correction method which performs the smoothing of the raw DC interferogram in the interferogram domain by an application of a running mean instead of high-pass filtering the corresponding spectrum after Fourier transformation of the raw DC interferogram. This smoothing can be performed with the onboard software of commercial instruments. The improvement of MCT spectra and subsequent ozone profile and total column retrievals is demonstrated. Application to InSb interferograms in the near infrared spectral region proves the equivalence with the established correction scheme.

  9. Emission Lines in the Near-infrared Spectra of the Infrared Quintuplet Stars in the Galactic Center

    Energy Technology Data Exchange (ETDEWEB)

    Najarro, F. [Departamento de Astrofísica, Centro de Astrobiología (CSIC-INTA), Ctra. Torrejón a Ajalvir km 4, E-28850 Torrejón de Ardoz (Spain); Geballe, T. R. [Gemini Observatory, 670 North A’ohoku Place, Hilo, HI 96720 (United States); Figer, D. F. [Center for Detectors, Rochester Institute of Technology, 74 Lomb Memorial Drive, Rochester, NY 14623 (United States); Fuente, D. de la [Instituto de Astronomía, Unidad Académica en Ensenada, Universidad Nacional Autónoma de México, Ensenada 22860, México (Mexico)

    2017-08-20

    We report the detection of a number of emission lines in the 1.0–2.4 μ m spectra of four of the five bright-infrared dust-embedded stars at the center of the Galactic center’s (GC) Quintuplet Cluster. Spectroscopy of the central stars of these objects is hampered not only by the large interstellar extinction that obscures all of the objects in the GC, but also by the large amounts of warm circumstellar dust surrounding each of the five stars. The pinwheel morphologies of the dust observed previously around two of them are indicative of Wolf–Rayet colliding wind binaries; however, infrared spectra of each of the five have until now revealed only dust continua steeply rising to long wavelengths and absorption lines and bands from interstellar gas and dust. The emission lines detected, from ionized carbon and from helium, are broad and confirm that the objects are dusty late-type carbon Wolf–Rayet stars.

  10. Interrelationship of crystal structure, infrared spectra and physicochemical properties of perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Bazuev, G V; Shveikin, G P [AN SSSR, Sverdlovsk. Inst. Khimii

    1975-12-01

    In the range 400-800 cm/sup -1/ a study has been made of infrared absorption spectra of perowskites ABO/sub 3/, where A is a rare-earth element or yttrium, B is Ti or V. A common feature of the infrared absorption spectra of perowskites ABO/sub 3/ is the presence of two intensive wide bands in the range 400-700 cm/sup -1/ one of which (low-frequency) is splitted into two or three components. The spectrum of LaTiO/sub 3/ is distinguished from spectra of other compounds. In the range measured this compound is non-transparent for electromagnetic radiation. On the basis of determination of temperature dependences of the electric resistance it is found that LaTiO/sub 3/ has metallic conductivity unlike other perowskites studied which are semiconductors. The spectrum of EuTiO/sub 3/ also differs from other spectra. It is close in its structure and position of bands to the spectrum of cubic perowskite, SrTiO/sub 3/. The splitting of the low-frequency band into two and in the case of TbVO/sub 3/ into three components is caused by deformation of crystal structures of these compounds. A direct dependence between the value of splitting and the deformation degree is observed.

  11. FBRDLR: Fast blind reconstruction approach with dictionary learning regularization for infrared microscopy spectra

    Science.gov (United States)

    Liu, Tingting; Liu, Hai; Chen, Zengzhao; Chen, Yingying; Wang, Shengming; Liu, Zhi; Zhang, Hao

    2018-05-01

    Infrared (IR) spectra are the fingerprints of the molecules, and the spectral band location closely relates to the structure of a molecule. Thus, specimen identification can be performed based on IR spectroscopy. However, spectrally overlapping components prevent the specific identification of hyperfine molecular information of different substances. In this paper, we propose a fast blind reconstruction approach for IR spectra, which is based on sparse and redundant representations over a dictionary. The proposed method recovers the spectrum with the discrete wavelet transform dictionary on its content. The experimental results demonstrate that the proposed method is superior because of the better performance when compared with other state-of-the-art methods. The method the authors used remove the instrument aging issue to a large extent, thus leading the reconstruction IR spectra a more convenient tool for extracting features of an unknown material and interpreting it.

  12. Experimental and theoretical study on the structure and vibrational spectra of β-2-aminopyridinium dihydrogenphosphate

    Science.gov (United States)

    Çırak, Çağrı; Demir, Selçuk; Ucun, Fatih; Çubuk, Osman

    2011-08-01

    Experimental and theoretical vibrational spectra of β-2-aminopyridinium dihydrogenphosphate (β-2APDP) have been investigated. The FT-IR spectrum of β-2APDP was recorded in the region 4000-400 cm -1. The optimized molecular structure and theoretical vibrational frequencies of β-2APDP have been investigated using ab initio Hartree-Fock (HF) and density functional B3LYP method with 6-311++G(d,p) basis set. The optimized geometric parameters (bond lengths and bond angles) and theoretical frequencies have been compared with the corresponding experimental data and it is found that they agree well with each other. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. Furthermore, the used scale factors were obtained from the ratio of the frequency values of the strongest peaks in the experimental and theoretical IR spectra. From the results it was concluded that the B3LYP method is superior to the HF method for the vibrational frequencies.

  13. Emission spectra of photoionized plasmas induced by intense EUV pulses: Experimental and theoretical investigations

    Science.gov (United States)

    Saber, Ismail; Bartnik, Andrzej; Skrzeczanowski, Wojciech; Wachulak, Przemysław; Jarocki, Roman; Fiedorowicz, Henryk

    2017-03-01

    Experimental measurements and numerical modeling of emission spectra in photoionized plasma in the ultraviolet and visible light (UV/Vis) range for noble gases have been investigated. The photoionized plasmas were created using laser-produced plasma (LPP) extreme ultraviolet (EUV) source. The source was based on a gas puff target; irradiated with 10ns/10J/10Hz Nd:YAG laser. The EUV radiation pulses were collected and focused using grazing incidence multifoil EUV collector. The laser pulses were focused on a gas stream, injected into a vacuum chamber synchronously with the EUV pulses. Irradiation of gases resulted in a formation of low temperature photoionized plasmas emitting radiation in the UV/Vis spectral range. Atomic photoionized plasmas produced this way consisted of atomic and ionic with various ionization states. The most dominated observed spectral lines originated from radiative transitions in singly charged ions. To assist in a theoretical interpretation of the measured spectra, an atomic code based on Cowan's programs and a collisional-radiative PrismSPECT code have been used to calculate the theoretical spectra. A comparison of the calculated spectral lines with experimentally obtained results is presented. Electron temperature in plasma is estimated using the Boltzmann plot method, by an assumption that a local thermodynamic equilibrium (LTE) condition in the plasma is validated in the first few ionization states. A brief discussion for the measured and computed spectra is given.

  14. A consensus successive projections algorithm--multiple linear regression method for analyzing near infrared spectra.

    Science.gov (United States)

    Liu, Ke; Chen, Xiaojing; Li, Limin; Chen, Huiling; Ruan, Xiukai; Liu, Wenbin

    2015-02-09

    The successive projections algorithm (SPA) is widely used to select variables for multiple linear regression (MLR) modeling. However, SPA used only once may not obtain all the useful information of the full spectra, because the number of selected variables cannot exceed the number of calibration samples in the SPA algorithm. Therefore, the SPA-MLR method risks the loss of useful information. To make a full use of the useful information in the spectra, a new method named "consensus SPA-MLR" (C-SPA-MLR) is proposed herein. This method is the combination of consensus strategy and SPA-MLR method. In the C-SPA-MLR method, SPA-MLR is used to construct member models with different subsets of variables, which are selected from the remaining variables iteratively. A consensus prediction is obtained by combining the predictions of the member models. The proposed method is evaluated by analyzing the near infrared (NIR) spectra of corn and diesel. The results of C-SPA-MLR method showed a better prediction performance compared with the SPA-MLR and full-spectra PLS methods. Moreover, these results could serve as a reference for combination the consensus strategy and other variable selection methods when analyzing NIR spectra and other spectroscopic techniques. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Combined use of infrared and Raman spectra in the characterization of orthoclase under various hydrostatic pressures.

    Science.gov (United States)

    Liu, Rui; Wang, Zhi-Hua; Xu, Qiang; Yu, Na; Cao, Miao-Cong

    2014-02-01

    Colorless and pink orthoclase from Balikun granite body, East Zhunger in Xinjiang, served as the samples for the research on hydrostatic pressure experiment. The in-situ hydrostatic pressure test for orthoclases was conducted at the room temperature and pressures from 100 to 600 MPa using cubic zirconia anvil cell, with quartz as pressure gauge. The water located in the orthoclases for the conditions of different hydrostatic pressures was characterized through the methods of Fourier transform infrared (FTIR) and Raman spectra. The results showed that there was a linear correlation between the shifting of Raman bands and hydrostatic pressure applied to the feldspar. All of vibration peaks of M-O structural groups in orthoclases, the bending vibration peaks of Si(Al(IV))-O-Si bond and tetrahedron groups of [SiO4] in Raman spectra shifted toward the higher frequency regularly, the drift distance is 2, 2.19 and less than 2 cm(-1) respectively. The spectra of FTIR suggested that there was more water in colorless orthoclases than the pink one under certain conditions of hydrostatic pressure. The intensity and integral area centered at 3420 cm(-1) in FTIR spectra increased with the rising of hydrostatic pressure. The integral area for colorless and pink feldspar in FTIR spectra rose from 120, 1383 cm(-1) under normal pressure to 1570, 2001 cm(-1) at 600 MPa respectively. The experimental results might indicate that the water in the earth crust could enter the orthoclases in certain condition of the aqueous confining pressure.

  16. Matrix isolation infrared spectroscopic and theoretical study of 1,1,1-trifluoro-2-chloroethane (HCFC-133a)

    Science.gov (United States)

    Rodrigues, Gessenildo Pereira; Lucena, Juracy Régis; Ventura, Elizete; Andrade do Monte, Silmar; Reva, Igor; Fausto, Rui

    2013-11-01

    The molecular structure and infrared spectrum of the atmospheric pollutant 1,1,1-trifluoro-2-chloroethane (HCFC-133a; CF3CH2Cl) in the ground electronic state were characterized experimentally and theoretically. Excited state calculations (at the CASSCF, MR-CISD, and MR-CISD+Q levels) have also been performed in the range up to ˜9.8 eV. The theoretical calculations show the existence of one (staggered) conformer, which has been identified spectroscopically for the monomeric compound isolated in cryogenic (˜10 K) argon and xenon matrices. The observed infrared spectra of the matrix-isolated HCFC-133a were interpreted with the aid of MP2/aug-cc-pVTZ calculations and normal coordinate analysis, which allowed a detailed assignment of the observed spectra to be carried out, including identification of bands due to different isotopologues (35Cl and 37Cl containing molecules). The calculated energies of the several excited states along with the values of oscillator strengths and previous results obtained for CFCs and HCFCs suggest that the previously reported photolyses of the title compound at 147 and 123.6 nm [T. Ichimura, A. W. Kirk, and E. Tschuikow-Roux, J. Phys. Chem. 81, 1153 (1977)] are likely to be initiated in the n-4s and n-4p Rydberg states, respectively.

  17. Infrared Spectra and Band Strengths of CH3SH, an Interstellar Molecule

    Science.gov (United States)

    Hudson, R. L.

    2016-01-01

    Three solid phases of CH3SH (methanethiol or methyl mercaptan) have been prepared and their mid-infrared spectra recorded at 10-110 degrees Kelvin, with an emphasis on the 17-100 degrees Kelvin region. Refractive indices have been measured at two temperatures and used to estimate ice densities and infrared band strengths. Vapor pressures for the two crystalline phases of CH3SH at 110 degrees Kelvin are estimated. The behavior of amorphous CH3SH on warming is presented and discussed in terms of Ostwald's step rule. Comparisons to CH3OH under similar conditions are made, and some inconsistencies and ambiguities in the CH3SH literature are examined and corrected.

  18. Infrared Spectra and Optical Constants of Astronomical Ices: II. Ethane and Ethylene

    Science.gov (United States)

    Hudson, Reggie L.; Gerakines, Perry A.; Moore, M. H.

    2014-01-01

    Infrared spectroscopic observations have established the presence of hydrocarbon ices on Pluto and other TNOs, but the abundances of such molecules cannot be deduced without accurate optical constants (n, k) and reference spectra. In this paper we present our recent measurements of near- and mid-infrared optical constants for ethane (C2H6) and ethylene (C2H4) in multiple ice phases and at multiple temperatures. As in our recent work on acetylene (C2H2), we also report new measurements of the index of refraction of each ice at 670 nm. Comparisons are made to earlier work where possible, and electronic versions of our new results are made available.

  19. Mid-infrared spectra of cometary dust: the evasion of its silicate mineralogy

    Science.gov (United States)

    Kimura, H.; Chigai, T.; Yamamoto, T.

    2008-04-01

    Infrared spectra of dust in cometary comae provide a way to identify its silicate constituents, and this is crucial for correctly understanding the condition under which our planetary system is formed. Recent studies assign a newly detected peak at a wavelength of 9.3 μm to pyroxenes and regard them as the most abundant silicate minerals in comets. Here we dispense with this pyroxene hypothesis to numerically reproduce the infrared features of cometary dust in the framework of our interstellar dust models. Presolar interstellar dust in a comet is modeled as fluffy aggregates consisting of submicrometer-sized organic grains with an amorphous-silicate core that undergoes nonthermal crystallization in a coma. We assert that forsterite (Mg2SiO4) is the carrier of all the observed features, including the 9.3 μm peak and that the major phase of iron is sulfides rather than iron-rich silicates.

  20. Infrared dispersion analysis and Raman scattering spectra of taurine single crystals

    Science.gov (United States)

    Moreira, Roberto L.; Lobo, Ricardo P. S. M.; Dias, Anderson

    2018-01-01

    A comprehensive set of optical vibrational modes of monoclinic taurine crystals was determined by Raman scattering, and infrared reflectivity and transmission spectroscopies. By using appropriate scattering/reflection geometries, the vibrational modes were resolved by polarization and the most relevant modes of the crystal could be assigned. In particular, we were able to review the symmetry of the gerade modes and to resolve ambiguities in the literature. Owing to the non-orthogonal character of Bu modes in monoclinic crystals (lying on the optic axial plane), we carried out a generalized Lorentz dispersion analysis consisting of simultaneous adjust of infrared-reflectivity spectra at various light polarization angles. The Au modes (parallel to the C2-axis) were treated within the classical Lorentz model. The behavior of off-diagonal and diagonal terms of the complex dielectric tensors and the presence of anomalous dispersion were discussed as consequences of the low symmetry of the crystal.

  1. THEORETICAL TRANSIT SPECTRA FOR GJ 1214b AND OTHER 'SUPER-EARTHS'

    Energy Technology Data Exchange (ETDEWEB)

    Howe, Alex R.; Burrows, Adam S., E-mail: arhowe@astro.princeton.edu, E-mail: burrows@astro.princeton.edu [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States)

    2012-09-10

    We present new calculations of transit spectra of super-Earths that allow for atmospheres with arbitrary proportions of common molecular species and haze. We test this method with generic spectra, reproducing the expected systematics and absorption features, then apply it to the nearby super-Earth GJ 1214b, which has produced conflicting observational data, leaving the questions of a hydrogen-rich versus hydrogen-poor atmosphere and the water content of the atmosphere ambiguous. We present representative transit spectra for a range of classes of atmosphere models for GJ 1214b. Our analysis supports a hydrogen-rich atmosphere with a cloud or haze layer, although a hydrogen-poor model with {approx}<10% water is not ruled out. Several classes of models are ruled out, however, including hydrogen-rich atmospheres with no haze, hydrogen-rich atmospheres with a haze of {approx}0.01 {mu}m tholin particles, and hydrogen-poor atmospheres with major sources of absorption other than water. We propose an observational test to distinguish hydrogen-rich from hydrogen-poor atmospheres. Finally, we provide a library of theoretical transit spectra for super-Earths with a broad range of parameters to facilitate future comparison with anticipated data.

  2. Infrared Spectra and Band Strengths of Amorphous and Crystalline N2O

    Science.gov (United States)

    Hudson, R. L.; Loeffler, M. J.; Gerakines, P. A.

    2017-01-01

    Infrared transmission spectra from 4000 to 400 cm (exp -1), and associated band strengths and absorption coefficients, are presented for the first time for both amorphous and crystalline N2O. Changes in the spectra as a function of ice thickness and ice temperature are shown. New measurements of density, refractive index, and specific refraction are reported for amorphous and crystalline N2O. Comparisons are made to published results, and the most-likely reason for some recent disagreements in the literature is discussed. As with CO2, its isoelectronic congener, the formation of amorphous N2O is found to require greater care than the formation of amorphous solids from more-polar molecules.

  3. THE INFRARED SPECTRA OF POLYCYCLIC AROMATIC HYDROCARBONS WITH SOME OR ALL HYDROGEN ATOMS REMOVED

    Energy Technology Data Exchange (ETDEWEB)

    Bauschlicher, Charles W. Jr. [Entry Systems and Technology Division, Mail Stop 230-3, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Ricca, Alessandra, E-mail: Charles.W.Bauschlicher@nasa.gov, E-mail: Alessandra.Ricca-1@nasa.gov [Carl Sagan Center, SETI Institute, 189 Bernardo Avenue, Mountain View, CA 94043 (United States)

    2013-10-20

    The loss of one hydrogen from C{sub 96}H{sub 24} does not significantly affect the infrared spectra of the neutral, cation, or anion. Excluding a very weak C-C stretching band at 5.1 μm, the loss of two adjacent duo hydrogens does not significantly affect the spectra compared with the parent. Removing all of the hydrogen atoms significantly increases the intensity of the new C-C stretching band, and, for the cation, shifts it to a longer (5.2 μm) wavelength. Observations show a feature near 5.25 μm, which has been attributed to overtone and combination bands from polycyclic aromatic hydrocarbons (PAHs). This current work suggests that dehydrogenated PAHs might also contribute to this band, but its weakness implies that fully dehydrogenated cationic or dicationic species are very rare.

  4. THE INFRARED SPECTRA OF POLYCYCLIC AROMATIC HYDROCARBONS WITH SOME OR ALL HYDROGEN ATOMS REMOVED

    International Nuclear Information System (INIS)

    Bauschlicher, Charles W. Jr.; Ricca, Alessandra

    2013-01-01

    The loss of one hydrogen from C 96 H 24 does not significantly affect the infrared spectra of the neutral, cation, or anion. Excluding a very weak C-C stretching band at 5.1 μm, the loss of two adjacent duo hydrogens does not significantly affect the spectra compared with the parent. Removing all of the hydrogen atoms significantly increases the intensity of the new C-C stretching band, and, for the cation, shifts it to a longer (5.2 μm) wavelength. Observations show a feature near 5.25 μm, which has been attributed to overtone and combination bands from polycyclic aromatic hydrocarbons (PAHs). This current work suggests that dehydrogenated PAHs might also contribute to this band, but its weakness implies that fully dehydrogenated cationic or dicationic species are very rare

  5. High-Resolution Infrared and Raman Spectra of the Polycrystalline Sinomenine Hydrochloride

    Directory of Open Access Journals (Sweden)

    Liu Xiao-Dong

    2016-01-01

    Full Text Available High-resolution infrared and Raman spectra of the polycrystalline sinomenine (SM hydrochloride have been measured to work out its whole really existing vibrational spectral bands. Except for the hydroxyl stretching modes and IR active bands less than 400 cm−1, most normal modes (about 34 are both IR and Raman active. In addition, 8 Raman bands less than 400 cm−1 are tentatively assigned, for the first time to our knowledge, to stretching/bending modes of the aromatic-ring−methoxyls and (SMH+–Cl− ions, respectively.

  6. Achromatic triplet and athermalized lens assembly for both midwave and longwave infrared spectra

    Science.gov (United States)

    Kuo, Chih-Wei

    2014-02-01

    Analytic solutions for finding the achromatic triplet in the midwave and longwave infrared spectra simultaneously are explored. The relationship between the combination of promising refractive materials and the system's optical power is also formulated. The principles for stabilizing the effective focal length of an air-spaced lens group with respect to temperature are explored, and the thermal properties of the optical component and mechanical elements mutually counterbalanced. An optical design based on these achromatic and athermal theories is demonstrated, and the image quality of the lens assembly seems to approach the diffractive limitation.

  7. Path integral Liouville dynamics: Applications to infrared spectra of OH, water, ammonia, and methane

    International Nuclear Information System (INIS)

    Liu, Jian; Zhang, Zhijun

    2016-01-01

    Path integral Liouville dynamics (PILD) is applied to vibrational dynamics of several simple but representative realistic molecular systems (OH, water, ammonia, and methane). The dipole-derivative autocorrelation function is employed to obtain the infrared spectrum as a function of temperature and isotopic substitution. Comparison to the exact vibrational frequency shows that PILD produces a reasonably accurate peak position with a relatively small full width at half maximum. PILD offers a potentially useful trajectory-based quantum dynamics approach to compute vibrational spectra of molecular systems

  8. Theoretical Atomic Physics code development IV: LINES, A code for computing atomic line spectra

    International Nuclear Information System (INIS)

    Abdallah, J. Jr.; Clark, R.E.H.

    1988-12-01

    A new computer program, LINES, has been developed for simulating atomic line emission and absorption spectra using the accurate fine structure energy levels and transition strengths calculated by the (CATS) Cowan Atomic Structure code. Population distributions for the ion stages are obtained in LINES by using the Local Thermodynamic Equilibrium (LTE) model. LINES is also useful for displaying the pertinent atomic data generated by CATS. This report describes the use of LINES. Both CATS and LINES are part of the Theoretical Atomic PhysicS (TAPS) code development effort at Los Alamos. 11 refs., 9 figs., 1 tab

  9. Strong scintillations during atmospheric occultations Theoretical intensity spectra. [radio scattering during spacecraft occultations by planetary atmospheres

    Science.gov (United States)

    Hinson, D. P.

    1986-01-01

    Each of the two Voyager spacecraft launched in 1977 has completed a reconnaissance of the Jovian and Saturnian systems. In connection with occultation experiments, strong scintillations were observed. Further theoretical work is required before these scintillations can be interpreted. The present study is, therefore, concerned with the derivation of a theory for strong scattering during atmospheric occultation experiments, taking into account as fundamental quantity of interest the spatial spectrum (or spectral density) of intensity fluctuations. Attention is given to a theory for intensity spectra, and numerical calculations. The new formula derived for Phi-i accounts for strong scattering of electromagnetic waves during atmospheric occultations.

  10. Preparation and infrared spectra of differently deuterated tetramethyl-derivatives of the IV. main group

    International Nuclear Information System (INIS)

    Biedermann, S.

    1972-01-01

    19 different deuterated tetramethyl derivates of the type (CH 3 )sub(4-n)M(CH 3 )sub(n) of C, Si, Ge, Sn and Pb were prepared. Gas cuvettes with polyethylene, NaCl and KBr windows were used to absorb the infra-red spectra, the IR equipment Beckman IR 11 and IR 12 were used. The infra-red spectra of the above mentioned compounds were indicated from 33 to 4,000 cm -1 , the ground, upper and combination vibrations assigned, the PR separations of the partly well resolved rotation-vibration outlines determined and were compared with the calculated PR separations. The revision of the correlations performed by Graham for γsub(s)CH 3 and γsub(as)CH 3 in the race of vibration F 2 with Sn(CH 3 ) 4 and Pb(CH 3 ) 4 and the proposed one with C(CH 3 ) 4 , Si(CH 3 ) 4 and Ge(CH 3 ) 4 could be disproved by the new experimental results. (FW) [de

  11. Vibrational infrared and Raman spectra of polypeptides: Fragments-in-fragments within molecular tailoring approach

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, Nityananda; Gadre, Shridhar R., E-mail: gadre@iitk.ac.in [Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)

    2016-03-21

    The present work reports the calculation of vibrational infrared (IR) and Raman spectra of large molecular systems employing molecular tailoring approach (MTA). Further, it extends the grafting procedure for the accurate evaluation of IR and Raman spectra of large molecular systems, employing a new methodology termed as Fragments-in-Fragments (FIF), within MTA. Unlike the previous MTA-based studies, the accurate estimation of the requisite molecular properties is achieved without performing any full calculations (FC). The basic idea of the grafting procedure is implemented by invoking the nearly basis-set-independent nature of the MTA-based error vis-à-vis the respective FCs. FIF has been tested out for the estimation of the above molecular properties for three isomers, viz., β-strand, 3{sub 10}- and α-helix of acetyl(alanine){sub n}NH{sub 2} (n = 10, 15) polypeptides, three conformers of doubly protonated gramicidin S decapeptide and trpzip2 protein (PDB id: 1LE1), respectively, employing BP86/TZVP, M06/6-311G**, and M05-2X/6-31G** levels of theory. For most of the cases, a maximum difference of 3 cm{sup −1} is achieved between the grafted-MTA frequencies and the corresponding FC values. Further, a comparison of the BP86/TZVP level IR and Raman spectra of α-helical (alanine){sub 20} and its N-deuterated derivative shows an excellent agreement with the existing experimental spectra. In view of the requirement of only MTA-based calculations and the ability of FIF to work at any level of theory, the current methodology provides a cost-effective solution for obtaining accurate spectra of large molecular systems.

  12. Modelling telluric line spectra in the optical and infrared with an application to VLT/X-Shooter spectra

    Science.gov (United States)

    Rudolf, N.; Günther, H. M.; Schneider, P. C.; Schmitt, J. H. M. M.

    2016-01-01

    Context. Earth's atmosphere imprints a large number of telluric absorption and emission lines on astronomical spectra, especially in the near infrared, that need to be removed before analysing the affected wavelength regions. Aims: These lines are typically removed by comparison to A- or B-type stars used as telluric standards that themselves have strong hydrogen lines, which complicates the removal of telluric lines. We have developed a method to circumvent that problem. Methods: For our IDL software package tellrem we used a recent approach to model telluric absorption features with the line-by-line radiative transfer model (LBLRTM). The broad wavelength coverage of the X-Shooter at VLT allows us to expand their technique by determining the abundances of the most important telluric molecules H2O, O2, CO2, and CH4 from sufficiently isolated line groups. For individual observations we construct a telluric absorption model for most of the spectral range that is used to remove the telluric absorption from the object spectrum. Results: We remove telluric absorption from both continuum regions and emission lines without systematic residuals for most of the processable spectral range; however, our method increases the statistical errors. The errors of the corrected spectrum typically increase by 10% for S/N ~ 10 and by a factor of two for high-quality data (S/N ~ 100), I.e. the method is accurate on the percent level. Conclusions: Modelling telluric absorption can be an alternative to the observation of standard stars for removing telluric contamination. Based on observations collected at the European Southern Observatory, Paranal, Chile, 085.C-0764(A) and 60.A-9022(C).The tellrem package is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/585/A113

  13. Time resolved spectra in the infrared absorption and emission from shock heated hydrocarbons. [in interstellar medium

    Science.gov (United States)

    Bauer, S. H.; Borchardt, D. B.

    1990-01-01

    The wavelength range of a previously constructed multichannel fast recording spectrometer was extended to the mid-infrared. With the initial configuration, light intensities were recorded simultaneously with a silicon-diode array simultaneously at 20 adjacent wavelengths, each with a 20-micron time resolution. For studies in the infrared, the silicon diodes were replaced by a 20-element PbSe array of similar dimensions, cooled by a three-stage thermoelectric device. It is proposed that infrared emissions could be due to shock-heated low molecular-weight hydrocarbons. The full Swan band system appeared in time-integrated emission spectra from shock-heated C2H2; no soot was generated. At low resolution, the profiles on the high-frequency side of the black body maximum show no distinctive features. These could be fitted to Planck curves, with temperatures that declined with time from an initial high that was intermediate between T5 (no conversion) and T5(eq).

  14. Water Vapor on Titan: The Stratospheric Vertical Profile from Cassini/CIRS Infrared Spectra

    Science.gov (United States)

    Cottini, V.; Jennings, D. E.; Nixon, C. A.; Anderson, C. M.; Gorius, N.; Bjoraker, G. L.; Coustenis, A.; Achterberg, R. K.; Teanby, N. A.; deKok, R.; hide

    2012-01-01

    Water vapor in Titan's middle atmosphere has previously been detected only by disk-average observations from the Infrared Space Observatory (Coustenis et al., 1998). We report here the successful detection of stratospheric water vapor using the Cassini Composite Infrared Spectrometer (CIRS, Flasar et al., 2004) following an earlier null result (de Kok et al., 2007a). CIRS senses water emissions in the far-infrared spectral region near 50 microns, which we have modeled using two independent radiative transfer and inversion codes (NEMESIS, Irwin et al 2008 and ART, Coustenis et al., 2010). From the analysis of nadir spectra we have derived a mixing ratio of (0.14 plus or minus 0.05) ppb at 100 km, corresponding to a column abundance of approximately (3.7 plus or minus 1.3) x 10(exp 14) moles per square centimeter. Using limb observations, we obtained mixing ratios of (0.13 plus or minus 0.04) ppb at 125 km and (0.45 plus or minus 0.15) ppb at 225 km of altitude, confirming that the water abundance has a positive vertical gradient as predicted by photochemical models. In the latitude range (80 deg. S - 30 deg. N) we see no evidence for latitudinal variations in these abundances within the error bars.

  15. MID-INFRARED SPECTRA OF TRANSITIONAL DISKS IN THE CHAMAELEON I CLOUD

    International Nuclear Information System (INIS)

    Kim, K. H.; Watson, Dan M.; Manoj, P.; Forrest, W. J.; Sargent, B.; McClure, M. K.; Green, J. D.; Harrold, Samuel T.; Furlan, E.; Najita, J.; Espaillat, C.; Calvet, N.; Luhman, K. L.

    2009-01-01

    We present 5-40 μm Spitzer Infrared Spectrograph spectra of a collection of transitional disks, objects for which the spectral energy distribution (SED) indicates central clearings (holes) or gaps in the dust distribution, in the Chamaeleon I star-forming region. Like their counterparts in the Taurus-Auriga star-forming region that we have previously observed, the spectra of these young objects (1-3 Myr old) reveal that the central clearings or gaps are very sharp-edged, and are surrounded by optically thick dusty disks similar to those around other classical T Tauri stars in the Chamaeleon I association. Also like the Taurus transitional disks, the Chamaeleon I transitional disks have extremely large depletion factors for small dust grains in their gaps, compared to the full accretion disks whose SEDs are represented by the median SED of Class II objects in the region. We find that the fraction of transitional disks in the Chamaeleon I cloud is somewhat higher than that in the Taurus-Auriga cloud, possibly indicating that the frequency of transitional disks, on average, increases with cluster age. We also find a significant correlation between the stellar mass and the radius of the outer edge of the gap. We discuss the disk structures implied by the spectra and the constraints they place on gap-formation mechanisms in protoplanetary disks.

  16. Modeling of aircraft exhaust emissions and infrared spectra for remote measurement of nitrogen oxides

    Directory of Open Access Journals (Sweden)

    K. Beier

    Full Text Available Infrared (IR molecular spectroscopy is proposed to perform remote measurements of NOx concentrations in the exhaust plume and wake of aircraft. The computer model NIRATAM is applied to simulate the physical and chemical properties of the exhaust plume and to generate low resolution IR spectra and synthetical thermal images of the aircraft in its natural surroundings. High-resolution IR spectra of the plume, including atmospheric absorption and emission, are simulated using the molecular line-by-line radiation model FASCODE2. Simulated IR spectra of a Boeing 747-400 at cruising altitude for different axial and radial positions in the jet region of the exhaust plume are presented. A number of spectral lines of NO can be identified that can be discriminated from lines of other exhaust gases and the natural atmospheric background in the region around 5.2 µm. These lines can be used to determine NO concentration profiles in the plume. The possibility of measuring nitrogen dioxide NO2 is also discussed briefly, although measurements turn out to be substantially less likely than those of NO. This feasibility study compiles fundamental data for the optical and radiometric design of an airborne Fourier transform spectrometer and the preparation of in-flight measurements for monitoring of aircraft pollutants.

  17. Modeling of aircraft exhaust emissions and infrared spectra for remote measurement of nitrogen oxides

    Directory of Open Access Journals (Sweden)

    K. Beier

    1994-08-01

    Full Text Available Infrared (IR molecular spectroscopy is proposed to perform remote measurements of NOx concentrations in the exhaust plume and wake of aircraft. The computer model NIRATAM is applied to simulate the physical and chemical properties of the exhaust plume and to generate low resolution IR spectra and synthetical thermal images of the aircraft in its natural surroundings. High-resolution IR spectra of the plume, including atmospheric absorption and emission, are simulated using the molecular line-by-line radiation model FASCODE2. Simulated IR spectra of a Boeing 747-400 at cruising altitude for different axial and radial positions in the jet region of the exhaust plume are presented. A number of spectral lines of NO can be identified that can be discriminated from lines of other exhaust gases and the natural atmospheric background in the region around 5.2 µm. These lines can be used to determine NO concentration profiles in the plume. The possibility of measuring nitrogen dioxide NO2 is also discussed briefly, although measurements turn out to be substantially less likely than those of NO. This feasibility study compiles fundamental data for the optical and radiometric design of an airborne Fourier transform spectrometer and the preparation of in-flight measurements for monitoring of aircraft pollutants.

  18. Post-maximum Near-infrared Spectra of SN 2014J: A Search for Interaction Signatures

    Science.gov (United States)

    Sand, D. J.; Hsiao, E. Y.; Banerjee, D. P. K.; Marion, G. H.; Diamond, T. R.; Joshi, V.; Parrent, J. T.; Phillips, M. M.; Stritzinger, M. D.; Venkataraman, V.

    2016-05-01

    We present near-infrared (NIR) spectroscopic and photometric observations of the nearby Type Ia SN 2014J. The 17 NIR spectra span epochs from +15.3 to +92.5 days after B-band maximum light, while the {{JHK}}s photometry include epochs from -10 to +71 days. These data are used to constrain the progenitor system of SN 2014J utilizing the Paβ line, following recent suggestions that this phase period and the NIR in particular are excellent for constraining the amount of swept-up hydrogen-rich material associated with a non-degenerate companion star. We find no evidence for Paβ emission lines in our post-maximum spectra, with a rough hydrogen mass limit of ≲ 0.1 M ⊙, which is consistent with previous limits in SN 2014J from late-time optical spectra of the Hα line. Nonetheless, the growing data set of high-quality NIR spectra holds the promise of very useful hydrogen constraints. Based on observations obtained at the Gemini Observatory under program GN-2014A-Q-8 (PI: Sand). Gemini is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil).

  19. Effect of Shear Applied During a Pharmaceutical Process on Near Infrared Spectra.

    Science.gov (United States)

    Hernández, Eduardo; Pawar, Pallavi; Rodriguez, Sandra; Lysenko, Sergiy; Muzzio, Fernando J; Romañach, Rodolfo J

    2016-03-01

    This study describes changes observed in the near-infrared (NIR) diffuse reflectance (DR) spectra of pharmaceutical tablets after these tablets were subjected to different levels of strain (exposure to shear) during the mixing process. Powder shearing is important in the mixing of powders that are cohesive. Shear stress is created in a system by moving one surface over another causing displacements in the direction of the moving surface and is part of the mixing dynamics of particulates in many industries including the pharmaceutical industry. In continuous mixing, shear strain is developed within the process when powder particles are in constant movement and can affect the quality attributes of the final product such as dissolution. These changes in the NIR spectra could affect results obtained from NIR calibration models. The aim of the study was to understand changes in the NIR diffuse reflectance spectra that can be associated with different levels of strain developed during blend shearing of laboratory samples. Shear was applied using a Couette cell and tablets were produced using a tablet press emulator. Tablets with different shear levels were measured using NIR spectroscopy in the diffuse reflectance mode. The NIR spectra were baseline corrected to maintain the scattering effect associated with the physical properties of the tablet surface. Principal component analysis was used to establish the principal sources of variation within the samples. The angular dependence of elastic light scattering shows that the shear treatment reduces the size of particles and produces their uniform and highly isotropic distribution. Tablet compaction further reduces the diffuse component of scattering due to realignment of particles. © The Author(s) 2016.

  20. Time resolved spectra in the infrared absorption and emission from shock heated hydrocarbons

    Science.gov (United States)

    Bauer, S. H.; Borchardt, D. B.

    1990-07-01

    We have extended the wavelength range of our previously constructed multichannel, fast recording spectrometer to the mid-infrared. With the initial configuration, using a silicon-diode (photovoltaic) array, we recorded light intensities simultaneously at 20 adjacent wavelengths, each with 20 μs time resolution. For studies in the infrared the silicon diodes are replaced by a 20 element PbSe (photoconducting) array of similar dimensions (1×4 mm/element), cooled by a three-stage thermoelectric device. These elements have useful sensitivities over 1.0-6.7 μm. Three interchangeable gratings in a 1/4 m monochromator cover the following spectral ranges: 1.0-2.5 μm (resolution 33.6 cm-1) 2.5-4.5 μm (16.8 cm-1) 4.0-6.5 μm (16.7 cm-1). Incorporated in the new housing there are individually controlled bias-power sources for each detector, two stages of analogue amplification and a 20-line parallel output to the previously constructed digitizer, and record/hold computer. The immediate application of this system is the study of emission and absorption spectra of shock heated hydrocarbons-C2H2, C4H4 and C6H6-which are possible precursors of species that generate infrared emissions in the interstellar medium. It has been recently proposed that these radiations are due to PAH that emit in the infrared upon relaxation from highly excited states. However, it is possible that such emissions could be due to shock-heated low molecular-weight hydrocarbons, which are known to be present in significant abundances, ejected into the interstellar medium during stellar outer atmospheric eruptions. The full Swan band system appeared in time-integrated emission spectra from shock heated C2H2 (1% in Ar; T5eq~=2500K) no soot was generated. At low resolution the profiles on the high frequency side of the black body maximum show no distinctive features. These could be fitted to Planck curves, with temperatures that declined with time from an initial high that was intermediate between T5 (no

  1. Predicting ambient aerosol Thermal Optical Reflectance (TOR) measurements from infrared spectra: organic carbon

    Science.gov (United States)

    Dillner, A. M.; Takahama, S.

    2014-11-01

    Organic carbon (OC) can constitute 50% or more of the mass of atmospheric particulate matter. Typically, the organic carbon concentration is measured using thermal methods such as Thermal-Optical Reflectance (TOR) from quartz fiber filters. Here, methods are presented whereby Fourier Transform Infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters are used to accurately predict TOR OC. Transmittance FT-IR analysis is rapid, inexpensive, and non-destructive to the PTFE filters. To develop and test the method, FT-IR absorbance spectra are obtained from 794 samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites sampled during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to artifact-corrected TOR OC. The FTIR spectra are divided into calibration and test sets by sampling site and date which leads to precise and accurate OC predictions by FT-IR as indicated by high coefficient of determination (R2; 0.96), low bias (0.02 μg m-3, all μg m-3 values based on the nominal IMPROVE sample volume of 32.8 m-3), low error (0.08 μg m-3) and low normalized error (11%). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision and accuracy to collocated TOR measurements. FT-IR spectra are also divided into calibration and test sets by OC mass and by OM / OC which reflects the organic composition of the particulate matter and is obtained from organic functional group composition; this division also leads to precise and accurate OC predictions. Low OC concentrations have higher bias and normalized error due to TOR analytical errors and artifact correction errors, not due to the range of OC mass of the samples in the calibration set. However, samples with low OC mass can be used to predict samples with high OC mass indicating that the

  2. Infrared Spectra and Optical Constants of Astronomical Ices: I. Amorphous and Crystalline Acetylene

    Science.gov (United States)

    Hudson, R. L.; Ferrante, R. F.; Moore, M. H.

    2013-01-01

    Here we report recent measurements on acetylene (C2H2) ices at temperatures applicable to the outer Solar System and the interstellar medium. New near- and mid-infrared data, including optical constants (n, k), absorption coefficients (alpha), and absolute band strengths (A), are presented for both amorphous and crystalline phases of C2H2 that exist below 70 K. Comparisons are made to earlier work. Electronic versions of the data are made available, as is a computer routine to use our reported n and k values to simulate the observed IR spectra. Suggestions are given for the use of the data and a comparison to a spectrum of Makemake is made.

  3. Matrix radiolysis and photoionization of CFCl3. Infrared spectra of CFCl+2 and the parent cation

    International Nuclear Information System (INIS)

    Prochaska, F.T.; Andrews, L.

    1978-01-01

    The ''Freon'' compound CFCl 3 has been subjected to radiolysis and photoionization during condensation with excess argon at 15 K. Infrared spectra of the matrix samples identified stable and free radical products and new absorptions which are attributed to charged species. The molecular ion bands exhibited three different behavior patterns on filtered mercury arc photolysis: The most photosensitive bands, destroyed by 420--1000 nm light, are assigned to the parent cation; several absorptions which photodissociated with 290--1000 nm radiation are due to a molecular anionic species; and new bands reduced by 220--1000 nm light are assigned to the daughter cation CFCl + 2 . The vibrational assignments were confirmed by carbon-13 substitution

  4. Extraction of Curcumin Pigment from Indonesian Local Turmeric with Its Infrared Spectra and Thermal Decomposition Properties

    Science.gov (United States)

    Nandiyanto, A. B. D.; Wiryani, A. S.; Rusli, A.; Purnamasari, A.; Abdullah, A. G.; Ana; Widiaty, I.; Hurriyati, R.

    2017-03-01

    Curcumin is one of the pigments which is used as a spice in Asian cuisine, traditional cosmetic, and medicine. Therefore, process for getting curcumin has been widely studied. Here, the purpose of this study was to demonstrate the simple method for extracting curcumin from Indonesian local turmeric and investigate the infrared spectra and thermal decomposition properties. In the experimental procedure, the washed turmeric was dissolved into an ethanol solution, and then put into a rotary evaporator to enrich curcumin concentration. The result showed that the present method is effective to isolate curcumin compound from Indonesian local turmeric. Since the process is very simple, this method can be used for home industrial application. Further, understanding the thermal decomposition properties of curcumin give information, specifically relating to the selection of treatment when curcumin must face the thermal-related process.

  5. Fourier transform infrared emission spectra of MnH and MnD

    Science.gov (United States)

    Gordon, Iouli E.; Appadoo, Dominique R. T.; Shayesteh, Alireza; Walker, Kaley A.; Bernath, Peter F.

    2005-01-01

    Fourier transform infrared emission spectra of MnH and MnD were observed in the ground X7Σ + electronic state. The vibration-rotation bands from v = 1 → 0 to v = 3 → 2 for MnH and from v = 1 → 0 to v = 4 → 3 for MnD were recorded at an instrumental resolution of 0.0085 cm -1. Spectroscopic constants were determined for each vibrational level and equilibrium constants were found from a Dunham-type fit. The equilibrium vibrational constant ( ωe) for MnH was found to be 1546.84518(65) cm -1, the equilibrium rotational constant ( Be) is 5.6856789(103) cm -1 and the eqilibrium bond distance ( re) was determined to be 1.7308601(47) Å.

  6. Hemoglobin concentration determination based on near infrared spatially resolved transmission spectra

    Science.gov (United States)

    Zhang, Linna; Li, Gang; Lin, Ling

    2016-10-01

    Spatially resolved diffuse reflectance spectroscopy method has been proved to be more effective than single point spectroscopy method in the experiment to predict the concentration of the Intralipid diluted solutions. However, Intralipid diluted solution is simple, cannot be the representative of turbid liquids. Blood is a natural and meaningful turbid liquid, more complicate. Hemoglobin is the major constituent of the whole blood. And hemoglobin concentration is commonly used in clinical medicine to diagnose many diseases. In this paper, near infrared spatially resolved transmission spectra (NIRSRTS) and Partial Least Square Regression (PLSR) were used to predict the hemoglobin concentration of human blood. The results showed the prediction ability for hemoglobin concentration of the proposed method is better than single point transmission spectroscopy method. This paper demonstrated the feasibility of the spatially resolved diffuse reflectance spectroscopy method for practical liquid composition analysis. This research provided a new thinking of practical turbid liquid composition analysis.

  7. Communications: On artificial frequency shifts in infrared spectra obtained from centroid molecular dynamics: Quantum liquid water

    Science.gov (United States)

    Ivanov, Sergei D.; Witt, Alexander; Shiga, Motoyuki; Marx, Dominik

    2010-01-01

    Centroid molecular dynamics (CMD) is a popular method to extract approximate quantum dynamics from path integral simulations. Very recently we have shown that CMD gas phase infrared spectra exhibit significant artificial redshifts of stretching peaks, due to the so-called "curvature problem" imprinted by the effective centroid potential. Here we provide evidence that for condensed phases, and in particular for liquid water, CMD produces pronounced artificial redshifts for high-frequency vibrations such as the OH stretching band. This peculiar behavior intrinsic to the CMD method explains part of the unexpectedly large quantum redshifts of the stretching band of liquid water compared to classical frequencies, which is improved after applying a simple and rough "harmonic curvature correction."

  8. Mid-infrared emission and Raman spectra analysis of Er(3+)-doped oxyfluorotellurite glasses.

    Science.gov (United States)

    Chen, Fangze; Xu, Shaoqiong; Wei, Tao; Wang, Fengchao; Cai, Muzhi; Tian, Ying; Xu, Shiqing

    2015-04-10

    This paper reports on the spectroscopic and structural properties in Er(3+)-doped oxyfluorotellurite glasses. The compositional variation accounts for the evolutions of Raman spectra, Judd-Ofelt parameters, radiative properties, and fluorescent emission. It is found that, when maximum phonon energy changes slightly, phonon density plays a crucial role in quenching the 2.7 μm emission generated by the Er(3+):(4)I11/2→(4)I13/2 transition. The comparative low phonon density contributes strong 2.7 μm emission intensity. The high branching ratio (18.63%) and large emission cross section (0.95×10(-20)  cm(2)) demonstrate that oxyfluorotellurite glass contained with 50 mol.% TeO2 has potential application in the mid-infrared region laser.

  9. Vibron Solitons and Soliton-Induced Infrared Spectra of Crystalline Acetanilide

    Science.gov (United States)

    Takeno, S.

    1986-01-01

    Red-shifted infrared spectra at low temperatures of amide I (C=O stretching) vibrations of crystalline acetanilide measured by Careri et al. are shown to be due to vibron solitons, which are nonlinearity-induced localized modes of vibrons arising from their nonlinear interactions with optic-type phonons. A nonlinear eigenvalue equation giving the eigenfrequency of stationary solitons is solved approximately by introducing lattice Green's functions, and the obtained result is in good agreement with the experimental result. Inclusion of interactions with acoustic phonons yields the Debye-Waller factor in the zero-phonon line spectrum of vibron solitons, in a manner analogous to the case of impurity-induced localized harmonic phonon modes in alkali halides.

  10. [Analysis of the stability and adaptability of near infrared spectra qualitative analysis model].

    Science.gov (United States)

    Cao, Wu; Li, Wei-jun; Wang, Ping; Zhang, Li-ping

    2014-06-01

    The stability and adaptability of model of near infrared spectra qualitative analysis were studied. Method of separate modeling can significantly improve the stability and adaptability of model; but its ability of improving adaptability of model is limited. Method of joint modeling can not only improve the adaptability of the model, but also the stability of model, at the same time, compared to separate modeling, the method can shorten the modeling time, reduce the modeling workload; extend the term of validity of model, and improve the modeling efficiency. The experiment of model adaptability shows that, the correct recognition rate of separate modeling method is relatively low, which can not meet the requirements of application, and joint modeling method can reach the correct recognition rate of 90%, and significantly enhances the recognition effect. The experiment of model stability shows that, the identification results of model by joint modeling are better than the model by separate modeling, and has good application value.

  11. Theoretical aspects and the experience of studying spectra of low-frequency microseisms

    Science.gov (United States)

    Birialtsev, E.; Vildanov, A.; Eronina, E.; Rizhov, D.; Rizhov, V.; Sharapov, I.

    2009-04-01

    The appearance of low-frequency spectral anomalies in natural microseismic noise over oil and gas deposits is observed since 1989 in different oil and gas regions (S. Arutunov, S. Dangel, G. Goloshubin). Several methods of prospecting and exploration of oil and gas deposits based on this effect (NTK ANCHAR, Spectraseis AG). There are several points of view (S. Arutunov, E. Birialtsev, Y. Podladchikov) about the physical model of effect which are based on fundamentally different geophysical mechanisms. One of them is based on the hypothesis of generation of the microseismic noise in to an oil and gas reservoir. Another point of view is based on the mechanism of the filtering microseismic noise in the geological medium where oil and gas reservoir is the contrast layer. For the first hypothesis an adequate quantity physical-mathematical model is absent. Second hypothesis has a discrepancy of distribution energy on theoretical calculated frequencies of waveguides «ground surface - oil deposit» eigenmodes. The fundamental frequency (less than 1 Hz for most cases) should have a highest amplitude as opposed to the regular observation range is 1-10 Hz. During 2005-2008 years by specialists of «Gradient» JSC were processed microsesmic signals from more 50 geological objects. The parameters of low-frequency anomalies were compared with medium properties (porosity, saturation and viscosity) defined according to drilling, allowed to carry out a statistical analysis and to establish some correlation. This paper presents results of theoretical calculation of spectra of microseisms in the zone of oil and gas deposits by mathematical modeling of propagation of seismic waves and comparing spectra of model microseisms with actually observed. Mathematical modeling of microseismic vibrations spectra showed good correlation of theoretical spectra and observed in practice. This is proof the applicability of microseismic methods of exploration for oil and gas. Correlation between

  12. Gas-phase infrared spectrum of phosphorus (III) oxycyanide, OPCN: experimental and theoretical investigations

    Science.gov (United States)

    Allaf, Abdul. W.; Kassem, M.; Alibrahim, M.; Boustani, Ihsan

    1999-03-01

    An attempt was made to observe the gas-phase infrared spectrum of Phosphorus (III) oxycyanide, OPCN for the first time. This molecule was produced by an on-line process using phosphorus (III) oxychloride, OPCl as precursor passed over heated AgCN. The products were characterised by the infrared spectra of their vapours. The low resolution gas-phase Fourier transform infrared spectrum shows two bands centered at 2165 and 1385 cm -1. These bands are assigned to, ν1 (CN stretch) and ν2 (OP stretch), respectively. Ab initio self-consistent-field (SCF) molecular orbital (MO) and Møller-Plesset second order perturbation theory (MP2) calculations were performed to determine the geometry, total energy and vibrational frequencies of OPCN.

  13. Correlation of vapor phase infrared spectra and regioisomeric structure in synthetic cannabinoids

    Science.gov (United States)

    Smith, Lewis W.; Thaxton-Weissenfluh, Amber; Abiedalla, Younis; DeRuiter, Jack; Smith, Forrest; Clark, C. Randall

    2018-05-01

    The twelve 1-n-pentyl-2-, 3-, 4-, 5-, 6- and 7-(1- and 2-naphthoyl)-indoles each have the same substituents attached to the indole ring, identical elemental composition (C24H23NO) yielding identical nominal and accurate masses. These twelve isomers cover all possible positions of carbonyl bridge substitution for both indole (positons 2-7) and naphthalene rings (positions 1 and 2). Regioisomeric compounds can represent significant challenges for mass based analytical methods however, infrared spectroscopy is a powerful tool for the identification of positional isomers in organic compounds. The vapor phase infrared spectra of these twelve uniquely similar compounds were evaluated in GC-IR experiments. These spectra show the bridge position on the indole ring is a dominating influence over the carbonyl absorption frequency observed for these compounds. Substitution on the pyrrole moiety of the indole ring yields the lowest Cdbnd O frequency values for position 2 and 3 giving a narrow range from 1656 to 1654 cm-1. Carbonyl absorption frequencies are higher when the naphthoyl group is attached to the benzene portion of the indole ring yielding absorption values from 1674 to 1671 cm-1. The aliphatic stretching bands in the 2900 cm-1 region yield a consistent triplet pattern because the N-alkyl substituent tail group remains unchanged for all twelve regioisomers. The asymmetric CH2 stretch is the most intense of these three bands. Changes in positional bonding for both the indole and naphthalene ring systems results in unique patterns within the 700 wavenumber out-of-plane region and these absorption bands are different for all 12 regioisomers.

  14. Fast forward modeling of Titan’s infrared spectra to invert VIMS/CASSINI hyperspectral images

    Science.gov (United States)

    Rodriguez, S.; Le Mouélic, S.; Rannou, P.; Combe, J.; Le Corre, L.; Griffith, C. A.; Tobie, G.; Barnes, J. W.; Sotin, C.; Brown, R. H.; Baines, K. H.; Buratti, B. J.; Clark, R. N.

    2009-12-01

    The surface of Titan, the largest icy moon of Saturn, is veiled by a very thick and hazy atmosphere. The Visual and Infrared Mapping Spectrometer onboard the Cassini spacecraft, in orbit around Saturn since July 2004, has been conducting an intensive survey of Titan with the objective of understanding the complex nature and interaction of the atmosphere and surface of this mysterious moon. Retrieving and separating contributions from the surface and the atmosphere in Titan’s infrared spectra requires accurate radiative transfer modeling, which is often very demanding of computer resources. As Cassini has gathered hitherto millions of spectra of Titan and will continue to observe it until at least 2010, we report here on the development of a new rapid, simple and versatile radiative transfer model specially designed to process VIMS datacubes. Currently, our model accounts for gas absorption, haze scattering and surface reflectance and can be implemented in an inversion scheme. First results of forward modeling provide spectral shapes that are consistent with VIMS measurements, as well as surface and aerosol properties in the range of validity for Titan. Further inversion tests will be carried on VIMS hyperspectral images for the estimate of spatial coherence of the results, accuracy of the surface reflectance within the atmospheric windows, and potential needs for improved input data and modeling. This work was partly performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to the National Aeronautics and Space Administration. Calibrated VIMS data appear courtesy of the VIMS team. We thank the CNES French agency for its financial support.

  15. Matrix-isolation FT-IR spectra and theoretical study of dimethyl sulfate

    Science.gov (United States)

    Borba, Ana; Gómez-Zavaglia, Andrea; Simões, Pedro N. N. L.; Fausto, Rui

    2005-05-01

    The preferred conformations of dimethyl sulfate and their vibrational spectra were studied by matrix-isolation FT-IR spectroscopy and theoretical methods (DFT and MP2, with basis sets of different sizes, including the quadruple-zeta, aug-cc-pVQZ basis). Conformer GG (of C 2 symmetry and exhibiting O sbnd S sbnd O sbnd C dihedral angles of 74.3°) was found to be the most stable conformer in both the gaseous phase and isolated in argon. Upon annealing of the matrix, the less stable observed conformer (GT; with C 1 symmetry) quickly converts to the GG conformer, with the resulting species being embedded in a matrix-cage which corresponds to the most stable matrix-site for GG form. The highest energy TT conformer, which was assumed to be the most stable conformer in previous studies, is predicted by the calculations to have a relative energy of ca. 10 kJ mol -1 and was not observed in the spectra of the matrix-isolated compound.

  16. Protonation effects on the UV/Vis absorption spectra of imatinib: a theoretical and experimental study.

    Science.gov (United States)

    Grante, Ilze; Actins, Andris; Orola, Liana

    2014-08-14

    An experimental and theoretical investigation of protonation effects on the UV/Vis absorption spectra of imatinib showed systematic changes of absorption depending on the pH, and a new absorption band appeared below pH 2. These changes in the UV/Vis absorption spectra were interpreted using quantum chemical calculations. The geometry of various imatinib cations in the gas phase and in ethanol solution was optimized with the DFT/B3LYP method. The resultant geometries were compared to the experimentally determined crystal structures of imatinib salts. The semi-empirical ZINDO-CI method was employed to calculate the absorption lines and electronic transitions. Our study suggests that the formation of the extra near-UV absorption band resulted from an increase of imatinib trication concentration in the solution, while the rapid increase of the first absorption maximum could be attributed to both the formation of imatinib trication and tetracation. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Infrared spectroscopy of copper-resveratrol complexes: A joint experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Chiavarino, B.; Crestoni, M. E.; Fornarini, S. [Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza - Universita di Roma, Piazzale A. Moro 5, 00185 Rome (Italy); Taioli, S. [Interdisciplinary Laboratory for Computational Science, FBK-CMM and University of Trento, Via Sommarive 18, 38123 Trento (Italy); Department of Physics, University of Trento, Via Sommarive 14, 38123 Trento (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Perugia (Italy); Department of Chemistry, University of Bologna, Via F. Selmi 2, I-40126 Bologna (Italy); Mancini, I.; Tosi, P. [Department of Physics, University of Trento, Via Sommarive 14, 38123 Trento (Italy)

    2012-07-14

    Infrared multiple-photon dissociation spectroscopy has been used to record vibrational spectra of charged copper-resveratrol complexes in the 3500-3700 cm{sup -1} and 1100-1900 cm{sup -1} regions. Minimum energy structures have been determined by density functional theory calculations using plane waves and pseudopotentials. In particular, the copper(I)-resveratrol complex presents a tetra-coordinated metal bound with two carbon atoms of the alkenyl moiety and two closest carbons of the adjoining resorcinol ring. For these geometries vibrational spectra have been calculated by using linear response theory. The good agreement between experimental and calculated IR spectra for the selected species confirms the overall reliability of the proposed geometries.

  18. Infrared spectroscopy of copper-resveratrol complexes: A joint experimental and theoretical study

    International Nuclear Information System (INIS)

    Chiavarino, B.; Crestoni, M. E.; Fornarini, S.; Taioli, S.; Mancini, I.; Tosi, P.

    2012-01-01

    Infrared multiple-photon dissociation spectroscopy has been used to record vibrational spectra of charged copper-resveratrol complexes in the 3500–3700 cm −1 and 1100–1900 cm −1 regions. Minimum energy structures have been determined by density functional theory calculations using plane waves and pseudopotentials. In particular, the copper(I)-resveratrol complex presents a tetra-coordinated metal bound with two carbon atoms of the alkenyl moiety and two closest carbons of the adjoining resorcinol ring. For these geometries vibrational spectra have been calculated by using linear response theory. The good agreement between experimental and calculated IR spectra for the selected species confirms the overall reliability of the proposed geometries.

  19. THE REINCARNATION OF INTERSTELLAR DUST: THE IMPORTANCE OF ORGANIC REFRACTORY MATERIAL IN INFRARED SPECTRA OF COMETARY COMAE AND CIRCUMSTELLAR DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Hiroshi, E-mail: hiroshi_kimura@cps-jp.org [Graduate School of Science, Kobe University, c/o CPS (Center for Planetary Science), Chuo-ku Minatojima Minamimachi 7-1-48, Kobe 650-0047 (Japan)

    2013-09-20

    We consider the reincarnation of interstellar dust to be reborn in protoplanetary disks as aggregates consisting of submicron-sized grains with a crystalline or amorphous silicate core and an organic-rich carbonaceous mantle. We find that infrared spectra of reincarnated interstellar dust reproduce emission peaks at correct wavelengths where the peaks were observed in cometary comae, debris disks, and protoplanetary disks if the volume fraction of organic refractory meets the constraints on elemental abundances. We discuss what we can learn from the infrared spectra of reincarnated interstellar dust in cometary comae and circumstellar disks.

  20. The Reincarnation of Interstellar Dust: The Importance of Organic Refractory Material in Infrared Spectra of Cometary Comae and Circumstellar Disks

    Science.gov (United States)

    Kimura, Hiroshi

    2013-09-01

    We consider the reincarnation of interstellar dust to be reborn in protoplanetary disks as aggregates consisting of submicron-sized grains with a crystalline or amorphous silicate core and an organic-rich carbonaceous mantle. We find that infrared spectra of reincarnated interstellar dust reproduce emission peaks at correct wavelengths where the peaks were observed in cometary comae, debris disks, and protoplanetary disks if the volume fraction of organic refractory meets the constraints on elemental abundances. We discuss what we can learn from the infrared spectra of reincarnated interstellar dust in cometary comae and circumstellar disks.

  1. THE REINCARNATION OF INTERSTELLAR DUST: THE IMPORTANCE OF ORGANIC REFRACTORY MATERIAL IN INFRARED SPECTRA OF COMETARY COMAE AND CIRCUMSTELLAR DISKS

    International Nuclear Information System (INIS)

    Kimura, Hiroshi

    2013-01-01

    We consider the reincarnation of interstellar dust to be reborn in protoplanetary disks as aggregates consisting of submicron-sized grains with a crystalline or amorphous silicate core and an organic-rich carbonaceous mantle. We find that infrared spectra of reincarnated interstellar dust reproduce emission peaks at correct wavelengths where the peaks were observed in cometary comae, debris disks, and protoplanetary disks if the volume fraction of organic refractory meets the constraints on elemental abundances. We discuss what we can learn from the infrared spectra of reincarnated interstellar dust in cometary comae and circumstellar disks

  2. Water Vapor in Titan's Stratosphere from Cassini CIRS Far-Infrared Spectra

    Science.gov (United States)

    Cottini, V.; Nixon, C. A.; Jennings, D. E.; Anderson, C. M.; Gorius, N.; Bjoraker, G. L.; Coustenis, A.; Teanby, N. A.; Achterberg, R. K.; Bezard, B.; hide

    2012-01-01

    Here we report the measurement of water vapor in Titan's stratosphere using the Cassini Composite Infrared Spectrometer (CIRS). CIRS senses water emissions in the far infrared spectral region near 50 micron, which we have modeled using two independent radiative transfer codes. From the analysis of nadir spectra we have derived a mixing ratio of 0.14 +/- 0.05 ppb at an altitude of 97 km, which corresponds to an integrated (from 0 to 600 km) surface normalized column abundance of 3.7 +/- 1.3 1014 molecules/cm2. In the latitude range 80S to 30N we see no evidence for latitudinal variations in these abundances within the error bars. Using limb observations, we obtained mixing ratios of 0.13 +/- 0.04 ppb at an altitude of 115 km and 0.45 +/- 0.15 ppb at an altitude of 230 km, confirming that the water abundance has a positive vertical gradient as predicted by photochemical models. We have also fitted our data using scaling factors of 0.1-0.6 to these photochemical model profiles, indicating that the models over-predict the water abundance in Titan's lower stratosphere.

  3. Infrared spectra of phosphate sorbed on iron hydroxide gel and the sorption products

    International Nuclear Information System (INIS)

    Nanzyo, M.

    1986-01-01

    Infrared absorption spectra of phosphate sorbed on iron hydroxide gel were obtained by applying the differential diffuse reflectance method. Absorption bands due to P-O stretching vibration were observed at 1,110 and 1,010 cm -1 at pH 12.3. With decreasing pH, these absorption bands gradually shifted to 1,100 and 1,020 cm -1 at pH 4.9. At pH 2.3, they became a broad single absorption band at 1,060 cm -1 . At pH 11 or above, the difference in the Na + adsorption between phosphated iron hydroxide gel and iron hydroxide gel was almost equal to the amount of phosphate sorption. This finding shows that phosphate was retained on the iron hydroxide gel surface as a bidentate ligand at a high pH. It was concluded that at a high pH phosphate was sorbed on iron hydroxide gel as a binuclear surface complex similar to that on goethite; the change in spectra for P-O stretching vibration with decreasing pH value was mainly caused by an increase in the fraction of amorphous iron phosphate; at pH 2.3, the phosphate sorption product consisted of amorphous iron phosphate. (author)

  4. Ensemble preprocessing of near-infrared (NIR) spectra for multivariate calibration

    International Nuclear Information System (INIS)

    Xu Lu; Zhou Yanping; Tang Lijuan; Wu Hailong; Jiang Jianhui; Shen Guoli; Yu Ruqin

    2008-01-01

    Preprocessing of raw near-infrared (NIR) spectral data is indispensable in multivariate calibration when the measured spectra are subject to significant noises, baselines and other undesirable factors. However, due to the lack of sufficient prior information and an incomplete knowledge of the raw data, NIR spectra preprocessing in multivariate calibration is still trial and error. How to select a proper method depends largely on both the nature of the data and the expertise and experience of the practitioners. This might limit the applications of multivariate calibration in many fields, where researchers are not very familiar with the characteristics of many preprocessing methods unique in chemometrics and have difficulties to select the most suitable methods. Another problem is many preprocessing methods, when used alone, might degrade the data in certain aspects or lose some useful information while improving certain qualities of the data. In order to tackle these problems, this paper proposes a new concept of data preprocessing, ensemble preprocessing method, where partial least squares (PLSs) models built on differently preprocessed data are combined by Monte Carlo cross validation (MCCV) stacked regression. Little or no prior information of the data and expertise are required. Moreover, fusion of complementary information obtained by different preprocessing methods often leads to a more stable and accurate calibration model. The investigation of two real data sets has demonstrated the advantages of the proposed method

  5. Oxygen infrared spectra of oxyhemoglobins and oxymyoglobins. Evidence of two major liganded O2 structures

    International Nuclear Information System (INIS)

    Potter, W.T.; Tucker, M.P.; Houtchens, R.A.; Caughey, W.S.

    1987-01-01

    The dioxygen stretch bands in infrared spectra for solutions of oxy species of human hemoglobin A and its separated subunits, human mutant hemoglobin Zurich (β63His to Arg), rabbit hemoglobin, lamprey, hemoglobin, sperm whale myoglobin, bovine myoglobin, and a sea worm chlorocruorin are examined. Each protein exhibits multiple isotope-sensitive bands between 1160 and 1060 cm -1 for the liganded 16 O 2 , 17 O 2 , and 18 O 2 . The O-O stretch bands for each of the mammalian myoglobins and hemoglobins are similar, with frequencies that differ between proteins by only 3-5 cm -1 . The spectra for the lamprey and sea worm hemoglobins exhibit greater diversity. For all proteins an O-O stretch band expected to occur near 1125 cm -1 for 16 O 2 and 17 O 2 , but not 18 O 2 , appears split by ∼25 cm -1 due to an unidentified perturbation. The spectrum for each dioxygen isotope, if unperturbed, would contain two strong bands for the mammalian myoglobins (1150 and 1120 cm -1 ) and hemoglobins (1155 and 1125 cm -1 ). Two strong bands separated by ∼30 cm -1 for each oxy heme protein subunit indicate that two major protein conformations (structure) that differ substantially in O 2 bonding are present. The two dioxygen structures can result from a combination of dynamic distal and proximal effects upon the O 2 ligand bound in a bent-end-on stereochemistry

  6. CHARACTERIZING THE INFRARED SPECTRA OF SMALL, NEUTRAL, FULLY DEHYDROGENATED POLYCYCLIC AROMATIC HYDROCARBONS

    Energy Technology Data Exchange (ETDEWEB)

    Mackie, C. J.; Peeters, E.; Cami, J. [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada); Bauschlicher, C. W. Jr., E-mail: mackie@strw.leidenuniv.nl [NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035 (United States)

    2015-02-01

    We present the results of a computational study to investigate the infrared spectroscopic properties of a large number of polycyclic aromatic hydrocarbon (PAH) molecules and their fully dehydrogenated counterparts. We constructed a database of fully optimized geometries for PAHs that is complete for eight or fewer fused benzene rings, thus containing 1550 PAHs and 805 fully dehydrogenated aromatics. A large fraction of the species in our database have clearly non-planar or curved geometries. For each species, we determined the frequencies and intensities of their normal modes using density functional theory calculations. Whereas most PAH spectra are fairly similar, the spectra of fully dehydrogenated aromatics are much more diverse. Nevertheless, these fully dehydrogenated species show characteristic emission features at 5.2 μm, 5.5 μm, and 10.6 μm; at longer wavelengths, there is a forest of emission features in the 16-30 μm range that appears as a structured continuum, but with a clear peak centered around 19 μm. We searched for these features in Spitzer-IRS spectra of various positions in the reflection nebula NGC 7023. We find a weak emission feature at 10.68 μm in all positions except that closest to the central star. We also find evidence for a weak 19 μm feature at all positions that is not likely due to C{sub 60}. We interpret these features as tentative evidence for the presence of a small population of fully dehydrogenated PAHs, and discuss our results in the framework of PAH photolysis and the formation of fullerenes.

  7. A CATALOG OF NEAR-INFRARED SPECTRA FROM TYPE Ia SUPERNOVAE

    International Nuclear Information System (INIS)

    Marion, G. H.; Wheeler, J. C.; Robinson, E. L.; Hoeflich, P.; Gerardy, C. L.; Vacca, W. D.

    2009-01-01

    We present 41 near-infrared (NIR, 0.7-2.5 μm) spectra from normal Type Ia supernovae (SNe Ia) obtained at epochs ranging from 14 days before to 75 days with respect to the maximum light date in the V band. All data were obtained at the Infrared Telescope Facility using the SpeX instrument. We identify many spectral features, measure the Doppler velocities, and discuss the chemical distribution of explosion products in SNe Ia. We describe procedures for smoothing data, fitting continua, and measuring absorption features to ensure consistency for measurement and analysis. This sample provides the first opportunity to examine and compare a large number of SNe Ia in this wavelength region. NIR data are a rich source of information about explosion products whose signatures are blended or obscured in other spectral regions and NIR observations probe a greater radial depth than optical wavelengths. We analyze similarities and differences in the spectra and we show that the progressive development of spectral features for normal SNe Ia in the NIR is consistent with time. We confirm the presence of O I, Mg II, Ca II, Si II, Fe II, and Co II in these SNe. Possible identifications are made for S I, Si III, Mn II, and Fe III. There is no evidence in these data for H I, He I, C I, or C II. As the explosion products expand and cool, progressively deeper layers are revealed. Thus, a time sequence of spectra examines the chemical structure and provides direct evidence of the physical properties of SNe Ia from the outer layers to deep inside the SN. Measured Doppler velocities indicate that burning products in SNe Ia are distributed in distinct layers with no large-scale mixing. Carbon is not detected in these data, in agreement with previous results with NIR data establishing very low limits on carbon abundance in SNe Ia. Carbon burning products, O and Mg, are plentiful in the outer layers suggesting that the entire progenitor is burned in the explosion. The data provide a

  8. Optical and Near-infrared Spectra of σ Orionis Isolated Planetary-mass Objects

    Energy Technology Data Exchange (ETDEWEB)

    Zapatero Osorio, M. R. [Centro de Astrobiología (CSIC-INTA), Crta. Ajalvir km 4, E-28850 Torrejón de Ardoz, Madrid (Spain); Béjar, V. J. S. [Instituto de Astrofísica de Canarias, C/. Vía Láctea s/n, E-38205 La Laguna, Tenerife (Spain); Ramírez, K. Peña, E-mail: mosorio@cab.inta-csic.es, E-mail: vbejar@iac.es, E-mail: karla.pena@uantof.cl [Unidad de Astronomía de la Universidad de Antofagasta, Av. U. de Antofagasta. 02800 Antofagasta (Chile)

    2017-06-10

    We have obtained low-resolution optical (0.7–0.98 μ m) and near-infrared (1.11–1.34 μ m and 0.8–2.5 μ m) spectra of 12 isolated planetary-mass candidates ( J = 18.2–19.9 mag) of the 3 Myr σ Orionis star cluster with the aim of determining the spectroscopic properties of very young, substellar dwarfs and assembling a complete cluster mass function. We have classified our targets by visual comparison with high- and low-gravity standards and by measuring newly defined spectroscopic indices. We derived L0–L4.5 and M9–L2.5 using high- and low-gravity standards, respectively. Our targets reveal clear signposts of youth, thus corroborating their cluster membership and planetary masses (6–13 M {sub Jup}). These observations complete the σ Orionis mass function by spectroscopically confirming the planetary-mass domain to a confidence level of ∼75%. The comparison of our spectra with BT-Settl solar metallicity model atmospheres yields a temperature scale of 2350–1800 K and a low surface gravity of log g ≈ 4.0 [cm s{sup −2}], as would be expected for young planetary-mass objects. We discuss the properties of the cluster’s least-massive population as a function of spectral type. We have also obtained the first optical spectrum of S Ori 70, a T dwarf in the direction of σ Orionis. Our data provide reference optical and near-infrared spectra of very young L dwarfs and a mass function that may be used as templates for future studies of low-mass substellar objects and exoplanets. The extrapolation of the σ Orionis mass function to the solar neighborhood may indicate that isolated planetary-mass objects with temperatures of ∼200–300 K and masses in the interval 6–13 M {sub Jup} may be as numerous as very low-mass stars.

  9. INFRARED AND ULTRAVIOLET SPECTRA OF METHANE DILUTED IN SOLID NITROGEN AND IRRADIATED WITH ELECTRONS DURING DEPOSITION AT VARIOUS TEMPERATURES

    International Nuclear Information System (INIS)

    Chin, Chih-Hao; Chen, Sian-Cong; Liu, Meng-Chen; Huang, Tzu-Ping; Wu, Yu-Jong

    2016-01-01

    We recorded the infrared and ultraviolet absorption spectra of CH 4 :N 2 matrix samples that underwent electron bombardment during deposition in the temperature range of 10–44 K. In contrast to a previous experiment on the IR spectroscopy of electron-bombarded icy samples, methyl and azide radicals became the main products upon electron bombardment during deposition; furthermore, reduced production of nitrile species was observed for deposition at 10 and 20 K. On the other hand, for deposition above 33 K, the observed bands of the radical species (such as methyl and azide) decreased, and bands of large nitriles appeared. This observation may suggest that radical species easily diffuse and recombine to form more complex molecules in solid nitrogen at higher temperatures. Further measurements of similar samples at 10–33 K in the UV region revealed the intense band of azide radicals at 272.5 nm and weak, broad, overlapping features of methyl and azide radicals in the 225–197 nm region. For deposition at 44 K, only a broad feature centered at 219.4 nm was observed, and the possible carriers of nitrile species were proposed based on the corresponding IR spectrum and theoretical predictions of excitation energy. This band is similar to the observed absorption feature of Pluto’s surface recorded by the Hubble telescope in terms of both band position and bandwidth. Our findings therefore further support the suggestion that complex nitrile species may exist on the surface of Pluto.

  10. Breast Cancer Spatial Heterogeneity in Near-Infrared Spectra and the Prediction of Neoadjuvant Chemotherapy Response

    Science.gov (United States)

    Santoro, Ylenia

    Breast cancer accounts for more than 20% of all female cancers. Many of these patients receive neoadjuvant chemotherapy (NAC) to reduce the size of the tumor before surgery and to anticipate the efficacy of treatments for after the procedure. Breast cancer is a heterogeneous disease that comes in several clinical and histological forms. The prediction of the efficacy of chemotherapy would potentially select good candidates who would respond while excluding poor candidates who would not benefit from treatment. In this work we investigate the possibility of noninvasively predicting chemotherapy response prior to treatment based on optical biomarkers obtained from tumor spatial heterogeneities of spectral features measured using Diffuse Optical Spectroscopy. We describe an algorithm to calculate an index that characterizes spatial differences in broadband near-infrared absorption spectra of tumor-containing breast tissue. Patient-specific tumor spatial heterogeneities are visualized through a Heterogeneity Spectrum (HS). HS is a biomarker that can be attributed to different molecular distributions within the tumor. To classify lesion heterogeneities, we built a Heterogeneity Index (HI) from the HS by weighing specific absorption bands. It has been shown that NAC response is potentially related to tumor heterogeneity. Therefore, we correlate the HI obtained prior to treatment with the final response to NAC. In this thesis we also present a novel digital parallel frequency domain system for tissue imaging. The systems employs a supercontinuum laser with high brightness, and a photomultiplier with a large detection area, both allowing a deep penetration with extremely low power on the sample. The digital parallel acquisition is performed through the use of the Flimbox and it decreases the time required for standard serial systems that need to scan through all modulation frequencies. The all-digital acquisition removes analog noise, avoids the analog mixer and it does not

  11. Signal-to-Noise Contribution of Principal Component Loads in Reconstructed Near-Infrared Raman Tissue Spectra

    NARCIS (Netherlands)

    Grimbergen, M. C. M.; van Swol, C. F. P.; Kendall, C.; Verdaasdonk, R. M.; Stone, N.; Bosch, J. L. H. R.

    The overall quality of Raman spectra in the near-infrared region, where biological samples are often studied, has benefited from various improvements to optical instrumentation over the past decade. However, obtaining ample spectral quality for analysis is still challenging due to device

  12. A setup for simultaneous measurement of infrared spectra and light scattering signals: Watching amyloid fibrils grow from intact proteins

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yang; Maurer, Jürgen; Roth, Andreas; Vogel, Vitali; Winter, Ernst; Mäntele, Werner, E-mail: maentele@biophysik.uni-frankfurt.de [Institut für Biophysik, Goethe-Universität Frankfurt am Main, Max-von Laue-Straße 1, D-60438 Frankfurt am Main (Germany)

    2014-08-15

    A setup for the simultaneous measurement of mid-infrared spectra and static light scattering is described that can be used for the analysis of the formation of nanoscale and microscopic aggregates from smaller molecules to biopolymers. It can be easily integrated into sample chambers of infrared spectrometers or combined with laser beams from tunable infrared lasers. Here, its use for the analysis of the formation of amyloid fibrils from intact proteins is demonstrated. The formation of amyloid fibrils or plaques from proteins is a widespread and pathogenetic relevant process, and a number of diseases are caused and correlated with the deposition of amyloid fibrils in cells and tissues. The molecular mechanisms of these transformations, however, are still unclear. We report here the simultaneous measurement of infrared spectra and static light scattering for the analysis of fibril formation from egg-white lysozyme. The transformation of the native form into non-native forms rich in β-sheet structure is measured by analysis of the amide I spectral region in the infrared spectra, which is sensitive for local structures. At the same time, light scattering signals at forward direction as well as the forward/backward ratio, which are sensitive for the number of scattering centers and their approximate sizes, respectively, are collected for the analysis of fibril growth. Thermodynamic and kinetic parameters as well as mechanistic information are deduced from the combination of the two complementary techniques.

  13. A setup for simultaneous measurement of infrared spectra and light scattering signals: Watching amyloid fibrils grow from intact proteins

    Science.gov (United States)

    Li, Yang; Maurer, Jürgen; Roth, Andreas; Vogel, Vitali; Winter, Ernst; Mäntele, Werner

    2014-08-01

    A setup for the simultaneous measurement of mid-infrared spectra and static light scattering is described that can be used for the analysis of the formation of nanoscale and microscopic aggregates from smaller molecules to biopolymers. It can be easily integrated into sample chambers of infrared spectrometers or combined with laser beams from tunable infrared lasers. Here, its use for the analysis of the formation of amyloid fibrils from intact proteins is demonstrated. The formation of amyloid fibrils or plaques from proteins is a widespread and pathogenetic relevant process, and a number of diseases are caused and correlated with the deposition of amyloid fibrils in cells and tissues. The molecular mechanisms of these transformations, however, are still unclear. We report here the simultaneous measurement of infrared spectra and static light scattering for the analysis of fibril formation from egg-white lysozyme. The transformation of the native form into non-native forms rich in β-sheet structure is measured by analysis of the amide I spectral region in the infrared spectra, which is sensitive for local structures. At the same time, light scattering signals at forward direction as well as the forward/backward ratio, which are sensitive for the number of scattering centers and their approximate sizes, respectively, are collected for the analysis of fibril growth. Thermodynamic and kinetic parameters as well as mechanistic information are deduced from the combination of the two complementary techniques.

  14. Atmospheric Circulation, Chemistry, and Infrared Spectra of Titan-like Exoplanets around Different Stellar Types

    Science.gov (United States)

    Lora, Juan M.; Kataria, Tiffany; Gao, Peter

    2018-01-01

    With the discovery of ever smaller and colder exoplanets, terrestrial worlds with hazy atmospheres must be increasingly considered. Our solar system’s Titan is a prototypical hazy planet, whose atmosphere may be representative of a large number of planets in our Galaxy. As a step toward characterizing such worlds, we present simulations of exoplanets that resemble Titan but orbit three different stellar hosts: G, K, and M dwarf stars. We use general circulation and photochemistry models to explore the circulation and chemistry of these Titan-like planets under varying stellar spectra, in all cases assuming a Titan-like insolation. Due to the strong absorption of visible light by atmospheric haze, the redder radiation accompanying later stellar types produces more isothermal stratospheres, stronger meridional temperature gradients at mbar pressures, and deeper and stronger zonal winds. In all cases, the planets’ atmospheres are strongly superrotating, but meridional circulation cells are weaker aloft under redder starlight. The photochemistry of hydrocarbon and nitrile species varies with stellar spectra, with variations in the FUV/NUV flux ratio playing an important role. Our results tentatively suggest that column haze production rates could be similar under all three hosts, implying that planets around many different stars could have similar characteristics to Titan’s atmosphere. Lastly, we present theoretical emission spectra. Overall, our study indicates that, despite important and subtle differences, the circulation and chemistry of Titan-like exoplanets are relatively insensitive to differences in the host star. These findings may be further probed with future space-based facilities, like WFIRST, LUVOIR, HabEx, and OST.

  15. Predicting ambient aerosol thermal-optical reflectance measurements from infrared spectra: elemental carbon

    Science.gov (United States)

    Dillner, A. M.; Takahama, S.

    2015-10-01

    Elemental carbon (EC) is an important constituent of atmospheric particulate matter because it absorbs solar radiation influencing climate and visibility and it adversely affects human health. The EC measured by thermal methods such as thermal-optical reflectance (TOR) is operationally defined as the carbon that volatilizes from quartz filter samples at elevated temperatures in the presence of oxygen. Here, methods are presented to accurately predict TOR EC using Fourier transform infrared (FT-IR) absorbance spectra from atmospheric particulate matter collected on polytetrafluoroethylene (PTFE or Teflon) filters. This method is similar to the procedure developed for OC in prior work (Dillner and Takahama, 2015). Transmittance FT-IR analysis is rapid, inexpensive and nondestructive to the PTFE filter samples which are routinely collected for mass and elemental analysis in monitoring networks. FT-IR absorbance spectra are obtained from 794 filter samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to collocated TOR EC measurements. The FT-IR spectra are divided into calibration and test sets. Two calibrations are developed: one developed from uniform distribution of samples across the EC mass range (Uniform EC) and one developed from a uniform distribution of Low EC mass samples (EC < 2.4 μg, Low Uniform EC). A hybrid approach which applies the Low EC calibration to Low EC samples and the Uniform EC calibration to all other samples is used to produce predictions for Low EC samples that have mean error on par with parallel TOR EC samples in the same mass range and an estimate of the minimum detection limit (MDL) that is on par with TOR EC MDL. For all samples, this hybrid approach leads to precise and accurate TOR EC predictions by FT-IR as indicated by high coefficient of determination (R2; 0.96), no bias (0.00 μg m-3, a

  16. Predicting ambient aerosol thermal-optical reflectance (TOR) measurements from infrared spectra: organic carbon

    Science.gov (United States)

    Dillner, A. M.; Takahama, S.

    2015-03-01

    Organic carbon (OC) can constitute 50% or more of the mass of atmospheric particulate matter. Typically, organic carbon is measured from a quartz fiber filter that has been exposed to a volume of ambient air and analyzed using thermal methods such as thermal-optical reflectance (TOR). Here, methods are presented that show the feasibility of using Fourier transform infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters to accurately predict TOR OC. This work marks an initial step in proposing a method that can reduce the operating costs of large air quality monitoring networks with an inexpensive, non-destructive analysis technique using routinely collected PTFE filter samples which, in addition to OC concentrations, can concurrently provide information regarding the composition of organic aerosol. This feasibility study suggests that the minimum detection limit and errors (or uncertainty) of FT-IR predictions are on par with TOR OC such that evaluation of long-term trends and epidemiological studies would not be significantly impacted. To develop and test the method, FT-IR absorbance spectra are obtained from 794 samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least-squares regression is used to calibrate sample FT-IR absorbance spectra to TOR OC. The FTIR spectra are divided into calibration and test sets by sampling site and date. The calibration produces precise and accurate TOR OC predictions of the test set samples by FT-IR as indicated by high coefficient of variation (R2; 0.96), low bias (0.02 μg m-3, the nominal IMPROVE sample volume is 32.8 m3), low error (0.08 μg m-3) and low normalized error (11%). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision to collocated TOR measurements. FT-IR spectra are also

  17. Predicting ambient aerosol Thermal Optical Reflectance (TOR) measurements from infrared spectra: elemental carbon

    Science.gov (United States)

    Dillner, A. M.; Takahama, S.

    2015-06-01

    Elemental carbon (EC) is an important constituent of atmospheric particulate matter because it absorbs solar radiation influencing climate and visibility and it adversely affects human health. The EC measured by thermal methods such as Thermal-Optical Reflectance (TOR) is operationally defined as the carbon that volatilizes from quartz filter samples at elevated temperatures in the presence of oxygen. Here, methods are presented to accurately predict TOR EC using Fourier Transform Infrared (FT-IR) absorbance spectra from atmospheric particulate matter collected on polytetrafluoroethylene (PTFE or Teflon) filters. This method is similar to the procedure tested and developed for OC in prior work (Dillner and Takahama, 2015). Transmittance FT-IR analysis is rapid, inexpensive, and non-destructive to the PTFE filter samples which are routinely collected for mass and elemental analysis in monitoring networks. FT-IR absorbance spectra are obtained from 794 filter samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to collocated TOR EC measurements. The FTIR spectra are divided into calibration and test sets. Two calibrations are developed, one which is developed from uniform distribution of samples across the EC mass range (Uniform EC) and one developed from a~uniform distribution of low EC mass samples (EC < 2.4 μg, Low Uniform EC). A hybrid approach which applies the low EC calibration to low EC samples and the Uniform EC calibration to all other samples is used to produces predictions for low EC samples that have mean error on par with parallel TOR EC samples in the same mass range and an estimate of the minimum detection limit (MDL) that is on par with TOR EC MDL. For all samples, this hybrid approach leads to precise and accurate TOR EC predictions by FT-IR as indicated by high coefficient of variation (R2; 0.96), no

  18. The 12C/ 13C isotopic ratio in Titan hydrocarbons from Cassini/CIRS infrared spectra

    Science.gov (United States)

    Nixon, C. A.; Achterberg, R. K.; Vinatier, S.; Bézard, B.; Coustenis, A.; Irwin, P. G. J.; Teanby, N. A.; de Kok, R.; Romani, P. N.; Jennings, D. E.; Bjoraker, G. L.; Flasar, F. M.

    2008-06-01

    We have analyzed infrared spectra of Titan recorded by the Cassini Composite Infrared Spectrometer (CIRS) to measure the isotopic ratio 12C/ 13C in each of three chemical species in Titan's stratosphere: CH 4, C 2H 2 and C 2H 6. This is the first measurement of 12C/ 13C in any C 2 molecule on Titan, and the first measurement of 12CH 4/ 13CH 4 (non-deuterated) on Titan by remote sensing. Our spectra cover five widely-spaced latitudes, 65° S to 71° N and we have searched for both latitude variability of 12C/ 13C within a given species, and also for differences between the 12C/ 13C in the three gases. For CH 4 alone, we find C12/C13=76.6±2.7 (1- σ), essentially in agreement with the 12CH 4/ 13CH 4 measured by the Huygens Gas Chromatograph/Mass Spectrometer instrument (GCMS) [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779-784]: 82.3±1.0, and also with measured values in H 13CN and 13CH 3D by CIRS at lower precision [Bézard, B., Nixon, C., Kleiner, I., Jennings, D., 2007. Icarus 191, 397-400; Vinatier, S., Bézard, B., Nixon, C., 2007. Icarus 191, 712-721]. For the C 2 species, we find C12/C13=84.8±3.2 in C 2H 2 and 89.8±7.3 in C 2H 6, a possible trend of increasingly value with molecular mass, although these values are both compatible with the Huygens GCMS value to within error bars. There are no convincing trends in latitude. Combining all fifteen measurements, we obtain a value of C12/C13=80.8±2.0, also compatible with GCMS. Therefore, the evidence is mounting that 12C/ 13C is some 8% lower on Titan than on the Earth (88.9, inorganic standard), and lower than typical for the outer planets ( 88±7 [Sada, P.V., McCabe, G.H., Bjoraker, G.L., Jennings, D.E., Reuter, D.C., 1996. Astrophys. J. 472, 903-907]). There is no current model for this enrichment, and we discuss several mechanisms that may be at work.

  19. Downwelling Far-Infrared Radiance Spectra Measured by FIRST at Cerro Toco, Chile

    Science.gov (United States)

    Mast, J. C.; Mlynczak, M. G.; Cageao, R.; Kratz, D. P.; Latvakoski, H.; Johnson, D. G.; Mlawer, E. J.; Turner, D. D.

    2015-12-01

    The Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument is a Fourier transform spectrometer developed by NASA Langley Research Center in collaboration with the Space Dynamics Laboratory and the Harvard-Smithsonian Center for Astrophysics. FIRST was initially developed for measuring the far-infrared portion of Earth's longwave spectrum as a balloon borne instrument and later was reconfigured to operate as a ground-based instrument. In its current ground-based configuration FIRST was deployed at 17500 ft on Cerro Toco, a mountain in the Atacama Desert of Chile, from August to October, 2009. There the integrated precipitable water (IPW) was as low as 0.02 cm. FIRST measurements from days with IPW between 0.024 and 0.035 cm during the campaign are presented here between 200 cm-1 and 800 cm-1. Significant spectral development in the far-IR is observed over the entire 200 cm-1 to 800 cm-1 band. Water vapor and temperature profiles from radiosonde and GVRP measurements are used as inputs to the AER Line-by-Line Radiative Transfer Model (LBLRTM) utilizing the AER v3.2 line parameter database. Uncertainties in both the measured and modeled radiances are accounted for in this study. The residual LBLRTM - FIRST is calculated to assess agreement between the measured and modeled spectra. Measured and model radiances generally agree to within the combined uncertainties for wavenumbers greater than 360 cm-1. At wavenumbers less than 360 cm-1 persistent troughs in the residual are present outside of the combined uncertainties. These features are present on different days and at different water vapor amounts. Possible solutions for these features are discussed.

  20. Experimental and theoretical studies on IR, Raman, and UV-Vis spectra of quinoline-7-carboxaldehyde.

    Science.gov (United States)

    Kumru, M; Küçük, V; Kocademir, M; Alfanda, H M; Altun, A; Sarı, L

    2015-01-05

    Spectroscopic properties of quinoline-7-carboxaldehyde (Q7C) have been studied in detail both experimentally and theoretically. The FT-IR (4000-50 cm(-1)), FT-Raman (4000-50 cm(-1)), dispersive-Raman (3500-50 cm(-1)), and UV-Vis (200-400 nm) spectra of Q7C were recorded at room temperature (25 °C). Geometry parameters, potential energy surface about CCH(O) bond, harmonic vibrational frequencies, IR and Raman intensities, UV-Vis spectrum, and thermodynamic characteristics (at 298.15K) of Q7C were computed at Hartree-Fock (HF) and density functional B3LYP levels employing the 6-311++G(d,p) basis set. Frontier molecular orbitals, molecular electrostatic potential, and Mulliken charge analyses of Q7C have also been performed. Q7C has two stable conformers that are energetically very close to each other with slight preference to the conformer that has oxygen atom of the aldehyde away from the nitrogen atom of the quinoline. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. An automated baseline correction protocol for infrared spectra of atmospheric aerosols collected on polytetrafluoroethylene (Teflon) filters

    Science.gov (United States)

    Kuzmiakova, Adele; Dillner, Ann M.; Takahama, Satoshi

    2016-06-01

    A growing body of research on statistical applications for characterization of atmospheric aerosol Fourier transform infrared (FT-IR) samples collected on polytetrafluoroethylene (PTFE) filters (e.g., Russell et al., 2011; Ruthenburg et al., 2014) and a rising interest in analyzing FT-IR samples collected by air quality monitoring networks call for an automated PTFE baseline correction solution. The existing polynomial technique (Takahama et al., 2013) is not scalable to a project with a large number of aerosol samples because it contains many parameters and requires expert intervention. Therefore, the question of how to develop an automated method for baseline correcting hundreds to thousands of ambient aerosol spectra given the variability in both environmental mixture composition and PTFE baselines remains. This study approaches the question by detailing the statistical protocol, which allows for the precise definition of analyte and background subregions, applies nonparametric smoothing splines to reproduce sample-specific PTFE variations, and integrates performance metrics from atmospheric aerosol and blank samples alike in the smoothing parameter selection. Referencing 794 atmospheric aerosol samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011, we start by identifying key FT-IR signal characteristics, such as non-negative absorbance or analyte segment transformation, to capture sample-specific transitions between background and analyte. While referring to qualitative properties of PTFE background, the goal of smoothing splines interpolation is to learn the baseline structure in the background region to predict the baseline structure in the analyte region. We then validate the model by comparing smoothing splines baseline-corrected spectra with uncorrected and polynomial baseline (PB)-corrected equivalents via three statistical applications: (1) clustering analysis, (2) functional group quantification

  2. Theoretical investigations of the structures and electronic spectra of 8-hydroxylquinoline derivatives

    Science.gov (United States)

    Ning, Pan; Ren, Tiegang; Zhang, Yanxin; Zhang, Jinglai

    2013-11-01

    The spectroscopic properties of 8-hydroxyquinoline derivatives are theoretically investigated by means of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The target molecules are divided into two groups: group (I): (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)quinolin-8-ol (A), together with corresponding potential reaction products of A with acetic acid, i.e., (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)quinolin-8-yl acetate (AR1), and (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)-8-hydroxyquinolinium (AR2); group (II): (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)quinolin-8-ol (B), as well as potential reaction products of B with acetic acid, i.e., (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)quinolin-8-yl acetate (BR1), and (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)-8-hydroxyquinolinium (BR2). The geometries are optimized by B3LYP and M06 methods. The results indicate that product molecules tend to be effectively planar compared with reactants. Subsequently, UV absorption spectra are simulated through TD-DFT method with PCM model to further confirm the reasonable products of two reactions. AR2 and BR2 are identified as the target molecules through the experimental spectra for the real products. It is worth noting that the maximum absorption wavelengths of compounds AR2 and BR2 present prominent red shift compared the initial reactants A and B, respectively, which should be ascribed to the enhancive planarity of products that mentioned above and the decreased HOMO-LUMO energy gap. Geometric structures and optical properties for corresponding compounds are discussed in detail.

  3. FAR-INFRARED LINE SPECTRA OF SEYFERT GALAXIES FROM THE HERSCHEL-PACS SPECTROMETER

    International Nuclear Information System (INIS)

    Spinoglio, Luigi; Pereira-Santaella, Miguel; Busquet, Gemma; Dasyra, Kalliopi M.; Calzoletti, Luca; Malkan, Matthew A.; Tommasin, Silvia

    2015-01-01

    We observed the far-IR fine-structure lines of 26 Seyfert galaxies with the Herschel-PACS spectrometer. These observations are complemented with Spitzer Infrared Spectrograph and Herschel SPIRE spectroscopy. We used the ionic lines to determine electron densities in the ionized gas and the [C I] lines, observed with SPIRE, to measure the neutral gas densities, while the [O I] lines measure the gas temperature, at densities below ∼10 4  cm –3 . Using the [O I]145 μm/63 μm and [S III]33/18 μm line ratios, we find an anti-correlation of the temperature with the gas density. Various fine-structure line ratios show density stratifications in these active galaxies. On average, electron densities increase with the ionization potential of the ions. The infrared lines arise partly in the narrow line region, photoionized by the active galactic nucleus (AGN), partly in H II regions photoionized by hot stars, and partly in photo-dissociated regions. We attempt to separate the contributions to the line emission produced in these different regions by comparing our observed emission line ratios to theoretical values. In particular, we tried to separate the contribution of AGNs and star formation by using a combination of Spitzer and Herschel lines, and we found that besides the well-known mid-IR line ratios, the line ratio of [O III]88 μm/[O IV]26 μm can reliably discriminate the two emission regions, while the far-IR line ratio of [C II]157 μm/[O I]63 μm is only able to mildly separate the two regimes. By comparing the observed [C II]157 μm/[N II]205 μm ratio with photoionization models, we also found that most of the [C II] emission in the galaxies we examined is due to photodissociation regions

  4. Experimental and theoretical study on Raman spectra of magnesium fluoride clusters and solids.

    Science.gov (United States)

    Neelamraju, S; Bach, A; Schön, J C; Fischer, D; Jansen, M

    2012-11-21

    In this study, the Raman and IR spectra of a large number of isomers of MgF(2) clusters and of possible bulk polymorphs of MgF(2) are calculated and compared with experimental data observed using a low-temperature atom beam deposition. The bulk polymorphs were taken from earlier work, while the cluster modifications for the neutral (MgF(2))(n) (n = 1-10) clusters and charged clusters (up to the trimer anion and cation, (Mg(3)F(7))(-) and (Mg(3)F(5))(+), respectively) are determined in the present work by global energy landscape explorations using simulated annealing. These theoretical calculations are complemented by an experimental study on both the vapor phase and the deposited films of MgF(2), which are generated in a low-temperature atom beam deposition setup for the synthesis of MgF(2) bulk phases. The MgF(2) vapor and film are characterized via Raman spectroscopy of the MgF(2) gas phase species embedded in an Ar-matrix and of the MgF(2)-films deposited onto a cooled substrate, respectively. We find that, in the vapor phase, there are monomers and dimers and charged species to be present in our experimental setup. Furthermore, the results suggest that in the amorphous bulk MgF(2), rutile-like domains are present and MgF(2) clusters similar to those in the matrix. Finally, peaks at about 800 cm(-1), which are in the same range as the A(g) modes of clusters with dangling fluorine atoms connected to three-coordinated Mg atoms, indicate that such dangling bonds are also present in amorphous MgF(2).

  5. Investigation of Effect of KBr Matrix on Drift Infrared Spectra of Some ...

    African Journals Online (AJOL)

    MBI

    2014-09-28

    Sep 28, 2014 ... mid – infrared range (wave-numbers between. 4000cm-1 to 400cm-1) ... The exact frequency at which any bond resonate is ... frequency through infrared spectroscopy, it will ... by crystal disorder and crystal symmetry causing.

  6. Infrared-transmission spectra and hydrogen content of hydrogenated amorphous silicon

    Science.gov (United States)

    Hu, Yuehi; Chen, Guanghua; Wu, Yueying; Yin, Shengyi; Gao, Zhuo; Wang, Qing; Song, Xuemei; Deng, Jinxiang

    2004-05-01

    In this paper, two kinds of methods of calculating the hydrogen content of a-Si:H thin film by means of the wagging mode and the stretching modes of infrared-transmission spectra, are investigated. The reason for the difference in these two calculation results is analyzed. If the contents of SiH2 and (SiH2) n are indicated in terms of a structure factor F=(/840+/880)//2000, it is shown that the calculation results obtained from the two different methods are almost equal when the refractive index n is approximately 3.4 or the fitting thickness is between 0.71 and 0.89 μm in the case of a small F. It is shown that the ways of fabrication of thin film can influences silicon-hydrogen bonding configuration of a-Si: H film, and different ways of fabrication can lead to different contents of SiH2 and (SiH2) n . The uniformity of the thin film with a big F is bad. In this case, there is great difference between the thickness measured by the SurfCom408A surface profile apparatus and the thickness obtained by fitting the fringes; and the hydrogen contents of a-Si:H films obtained by means of the wagging mode and the stretching modes are different, too. But the fabrication of the MWECR CVD assisted by CAT CVD can effectively restrain the formation of SiH2 and (SiH2) n .

  7. Modeling midwave infrared muzzle flash spectra from unsuppressed and flash-suppressed large caliber munitions

    Science.gov (United States)

    Steward, Bryan J.; Perram, Glen P.; Gross, Kevin C.

    2012-07-01

    Time-resolved infrared spectra of firings from a 152 mm howitzer were acquired over an 1800-6000 cm-1 spectral range using a Fourier-transform spectrometer. The instrument collected primarily at 32 cm-1 spectral and 100 Hz temporal resolutions. Munitions included unsuppressed and chemically flash suppressed propellants. Secondary combustion occurred with unsuppressed propellants resulting in flash emissions lasting ˜100 ms and dominated by H2O and CO2 spectral structure. Non-combusting plume emissions were one-tenth as intense and approached background levels within 20-40 ms. A low-dimensional phenomenological model was used to reduce the data to temperatures, soot absorbances, and column densities of H2O, CO2, CH4, and CO. The combusting plumes exhibit peak temperatures of ˜1400 K, areas of greater than 32 m2, low soot emissivity of ˜0.04, with nearly all the CO converted to CO2. The non-combusting plumes exhibit lower temperatures of ˜1000 K, areas of ˜5 m2, soot emissivity of greater than 0.38 and CO as the primary product. Maximum fit residual relative to peak intensity are 14% and 8.9% for combusting and non-combusting plumes, respectively. The model was generalized to account for turbulence-induced variations in the muzzle plumes. Distributions of temperature and concentration in 1-2 spatial regions demonstrate a reduction in maximum residuals by 40%. A two-region model of combusting plumes provides a plausible interpretation as a ˜1550 K, optically thick plume core and ˜2550 K, thin, surface-layer flame-front. Temperature rate of change was used to characterize timescales and energy release for plume emissions. Heat of combustion was estimated to be ˜5 MJ/kg.

  8. Relationship between wine scores and visible-near-infrared spectra of Australian red wines.

    Science.gov (United States)

    Cozzolino, D; Cowey, G; Lattey, K A; Godden, P; Cynkar, W U; Dambergs, R G; Janik, L; Gishen, M

    2008-06-01

    Sensory analysis of wine involves the measurement, interpretation and understanding of human responses to the properties perceived by the senses such as sight, smell and taste. The sensory evaluation of wine is often carried out by wine judges, winemakers and technical staff, and allows characterization of the quality of the wine. However, this method is lengthy, expensive, and its results depend on panel training and the specific vocabulary used by the panel. A robust, rapid, unbiased and inexpensive method to assist in quality assessment purposes will therefore be beneficial for the modern wine industry. This study aims to investigate the relationship between sensory analysis, visible (VIS) and near-infrared (NIR) spectroscopy to assess sensory properties of commercial Australian wine varieties. For the purposes of this study 118 red wine samples (Cabernet Sauvignon, Shiraz, Pinot Noir, Tempranillo, Nebbiolo and blends) graded by a panel of experienced tasters and scored according to the Australian wine show system were scanned in transmission in the VIS and NIR range (400-2,500 nm). Partial least squares regression models were developed between the overall score given by the judges and the combined VIS-NIR spectra, using full cross validation (leave-one-out method). The results showed that NIR spectroscopy was able to predict wine quality scores in red wine samples (R = 0.61 and standard error of prediction of 0.81). The practical implication of this study is that instrumental methods such as VIS-NIR spectroscopy can be used to complement sensory analysis and can facilitate the task at early stages of product development, making high-throughput screening of novel products feasible or maintaining the consistency of the product.

  9. Experimental and theoretical studies of the VUV emission and absorption spectra of H2, HD and D2 molecules

    International Nuclear Information System (INIS)

    Roudjane, M.

    2007-12-01

    The aim of this thesis is to carry out an experimental study of the absorption and emission spectra of the D 2 and HD isotopes, with high resolution, in the VUV domain and to supplement it by a theoretical study of the excited electronic states involved in the observed transitions. The emission spectra of HD and D 2 are produced by Penning discharge source operating under low pressure and are recorded in the spectral range 78 - 170 nm. The recorded spectra contains more than 20.000 lines. The analysis of the spectrum consists in identifying and assigning the lines to the electronic transitions between energy levels of the molecule. The present analysis is based on our theoretical calculations of the ro-vibrational energy levels of the excited electronic states and the transition probabilities from these states towards the energy levels of the fundamental state. The theoretical results are obtained by resolving the coupled equations between the excited electronic states B 1 Σ u 1 , B' 1 Σ u 1 , C 1 Π u 1 and D 1 Π u 1 , taking into account the nonadiabatic couplings between these states, and they are obtained in the adiabatic approximation for the excited electronic states B''B-bar 1 Σ u + , D' 1 Π u 1 and D'' 1 Π u 1 . The equations are resolved using a modern method based on the discretization variables representation method. In addition, we have carried out a study of the absorption spectra of the HD and D 2 molecules

  10. Adding a dimension to the infrared spectra of interfaces: 2D SFG spectroscopy via mid-IR pulse shaping

    Science.gov (United States)

    Zanni, Martin

    2012-02-01

    Sum-frequency generation spectroscopy provides an infrared spectrum of interfaces and thus has widespread use in the materials and chemical sciences. In this presentation, I will present our recent work in developing a 2D pulse sequence to generate 2D SFG spectra of interfaces, in analogy to 2D infrared spectra used to measure bulk species. To develop this spectroscopy, we have utilized many of the tricks-of-the-trade developed in the 2D IR and 2D Vis communities in the last decade, including mid-IR pulse shaping. With mid-IR pulse shaping, the 2D pulse sequence is manipulated by computer programming in the desired frequency resolution, rotating frame, and signal pathway. We believe that 2D SFG will become an important tool in the interfacial sciences in an analogous way that 2D IR is now being used in many disciplines.

  11. Application of class-modelling techniques to infrared spectra for analysis of pork adulteration in beef jerkys.

    Science.gov (United States)

    Kuswandi, Bambang; Putri, Fitra Karima; Gani, Agus Abdul; Ahmad, Musa

    2015-12-01

    The use of chemometrics to analyse infrared spectra to predict pork adulteration in the beef jerky (dendeng) was explored. In the first step, the analysis of pork in the beef jerky formulation was conducted by blending the beef jerky with pork at 5-80 % levels. Then, they were powdered and classified into training set and test set. The second step, the spectra of the two sets was recorded by Fourier Transform Infrared (FTIR) spectroscopy using atenuated total reflection (ATR) cell on the basis of spectral data at frequency region 4000-700 cm(-1). The spectra was categorised into four data sets, i.e. (a) spectra in the whole region as data set 1; (b) spectra in the fingerprint region (1500-600 cm(-1)) as data set 2; (c) spectra in the whole region with treatment as data set 3; and (d) spectra in the fingerprint region with treatment as data set 4. The third step, the chemometric analysis were employed using three class-modelling techniques (i.e. LDA, SIMCA, and SVM) toward the data sets. Finally, the best result of the models towards the data sets on the adulteration analysis of the samples were selected and the best model was compared with the ELISA method. From the chemometric results, the LDA model on the data set 1 was found to be the best model, since it could classify and predict 100 % accuracy of the sample tested. The LDA model was applied toward the real samples of the beef jerky marketed in Jember, and the results showed that the LDA model developed was in good agreement with the ELISA method.

  12. Meeting the Cool Neighbors. XII. An Optically Anchored Analysis of the Near-infrared Spectra of L Dwarfs

    Science.gov (United States)

    Cruz, Kelle L.; Núñez, Alejandro; Burgasser, Adam J.; Abrahams, Ellianna; Rice, Emily L.; Reid, I. Neill; Looper, Dagny

    2018-01-01

    Discrepancies between competing optical and near-infrared (NIR) spectral typing systems for L dwarfs have motivated us to search for a classification scheme that ties the optical and NIR schemes together, and addresses complexities in the spectral morphology. We use new and extant optical and NIR spectra to compile a sample of 171 L dwarfs, including 27 low-gravity β and γ objects, with spectral coverage from 0.6–2.4 μm. We present 155 new low-resolution NIR spectra and 19 new optical spectra. We utilize a method for analyzing NIR spectra that partially removes the broad-band spectral slope and reveals similarities in the absorption features between objects of the same optical spectral type. Using the optical spectra as an anchor, we generate near-infrared spectral average templates for L0–L8, L0–L4γ, and L0–L1β type dwarfs. These templates reveal that NIR spectral morphologies are correlated with the optical types. They also show the range of spectral morphologies spanned by each spectral type. We compare low-gravity and field-gravity templates to provide recommendations on the minimum required observations for credibly classifying low-gravity spectra using low-resolution NIR data. We use the templates to evaluate the existing NIR spectral standards and propose new ones where appropriate. Finally, we build on the work of Kirkpatrick et al. to provide a spectral typing method that is tied to the optical and can be used when only H or K band data are available. The methods we present here provide resolutions to several long-standing issues with classifying L dwarf spectra and could also be the foundation for a spectral classification scheme for cloudy exoplanets.

  13. Theoretical analysis, infrared and structural investigations of energy dissipation in metals under cyclic loading

    International Nuclear Information System (INIS)

    Plekhov, O.A.; Saintier, N.; Palin-Luc, T.; Uvarov, S.V.; Naimark, O.B.

    2007-01-01

    The infrared and structural investigations of energy dissipation processes in metals subjected to cyclic loading have given impetus to the development of a new thermodynamic model with the capability of describing the energy balance under plastic deformation. The model is based on the statistical description of the mesodefect ensemble evolution and its influence on the dissipation ability of the material. Constitutive equations have been formulated for plastic and structural strains, which allow us to describe the stored and dissipated parts of energy under plastic flow. Numerical results indicate that theoretical predictions are in good agreement with the experimentally observed temperature data

  14. Strong spin-phonon coupling in infrared and Raman spectra of SrMnO.sub.3./sub..

    Czech Academy of Sciences Publication Activity Database

    Kamba, Stanislav; Goian, Veronica; Skoromets, Volodymyr; Hejtmánek, Jiří; Bovtun, Viktor; Kempa, Martin; Borodavka, Fedir; Vaněk, Přemysl; Belik, A.A.; Lee, J.H.; Pacherová, Oliva; Rabe, K.M.

    2014-01-01

    Roč. 89, č. 6 (2014), "064308-1"-"064308-9" ISSN 1098-0121 R&D Projects: GA MŠk LH13048; GA ČR GAP204/12/1163; GA MŠk LD12026; GA ČR GP14-14122P Institutional support: RVO:68378271 Keywords : multiferroics * spin-phonon coupling * infrared and Raman spectra Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  15. VizieR Online Data Catalog: Low-resolution near-infrared stellar spectra from CIBER (Kim+, 2017)

    Science.gov (United States)

    Kim, M. G.; Lee, H. M.; Arai, T.; Bock, J.; Cooray, A.; Jeong, W.-S.; Kim, S. J.; Korngut, P.; Lanz, A.; Lee, D. H.; Lee, M. G.; Matsumoto, T.; Matsuura, S.; Nam, U. W.; Onishi, Y.; Shirahata, M.; Smidt, J.; Tsumura, K.; Yamamura, I.; Zemcov, M.

    2017-06-01

    We present flux-calibrated near-infrared spectra of 105 stars from 0.8{skin, we do not use the first flight data in this work. The star spectral types are determined by fitting known spectral templates to the measured LRS spectra. We use the Infrared Telescope Facility (IRTF) and Pickles 1998 (Cat. J/PASP/110/863) templates for the SED fitting. The SpeX instrument installed on the IRTF observed stars using a medium-resolution spectrograph (R=2000). The template library contains spectra for 210 cool stars (F to M type) with wavelength coverage from 0.8 to 2.5μm (Cushing 2005ApJ...623.1115C; Rayner 2009ApJS..185..289R). The Pickles library is a synthetic spectral library that combines spectral data from various observations to achieve wavelength coverage from the UV (0.115μm) to the near-infrared (2.5μm). It contains 131 spectral templates for all star types (i.e., O to M type) with a uniform sampling interval of 5Å. (6 data files).

  16. Estimation of raw material performance in mammalian cell culture using near infrared spectra combined with chemometrics approaches.

    Science.gov (United States)

    Lee, Hae Woo; Christie, Andrew; Liu, Jun Jay; Yoon, Seongkyu

    2012-01-01

    Understanding variability in raw materials and their impacts on product quality is of critical importance in the biopharmaceutical manufacturing processes. For this purpose, several spectroscopic techniques have been studied for raw material characterization, providing fast and nondestructive ways to measure quality of raw materials. However, investigations of correlation between spectra of raw materials and cell culture performance have been scarce due to their complexity and uncertainty. In this study, near-infrared spectra and bioassays of multiple soy hydrolysate lots manufactured by different vendors were analyzed using chemometrics approaches in order to address variability of raw materials as well as correlation between raw material properties and corresponding cell culture performance. Principal component analysis revealed that near-infrared spectra of different soy lots contain enough physicochemical information about soy hydrolysates to allow identification of lot-to-lot variability as well as vendor-to-vendor differences. The identified compositional variability was further analyzed in order to estimate cell growth and protein production of two mammalian cell lines under the condition of varying soy dosages using partial least square regression combined with optimal variable selection. The performance of the resulting models demonstrates the potential of near-infrared spectroscopy as a robust lot selection tool for raw materials while providing a biological link between chemical composition of raw materials and cell culture performance. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

  17. FAR-INFRARED LINE SPECTRA OF SEYFERT GALAXIES FROM THE HERSCHEL-PACS SPECTROMETER

    Energy Technology Data Exchange (ETDEWEB)

    Spinoglio, Luigi; Pereira-Santaella, Miguel; Busquet, Gemma [Istituto di Astrofisica e Planetologia Spaziali, INAF, Via Fosso del Cavaliere 100, I-00133 Roma (Italy); Dasyra, Kalliopi M. [Observatoire de Paris, LERMA (CNRS:UMR8112), 61 Av. de l' Observatoire, F-75014, Paris (France); Calzoletti, Luca [Agenzia Spaziale Italiana (ASI) Science Data Center, I-00044 Frascati (Roma) (Italy); Malkan, Matthew A. [Astronomy Division, University of California, Los Angeles, CA 90095-1547 (United States); Tommasin, Silvia, E-mail: luigi.spinoglio@iaps.inaf.it [Weizmann Institute of Science, Department of Neurobiology, Rehovot 76100 (Israel)

    2015-01-20

    We observed the far-IR fine-structure lines of 26 Seyfert galaxies with the Herschel-PACS spectrometer. These observations are complemented with Spitzer Infrared Spectrograph and Herschel SPIRE spectroscopy. We used the ionic lines to determine electron densities in the ionized gas and the [C I] lines, observed with SPIRE, to measure the neutral gas densities, while the [O I] lines measure the gas temperature, at densities below ∼10{sup 4} cm{sup –3}. Using the [O I]145 μm/63 μm and [S III]33/18 μm line ratios, we find an anti-correlation of the temperature with the gas density. Various fine-structure line ratios show density stratifications in these active galaxies. On average, electron densities increase with the ionization potential of the ions. The infrared lines arise partly in the narrow line region, photoionized by the active galactic nucleus (AGN), partly in H II regions photoionized by hot stars, and partly in photo-dissociated regions. We attempt to separate the contributions to the line emission produced in these different regions by comparing our observed emission line ratios to theoretical values. In particular, we tried to separate the contribution of AGNs and star formation by using a combination of Spitzer and Herschel lines, and we found that besides the well-known mid-IR line ratios, the line ratio of [O III]88 μm/[O IV]26 μm can reliably discriminate the two emission regions, while the far-IR line ratio of [C II]157 μm/[O I]63 μm is only able to mildly separate the two regimes. By comparing the observed [C II]157 μm/[N II]205 μm ratio with photoionization models, we also found that most of the [C II] emission in the galaxies we examined is due to photodissociation regions.

  18. Thermally and vibrationally induced conformational isomerizations, infrared spectra, and photochemistry of gallic acid in low-temperature matrices

    Science.gov (United States)

    Justino, Licínia L. G.; Reva, Igor; Fausto, Rui

    2016-07-01

    Near-infrared (near-IR) narrowband selective vibrational excitation and annealing of gallic acid (3,4,5-trihydroxybenzoic acid) isolated in cryogenic matrices were used to induce interconversions between its most stable conformers. The isomerizations were probed by infrared spectroscopy. An extensive set of quantum chemical calculations, carried out at the DFT(B3LYP)/6-311++G(d,p) level of approximation, was used to undertake a detailed analysis of the ground state potential energy surface of the molecule. This investigation of the molecule conformational space allowed extracting mechanistic insights into the observed annealing- or near-IR-induced isomerization processes. The infrared spectra of the two most stable conformers of gallic acid in N2, Xe, and Ar matrices were fully assigned. Finally, the UV-induced photochemistry of the matrix isolated compound was investigated.

  19. Thermally and vibrationally induced conformational isomerizations, infrared spectra, and photochemistry of gallic acid in low-temperature matrices

    International Nuclear Information System (INIS)

    Justino, Licínia L. G.; Reva, Igor; Fausto, Rui

    2016-01-01

    Near-infrared (near-IR) narrowband selective vibrational excitation and annealing of gallic acid (3,4,5-trihydroxybenzoic acid) isolated in cryogenic matrices were used to induce interconversions between its most stable conformers. The isomerizations were probed by infrared spectroscopy. An extensive set of quantum chemical calculations, carried out at the DFT(B3LYP)/6-311++G(d,p) level of approximation, was used to undertake a detailed analysis of the ground state potential energy surface of the molecule. This investigation of the molecule conformational space allowed extracting mechanistic insights into the observed annealing- or near-IR-induced isomerization processes. The infrared spectra of the two most stable conformers of gallic acid in N 2 , Xe, and Ar matrices were fully assigned. Finally, the UV-induced photochemistry of the matrix isolated compound was investigated.

  20. Thermally and vibrationally induced conformational isomerizations, infrared spectra, and photochemistry of gallic acid in low-temperature matrices

    Energy Technology Data Exchange (ETDEWEB)

    Justino, Licínia L. G., E-mail: liciniaj@ci.uc.pt; Reva, Igor; Fausto, Rui [CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra (Portugal)

    2016-07-07

    Near-infrared (near-IR) narrowband selective vibrational excitation and annealing of gallic acid (3,4,5-trihydroxybenzoic acid) isolated in cryogenic matrices were used to induce interconversions between its most stable conformers. The isomerizations were probed by infrared spectroscopy. An extensive set of quantum chemical calculations, carried out at the DFT(B3LYP)/6-311++G(d,p) level of approximation, was used to undertake a detailed analysis of the ground state potential energy surface of the molecule. This investigation of the molecule conformational space allowed extracting mechanistic insights into the observed annealing- or near-IR-induced isomerization processes. The infrared spectra of the two most stable conformers of gallic acid in N{sub 2}, Xe, and Ar matrices were fully assigned. Finally, the UV-induced photochemistry of the matrix isolated compound was investigated.

  1. Downwelling Far-Infrared Emission Spectra Measured By First at Cerro Toco, Chile and Table Mountain, California

    Science.gov (United States)

    Mast, J. C.; Mlynczak, M. G.; Cageao, R.; Kratz, D. P.; Johnson, D. G.; Mlawer, E. J.; Turner, D. D.

    2014-12-01

    The Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument is a Fourier transform spectrometer developed to measure the important far-infrared spectrum between 100 and 650 cm-1. Presented here are measurements made by FIRST during two successful deployments in a ground-based configuration to measure downwelling longwave radiation at Earth's surface. The initial deployment was to Cerro Toco, Chile, where FIRST operated from August to October, 2009 as part of the Radiative Heating in Underexplored Bands Campaign (RHUBC-II) campaign. After recalibration, FIRST was deployed to the Table Mountain Facility from September through October, 2012. Spectra observed at each location are substantially different, due in large part to the order of magnitude difference in integrated precipitable water vapor (0.3 cm at Table Mountain, 0.03 cm at Cerro Toco). Dry days for both campaigns are chosen for analysis - 09/24/2009 and 10/19/2012. Also available during both deployments are coincident radiosonde temperature and water vapor vertical profiles which are used as inputs a line-by-line radiative transfer program. Comparisons between measured and modeled spectra are presented over the 200 to 800 cm-1 range. An extensive error analysis of both the measured and modeled spectra is presented. In general, the differences between the measured and modeled spectra are within their combined uncertainties.

  2. Visible and near-infrared (0.4-2.5 μm) reflectance spectra of playa evaporite minerals

    Science.gov (United States)

    Crowley, James K.

    1991-01-01

    Visible and near-infrared (VNIR; 0.4–2.4 μm) reflectance spectra were recorded for 35 saline minerals that represent the wide range of mineral and brine chemical compositions found in playa evaporite settings. The spectra show that many of the saline minerals exhibit diagnostic near-infrared absorption bands, chiefly attributable to vibrations of hydrogen-bonded structural water molecules. VNIR reflectance spectra can be used to detect minor hydrate phases present in mixtures dominated by anhydrous halite or thenardite, and therefore will be useful in combination with X ray diffraction data for characterizing natural saline mineral assemblages. In addition, VNIR reflectance spectra are sensitive to differences in sample hydration state and should facilitate in situ studies of minerals that occur as fragile, transitory dehydration products in natural salt crusts. The use of spectral reflectance measurements in playa studies should aid in mapping evaporite mineral distributions and may provide insight into the geochemical and hydrological controls on playa mineral and brine development.

  3. Theoretical study, and infrared and Raman spectra of copper(II) chelated complex with dibenzoylmethane

    DEFF Research Database (Denmark)

    Nekoei, A.-R.; Vakili, M.; Hakimi-Tabar, M.

    2014-01-01

    assignment for Cu(dbm)2 in the literatures. Density functional theory (DFT) at the B3LYP level and also MP2 calculations using different basis sets, besides Natural Bond Orbital (NBO) and Atoms-in-Molecules (AIM) analyses, have been employed to investigate the effect of methyl substitution with the phenyl...

  4. Theoretically predicted soft x-ray emission and absorption spectra of graphitic-structured BC2N

    Science.gov (United States)

    Muramatsu, Yasuji

    Theoretical B K, C K and N K x-ray emission/absorption spectra of three possible graphitic-structured BC2N clusters are predicted based on the B2p-, C2p-, and N2p- density-of-states (DOS) calculated by discrete variational (DV)-X[alpha] molecular orbital calculations. Several prominent differences in DOS spectral features among BC2Ns, h-BN, and graphite are confirmed from comparison of calculated B2p-, C2p-, and N2p-DOS spectra. These variations in the spectra allow BC2N structures to be positively identified by high-resolution x-ray emission/absorption spectroscopy in the B K, C K, and N K regions.

  5. Theoretical and Experimental Research in Neutron Spectra and Nuclear Waste Transmutation on Fast Subcritical Assembly with MOX Fuel

    Science.gov (United States)

    Arkhipkin, D. A.; Buttsev, V. S.; Chigrinov, S. E.; Kutuev, R. Kh.; Polanski, A.; Rakhno, I. L.; Sissakian, A.; Zulkarneev, R. Ya.; Zulkarneeva, Yu. R.

    2003-07-01

    The paper deals with theoretical and experimental investigation of transmutation rates for a number of long-lived fission products and minor actinides, as well as with neutron spectra formed in a subcritical assembly driven with the following monodirectional beams: 660-MeV protons and 14-MeV neutrons. In this work, the main objective is the comparison of neutron spectra in the MOX assembly for different external driving sources: a 660-MeV proton accelerator and a 14-MeV neutron generator. The SAD project (JINR, Russia) has being discussed. In the context of this project, a subcritical assembly consisting of a cylindrical lead target surrounded by a cylindrical MOX fuel layer will be constructed. Present conceptual design of the subcritical assembly is based on the core with a nominal unit capacity of 15 kW (thermal). This corresponds to a multiplication coefficient, keff= 0.945, and an accelerator beam power of 0.5 kW. The results of theoretical investigations on the possibility of incinerating long-lived fission products and minor actinides in fast neutron spectrum and formation of neutron spectra with different hardness in subcritical systems based on the MOX subcritical assembly are discussed. Calculated neutron spectra emitted from a lead target irradiated by a 660-MeV protons are also presented.

  6. Multivariate curve resolution using a combination of mid-infrared and near-infrared spectra for the analysis of isothermal epoxy curing reaction

    Science.gov (United States)

    Yamasaki, Hideki; Morita, Shigeaki

    2018-05-01

    Multivariate curve resolution (MCR) was applied to a hetero-spectrally combined dataset consisting of mid-infrared (MIR) and near-infrared (NIR) spectra collected during the isothermal curing reaction of an epoxy resin. An epoxy monomer, bisphenol A diglycidyl ether (BADGE), and a hardening agent, 4,4‧-diaminodiphenyl methane (DDM), were used for the reaction. The fundamental modes of the Nsbnd H and Osbnd H stretches were highly overlapped in the MIR region, while their first overtones could be independently identified in the NIR region. The concentration profiles obtained by MCR using the hetero-spectral combination showed good agreement with the results of calculations based on the Beer-Lambert law and the mass balance. The band assignments and absorption sites estimated by the analysis also showed good agreement with the results using two-dimensional (2D) hetero-correlation spectroscopy.

  7. Artificial neural networks as a tool for identity confirmation of infrared spectra

    NARCIS (Netherlands)

    Visser T; Luinge HJ; LOC

    1995-01-01

    Onderzoek is uitgevoerd naar de bruikbaarheid van kunstmatige neurale netwerken als criterium voor de identiteitsbevestiging van infrarood-(IR) spectra. Doel van het onderzoek is de identificatie van spectra met hoge ruisniveaus, verkregen met behulp van gecombineeerde gaschromatografie (GC)IR

  8. Dielectric constant and low-frequency infrared spectra for liquid water and ice Ih within the E3B model

    Energy Technology Data Exchange (ETDEWEB)

    Shi, L.; Ni, Y.; Drews, S. E. P.; Skinner, J. L. [Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)

    2014-08-28

    Two intrinsic difficulties in modeling condensed-phase water with conventional rigid non-polarizable water models are: reproducing the static dielectric constants for liquid water and ice Ih, and generating the peak at about 200 cm{sup −1} in the low-frequency infrared spectrum for liquid water. The primary physical reason for these failures is believed to be the missing polarization effect in these models, and consequently various sophisticated polarizable water models have been developed. However, in this work we pursue a different strategy and propose a simple empirical scheme to include the polarization effect only on the dipole surface (without modifying a model's intermolecular interaction potential). We implement this strategy for our explicit three-body (E3B) model. Our calculated static dielectric constants and low-frequency infrared spectra are in good agreement with experiment for both liquid water and ice Ih over wide temperature ranges, albeit with one fitting parameter for each phase. The success of our modeling also suggests that thermal fluctuations about local minima and the energy differences between different proton-disordered configurations play minor roles in the static dielectric constant of ice Ih. Our analysis shows that the polarization effect is important in resolving the two difficulties mentioned above and sheds some light on the origin of several features in the low-frequency infrared spectra for liquid water and ice Ih.

  9. CRYSTALLIZATION EXPERIMENTS ON AMORPHOUS MAGNESIUM SILICATE. II. EFFECT OF STACKING FAULTS ON INFRARED SPECTRA OF ENSTATITE

    International Nuclear Information System (INIS)

    Murata, K.; Chihara, H.; Koike, C.; Takakura, T.; Imai, Y.; Tsuchiyama, A.; Noguchi, T.

    2009-01-01

    We carried out experiments of low-temperature infrared spectroscopy and transmission electron microscopy of enstatite (MgSiO 3 ) synthesized by heating of amorphous magnesium silicate. There is a discrepancy between the infrared feature of enstatite obtained in this experiment and that of fine powdered single crystals. This reflects stacking disorder of enstatite. We show that circumstellar dust emission of enstatite is similar to the infrared feature measured in this experiment. This result strongly suggests that circumstellar enstatite has abundant stacking faults and is different from the single crystal.

  10. A Comparison of Theoretical and Experimental Values of the Activation Doppler Effect in Some Fast Reactor Spectra

    International Nuclear Information System (INIS)

    Haeggblom, H.; Tiren, L.I.

    1968-08-01

    Results of activation Doppler measurements on the U 238 (n,γ) and U 235 (n, fission) reactions in the FR0 and MSCA fast critical assemblies have been compared with theoretical values. The study covers neutron spectra with median fission energies from 50 to 240 keV. The calculated Doppler effect in U 238 in the FR0 cores is 20 - 35 % lower than the measured values. The sensitivity of the theoretical result with regard to changes in cross sections and neutron spectrum has been studied. The theoretical value for U 235 (FR0 core 5) is 4 times higher than the measured one. The report includes a brief description of the DORIX-2 method of calculating effective resonance cross sections appropriate to activation Doppler measurements. References to the cross section data used for the comparisons are also given

  11. The structure, vibrational spectra and nonlinear optical properties of the L-lysine × tartaric acid complex—Theoretical studies

    Science.gov (United States)

    Drozd, M.; Marchewka, M. K.

    2006-05-01

    The room temperature X-ray studies of L-lysine × tartaric acid complex are not unambiguous. The disorder of three atoms of carbon in L-lysine molecule is observed. These X-ray studies are ambiguous. The theoretical geometry study performed by DFT methods explain the most doubts which are connected with crystallographic measurements. The theoretical vibrational frequencies and potential energy distribution (PED) of L-lysine × tartaric acid were calculated by B3LYP method. The calculated frequencies were compared with experimental measured IR spectra. The complete assignment of the bands has been made on the basis of the calculated PED. The restricted Hartee-Fock (RHF) methods were used for calculation of the hyperpolarizability for investigated compound. The theoretical results are compared with experimental value of β.

  12. A Comparison of Theoretical and Experimental Values of the Activation Doppler Effect in Some Fast Reactor Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Haeggblom, H; Tiren, L I

    1968-08-15

    Results of activation Doppler measurements on the U{sup 238} (n,{gamma}) and U{sup 235} (n, fission) reactions in the FR0 and MSCA fast critical assemblies have been compared with theoretical values. The study covers neutron spectra with median fission energies from 50 to 240 keV. The calculated Doppler effect in U{sup 238} in the FR0 cores is 20 - 35 % lower than the measured values. The sensitivity of the theoretical result with regard to changes in cross sections and neutron spectrum has been studied. The theoretical value for U{sup 235} (FR0 core 5) is 4 times higher than the measured one. The report includes a brief description of the DORIX-2 method of calculating effective resonance cross sections appropriate to activation Doppler measurements. References to the cross section data used for the comparisons are also given.

  13. Theoretical Studies Of Molecular Structure And Vibrational Spectra Of 5-Aminolevulinic Acid Hexyl Ester

    International Nuclear Information System (INIS)

    Comert, H.

    2010-01-01

    The molecular geometry and vibrational frequencies of The 5-Aminolevulinic acid's hexyl ester (ALA-H) in the ground state have been calculated using Hartree-Fock (HF) and Density functional method (B3LYP) with 6-31++G(d) basis set. The calculated vibrational spectra and geometric parameters of title compound were compered with experimental ones.

  14. Theoretical Interpretation of the Fluorescence Spectra of Toluene and P- Cresol

    Science.gov (United States)

    1994-07-01

    NUMBER OF PAGES Toluene Geometrica 25 p-Cresol Fluorescence Is. PRICE CODE Spectra 17. SECURITY CLASSIFICATION 13. SECURITY CLASSIFICATION 19...State Frequencies of Toluene ................ 19 6 Computed and exp" Ground State Frequencies of p-Cresol ............... 20 7 Correction Factors for...Computed Ground State Vibrational Frequencies ....... 21 8 Computed and Corrected Excited State Frequencies of Toluene ............. 22 9 Computed and

  15. Correcting attenuated total reflection-fourier transform infrared spectra for water vapor and carbon dioxide

    DEFF Research Database (Denmark)

    Bruun, Susanne Wrang; Kohler, Achim; Adt, Isabelle

    2006-01-01

    an absorption band from either water vapor or CO(2). From two calibration data sets, gas model spectra were estimated in each of the four spectral regions, and these model spectra were applied for correction of gas absorptions in two independent test sets (spectra of aqueous solutions and a yeast biofilm (C...... of the growing yeast biofilm, the gas correction revealed otherwise hidden variations of relevance for modeling the growth dynamics. As the presented method improved the interpretation of the principle component analysis (PCA) models, it has proven to be a valuable tool for filtering atmospheric variation in ATR...

  16. An experimental and theoretical study of the valence shell photoelectron spectra of 2-chloropyridine and 3-chloropyridine

    Science.gov (United States)

    Holland, D. M. P.; Powis, I.; Trofimov, A. B.; Menzies, R. C.; Potts, A. W.; Karlsson, L.; Badsyuk, I. L.; Moskovskaya, T. E.; Gromov, E. V.; Schirmer, J.

    2017-10-01

    The valence shell photoelectron spectra of 2-chloropyridine and 3-chloropyridine have been studied both experimentally and theoretically. Synchrotron radiation has been employed to record angle resolved photoelectron spectra in the photon energy range 20-100 eV, and these have enabled anisotropy parameters and branching ratios to be derived. The experimental results have been compared with theoretical predictions obtained using the continuum multiple scattering Xα approach. This comparison shows that the anisotropy parameter associated with the nominally chlorine lone-pair orbital lying in the molecular plane is strongly affected by the atomic Cooper minimum. In contrast, the photoionization dynamics of the second lone-pair orbital, orientated perpendicular to the molecular plane, seem relatively unaffected by this atomic phenomenon. The outer valence ionization has been studied theoretically using the third-order algebraic-diagrammatic construction (ADC(3)) approximation scheme for the one-particle Green's function, the outer valence Green's function method, and the equation-of-motion (EOM) coupled cluster (CC) theory at the level of the EOM-IP-CCSD and EOM-EE-CC3 models. The convergence of the results to the complete basis set limit has been investigated. The ADC(3) method has been employed to compute the complete valence shell ionization spectra of 2-chloropyridine and 3-chloropyridine. The relaxation mechanism for ionization of the nitrogen σ-type lone-pair orbital (σN LP) has been found to be different to that for the corresponding chlorine lone-pair (σCl LP). For the σN LP orbital, π-π* excitations play the main role in the screening of the lone-pair hole. In contrast, excitations localized at the chlorine site involving the chlorine πCl LP lone-pair and the Cl 4p Rydberg orbital are the most important for the σCl LP orbital. The calculated photoelectron spectra have allowed assignments to be proposed for most of the structure observed in the

  17. Pre-processing of Fourier transform infrared spectra by means of multivariate analysis implemented in the R environment.

    Science.gov (United States)

    Banas, Krzysztof; Banas, Agnieszka; Gajda, Mariusz; Pawlicki, Bohdan; Kwiatek, Wojciech M; Breese, Mark B H

    2015-04-21

    Pre-processing of Fourier transform infrared (FTIR) spectra is typically the first and crucial step in data analysis. Very often hyperspectral datasets include the regions characterized by the spectra of very low intensity, for example two-dimensional (2D) maps where the areas with only support materials (like mylar foil) are present. In that case segmentation of the complete dataset is required before subsequent evaluation. The method proposed in this contribution is based on a multivariate approach (hierarchical cluster analysis), and shows its superiority when compared to the standard method of cutting-off by using only the mean spectral intensity. Both techniques were implemented and their performance was tested in the R statistical environment - open-source platform - that is a favourable solution if the repeatability and transparency are the key aspects.

  18. Prediction of long-residue properties of potential blends from mathematically mixed infrared spectra of pure crude oils by partial least-squares regression models

    NARCIS (Netherlands)

    de Peinder, P.; Visser, T.; Petrauskas, D.D.; Salvatori, F.; Soulimani, F.; Weckhuysen, B.M.

    2009-01-01

    Research has been carried out to determine the feasibility of partial least-squares (PLS) regression models to predict the long-residue (LR) properties of potential blends from infrared (IR) spectra that have been created by linearly co-adding the IR spectra of crude oils. The study is the follow-up

  19. Infrared reflection spectra of multilayer epitaxial heterostructures with embedded InAs and GaAs layers

    International Nuclear Information System (INIS)

    Seredin, P. V.; Domashevskaya, E. P.; Lukin, A. N.; Arsent'ev, I. N.; Vinokurov, D. A.; Tarasov, I. S.

    2008-01-01

    The effect of the thickness of embedded InAs and GaAs layers on the infrared reflection spectra of lattice vibrations for AlInAs/InAs/AlInAs, InGaAs/GaAs/InGaAs, and AlInAs/InGaAs/GaAs/InGaAs/AlInAs multilayer epitaxial heterostructures grown by MOC hydride epitaxy on InP (100) substrates is studied. Relative stresses emerging in the layers surrounding the embedded layers with variation in the number of monolayers from which the quantum dots are formed and with variation the thickness of the layers themselves surrounding the embedded layers are evaluated.

  20. Synthesis and purification of some alkyl phenanthrenes and presentation of their infrared, ultraviolet, nuclear magnetic resonance and mass spectra

    International Nuclear Information System (INIS)

    Persaud, K.

    1965-01-01

    We have carried out the synthesis of: - phenanthrene - its five monomethyl derivatives - three dimethyl derivatives - two trimethyl derivatives. We have then purified these products as well as a certain number of others obtained from various sources. We have been able to obtain in the majority of cases, a purity of 99.5 per cent or over, these figures being obtained by low voltage mass spectrometry. Finally we have recorded the infrared, ultraviolet, nuclear magnetic resonance and mass spectra of these products for which an atlas has been drawn up. (author) [fr

  1. Infrared spectra of 4HeH+, 4HeD+, 3HeH+, and 3HeD+

    International Nuclear Information System (INIS)

    Crofton, M.W.; Altman, R.S.; Haese, N.N.; Oka, T.

    1989-01-01

    Isotopic species of the HeH + molecular ion provide an excellent testing ground for studying isotopic dependence of vibration--rotation constants because of the small masses of He and H isotopes. We have observed infrared spectra of the hot band v=2 left-arrow 1 of HeH + and fundamental bands of isotopic species HeD + , 3 HeH + , and 3 HeD + , and obtained the Dunham coefficients Y kl , and the isotopically independent parameters U kl , Δ He kl , and Δ H kl

  2. CH_3Cl, CH_2Cl_2, CHCl_3, and CCl_4: Infrared spectra, radiative efficiencies, and global warming potentials

    International Nuclear Information System (INIS)

    Wallington, Timothy J.; Pivesso, Bruno Pasquini; Lira, Alane Moura; Anderson, James E.; Nielsen, Claus Jørgen; Andersen, Niels Højmark; Hodnebrog, Øivind

    2016-01-01

    Infrared spectra for the title compounds were measured experimentally in 700 Torr of air at 295 K and systematically modeled in B3LYP, M06-2X and MP2 calculations employing various basis sets. Calibrated infrared spectra over the wavenumber range 600–3500 cm"−"1 are reported and combined with literature data to provide spectra for use in experimental studies and radiative transfer calculations. Integrated absorption cross sections are (units of cm"−"1 molecule"−"1): CH_3Cl, 660–780 cm"−"1, (3.89±0.19)×10"−"1"8; CH_2Cl_2, 650–800 cm"−"1, (2.16±0.11)×10"−"1"7; CHCl_3, 720–810 cm"−"1, (4.08±0.20)×10"−"1"7; and CCl_4, 730–825 cm"−"1, (6.30±0.31)×10"−"1"7. CH_3Cl, CH_2Cl_2, CHCl_3, and CCl_4 have radiative efficiencies of 0.004, 0.028, 0.070, and 0.174 W m"−"2 ppb"−"1 and global warming potentials (100 year horizon) of 5, 8, 15, and 1775, respectively. Quantum chemistry calculations generally predict larger band intensities than the experimental values. The best agreement with experiments is obtained in MP2(Full) calculations employing basis sets of at least triple-zeta quality augmented by diffuse functions. The B3LYP functional is found ill-suited for calculating vibrational frequencies and infrared intensities of halocarbons. - Highlights: • Infrared spectra reported for CH_3Cl, CH_2Cl_2, CHCl_3, and CCl_4. • REs of CH_3Cl, CH_2Cl_2, CHCl_3, and CCl_4 are 0.004, 0.028, 0.070, and 0.174 W m"−"2 ppb"−"1, respectively. • GWPs of CH_3Cl, CH_2Cl_2, CHCl_3, and CCl_4 are 5, 8, 15, and 1775, respectively.

  3. Accurate Theoretical Methane Line Lists in the Infrared up to 3000 K and Quasi-continuum Absorption/Emission Modeling for Astrophysical Applications

    Science.gov (United States)

    Rey, Michael; Nikitin, Andrei V.; Tyuterev, Vladimir G.

    2017-10-01

    Modeling atmospheres of hot exoplanets and brown dwarfs requires high-T databases that include methane as the major hydrocarbon. We report a complete theoretical line list of 12CH4 in the infrared range 0-13,400 cm-1 up to T max = 3000 K computed via a full quantum-mechanical method from ab initio potential energy and dipole moment surfaces. Over 150 billion transitions were generated with the lower rovibrational energy cutoff 33,000 cm-1 and intensity cutoff down to 10-33 cm/molecule to ensure convergent opacity predictions. Empirical corrections for 3.7 million of the strongest transitions permitted line position accuracies of 0.001-0.01 cm-1. Full data are partitioned into two sets. “Light lists” contain strong and medium transitions necessary for an accurate description of sharp features in absorption/emission spectra. For a fast and efficient modeling of quasi-continuum cross sections, billions of tiny lines are compressed in “super-line” libraries according to Rey et al. These combined data will be freely accessible via the TheoReTS information system (http://theorets.univ-reims.fr, http://theorets.tsu.ru), which provides a user-friendly interface for simulations of absorption coefficients, cross-sectional transmittance, and radiance. Comparisons with cold, room, and high-T experimental data show that the data reported here represent the first global theoretical methane lists suitable for high-resolution astrophysical applications.

  4. Influence of temperature on water and aqueous glucose absorption spectra in the near- and mid-infrared regions at physiologically relevant temperatures

    DEFF Research Database (Denmark)

    Jensen, P.S.; Bak, J.; Andersson-Engels, S.

    2003-01-01

    transmission cell controlled within 0.02 degreesC. Pathlengths of 50 mum and 0.4 mm were used in the mid- and near-infrared spectral region, respectively. Difference spectra were used to determine the effect of temperature on the water spectra quantitatively. These spectra were obtained by subtracting the 37...... degreesC water spectrum from the spectra measured at other temperatures. The difference spectra reveal that the effect of temperature is highest in the vicinity of the strong absorption bands, with a number of isosbestic points with no temperature dependence and relatively flat plateaus in between......Near- and mid-infrared absorption spectra of pure water and aqueous 1.0 g/dL glucose solutions in the wavenumber range 8000-950 cm(-1) were measured in the temperature range 30-42 C in steps of 2 degreesC. Measurements were carried out with an FT-IR spectrometer and a variable pathlength...

  5. Valter Ritz as a theoretical physicist and his research on atomic spectra theory

    International Nuclear Information System (INIS)

    El'yashevich, M.A.; Kemberovskaya, N.G.; Tomil'chik, L.M.

    1995-01-01

    The article presents a historic-methodological analysis of the scientific heritage of an outstanding Swiss physicist Walter Ritz (1878-1909); the analysis is based on the study of a complete collection of his works published in 1911. In addition to a general description of Ritz's works which comprise publications in spectroscopy, variational method and electrodynamics, the article deals in detail with this fundamental research into atomic spectra theory. Elastic and magnetic model of the atom proposed by Ritz for explaining atomic spectra within the framework of the classical approach are discussed. It is shown that the generalized formulas of Balmer and Rydbery, as well as the combination principle which served later as a basis for formalting Bohr's condition of frequencies, were derived by Ritz as regions corollaries of this models and were out of semiempiric nature, as was assumed. 124 refs

  6. Infrared spectra of complex organic molecules in astronomically relevant ice matrices. I. Acetaldehyde, ethanol, and dimethyl ether

    Science.gov (United States)

    Terwisscha van Scheltinga, J.; Ligterink, N. F. W.; Boogert, A. C. A.; van Dishoeck, E. F.; Linnartz, H.

    2018-03-01

    Context. The number of identified complex organic molecules (COMs) in inter- and circumstellar gas-phase environments is steadily increasing. Recent laboratory studies show that many such species form on icy dust grains. At present only smaller molecular species have been directly identified in space in the solid state. Accurate spectroscopic laboratory data of frozen COMs, embedded in ice matrices containing ingredients related to their formation scheme, are still largely lacking. Aim. This work provides infrared reference spectra of acetaldehyde (CH3CHO), ethanol (CH3CH2OH), and dimethyl ether (CH3OCH3) recorded in a variety of ice environments and for astronomically relevant temperatures, as needed to guide or interpret astronomical observations, specifically for upcoming James Webb Space Telescope observations. Methods: Fourier transform transmission spectroscopy (500-4000 cm-1/20-2.5 μm, 1.0 cm-1 resolution) was used to investigate solid acetaldehyde, ethanol and dimethyl ether, pure or mixed with water, CO, methanol, or CO:methanol. These species were deposited on a cryogenically cooled infrared transmissive window at 15 K. A heating ramp was applied, during which IR spectra were recorded until all ice constituents were thermally desorbed. Results: We present a large number of reference spectra that can be compared with astronomical data. Accurate band positions and band widths are provided for the studied ice mixtures and temperatures. Special efforts have been put into those bands of each molecule that are best suited for identification. For acetaldehyde the 7.427 and 5.803 μm bands are recommended, for ethanol the 11.36 and 7.240 μm bands are good candidates, and for dimethyl ether bands at 9.141 and 8.011 μm can be used. All spectra are publicly available in the Leiden Database for Ice.

  7. Microwave, infrared and Raman spectra, adjusted r{sub 0} structural parameters, conformational stability, and vibrational assignment of cyclopropylfluorosilane

    Energy Technology Data Exchange (ETDEWEB)

    Panikar, Savitha S. [Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110 (United States); Guirgis, Gamil A.; Eddens, Matthew T.; Dukes, Horace W. [Department of Chemistry and Biochemistry, College of Charleston, Charleston, SC 29424 (United States); Conrad, Andrew R.; Tubergen, Michael J. [Department of Chemistry, Kent State University, Kent, OH 44242 (United States); Gounev, Todor K. [Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110 (United States); Durig, James R., E-mail: durigj@umkc.edu [Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110 (United States)

    2013-03-29

    Highlights: ► The most stable gauche conformer has been identified from microwave spectra. ► Enthalpy difference has been determined between the two forms. ► Adjusted r{sub 0} structures were obtained for the gauche form. ► Ab initio calculations were performed for the two conformers. - Abstract: FT-microwave, infrared spectra of gas and Raman spectra of liquid for cyclopropylfluorosilane, c-C{sub 3}H{sub 5}SiH{sub 2}F have been recorded. 51 transitions for the {sup 28}Si, {sup 29}Si, and {sup 30}Si isotopomers have been assigned for the gauche conformer. Enthalpy differences in xenon solution by variable temperature infrared spectra between the more stable gauche and lesser stable cis form gave 109 ± 9 cm{sup −1}. From the microwave rotational constants for the three isotopomers ({sup 28}Si, {sup 29}Si, {sup 30}Si) combined with structural parameters predicted from MP2(full)/6-311+G(d, p) calculations, adjusted r{sub 0} structural parameters were obtained for the gauche conformer. The heavy atom distances (Å): Si–C{sub 2} = 1.836(3); C{sub 2}–C{sub 4} = 1.525(3); C{sub 2}–C{sub 5} = 1.519(3); C{sub 4}–C{sub 5} = 1.494(3); Si–F = 1.594(3) and angles (°): ∠CSiF = 111.2(5); ∠SiC{sub 2}C{sub 4} = 117.5(5); ∠SiC{sub 2}C{sub 5} = 119.2(5). To support the vibrational assignments, MP2(full)/6-31G(d) calculations were carried out. Results are discussed and compared to the corresponding properties of some similar molecules.

  8. Theoretical UV absorption spectra of hydrodynamically escaping O2/CO2-rich exoplanetary atmospheres

    International Nuclear Information System (INIS)

    Gronoff, G.; Mertens, C. J.; Norman, R. B.; Maggiolo, R.; Wedlund, C. Simon; Bell, J.; Bernard, D.; Parkinson, C. J.; Vidal-Madjar, A.

    2014-01-01

    Characterizing Earth- and Venus-like exoplanets' atmospheres to determine if they are habitable and how they are evolving (e.g., equilibrium or strong erosion) is a challenge. For that endeavor, a key element is the retrieval of the exospheric temperature, which is a marker of some of the processes occurring in the lower layers and controls a large part of the atmospheric escape. We describe a method to determine the exospheric temperature of an O 2 - and/or CO 2 -rich transiting exoplanet, and we simulate the respective spectra of such a planet in hydrostatic equilibrium and hydrodynamic escape. The observation of hydrodynamically escaping atmospheres in young planets may help constrain and improve our understanding of the evolution of the solar system's terrestrial planets' atmospheres. We use the dependency of the absorption spectra of the O 2 and CO 2 molecules on the temperature to estimate the temperature independently of the total absorption of the planet. Combining two observables (two parts of the UV spectra that have a different temperature dependency) with the model, we are able to determine the thermospheric density profile and temperature. If the slope of the density profile is inconsistent with the temperature, then we infer the hydrodynamic escape. We address the question of the possible biases in the application of the method to future observations, and we show that the flare activity should be cautiously monitored to avoid large biases.

  9. An interpretation of the absorption and emission spectra of the gold dimer using modern theoretical tools

    DEFF Research Database (Denmark)

    Geethalakshmi, K. R.; Ruiperez, F.; Knecht, S.

    2012-01-01

    The excited states of the gold dimer have been investigated using modern theoretical tools including the multiconfigurational exact molecular mean-field intermediate Hamiltonian Fock-space Coupled Cluster, X2Cmmf-IHFSCC, and the complete active space self-consistent field followed by second order...

  10. An interpretation of the absorption and emission spectra of the gold dimer using modern theoretical tools

    NARCIS (Netherlands)

    Geethalakshmi, K R; Ruipérez, Fernando; Knecht, Stefan; Ugalde, Jesus M.; Morse, Michael D.; Infante, Ivan

    2012-01-01

    The excited states of the gold dimer have been investigated using modern theoretical tools including the multiconfigurational exact molecular mean-field intermediate Hamiltonian Fock-space Coupled Cluster, X2Cmmf-IHFSCC, and the complete active space self-consistent field followed by second order

  11. A comparative theoretical study on core-hole excitation spectra of azafullerene and its derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Yunfeng [Guizhou Provincial Key Laboratory of Computational Nano-material Science, Guizhou Normal College, Guiyang 550018 (China); Department of Physics, Guizhou University, Guiyang 550025 (China); Gao, Bin, E-mail: bin.gao@uit.no [Guizhou Provincial Key Laboratory of Computational Nano-material Science, Guizhou Normal College, Guiyang 550018 (China); Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry, University of Tromsø—The Arctic University of Norway, N-9037 Tromsø (Norway); Deng, Mingsen, E-mail: deng@gznc.edu.cn [Guizhou Provincial Key Laboratory of Computational Nano-material Science, Guizhou Normal College, Guiyang 550018 (China); Luo, Yi [Guizhou Provincial Key Laboratory of Computational Nano-material Science, Guizhou Normal College, Guiyang 550018 (China); Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, SE-10691 Stockholm (Sweden)

    2014-03-28

    The core-hole excitation spectra—near-edge x-ray absorption spectroscopy (NEXAFS), x-ray emission spectroscopy (XES), and x-ray photoelectron spectroscopy (XPS) shake-up satellites have been simulated at the level of density functional theory for the azafullerene C{sub 59}N and its derivatives (C{sub 59}N){sup +}, C{sub 59}HN, (C{sub 59}N){sub 2}, and C{sub 59}N–C{sub 60}, in which the XPS shake-up satellites were simulated using our developed equivalent core hole Kohn-Sham (ECH-KS) density functional theory approach [B. Gao, Z. Wu, and Y. Luo, J. Chem. Phys. 128, 234704 (2008)] which aims for the study of XPS shake-up satellites of large-scale molecules. Our calculated spectra are generally in good agreement with available experimental results that validates the use of the ECH-KS method in the present work. The nitrogen K-edge NEXAFS, XES, and XPS shake-up satellites spectra in general can be used as fingerprints to distinguish the azafullerene C{sub 59}N and its different derivatives. Meanwhile, different carbon K-edge spectra could also provide detailed information of (local) electronic structures of different molecules. In particular, a peak (at around 284.5 eV) in the carbon K-edge NEXAFS spectrum of the heterodimer C{sub 59}N–C{sub 60} is confirmed to be related to the electron transfer from the C{sub 59}N part to the C{sub 60} part in this charge-transfer complex.

  12. Theoretical analysis of microdosimetric spectra and cluster formation for 103Pd and 125I photon emitters

    International Nuclear Information System (INIS)

    Reniers, B; Vynckier, S; Verhaegen, F

    2004-01-01

    In this work we have compared 125 I or 103 Pd from a microdosimetric point of view. The photon spectra at different positions around the seeds have first been calculated using EGSnrc Monte Carlo (MC) code. These photon spectra are used as input for the event-by-event MC code TRION to calculate the microdosimetric lineal energy (y) distribution for each isotope. The microdosimetric dose average lineal energy, y D , calculated in a sphere of 1 μm is 3.5 keV μm -1 for 125 I and 4.0 keV μm -1 for 103 Pd, agreeing well with values reported in the literature. y D in a 1 μm sphere diminishes slightly with the distance from the seed for 103 Pd. This is due to the spectral hardening caused by the presence of a gamma-ray of 357.5 keV in the initial spectrum of 103 Pd. In parallel with the calculation of the microdosimetric spectra, we have analysed the distribution of the size of the energy deposition clusters generated by these low energy photons in structures of 2 and 10 nm of radius. Due to Compton interactions, the fraction of very low energy electrons ( 125 I photons is 51%, whereas it is only 27% for 103 Pd. As these electrons deposit their energy very locally, the pattern of energy depositions contains more clusters of a few nm of radius for 125 I than for 103 Pd; the mean cluster orders are respectively 3.3 and 3.0 for 10 nm clusters. This is in opposition with the prediction based on the microdosimetric spectrum and the parameter y D and could be of importance for the damage to the cells

  13. Infrared and Raman Spectra of Magnesium Ammonium Phosphate Hexahydrate (Struvite) and its Isomorphous Analogues. VIII. Spectra of Protiated and Partially Deuterated Magnesium Rubidium Phosphate Hexahydrate and Magnesium Thallium Phosphate Hexahydrate.

    Science.gov (United States)

    Soptrajanov, Bojan; Cahil, Adnan; Najdoski, Metodija; Koleva, Violeta; Stefov, Viktor

    2011-09-01

    The infrared and Raman spectra of magnesium rubidium phosphate hexahydrate MgRbPO4 • 6H2O and magnesium thallium phosphate hexahydrate, MgTlPO4 • 6H2O were recorded at room temperature (RT) and the boiling temperature of liquid nitrogen (LNT). To facilitate their analysis, also recorded were the spectra of partially deuterated analogues with varying content of deuterium. The effects of deuteration and those of lowering the temperature were the basis of the conclusions drawn regarding the origin of the observed bands which were assigned to vibrations which are predominantly localized in the water molecules (four crystallographically different types of such molecules exist in the structures) and those with PO43- character. It was concluded that in some cases coupling of phosphate and water vibrations is likely to take place. The appearance of the infrared spectra in the O-H stretching regions of the infrared spectra is explained as being the result of an extensive overlap of bands due to components of the fundamental stretching modes of the H2O units with a possible participation of bands due to second-order transitions. A broad band reminiscent of the B band of the well-known ABC trio characteristic of spectra of substances containing strong hydrogen bonds in their structure was found around 2400 cm-1 in the infrared spectra of the two studied compounds.

  14. Alternative interpretation of infrared spectra of the zeolite NaHY and 1-butene system

    Energy Technology Data Exchange (ETDEWEB)

    Foerster, H.; Seelemann, R.

    1979-01-01

    A Fourier transform IR study of the adsorption and isomerization of n-butenes on type A zeolites showed an essential similarity of the IR spectra of pure 1-butene absorbed on NaY and NaA zeolites. This led to an interpretation of the IR spectra of 1-butene on NaHY zeolites in terms of the isomerization to the cis- and trans-2-butene, rather than oligomerization on NaY and oligomerization, isomerization, fragmentation, or further side reaction on NaHY, as suggested by Ceckiewicz et al. The temperature-programed desorption measurements at temperatures up to 700/sup 0/K used by Ceckiewicz to analyze IR spectra taken at room temperature seem to be unsuitable for this purpose since subsequent reactions at higher temperatures cannot be ruled out.

  15. Proton location in (CH3)3N-H+-(CH3OH)n: A theoretical and infrared spectroscopic study

    International Nuclear Information System (INIS)

    Bing, Dan; Hamashima, Toru; Tsai, Chen-Wei; Fujii, Asuka; Kuo, Jer-Lai

    2013-01-01

    Highlights: • Preferential location of the excess proton in the trimethylamine-methanol clusters. • Collaboration between DFT calculations and IR spectroscopy. • The excess proton prefers the protonation to the trimethylamine moiety. - Abstract: The dependence of the preferential protonated site in (CH 3 ) 3 N-H + -(CH 3 OH) n on the cluster size was investigated using theoretical calculations and infrared spectroscopy measurements. While simple estimation from the magnitude of proton affinity suggested that the excess proton prefers the methanol site in n ⩾ 4, density functional theory calculations of the stabilization energy indicated the clear preference as protonation of the trimethylamine site, even for n = 9. Infrared spectra of the clusters were observed for n = 3–7. Spectral simulations were also performed using the quantum harmonic superposition approximation. The observed (CH 3 ) 3 N-H + -(CH 3 OH) n spectra were well interpreted by simulations of the isomers with the protonated trimethylamine ion core. It was shown that both the proton affinity and the mutual solvation energy govern the preferential location of the excess proton in binary component clusters

  16. Comparison of optical and electron spectra in an infra-red free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    MacLeod, A.M.; Gillespie, W.A.; Martin, P.F. [Univ. of Abertay, Dundee (United Kingdom)] [and others

    1995-12-31

    Time-resolved electron and optical spectra recently acquired at the FELIX facility are presented, showing the evolution of the respective macropulses. A comparison is made between the optical power output during the macropulse and the measured power extracted from the electron beam using a simple model of the cavity losses. Data are available for a wide range of operating conditions: the wavelength range is from 9 {mu}m to 28 {mu}m and detuning are between 1/4{lambda} and 2{lambda}. The effect of rapid electron beam energy changes on the optical and electron spectra will also be discussed.

  17. Theoretical study of IR and photoelectron spectra of small gallium-arsenide clusters

    Energy Technology Data Exchange (ETDEWEB)

    Pouchan, Claude; Marchal, Rémi; Hayashi, Shinsuke [Université de Pau et des Pays de l' Adour, IPREM/ECP, UMR CNRS 5254 (France)

    2015-01-22

    Relative stabilities of small Ga{sub n}As{sub m} clusters, as well as their structural electronic and vibrational properties, were computed and analysed using a CCSD(T) reference method since experimental data in this area are sparse or unknown. With the aim of investigating larger clusters, we explored several DFT functionals and basis sets able to mimic the reliable CCSD(T) approach. Among them, the PBE0/SBKJC+sp,d appears as the most efficient to describe the structural and vibrational properties since average differences of about 0.042Å and 5.1cm{sup −1} were obtained for bond lengths and fundamental vibrational frequencies, respectively for the first small clusters [1] of the series found from our GSAM method [2]. As further test, this model is used in order to investigate and revisit an experimental IR spectrum of Ga{sub n}As{sub m} mixture previously published by Li et al. [3]. More complicated is the difficulty which arises in the electronic description due to the presence of numerous low lying electronic states nearly degenerated to correctly describe the electronic structure. The case of Ga{sub 2}As will be discussed and the photoelectron spectra of the Ga{sub 2}As anion reanalyzed on the ground of our calculations [4] comparatively to the experimental spectra obtained by Neumark and co-workers [5].

  18. From theoretical stellar spectra to realistic models of the Milky Way : a never ending Odyssey

    OpenAIRE

    Ammon, Karin

    2007-01-01

    The last chapter is dedicated to the compilation of the results and the discussion about the success of - but also about the problems that have arisen during - and in part also survived - this work. The main goal of this thesis was, firstly, to convert the stellar parameters given by galaxy models into observables, and then to compare these theoretical stellar distributions in different viewing directions with real observational data to check, if it is possible to find a best-fitt...

  19. Theoretical Study on Vibrational Spectra, Detonation Properties and Pyrolysis Mechanism for Cyclic 2-Diazo-4,6-dinitrophenol

    Science.gov (United States)

    Li, Xiao-hong; Yin, Geng-xin; Zhang, Xian-zhou

    2012-10-01

    Based on the full optimized molecular geometrical structures at the DFT-B3LYP/6-311+G** level, there exists intramolecular hydrogen bond interaction for cyclic 2-diazo-4,6-dinitrophenol. The assigned infrared spectrum is obtained and used to compute the thermodynamic properties. The results show that there are four main characteristic regions in the calculated IR spectra of the title compound. The detonation velocities and pressures are also evaluated by using Kamlet-Jacobs equations based on the calculated density and condensed phase heat of formation. Thermal stability and the pyrolysis mechanism of 2-diazo-4,6-dinitrophenol are investigated by calculating the bond dissociation energies at the B3LYP/6-311+G** level.

  20. Infrared and Raman Spectra of and Isotopomers: A DFT-PT2 Anharmonic Study

    Directory of Open Access Journals (Sweden)

    Andrea Alparone

    2013-01-01

    Full Text Available IR and Raman spectra of selenophene and of its perdeuterated isotopomer have been obtained in gas phase through density-functional theory (DFT computations. Vibrational wavenumbers have been calculated using harmonic and anharmonic second-order perturbation theory (PT2 procedures with the B3LYP method and the 6-311 basis set. Anharmonic overtones have been determined by means of the PT2 method. The introduction of anharmonic terms decreases the harmonic wavenumbers, giving a significantly better agreement with the experimental data. The most significant anharmonic effects occur for the C–H and C–D stretching modes, the observed H/D isotopic wavenumber redshifts being satisfactorily reproduced by the PT2 computations within 6–20 cm−1 (1–3%. In the spectral region between 500 cm−1 and 1500 cm−1, the IR spectra are dominated by the out-of-plane C–H (C–D bending transition, whereas the Raman spectra are mainly characterized by a strong peak mainly attributed to the C=C + C–C bonds stretching vibration with the contribution of the in-plane C–H (C–D bending deformation. The current results confirm that the PT2 approach combined with the B3LYP/6-311 level of calculation is a satisfactory choice for predicting vibrational spectra of cyclic molecules.

  1. Iron oxide bands in the visible and near-infrared reflectance spectra of primitive asteroids

    Science.gov (United States)

    Jarvis, Kandy S.; Vilas, Faith; Gaffey, Michael J.

    1993-01-01

    High resolution reflectance spectra of primitive asteroids (C, P, and D class and associated subclasses) have commonly revealed an absorption feature centered at 0.7 microns attributed to an Fe(2+)-Fe(3+) charge transfer transition in iron oxides and/or oxidized iron in phyllosilicates. A smaller feature identified at 0.43 microns has been attributed to an Fe(3+) spin-forbidden transition in iron oxides. In the spectra of the two main-belt primitive asteroids 368 Haidea (D) and 877 Walkure (F), weak absorption features which were centered near the location of 0.60-0.65 microns and 0.80-0.90 microns prompted a search for features at these wavelengths and an attempt to identify their origin(s). The CCD reflectance spectra obtained between 1982-1992 were reviewed for similar absorption features located near these wavelengths. The spectra of asteroids in which these absorption features have been identified are shown. These spectra are plotted in order of increasing heliocentric distance. No division of the asteroids by class has been attempted here (although the absence of these features in the anhydrous S-class asteroids, many of which have presumably undergone full heating and differentiation should be noted). For this study, each spectrum was treated as a continuum with discrete absorption features superimposed on it. For each object, a linear least squares fit to the data points defined a simple linear continuum. The linear continuum was then divided into each spectrum, thus removing the sloped continuum and permitting the intercomparison of residual spectral features.

  2. A Study of Precataclysmic Binaries Through Theoretic Modeling of Light Curves and Spectra

    Science.gov (United States)

    Mitrofanova, A. A.; Shimansky, V. V.; Borisov, N. V.

    2017-06-01

    The article presents results of three pre-cataclysmic binaries (PN G068.1+11.0, TW Crv and RE J2013+4002) investigation. Spectroscopic and photometric observations were obtained on BTA and Zeiss-1000 of SAO RAS and on RTT-150. We used the modeling of light curves and spectra to determine the fundamental parameters for all three systems. The PN G068.1+11.0 parameters were obtained with the use of the evolutionary tracks for the nuclei of planetary nebulae of different masses. According to the results of the study, it was found that the secondary components of PN G068.1+11.0 and TW Crv have luminosity excess, but secondary component of RE J2013+4002 doesn't have one.

  3. Theoretical photoionization spectra in the UV photon energy range for a Mg-like Al+ ion

    International Nuclear Information System (INIS)

    Kim, Dae-Soung; Kim, Young Soon

    2008-01-01

    In the present work, we report the photoionization cross sections of the Al + ion calculated for the photon energy range 20-26 eV and 30-50 eV. We have expanded our previous calculation (2007 J. Phys. Soc. Japan 76 014302) with an optimized admixture of the initial ground state 3s 21 S and exited states 3s3p 1,3 P, 3s3d 1,3 D and 3s4s 1,3 S, and obtained significantly improved predictions for the main background and autoionizing resonance structures of the reported experimental spectra. The absolute measurements of the photoionization cross sections of the Al + ion in these energy ranges have been performed by West et al (2001 Phys. Rev. A 63 052719), and they reported that the prominent peaks around 21 eV were attributed to the effects of the significant influence of the small fraction of the fourth-order radiation with energies around 84 eV from the synchrotron source. In our previous work, the main shape for these cross sections was calculated assuming an admixture of initial 3s 21 S and 3s3p 3 P states, only with a rough overall estimate for the experimental spectra in the photon energy range 20-26 eV, and without these peaks around 21 eV. The report of the experimental assignment attributes these peaks to the excitation of a 2p electron from the core. However, our present results with the new admixture reveal similar peaks without considering the possibility of the core excitation

  4. Ab-initio modeling of an iron laser-induced plasma: Comparison between theoretical and experimental atomic emission spectra

    International Nuclear Information System (INIS)

    Colgan, J.; Judge, E.J.; Kilcrease, D.P.; Barefield, J.E.

    2014-01-01

    We report on efforts to model the Fe emission spectrum generated from laser-induced breakdown spectroscopy (LIBS) measurements on samples of pure iron oxide (Fe 2 O 3 ). Our modeling efforts consist of several components. We begin with ab-initio atomic structure calculations performed by solving the Hartree–Fock equations for the neutral and singly ionized stages of Fe. Our energy levels are then adjusted to their experimentally known values. The atomic transition probabilities and atomic collision quantities are also computed in an ab-initio manner. We perform LTE or non-LTE calculations that generate level populations and, subsequently, an emission spectrum for the iron plasma for a range of electron temperatures and electron densities. Such calculations are then compared to the experimental spectrum. We regard our work as a preliminary modeling effort that ultimately strives towards the modeling of emission spectra from even more complex samples where less atomic data are available. - Highlights: • LIBS plasma of iron oxide • Ab-initio theoretical Modeling • Discussion of LTE versus non-LTE criteria and assessment • Boltzmann plots for Fe—determination of when LTE is a valid assumption • Emission spectra for Fe—comparison of theoretical modeling and measurement: good agreement obtained

  5. Far-infrared spectra of yttrium-doped gold clusters Au(n)Y (n=1-9).

    Science.gov (United States)

    Lin, Ling; Claes, Pieterjan; Gruene, Philipp; Meijer, Gerard; Fielicke, André; Nguyen, Minh Tho; Lievens, Peter

    2010-06-21

    The geometric, spectroscopic, and electronic properties of neutral yttrium-doped gold clusters Au(n)Y (n=1-9) are studied by far-infrared multiple photon dissociation (FIR-MPD) spectroscopy and quantum chemical calculations. Comparison of the observed and calculated vibrational spectra allows the structures of the isomers present in the molecular beam to be determined. Most of the isomers for which the IR spectra agree best with experiment are calculated to be the energetically most stable ones. Attachment of xenon to the Au(n)Y cluster can cause changes in the IR spectra, which involve band shifts and band splittings. In some cases symmetry changes, as a result of the attachment of xenon atoms, were also observed. All the Au(n)Y clusters considered prefer a low spin state. In contrast to pure gold clusters, which exhibit exclusively planar lowest-energy structures for small sizes, several of the studied species are three-dimensional. This is particularly the case for Au(4)Y and Au(9)Y, while for some other sizes (n=5, 8) the 3D structures have an energy similar to that of their 2D counterparts. Several of the lowest-energy structures are quasi-2D, that is, slightly distorted from planar shapes. For all the studied species the Y atom prefers high coordination, which is different from other metal dopants in gold clusters.

  6. A rapid method to screen for cell-wall mutants using discriminant analysis of Fourier transform infrared spectra

    International Nuclear Information System (INIS)

    Chen LiMei; Carpita, N.C.; Reiter, W.D.; Wilson, R.H.; Jeffries, C.; McCann, M.C.

    1998-01-01

    We have developed a rapid method to screen large numbers of mutant plants for a broad range of cell wall phenotypes using Fourier transform infrared (FTIR) microspectroscopy of leaves. We established and validated a model that can discriminate between the leaves of wild-type and a previously defined set of cell-wall mutants of Arabidopsis. Exploratory principal component analysis indicated that mutants deficient in different cell-wall sugars can be distinguished from each other. Discrimination of cell-wall mutants from wild-type was independent of variability in starch content or additional unrelated mutations that might be present in a heavily mutagenised population. We then developed an analysis of FTIR spectra of leaves obtained from over 1000 mutagenised flax plants, and selected 59 plants whose spectral variation from wild-type was significantly out of the range of a wild-type population, determined by Mahalanobis distance. Cell wall sugars from the leaves of selected putative mutants were assayed by gas chromatography-mass spectrometry and 42 showed significant differences in neutral sugar composition. The FTIR spectra indicated that six of the remaining 17 plants have altered ester or protein content. We conclude that linear discriminant analysis of FTIR spectra is a robust method to identify a broad range of structural and architectural alterations in cell walls, appearing as a consequence of developmental regulation, environmental adaptation or genetic modification. (author)

  7. Combined effect of solvents and gamma irradiation on the infrared absorption spectra of polyethylene terephthalate

    International Nuclear Information System (INIS)

    Rabie, S.M.; ElBially, A.; Elshourbaguie, S.

    1991-01-01

    The combined effect of solvents and gamma irradiation on the intensities of infrared absorption bands of polyethylene terephthalate, particularly the bands sensitive to conformational changes, were studied. The results revealed that solvent treatment of PET results in significant changes in the intensities of its infrared absorption bands and the exposure of PET to gamma radiation in the presence of solvents helps in the appearance of the two bands at 1550 and 1630 cm . Also, the combined effect of solvents and gamma irradiation on the intensities of the absorption bands is greater than the effect of each agent alone. The extent of the induced changes depends on the nature of solvent and the applied dosage. Further more, for any given solvent or dosage, the rate of change of the intensities of the trans band is not equal to that of the gauche bands.3 fig

  8. Infrared spectra of proton transfer complexes of the cycleanine alkaloid in solid state

    Science.gov (United States)

    Kasende, Okuma E.; de Waal, D.

    2003-01-01

    Proton transfer complexes obtained between the cycleanine alkaloid and hydrogen chloride, hydrogen bromide and nitric acids have been investigated by infrared spectroscopic technique between 4000 and 400 cm -1 in KBr. The vibrational perturbations brought about by proton transfer complex formation, discussed in terms of preferred site of interaction, show that the proton of the inorganic acids is transferred to cycleanine through one of its N sites.

  9. Infrared

    Science.gov (United States)

    Vollmer, M.

    2013-11-01

    'Infrared' is a very wide field in physics and the natural sciences which has evolved enormously in recent decades. It all started in 1800 with Friedrich Wilhelm Herschel's discovery of infrared (IR) radiation within the spectrum of the Sun. Thereafter a few important milestones towards widespread use of IR were the quantitative description of the laws of blackbody radiation by Max Planck in 1900; the application of quantum mechanics to understand the rotational-vibrational spectra of molecules starting in the first half of the 20th century; and the revolution in source and detector technologies due to micro-technological breakthroughs towards the end of the 20th century. This has led to much high-quality and sophisticated equipment in terms of detectors, sources and instruments in the IR spectral range, with a multitude of different applications in science and technology. This special issue tries to focus on a few aspects of the astonishing variety of different disciplines, techniques and applications concerning the general topic of infrared radiation. Part of the content is based upon an interdisciplinary international conference on the topic held in 2012 in Bad Honnef, Germany. It is hoped that the information provided here may be useful for teaching the general topic of electromagnetic radiation in the IR spectral range in advanced university courses for postgraduate students. In the most general terms, the infrared spectral range is defined to extend from wavelengths of 780 nm (upper range of the VIS spectral range) up to wavelengths of 1 mm (lower end of the microwave range). Various definitions of near, middle and far infrared or thermal infrared, and lately terahertz frequencies, are used, which all fall in this range. These special definitions often depend on the scientific field of research. Unfortunately, many of these fields seem to have developed independently from neighbouring disciplines, although they deal with very similar topics in respect of the

  10. INFRARED SPECTRA AND OPTICAL CONSTANTS OF NITRILE ICES RELEVANT TO TITAN's ATMOSPHERE

    International Nuclear Information System (INIS)

    Moore, Marla H.; Hudson, Reggie; Ferrante, Robert F.; James Moore, W.

    2010-01-01

    Spectra and optical constants of nitrile ices known or suspected to be in Titan's atmosphere are presented from 2.0 to 333.3 μm (∼5000-30 cm -1 ). These results are relevant to the ongoing modeling of Cassini CIRS observations of Titan's winter pole. Ices studied are: HCN, hydrogen cyanide; C 2 N 2 , cyanogen; CH 3 CN, acetonitrile; C 2 H 5 CN, propionitrile; and HC 3 N, cyanoacetylene. For each of these molecules, we also report new cryogenic measurements of the real refractive index, n, determined in both the amorphous and crystalline phases at 670 nm. These new values have been incorporated into our optical constant calculations. Spectra were measured and optical constants were calculated for each nitrile at a variety of temperatures, including, but not limited to, 20, 35, 50, 75, 95, and 110 K, in both the amorphous phase and the crystalline phase. This laboratory effort used a dedicated FTIR spectrometer to record transmission spectra of thin-film ice samples. Laser interference was used to measure film thickness during condensation onto a transparent cold window attached to the tail section of a closed-cycle helium cryostat. Optical constants, real (n) and imaginary (k) refractive indices, were determined using Kramers-Kronig analysis. Our calculation reproduces the complete spectrum, including all interference effects.

  11. Infrared Spectra, Index of Refraction, and Optical Constants of Nitrile Ices Relevant to Titan's Atmosphere

    Science.gov (United States)

    Moore, Marla; Ferrante, Robert; Moore, William; Hudson, Reggie

    2010-01-01

    Spectra and optical constants of nitrite ices known or suspected to be in Titan's atmosphere are presented from 2.5 to 200 microns (4000 to 50 per cm ). These results are relevant to the ongoing modeling of Cassini CIRS observations of Titan's winter pole. Ices studied include: HCN, hydrogen cyanide; C2N2, cyanogen; CH3CN, acetonitrile; C 2H5CN, propionitrile; and HC3N, cyanoacetylene. For each of these molecules we report new measurements of the index of refraction, n, determined in both the amorphous- and crystallinephase at 670 nm. Spectra were measured and optical constants were calculated for each nitrite at a variety of temperatures including 20, 35, 50, 75, 95, and 110 K, in the amorphous- and crystalline-phase. This laboratory effort uses a dedicated FTIR spectrometer to record transmission spectra of thin-film ice samples. Laser interference is used to measure film thickness during condensation onto a transparent cold window attached to the tail section of a closed-cycle helium cryostat. Optical constants, real (n) and imaginary (k) refractive indices, are determined using Kramers-Kronig (K-K) analysis. Our calculation reproduces the complete spectrum, including all interference effects. Index of refraction measurements are made in a separate dedicated FTIR spectrometer where interference deposit fringes are measured using two 670 nm lasers at different angles to the ice substrate. A survey of these new measurements will be presented along with a discussion of their validation, errors, and application to Titan data.

  12. Theoretical investigation of the energy spectra of the oxygen isoelectronic sequences taking into account relativistic corrections

    International Nuclear Information System (INIS)

    Bogdanovich, P.O.; Shadzhyuvene, S.D.; Boruta, I.I.; Rudzikas, Z.B.

    1976-01-01

    A method for calculating energy spectra of atoms and ions having complex electron configurations is developed which takes into account relativistic corrections of the order of magnitude of the square of the structure constant. The corrections included are caused by the dependence of the electron mass on velocity; by orbit-orbit interaction; by contact interaction and by spin-orbit interaction. The method described is realized in the form of universal algorithms and programs which are written in the Fortran 4 in the BESM-6 version. Examples are given of calculating the ground ls 2 2s 2 2p 6 configuration and two excited ls 2 2s 2 2p 3 3s and ls 2 2s2p 5 ones of the isoelectronic oxygen series, both with and without taking into account the relativistic corrections. The value of the nuclear charge varies from Z=8 to Z=80. The contribution of relativistic corrections increases with Z. The effect of relativistic corrections on the distance between the centers of gravity of ground and excited configurations increases with Z. The comparison of the results obtained with experimental data is made

  13. Theoretical and experimental study of the electronic states and spectra of LiSb

    Science.gov (United States)

    Setzer, K. D.; Fink, E. H.; Alekseyev, A. B.; Liebermann, H.-P.; Buenker, R. J.

    2018-05-01

    Gas phase emission spectra of the hitherto unknown free radical LiSb were measured in the NIR range with a Fourier-transform spectrometer. The emissions were observed from a fast-flow system in which antimony vapor in argon carrier gas was passed through a microwave discharge and mixed with lithium vapor in an observation tube. A number of blue-degraded bands observed in the range 6200-7800 cm-1 are assigned to transitions from four excited states A21, A30+, A40- and a2 to the X10+ and/or X21 components of the X3Σ- ground state. The 0-0 bands of six transitions were measured at high spectral resolution and rotationally analysed. The rotational and vibrational analyses have yielded the spectroscopic parameters of all six states. In order to aid in the analysis of the experimental data, a series of relativistic configuration interaction calculations has been carried out to obtain potential energy curves and spectroscopic constants for the low-lying states of LiSb as well as electric-dipole transition moments and radiative lifetimes.

  14. On the nature of unusual intensity changes in the infrared spectra of the enflurane ... acetone complexes

    Czech Academy of Sciences Publication Activity Database

    Zierkiewicz, W.; Zalesny, R.; Hobza, Pavel

    2013-01-01

    Roč. 15, č. 16 (2013), s. 6001-6007 ISSN 1463-9076 Institutional support: RVO:61388963 Keywords : shifting hydrogen-bonds * center-dot-o * molecular-orbital methods Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.198, year: 2013

  15. Prediction of specialty coffee cup quality based on near infrared spectra of green coffee beans.

    Science.gov (United States)

    Tolessa, Kassaye; Rademaker, Michael; De Baets, Bernard; Boeckx, Pascal

    2016-04-01

    The growing global demand for specialty coffee increases the need for improved coffee quality assessment methods. Green bean coffee quality analysis is usually carried out by physical (e.g. black beans, immature beans) and cup quality (e.g. acidity, flavour) evaluation. However, these evaluation methods are subjective, costly, time consuming, require sample preparation and may end up in poor grading systems. This calls for the development of a rapid, low-cost, reliable and reproducible analytical method to evaluate coffee quality attributes and eventually chemical compounds of interest (e.g. chlorogenic acid) in coffee beans. The aim of this study was to develop a model able to predict coffee cup quality based on NIR spectra of green coffee beans. NIR spectra of 86 samples of green Arabica beans of varying quality were analysed. Partial least squares (PLS) regression method was used to develop a model correlating spectral data to cupping score data (cup quality). The selected PLS model had a good predictive power for total specialty cup quality and its individual quality attributes (overall cup preference, acidity, body and aftertaste) showing a high correlation coefficient with r-values of 90, 90,78, 72 and 72, respectively, between measured and predicted cupping scores for 20 out of 86 samples. The corresponding root mean square error of prediction (RMSEP) was 1.04, 0.22, 0.27, 0.24 and 0.27 for total specialty cup quality, overall cup preference, acidity, body and aftertaste, respectively. The results obtained suggest that NIR spectra of green coffee beans are a promising tool for fast and accurate prediction of coffee quality and for classifying green coffee beans into different specialty grades. However, the model should be further tested for coffee samples from different regions in Ethiopia and test if one generic or region-specific model should be developed. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. NEAR-INFRARED SPECTRA OF GALACTIC STELLAR CLUSTERS DETECTED ON SPITZER/GLIMPSE IMAGES

    International Nuclear Information System (INIS)

    Messineo, Maria; Davies, Ben; Figer, Donald F.; Ivanov, Valentin D.; Schuller, Frederic; Menten, Karl M.; Habing, Harm J.; Petr-Gotzens, Monika G.

    2009-01-01

    We present near-infrared spectroscopic observations of massive stars in three stellar clusters located in the direction of the inner Galaxy. One of them, the Quartet, is a new discovery while the other two were previously reported as candidate clusters identified on mid-infrared Spitzer images (GLIMPSE20 and GLIMPSE13). Using medium-resolution (R = 900-1320) H and K spectroscopy, we firmly establish the nature of the brightest stars in these clusters, yielding new identifications of an early WC and two Ofpe/WN9 stars in the Quartet and an early WC star in GLIMPSE20. We combine this information with the available photometric measurements from Two Micron All Sky Survey, to estimate cluster masses, ages, and distances. The presence of several massive stars places the Quartet and GLIMPSE20 among the small sample of known Galactic stellar clusters with masses of a few 10 3 M sun , and ages from 3 to 8 Myr. We estimate a distance of about 3.5 kpc for GLIMPSE20 and 6.0 kpc for Quartet. The large number of giant stars identified in GLIMPSE13 indicates that it is another massive (∼6500 M sun ) cluster, but older, with an age between 30 and 100 Myr, at a distance of about 3 kpc.

  17. Theoretical Investigation on the Molecular Structure, Vibrational and NMR Spectra of N, N, 4-Tri chlorobenzenesulfonamide

    International Nuclear Information System (INIS)

    Cinar, M.

    2008-01-01

    In the present study, the structural properties of N,N,4-Tri chlorobenzenesulfonamide have been studied extensively using Density Functional Theory (DFT) employing B3LYP exchange correlation. The geometry of the molecule was fully optimized, vibrational spectrum was calculated and fundamental vibrations were assigned based on the scaled theoretical wavenumbers. The 1 H and 13 C nuclear magnetic resonance (NMR) chemical shifts of the compound were calculated using the Gauge-Invariant Atomic Orbital (GIAO) method. To investigate the basis set effects, calculations were performed at the 6-31G(d,p), 6-311G(d,p), 6-31++G(d,p) and 6-311++G(d,p) levels. Finally, geometric parameters, vibrational bands and isotropic chemical shifts were compared with available experimental data of compound. The fully optimized geometry of the molecule was found to be consistent with the X-ray crystal structure. The observed and calculated frequencies and chemical shifts were found to be in very good agreement. The computed results appear that the basis set has slight effect on the molecular geometry of N,N,4-Tri chlorobenzenesulfonamide

  18. Microscopic theoretical study of Raman spectra in charge and spin ordered cuprate systems

    International Nuclear Information System (INIS)

    Raj, B.K.; Panda, S.K.; Rout, G.C.

    2013-01-01

    Highlights: • The model calculation treats CDW interaction as pseudogap for cuprates. • The interplay of Raman active CDW-SDW mixed modes are investigated. • Independent CDW and SDW gap values can be determined from experimental data. -- Abstract: Raman scattering is one of the most powerful methods to investigate the electron as well as the phonon excitations in the systems. In this communication, we present a theoretical study of Raman scattering in the normal state of the high-T C systems in the under-doped region displaying the interplay of the spin-density-wave (SDW) and charge-density-wave (CDW) interactions. The SDW order arises from the repulsive Coulomb interaction of electrons, while the CDW order arises due to strong electron–phonon interaction giving rise to Fermi surface instability. We calculate phonon response function in order to examine the possibility of observing the SDW excitation mode in presence of the CDW interaction present in the same conduction band. The Raman scattering intensity is calculated from the imaginary part of the phonon Green’s function assigning an arbitrary spectral width. The spectral density function displays two mixed modes of excitation peaks at energies 2(Δ c ± Δ s ). The evolution of excitation peaks are investigated by varying CDW coupling, SDW coupling and the phonon momentum transfer energy

  19. Microscopic theoretical study of Raman spectra in charge and spin ordered cuprate systems

    Energy Technology Data Exchange (ETDEWEB)

    Raj, B. K. [Dept. of Physics, Govt. Autonomous College, Angul, Orissa (India); Panda, S. K. [KD Science College, Pochilima, Hinjilicut, 761 101 Ganjam, Orissa (India); Rout, G.C., E-mail: gcr@iopb.res.in [Condensed Matter Physics Group, PG Dept. of Applied Physics and Ballistics, FM University, Balasore 756 019 (India)

    2013-09-15

    Highlights: • The model calculation treats CDW interaction as pseudogap for cuprates. • The interplay of Raman active CDW-SDW mixed modes are investigated. • Independent CDW and SDW gap values can be determined from experimental data. -- Abstract: Raman scattering is one of the most powerful methods to investigate the electron as well as the phonon excitations in the systems. In this communication, we present a theoretical study of Raman scattering in the normal state of the high-T{sub C} systems in the under-doped region displaying the interplay of the spin-density-wave (SDW) and charge-density-wave (CDW) interactions. The SDW order arises from the repulsive Coulomb interaction of electrons, while the CDW order arises due to strong electron–phonon interaction giving rise to Fermi surface instability. We calculate phonon response function in order to examine the possibility of observing the SDW excitation mode in presence of the CDW interaction present in the same conduction band. The Raman scattering intensity is calculated from the imaginary part of the phonon Green’s function assigning an arbitrary spectral width. The spectral density function displays two mixed modes of excitation peaks at energies 2(Δ{sub c} ± Δ{sub s}). The evolution of excitation peaks are investigated by varying CDW coupling, SDW coupling and the phonon momentum transfer energy.

  20. Infrared Spectra and Optical Constants of Nitrile Ices Relevant to Titan's Atmosphere

    Science.gov (United States)

    Anderson, Carrie; Ferrante, Robert F.; Moore, W. James; Hudson, Reggie; Moore, Marla H.

    2011-01-01

    Spectra and optical constants of nitrile ices known or suspected to be in Titan?s atmosphere have been determined from 2.0 to 333.3 microns (approx.5000 to 30/cm). These results are relevant to the ongoing modeling of Cassini CIRS observations of Titan?s winter pole. Ices studied were: HCN, hydrogen cyanide; C2N2, cyanogen; CH3CN, acetonitrile; C2H5CN, propionitrile; and HC3N, cyanoacetylene. Optical constants were calculated, using Kramers-Kronig analysis, for each nitrile ice?s spectrum measured at a variety of temperatures, in both the amorphous- and crystalline phases. Spectra were also measured for many of the nitriles after quenching at the annealing temperature and compared with those of annealed ices. For each of these molecules we also measured the real component, n, of the refractive index for amorphous and crystalline phases at 670 nm. Several examples of the information contained in these new data sets and their usefulness in modeling Titan?s observed features will be presented (e.g., the broad emission feature at 160/cm; Anderson and Samuelson, 2011).

  1. Iron alteration minerals in the visible and near-infrared spectra of low-albedo asteroids

    Science.gov (United States)

    Vilas, Faith; Jarvis, Kandy S.; Gaffey, Michael J.

    1994-01-01

    Absorption features centered near 0.60-0.65 and 0.80-0.90 micrometers have been identified in the spectra of five low-albedo main-belt and outer-belt asteroids. These absorption features are attributed respectively to the (6)A(sub 1) goes to (4)T(sub 2)(G) and (6)A(sub 1) goes to (4)T(sub 1)(G) charge transfer transitions in minerals such as goethite, hematite, and jarosite that are products of the aqueous alteration of anhydrous silicates. A shoulder near 0.63 micrometers has also been identified in the absorption feature centered near 0.7 micrometers attributed to oxidized iron in phyllosilicates found predominantly in C- and G-class asteroids reflectance spectra. The coexistence of iron oxides with phyllosilicates in asteroids believed to have undergone aqueous alteration would be expected based upon analogy with terrestrial aqueous alteration and the observed mineralogy of carbonaceous chondrites. The number of low-albedo asteroids having only iron alteration absorption features compared to the number of low-albedo asteroids having spectral characteristics indicative of phyllosilicates is small. Either the conditions under which these asteroids formed are rare, or the iron alteration minerals could be formed in the interiors of objects where phyllosilicates dominate the surface mineralogy.

  2. The application of chemometrics on Infrared and Raman spectra as a tool for the forensic analysis of paints.

    Science.gov (United States)

    Muehlethaler, Cyril; Massonnet, Genevieve; Esseiva, Pierre

    2011-06-15

    The aim of this work is to evaluate the capabilities and limitations of chemometric methods and other mathematical treatments applied on spectroscopic data and more specifically on paint samples. The uniqueness of the spectroscopic data comes from the fact that they are multivariate - a few thousands variables - and highly correlated. Statistical methods are used to study and discriminate samples. A collection of 34 red paint samples was measured by Infrared and Raman spectroscopy. Data pretreatment and variable selection demonstrated that the use of Standard Normal Variate (SNV), together with removal of the noisy variables by a selection of the wavelengths from 650 to 1830 cm(-1) and 2730-3600 cm(-1), provided the optimal results for infrared analysis. Principal component analysis (PCA) and hierarchical clusters analysis (HCA) were then used as exploratory techniques to provide evidence of structure in the data, cluster, or detect outliers. With the FTIR spectra, the Principal Components (PCs) correspond to binder types and the presence/absence of calcium carbonate. 83% of the total variance is explained by the four first PCs. As for the Raman spectra, we observe six different clusters corresponding to the different pigment compositions when plotting the first two PCs, which account for 37% and 20% respectively of the total variance. In conclusion, the use of chemometrics for the forensic analysis of paints provides a valuable tool for objective decision-making, a reduction of the possible classification errors, and a better efficiency, having robust results with time saving data treatments. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  3. A theoretical investigation of spectra utilization for a CMOS based indirect detector for dual energy applications

    International Nuclear Information System (INIS)

    Kalyvas, N; Michail, C; Valais, I; Kandarakis, I; Fountos, G; Martini, N; Koukou, V; Sotiropoulou, P

    2015-01-01

    Dual Energy imaging is a promising method for visualizing masses and microcalcifications in digital mammography. Currently commercially available detectors may be suitable for dual energy mammographic applications. The scope of this work was to theoretically examine the performance of the Radeye CMOS digital indirect detector under three low- and high-energy spectral pairs. The detector was modeled through the linear system theory. The pixel size was equal to 22.5μm and the phosphor material of the detector was a 33.9 mg/cm 2 Gd 2 O 2 S:Tb phosphor screen. The examined spectral pairs were (i) a 40kV W/Ag (0.01cm) and a 70kV W/Cu (0.1cm) target/filter combinations, (ii) a 40kV W/Cd (0.013cm) and a 70kV W/Cu (0.1cm) target/filter combinations and (iii) a 40kV W/Pd (0.008cm) and a 70kV W/Cu (0.1cm) target/filter combinations. For each combination the Detective Quantum Efficiency (DQE), showing the signal to noise ratio transfer, the detector optical gain (DOG), showing the sensitivity of the detector and the coefficient of variation (CV) of the detector output signal were calculated. The second combination exhibited slightly higher DOG (326 photons per X-ray) and lower CV (0.755%) values. In terms of electron output from the RadEye CMOS, the first two combinations demonstrated comparable DQE values; however the second combination provided an increase of 6.5% in the electron output. (paper)

  4. INTERPRETATION OF INFRARED VIBRATION-ROTATION SPECTRA OF INTERSTELLAR AND CIRCUMSTELLAR MOLECULES

    International Nuclear Information System (INIS)

    Lacy, John H.

    2013-01-01

    Infrared vibration-rotation lines can be valuable probes of interstellar and circumstellar molecules, especially symmetric molecules, which have no pure rotational transitions. But most such observations have been interpreted with an isothermal absorbing slab model, which leaves out important radiative transfer and molecular excitation effects. A more realistic non-LTE and non-isothermal radiative transfer model has been constructed. The results of this model are in much better agreement with the observations, including cases where lines in one branch of a vibration-rotation band are in absorption and another in emission. In general, conclusions based on the isothermal absorbing slab model can be very misleading, but the assumption of LTE may not lead to such large errors, particularly if the radiation field temperature is close to the gas temperature.

  5. Infrared spectra of the ammonium ion in ammonium hexavanadate (NH 4) 2V 6O 16

    Science.gov (United States)

    de Waal, D.; Heyns, A. M.; Range, K.-J.; Eglmeier, C.

    The infrared bands of the NH +4 and ND +4 groups in (NH 4) 2V 6O 16 and its deuterated analogue can be assigned with a fair amount of certainty at 90 K under the space group P2 1/ m( C22 h). The ND stretching modes of isotopically dilute NH 3D + ions in the crystal are in agreement with the predicted splitting into Cs, Cs and C1(2) components. The frequencies, shapes and temperature dependence of these modes suggest that both normal and bifurcated hydrogen bonds are formed. The latter closely resembles corresponding bonds in NH 4VO 3, but the normal hydrogen bonds are not as strong as the similar bonds in NH 4VO 3. This can be expected as NH +4 ions are dynamic in character in (NH 4) 2V 6O 16 and remain so down to temperatures of 90 K.

  6. Infrared spectra of the ammonium ion in ammonium metavanadate NH 4VO 3

    Science.gov (United States)

    de Waal, D.; Heyns, A. M.; Range, K.-J.; Eglmeier, C.

    The ND stretching modes of isotopically dilute NH 3D + ions in NH 4VO 3 are in agreement with the predicted splitting into C s, C s and C1(2) components under C s site symmetry for the NH +4 ion. The three bands observed represent the three NH bonding distances in the crystal, and the position, shape and low temperature behaviour of each band confirms the existence of two types of hydrogen bonding in NH 4VO 3. The low temperature infrared modes of NH +4 and ND +4 in NH 4VO 3 and ND 4VO 3, respectively, can be assigned under space group Pbcm. Temperature dependence of these modes also reflects the presence of both normal and bifurcated hydrogen bonds in NH 4VO 3.

  7. Size Effect on the Infrared Spectra of Condensed Media under Conditions of 1D, 2D, and 3D Dielectric Confinement

    KAUST Repository

    Shaganov, Igor I.

    2010-10-07

    The effect of dielectric confinement on the peak position of intramolecular and a lattice vibration in the infrared spectra of various condensed media is investigated. Liquid benzene, carbon disulfide, and chloroform, as well as amorphous SiO2 and microcrystalline MgO particles, were characterized in this study. The absorption spectra of organic liquids and aqueous solutions of a silica submicrometer powder were measured under a variety of dielectric confinement configurations using Fourier transform Infrared spectroscopy. A significant shift of the resonant absorption band of liquid mesoparticles has been observed under dielectric confinement, which is in good agreement with model predictions. A corresponding expression for the dielectric loss spectrum of an absorbing composite medium was obtained using a Maxwell-Garnett generalized equation for the cases of one, two, and three-dimensional dielectric confinement in both ordered and disordered thin layers (disks), rods (wires or needles), and spheres of an absorbing medium. The experimental data on peak positions obtained from the infrared spectra of the organic liquids investigated in this work, as well as from the infrared spectra of amorphous quartz spherical particles and rods, are in good agreement with the calculated data. It is shown using simulations of the absorption spectrum of MgO powder that the approach suggested can be applied under certain conditions to the modeling of the spectra of microcrystalline particles of nonspheroidal shape. © 2010 American Chemical Society.

  8. The effect of grain size and phosphorous-doping of polycrystalline 3C–SiC on infrared reflectance spectra

    International Nuclear Information System (INIS)

    Rooyen, I.J. van; Engelbrecht, J.A.A.; Henry, A.; Janzén, E.; Neethling, J.H.; Rooyen, P.M. van

    2012-01-01

    Highlights: ► IR is investigated as a technique to measure grain size and P-doping of polycrystalline SiC. ► Infrared plasma minima can be used to determine doping levels in 3C–SiC for doping levels greater than 5 × 10 17 cm −3 . ► A linear relationship is found between FWHM and the inverse of grain size of 3C–SiC irrespective of P-doping level. ► It is further found that ω p is not influenced by the grain size. ► P-doping level has no significant effect on the linear relationship between grain size and surface roughness. - Abstract: The effect of P-doping and grain size of polycrystalline 3C–SiC on the infrared reflectance spectra is reported. The relationship between grain size and full width at half maximum (FWHM) suggest that the behavior of the 3C–SiC with the highest phosphorous doping level (of 1.2 × 10 19 at. cm −3 ) is different from those with lower doping levels ( 18 at. cm −3 ). It is also further demonstrated that the plasma resonance frequency (ω p ) is not influenced by the grain size.

  9. The effect of grain size and phosphorous-doping of polycrystalline 3C-SiC on infrared reflectance spectra

    Energy Technology Data Exchange (ETDEWEB)

    Rooyen, I.J. van, E-mail: Isabella.vanRooyen@inl.gov [Fuel Performance and Design Department, Idaho National Laboratory, Idaho Falls, ID 83415-6188 (United States); Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Engelbrecht, J.A.A. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Henry, A.; Janzen, E. [Department of Physics, Chemistry and Biology, Semiconductor Materials, Linkoeping University, Linkoeping 58183 (Sweden); Neethling, J.H. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Rooyen, P.M. van [Philip M van Rooyen Network Consultants, Midlands Estates (South Africa)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer IR is investigated as a technique to measure grain size and P-doping of polycrystalline SiC. Black-Right-Pointing-Pointer Infrared plasma minima can be used to determine doping levels in 3C-SiC for doping levels greater than 5 Multiplication-Sign 10{sup 17} cm{sup -3}. Black-Right-Pointing-Pointer A linear relationship is found between FWHM and the inverse of grain size of 3C-SiC irrespective of P-doping level. Black-Right-Pointing-Pointer It is further found that {omega}{sub p} is not influenced by the grain size. Black-Right-Pointing-Pointer P-doping level has no significant effect on the linear relationship between grain size and surface roughness. - Abstract: The effect of P-doping and grain size of polycrystalline 3C-SiC on the infrared reflectance spectra is reported. The relationship between grain size and full width at half maximum (FWHM) suggest that the behavior of the 3C-SiC with the highest phosphorous doping level (of 1.2 Multiplication-Sign 10{sup 19} at. cm{sup -3}) is different from those with lower doping levels (<6.6 Multiplication-Sign 10{sup 18} at. cm{sup -3}). It is also further demonstrated that the plasma resonance frequency ({omega}{sub p}) is not influenced by the grain size.

  10. Infrared (1.4-4.1μm) spectra of Wolf-Rayet stars

    International Nuclear Information System (INIS)

    Williams, P.M.

    1982-01-01

    The spectra of a variety of Wolf-Rayet stars have been observed with approximately 1% spectral resolution in the 1.4-4.1μm region using UKIRT. Strong lines due to ions of helium and carbon are observed and their relative strengths discussed. The He I singlet at 2.058μm is anomalously strong relative to other He I lines in WC stars and is responsible for the difference in the (H-K) colours of WN and WC stars. Emission line corrections to H, K and L magnitudes of different types are discussed. The Sanduleak O VI star ST 3 shows very strong C IV lines like the WC5 stars but not the strong He I. (Auth.)

  11. Understanding the interface between silicon-based materials and water: Molecular-dynamics exploration of infrared spectra

    Directory of Open Access Journals (Sweden)

    José A. Martinez-Gonzalez

    2017-11-01

    Full Text Available Molecular-dynamics simulations for silicon, hydrogen- and hydroxyl-terminated silicon in contact with liquid water, at 220 and 300 K, display water-density ‘ordering’ along the laboratory z-axis, emphasising the hydrophobicity of the different systems and the position of this first adsorbed layer. Density of states (DOS of the oxygen and proton velocity correlation functions (VACFs and infrared (IR spectra of the first monolayer of adsorbed water, calculated via Fourier transformation, indicate similarities to more confined, ice-like dynamical behaviour (redolent of ice. It was observed that good qualitative agreement is obtained between the DOS for this first layer in all systems. The DOS for the lower-frequency zone indicates that for the interface studied (i.e., the first layer near the surface, the water molecules try to organise in a similar form, and that this form is intermediate between liquid water and ice. For IR spectra, scrutiny of the position of the highest-intensity peaks for the stretching and bending bands indicate that such water molecules in the first solvating layer are organised in an intermediate fashion between ice and liquid water.

  12. The application of near-infrared spectra micro-image in the imaging analysis of biology samples

    Directory of Open Access Journals (Sweden)

    Dong Wang

    2014-07-01

    Full Text Available In this research, suitable imaging methods were used for acquiring single compound images of biology samples of chicken pectorales tissue section, tobacco dry leaf, fresh leaf and plant glandular hair, respectively. The adverse effects caused by the high water content and the thermal effect of near infrared (NIR light were effectively solved during the experiment procedures and the data processing. PCA algorithm was applied to the NIR micro-image of chicken pectorales tissue. Comparing the loading vector of PC3 with the NIR spectrum of dry albumen, the information of PC3 was confirmed to be provided mainly by protein, i.e., the 3rd score image represents the distribution trend of protein mainly. PCA algorithm was applied to the NIR micro-image of tobacco dry leaf. The information of PC2 was confirmed to be provided by carbohydrate including starch mainly. Compared to the 2nd score image of tobacco dry leaf, the compared correlation image with the reference spectrum of starch had the same distribution trend as the 2nd score image. The comparative correlation images with the reference spectra of protein, glucose, fructose and the total plant alkaloid were acquired to confirm the distribution trend of these compounds in tobacco dry leaf respectively. Comparative correlation images of fresh leaf with the reference spectra of protein, starch, fructose, glucose and water were acquired to confirm the distribution trend of these compounds in fresh leaf. Chemimap imaging of plant glandular hair was acquired to show the tubular structure clearly.

  13. Laboratory Infrared Spectra of Polycyclic Aromatic Nitrogen Heterocycles: Quinoline, and Phenanthridine in Solid Argon and H2O

    Science.gov (United States)

    Bernstein, M. P.; Mattioda, A. L.; Sandford, S. A.; Hudgins, D. M.

    2004-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are common throughout the universe. Their detection and identification are based on telescopic infrared (IR) spectra compared with laboratory data. Polycyclic Aromatic Nitrogen Heterocycles (PANHs) are heterocyclic aromatics i.e., PAHs with carbon atoms replaced by a nitrogen atom. These molecules should be present in the interstellar medium, but have received relatively little attention. We present mid-IR spectra of two PANHs, quinoline (C9H7N), and phenanthridine (C13H9N) isolated in solid argon and frozen in solid H2O at 12 K, conditions yielding data directly comparable to astronomical observations. In contrast to simple PAHs, that do not interact strongly with solid H2O, the nitrogen atoms in PANHs are potentially capable of hydrogen bonding with H2O. Whereas the IR spectrum of phenanthridine in H2O is similar to that of the same compound isolated in an argon matrix, quinoline absorptions shift up to 16 cm(sup -1) (0.072 mm) between argon and H2O. Thus, astronomers will not always be able to rely on IR band positions of matrix isolated PANHs to correctly interpret the absorptions of PANHs frozen in H2O ice grains. Furthermore, our data suggest that relative band areas also vary, so determining column densities to better than a factor of 3 will require knowledge of the matrix in which the PANH is embedded and laboratory studies of relevant samples.

  14. Transmission Spectra of HgTe-Based Quantum Wells and Films in the Far-Infrared Range

    Science.gov (United States)

    Savchenko, M. L.; Vasil'ev, N. N.; Yaroshevich, A. S.; Kozlov, D. A.; Kvon, Z. D.; Mikhailov, N. N.; Dvoretskii, S. A.

    2018-04-01

    Strained 80-nm-thick HgTe films belong to a new class of materials referred to as three-dimensional topological insulators (i.e., they have a bulk band gap and spin-nondegenerate surface states). Though there are a number of studies devoted to analysis of the properties of surface states using both transport and magnetooptical techniques in the THz range, the information about direct optical transitions between bulk and surface bands in these systems has not been reported. This study is devoted to the analysis of transmission and reflection spectra of HgTe films of different thicknesses in the far-infrared range recorded in a wide temperature range in order to detect the above interband transitions. A peculiarity at 15 meV, which is sensitive to a change in the temperature, is observed in spectra of both types. Detailed analysis of the data obtained revealed that this feature is related to absorption by HgTe optical phonons, while the interband optical transitions are suppressed.

  15. DERIVING METALLICITIES FROM THE INTEGRATED SPECTRA OF EXTRAGALACTIC GLOBULAR CLUSTERS USING THE NEAR-INFRARED CALCIUM TRIPLET

    International Nuclear Information System (INIS)

    Foster, Caroline; Forbes, Duncan A.; Proctor, Robert N.; Spitler, Lee R.; Strader, Jay; Brodie, Jean P.

    2010-01-01

    The Ca II triplet (CaT) feature in the near-infrared has been employed as a metallicity indicator for individual stars as well as integrated light of Galactic globular clusters (GCs) and galaxies with varying degrees of success, and sometimes puzzling results. Using the DEIMOS multi-object spectrograph on Keck we obtain a sample of 144 integrated light spectra of GCs around the brightest group galaxy NGC 1407 to test whether the CaT index can be used as a metallicity indicator for extragalactic GCs. Different sets of single stellar population models make different predictions for the behavior of the CaT as a function of metallicity. In this work, the metallicities of the GCs around NGC 1407 are obtained from CaT index values using an empirical conversion. The measured CaT/metallicity distributions show unexpected features, the most remarkable being that the brightest red and blue GCs have similar CaT values despite their large difference in mean color. Suggested explanations for this behavior in the NGC 1407 GC system are (1) the CaT may be affected by a population of hot blue stars, (2) the CaT may saturate earlier than predicted by the models, and/or (3) color may not trace metallicity linearly. Until these possibilities are understood, the use of the CaT as a metallicity indicator for the integrated spectra of extragalactic GCs will remain problematic.

  16. Simulated aging of lubricant oils by chemometric treatment of infrared spectra: potential antioxidant properties of sulfur structures.

    Science.gov (United States)

    Amat, Sandrine; Braham, Zeineb; Le Dréau, Yveline; Kister, Jacky; Dupuy, Nathalie

    2013-03-30

    Lubricant oils are complex mixtures of base oils and additives. The evolution of their performance over time strongly depends on its resistance to thermal oxidation. Sulfur compounds revealed interesting antioxidant properties. This study presents a method to evaluate the lubricant oil oxidation. Two samples, a synthetic and a paraffinic base oils, were tested pure and supplemented with seven different sulfur compounds. An aging cell adapted to a Fourier Transform InfraRed (FT-IR) spectrometer allows the continuous and direct analysis of the oxidative aging of base oils. Two approaches were applied to study the oxidation/anti-oxidation phenomena. The first one leads to define a new oxidative spectroscopic index based on a reduced spectral range where the modifications have been noticed (from 3050 to 2750 cm(-1)). The second method is based on chemometric treatments of whole spectra (from 4000 to 400 cm(-1)) to extract underlying information. A SIMPLe-to-use Interactive Self Modeling Analysis (SIMPLISMA) method has been used to identify more precisely the chemical species produced or degraded during the thermal treatment and to follow their evolution. Pure spectra of different species present in oil were obtained without prior information of their existence. The interest of this tool is to supply relative quantitative information reflecting evolution of the relative abundance of the different products over thermal aging. Results obtained by these two ways have been compared to estimate their concordance. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Theoretical Time Dependent Thermal Neutron Spectra and Reaction Rates in H2O and D2O

    International Nuclear Information System (INIS)

    Purohit, S.N.

    1966-04-01

    The early theoretical and experimental time dependent neutron thermalization studies were limited to the study of the transient spectrum in the diffusion period. The recent experimental measurements of the time dependent thermal neutron spectra and reaction rates, for a number of moderators, have generated considerable interest in the study of the time dependent Boltzmann equation. In this paper we present detailed results for the time dependent spectra and the reaction rates for resonance detectors using several scattering models of H 2 O and D 2 O. This study has been undertaken in order to interpret the integral time dependent neutron thermalization experiments in liquid moderators which have been performed at the AB Atomenergi. The proton gas and the deuteron gas models are inadequate to explain the measured reaction rates in H 2 O and D 2 O. The bound models of Nelkin for H 2 O and of Butler for D 2 O give much better agreement with the experimental results than the gas models. Nevertheless, some disagreement between theoretical and experimental results still persists. This study also indicates that the bound model of Butler and the effective mass 3. 6 gas model of Brown and St. John give almost identical reaction rates. It is also surprising to note that the calculated reaction rate for Cd for the Butler model appears to be in better agreement with the experimental results of D 2 O than of the Nelkin model with H 2 O experiments. The present reaction rate studies are sensitive enough so as to distinguish between the gas model and the bound model of a moderator. However, to investigate the details of a scattering law (such as the effect of the hindered rotations in H 2 O and D 2 O and the weights of different dynamical modes) with the help of these studies would require further theoretical as well as experimental investigations. Theoretical results can be further improved by improving the source for thermal neutrons, the group structure and the scattering

  18. THE INFRARED SPECTRA OF VERY LARGE IRREGULAR POLYCYCLIC AROMATIC HYDROCARBONS (PAHs): OBSERVATIONAL PROBES OF ASTRONOMICAL PAH GEOMETRY, SIZE, AND CHARGE

    International Nuclear Information System (INIS)

    Bauschlicher, Charles W.; Peeters, Els; Allamandola, Louis J.

    2009-01-01

    The mid-infrared (IR) spectra of six large, irregular polycyclic aromatic hydrocarbons (PAHs) with formulae (C 84 H 24 -C 120 H 36 ) have been computed using density functional theory (DFT). Trends in the dominant band positions and intensities are compared to those of large, compact PAHs as a function of geometry, size, and charge. Irregular edge moieties that are common in terrestrial PAHs, such as bay regions and rings with quartet hydrogens, are shown to be uncommon in astronomical PAHs. As for all PAHs comprised solely of C and H reported to date, mid-IR emission from irregular PAHs fails to produce a strong CC str band at 6.2 μm, the position characteristic of the important, class A astronomical PAH spectra. Earlier studies showed that inclusion of nitrogen within a PAH shifts this to 6.2 μm for PAH cations. Here we show that this band shifts to 6.3 μm in nitrogenated PAH anions, close to the position of the CC stretch in class B astronomical PAH spectra. Thus, nitrogenated PAHs may be important in all sources and the peak position of the CC stretch near 6.2 μm appears to directly reflect the PAH cation to anion ratio. Large irregular PAHs exhibit features at 7.8 μm but lack them near 8.6 μm. Hence, the 7.7 μm astronomical feature is produced by a mixture of small and large PAHs while the 8.6 μm band can only be produced by large compact PAHs. As with the CC str , the position and profile of these bands reflect the PAH cation to anion ratio.

  19. Comparison of various molecular forms of bovine trypsin: Correlation of infrared spectra with X-ray crystal structures

    Energy Technology Data Exchange (ETDEWEB)

    Prestrelski, S.J. (Mount Sinai School of Medicine of the City Univ. of New York (USA)); Byler, D.M. (U.S. Department of Agriculture, Philadelphia, PA (USA)); Liebman, M.N. (AMOCO Technology Corporation, Naperville, IL (USA))

    1991-01-01

    Fourier-transform infrared spectroscopy is a valuable method for the study of protein conformation in solution primarily because of the sensitivity to conformation of the amide I band (1700-1620 cm{sup {minus}1}) which arises from the backbone C{double bond}O stretching vibration. Combined with resolution-enhancement techniques such as derivative spectroscopy and self-deconvolution, plus the application of iterative curve-fitting techniques, this method provides a wealth of information concerning protein secondary structure. Further extraction of conformational information from the amide I band is dependent upon discerning the correlations between specific conformation types and component bands in the amide I region. In this paper the authors report spectra-structure correlations derived from conformational perturbations in bovine trypsin which arise from autolytic processing, zymogen activation, and active-site inhibition. IR spectra were collected for the single-chain ({beta}-trypsin) and once-cleaved, double-chain ({alpha}-trypsin) forms as well as at various times during the course of autolysis and also for zymogen, trypsinogen, and {beta}-trypsin inhibited with diisopropyl fluorophosphate. Spectral differences among the various molecular forms were interpreted in light of previous biochemical studies of autolysis and the known three-dimensional structures of the zymogen, the active enzyme, and the DIP-inhibited form. The spectroscopic results from these proteins in D{sub 2}O imply that certain loop structures may absorb in the region of 1655 cm{sup {minus}1}. They estimate that this approach to data analysis and interpretation is sensitive to changes of 0.01 unit or less in the relative integrated intensities of component bands in spectra whose peaks are well resolved.

  20. Theoretical modeling and analysis of the emission spectra of a ChemCam standard: Basalt BIR-1A

    Energy Technology Data Exchange (ETDEWEB)

    Colgan, J. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Judge, E.J. [Chemical Diagnostics and Engineering, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Johns, H.M.; Kilcrease, D.P. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Barefield, J.E. [Chemical Diagnostics and Engineering, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); McInroy, R. [Physical Chemistry and Applied Spectroscopy, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hakel, P. [Computational Physics Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Wiens, R.C. [Space and Remote Sensing Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Clegg, S.M. [Physical Chemistry and Applied Spectroscopy, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2015-08-01

    We report on efforts to perform theoretical modeling of the emission spectrum measured from a basalt sample. We compare our calculations with measurements that were made to provide standards for the ChemCam instrument on the Mars Science Laboratory. We find that to obtain good agreement between modeling and the measurement, it is necessary to determine atomic and ionic level populations via a multi-element approach in which the free electron density that is created influences all the species within the plasma. Calculations that consider each element separately are found to be in poorer agreement with the measured spectrum, indicating that the ‘matrix effect’ term often used to describe the influence of other species on the emission spectrum from a given element is due to the influence of the global electron density of the plasma. We explore the emission features in both the visible and near-infrared wavelength ranges, and also examine radiation transport effects for some of the most intense features found in the basalt spectrum. Finally, we also provide comparisons of the ChemCam measurement with new high-resolution spectral measurements. - Highlights: • LIBS basalt spectrum • Ab-initio theoretical modeling • Discussion of matrix effects • Discussion of radiation transport effects • High-resolution measurements of Basalt.

  1. Fourier transform infrared and FT-Raman spectra, assignment, ab initio, DFT and normal co-ordinate analysis of 2-chloro-4-methylaniline and 2-chloro-6-methylaniline.

    Science.gov (United States)

    Arjunan, V; Mohan, S

    2009-03-01

    The Fourier transform infrared (FTIR) and FT-Raman spectra of 2-chloro-4-methylaniline and 2-chloro-6-methylaniline have been measured in the range 4000-400 and 4000-100cm(-1), respectively. Utilising the observed FTIR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compounds were carried out. The vibrational frequency which were determined experimentally are compared with those obtained theoretically from ab initio HF and DFT gradient calculations employing the HF/6-31G(d,p) and B3LYP/6-31G(d,p) methods for optimised geometries. The geometries and normal modes of vibration obtained from the HF and DFT methods are in good agreement with the experimental data. The normal co-ordinate analysis was also carried out on the basis of ab initio force fields utilising Wilson's FG matrix method. The manifestations of NH-pi interactions and the influence of bulky chlorine and methyl group on the vibrational modes of the amino group are investigated.

  2. Accurate Theoretical Methane Line Lists in the Infrared up to 3000 K and Quasi-continuum Absorption/Emission Modeling for Astrophysical Applications

    Energy Technology Data Exchange (ETDEWEB)

    Rey, Michael; Tyuterev, Vladimir G. [Groupe de Spectrométrie Moléculaire et Atmosphérique, UMR CNRS 7331, BP 1039, F-51687, Reims Cedex 2 (France); Nikitin, Andrei V., E-mail: michael.rey@univ-reims.fr [Laboratory of Theoretical Spectroscopy, Institute of Atmospheric Optics, SB RAS, 634055 Tomsk (Russian Federation)

    2017-10-01

    Modeling atmospheres of hot exoplanets and brown dwarfs requires high- T databases that include methane as the major hydrocarbon. We report a complete theoretical line list of {sup 12}CH{sub 4} in the infrared range 0–13,400 cm{sup −1} up to T {sub max} = 3000 K computed via a full quantum-mechanical method from ab initio potential energy and dipole moment surfaces. Over 150 billion transitions were generated with the lower rovibrational energy cutoff 33,000 cm{sup −1} and intensity cutoff down to 10{sup −33} cm/molecule to ensure convergent opacity predictions. Empirical corrections for 3.7 million of the strongest transitions permitted line position accuracies of 0.001–0.01 cm{sup −1}. Full data are partitioned into two sets. “Light lists” contain strong and medium transitions necessary for an accurate description of sharp features in absorption/emission spectra. For a fast and efficient modeling of quasi-continuum cross sections, billions of tiny lines are compressed in “super-line” libraries according to Rey et al. These combined data will be freely accessible via the TheoReTS information system (http://theorets.univ-reims.fr, http://theorets.tsu.ru), which provides a user-friendly interface for simulations of absorption coefficients, cross-sectional transmittance, and radiance. Comparisons with cold, room, and high- T experimental data show that the data reported here represent the first global theoretical methane lists suitable for high-resolution astrophysical applications.

  3. Analysis of near infrared spectra for age-grading of wild populations of Anopheles gambiae

    Directory of Open Access Journals (Sweden)

    Benjamin J. Krajacich

    2017-11-01

    Full Text Available Abstract Background Understanding the age-structure of mosquito populations, especially malaria vectors such as Anopheles gambiae, is important for assessing the risk of infectious mosquitoes, and how vector control interventions may impact this risk. The use of near-infrared spectroscopy (NIRS for age-grading has been demonstrated previously on laboratory and semi-field mosquitoes, but to date has not been utilized on wild-caught mosquitoes whose age is externally validated via parity status or parasite infection stage. In this study, we developed regression and classification models using NIRS on datasets of wild An. gambiae (s.l. reared from larvae collected from the field in Burkina Faso, and two laboratory strains. We compared the accuracy of these models for predicting the ages of wild-caught mosquitoes that had been scored for their parity status as well as for positivity for Plasmodium sporozoites. Results Regression models utilizing variable selection increased predictive accuracy over the more common full-spectrum partial least squares (PLS approach for cross-validation of the datasets, validation, and independent test sets. Models produced from datasets that included the greatest range of mosquito samples (i.e. different sampling locations and times had the highest predictive accuracy on independent testing sets, though overall accuracy on these samples was low. For classification, we found that intramodel accuracy ranged between 73.5–97.0% for grouping of mosquitoes into “early” and “late” age classes, with the highest prediction accuracy found in laboratory colonized mosquitoes. However, this accuracy was decreased on test sets, with the highest classification of an independent set of wild-caught larvae reared to set ages being 69.6%. Conclusions Variation in NIRS data, likely from dietary, genetic, and other factors limits the accuracy of this technique with wild-caught mosquitoes. Alternative algorithms may help improve

  4. Analysis of near infrared spectra for age-grading of wild populations of Anopheles gambiae.

    Science.gov (United States)

    Krajacich, Benjamin J; Meyers, Jacob I; Alout, Haoues; Dabiré, Roch K; Dowell, Floyd E; Foy, Brian D

    2017-11-07

    Understanding the age-structure of mosquito populations, especially malaria vectors such as Anopheles gambiae, is important for assessing the risk of infectious mosquitoes, and how vector control interventions may impact this risk. The use of near-infrared spectroscopy (NIRS) for age-grading has been demonstrated previously on laboratory and semi-field mosquitoes, but to date has not been utilized on wild-caught mosquitoes whose age is externally validated via parity status or parasite infection stage. In this study, we developed regression and classification models using NIRS on datasets of wild An. gambiae (s.l.) reared from larvae collected from the field in Burkina Faso, and two laboratory strains. We compared the accuracy of these models for predicting the ages of wild-caught mosquitoes that had been scored for their parity status as well as for positivity for Plasmodium sporozoites. Regression models utilizing variable selection increased predictive accuracy over the more common full-spectrum partial least squares (PLS) approach for cross-validation of the datasets, validation, and independent test sets. Models produced from datasets that included the greatest range of mosquito samples (i.e. different sampling locations and times) had the highest predictive accuracy on independent testing sets, though overall accuracy on these samples was low. For classification, we found that intramodel accuracy ranged between 73.5-97.0% for grouping of mosquitoes into "early" and "late" age classes, with the highest prediction accuracy found in laboratory colonized mosquitoes. However, this accuracy was decreased on test sets, with the highest classification of an independent set of wild-caught larvae reared to set ages being 69.6%. Variation in NIRS data, likely from dietary, genetic, and other factors limits the accuracy of this technique with wild-caught mosquitoes. Alternative algorithms may help improve prediction accuracy, but care should be taken to either maximize

  5. Infrared spectra of cyanoacetaldehyde (NCCH2CHO): a potential prebiotic compound of astrochemical interest.

    Science.gov (United States)

    Benidar, Abdessamad; Georges, Robert; Guillemin, Jean-Claude; Mó, Otilia; Yáñez, Manuel

    2013-08-26

    Cyanoacetaldehyde (NC-CH2CH=O) and its isomer, cyanovinylalcohol (NC-CH=CH-OH), as possible components of the interstellar medium, comets, or planetary atmospheres, exist in equilibrium in the gas phase, although the latter compound is very much in the minority (2%). The recording and analysis of the gas-phase infrared spectrum of the former compound within the 4000-500 cm(-1) spectroscopic range and the potential presence of the latter isomer, which could be vital for their detection in these media, are reported. CCSD(T) and G4 high-level ab initio methods, as well as density functional theory calculations, predict the existence of two stable rotamers of cyanoacetaldehyde. The global minimum has a structure with an unusual O-C-C-C dihedral angle (150°) that falls between the antiperiplanar (180°) and anticlinal forms (120°). The second rotamer, which is about 4.0 kJ mol(-1) less stable in terms of free energy, has a planar structure that corresponds to the synperiplanar form (O-C-C-C dihedral angle: 0°). The absorption vibrational bands of the two aldehyde rotamers that are present in the mixture lead to a spectrum with a very complex structure in the region of deformation movements, in which several low-intensity bands overlap. A complete and unambiguous assignment of the experimental spectrum has been achieved by using the calculated harmonic and anharmonic vibrational frequencies. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. High resolution infrared spectra of Bulge Globular Clusters: Liller 1, NGC 6553, and Ter 5

    Science.gov (United States)

    Origlia, L.; Rich, R. M.; Castro, S. M.

    2001-12-01

    Using the NIRSPEC spectrograph at Keck II, we have obtained echelle spectra covering the range 1.5-1.8μ m for 2 of the brightest giants in Liller 1 and NGC 6553, old metal rich globular clusters in the Galactic bulge. We also report a preliminary analysis for two giants in the obscured bulge globular cluster Ter 5. We use spectrum synthesis for the abundance analysis, and find [Fe/H]=-0.3+/-0.2 and [O/H]=+0.3+/- 0.1 (from the OH lines) for the giants in Liller 1 and NGC 6553. We measure strong lines for the alpha elements Mg, Ca, and Si, but the lower sensitivity of these lines to abundance permits us to only state a general [α /Fe]=+0.3+/-0.2 dex. The composition of the clusters is similar to that of field stars in the bulge and is consistent with a scenario in which the clusters formed early, with rapid enrichment. Our iron abundance for NGC 6553 is poorly consistent with either the low or the high values recently reported in the literature, unless unusally large, or no α -element enhancements are adopted, respectively. We will also present an abundance analsyis for 2 giants in the highly reddened bulge cluster Ter 5, which appears to be near the Solar metallicity. R. Michael Rich acknowledges finacial support from grant AST-0098739, from the National Science Foundation. Data presented herein were obtained at the W.M.Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The authors gratefully acknowledge those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented would have been possible.

  7. Partial least squares modeling of combined infrared, 1H NMR and 13C NMR spectra to predict long residue properties of crude oils

    NARCIS (Netherlands)

    de Peinder, P.; Visser, T.; Petrauskas, D.D.; Salvatori, F.; Soulimani, F.; Weckhuysen, B.M.

    2009-01-01

    Research has been carried out to determine the potential of partial least squares (PLS) modeling of mid-infrared (IR) spectra of crude oils combined with the corresponding 1H and 13C nuclear magnetic resonance (NMR) data, to predict the long residue (LR) properties of these substances. The study

  8. Assignment of phantom bands in the solid-state infrared and Raman spectra of coronene: the importance of a minute out-of-plane distortion

    NARCIS (Netherlands)

    Todorov, P.D.; Jenneskens, L.W.; van Lenthe, J.H.

    2010-01-01

    The molecular geometry and the normal modes properties of coronene are investigated by means of DFT B3LYP and restricted/Hartree–Fock calculations utilizing basis sets of triple zeta +polarization quality. The interpretation of the infrared and Raman spectra of coronene, especially in solid state,

  9. Near-infrared spectra of Penicillium camemberti strains separated by extended multiplicative signal correction improved prediction of physical and chemical variations

    DEFF Research Database (Denmark)

    Decker, Marianne; Nielsen, Per Væggemose; Martens, Harald

    2005-01-01

    signal correction (TWEMSC) preprocessing, whereby three patterns of variation in near-infrared (NIR) log(1/R) spectra of fungal colonies could be separated mathematically: (1) physical light scattering and its wavelength dependency, (2) differences in light absorption of water due to varying sample...

  10. Infra-red spectra of systems containing hydrogen-bonds; Spectres dans l'infrarouge de corps a liaison hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Marechal, Y [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    A new theory of the infrared spectra of H-bonded systems is presented, which analyses the different stretching motions in an X-H...Y bond, and studies the validity of their separation. We attribute the structure in the spectra of H-bond stretching motions to the anharmonic coupling of the modes X-H...Y with the modes X-H...H. Starting with the hypothesis that the X-H...Y motion is harmonic, but depends parametrically upon the X...Y distance, and taking into account the interaction between different H-bonds, we have been able to simulate quantitatively (intensity and position) the I.R. spectra of species such as imidazole and acetic acid dimers, which are the experimentally best resolved spectra. The isotope effect (substitution of H by D) is explained quite naturally, and the experimental spectrum of deuterated species is simulated quantitatively, without introducing any other hypothesis; this fact gives us a positive test for the validity of our theory. We have extended those previous considerations to the case of H-bonded crystals, in view of a future reconstitution of their I.R. spectra. The physical meaning of our theory is quite different to most of the previously proposed theories, which have not been confirmed quantitatively, to the best of our knowledge. Those theories did not take into account the interactions between different H-bonds. Thus our quantitative simulation of complex spectra of imidazole and acetic acid, together with the correct prediction of the isotope effect, help us thinking that the proposed mechanism is responsible for the different stretching motions in H-bonded systems. (author) [French] Nous exposons une nouvelle theorie des spectres infra-rouge de la liaison hydrogene, basee sur l'analyse des mouvements d'elongation des atomes d'une liaison X-H...Y, et nous recherchons les conditions de la separabilite de ces differents mouvements. L'origine de la structure des spectres d'elongation de l'hydrogene est attribuee au couplage des modes

  11. DISCOVERY OF RUBIDIUM, CADMIUM, AND GERMANIUM EMISSION LINES IN THE NEAR-INFRARED SPECTRA OF PLANETARY NEBULAE

    Energy Technology Data Exchange (ETDEWEB)

    Sterling, N. C. [Department of Physics, University of West Georgia, 1601 Maple Street, Carrollton, GA 30118 (United States); Dinerstein, Harriet L.; Kaplan, Kyle F. [Department of Astronomy, University of Texas, 2515 Speedway, C1400, Austin, TX 78712-1205 (United States); Bautista, Manuel A., E-mail: nsterlin@westga.edu, E-mail: harriet@astro.as.utexas.edu, E-mail: kfkaplan@astro.as.utexas.edu, E-mail: manuel.bautista@wmich.edu [Department of Physics, Western Michigan University, Kalamazoo, MI 49008 (United States)

    2016-03-01

    We identify [Rb iv] 1.5973 and [Cd iv] 1.7204 μm emission lines in high-resolution (R = 40,000) near-infrared spectra of the planetary nebulae (PNe) NGC 7027 and IC 5117, obtained with the Immersion GRating INfrared Spectrometer (IGRINS) on the 2.7 m telescope at McDonald Observatory. We also identify [Ge vi] 2.1930 μm in NGC 7027. Alternate identifications for these features are ruled out based on the absence of other multiplet members and/or transitions with the same upper levels. Ge, Rb, and Cd can be enriched in PNe by s-process nucleosynthesis during the asymptotic giant branch stage of evolution. To determine ionic abundances, we calculate [Rb iv] collision strengths and use approximations for those of [Cd iv] and [Ge vi]. Our identification of [Rb iv] 1.5973 μm is supported by the agreement between Rb{sup 3+}/H{sup +} abundances found from this line and the 5759.55 Å feature in NGC 7027. Elemental Rb, Cd, and Ge abundances are derived with ionization corrections based on similarities in ionization potential ranges between the detected ions and O and Ne ionization states. Our analysis indicates abundances 2–4 times solar for Rb and Cd in both nebulae. Ge is subsolar in NGC 7027, but its abundance is uncertain due to the large and uncertain ionization correction. The general consistency of the measured relative s-process enrichments with predictions from models appropriate for these PNe (2.0–2.5 M{sub ⊙}, [Fe/H] = −0.37) demonstrates the potential of using PN compositions to test s-process nucleosynthesis models.

  12. Comparison of XH2O Retrieved from GOSAT Short-Wavelength Infrared Spectra with Observations from the TCCON Network

    Directory of Open Access Journals (Sweden)

    Eric Dupuy

    2016-05-01

    Full Text Available Understanding the atmospheric distribution of water (H 2 O is crucial for global warming studies and climate change mitigation. In this context, reliable satellite data are extremely valuable for their global and continuous coverage, once their quality has been assessed. Short-wavelength infrared spectra are acquired by the Thermal And Near-infrared Sensor for carbon Observation-Fourier Transform Spectrometer (TANSO-FTS aboard the Greenhouse gases Observing Satellite (GOSAT. From these, column-averaged dry-air mole fractions of carbon dioxide, methane and water vapor (XH 2 O have been retrieved at the National Institute for Environmental Studies (NIES, Japan and are available as a Level 2 research product. We compare the NIES XH 2 O data, Version 02.21, with retrievals from the ground-based Total Carbon Column Observing Network (TCCON, Version GGG2014. The datasets are in good overall agreement, with GOSAT data showing a slight global low bias of −3.1% ± 24.0%, good consistency over different locations (station bias of −1.53% ± 10.35% and reasonable correlation with TCCON (R = 0.89. We identified two potential sources of discrepancy between the NIES and TCCON retrievals over land. While the TCCON XH 2 O amounts can reach 6000–7000 ppm when the atmospheric water content is high, the correlated NIES values do not exceed 5500 ppm. This could be due to a dry bias of TANSO-FTS in situations of high humidity and aerosol content. We also determined that the GOSAT-TCCON differences directly depend on the altitude difference between the TANSO-FTS footprint and the TCCON site. Further analysis will account for these biases, but the NIES V02.21 XH 2 O product, after public release, can already be useful for water cycle studies.

  13. Visible-near infrared spectra of hydrous carbonates, with implications for the detection of carbonates in hyperspectral data of Mars

    Science.gov (United States)

    Harner, Patrick L.; Gilmore, Martha S.

    2015-04-01

    We present visible-near infrared (VNIR, 0.35-5 μm) spectra for a suite of hydrous carbonates that may be relevant to the surface of Mars. This includes VNIR spectra for ikaite, nesquehonite, synthetic monohydrocalcite and lansfordite over the 0.35-2.5 μm range that are new to the literature. The spectral features of the hydrous carbonates are dominated by absorptions at ∼1.0, 1.2, 1.4-1.5, 1.9 and 2.8 μm that are due to overtones and combinations of fundamental water and hydroxyl vibrations. Absorptions due to (CO3)2-, Mg-OH, Fe-OH, and/or water are seen at ∼2.3-2.5, 3.4, and 3.9 μm in hydrous Mg and Mg-Fe3+ carbonates containing hydroxyl groups, but are weaker than in the common anhydrous carbonates. When present in the hydrous carbonates, the positions of the centers of the 2.3 μm and/or 2.5 μm absorptions are often shifted relative to the anhydrous carbonates, which may be diagnostic. Some or all of the (CO3)2- absorptions typical of anhydrous carbonates are weak to absent in the hydrous carbonates, and thus this group may be difficult to distinguish from other hydrous minerals like sulfates, phyllosilicates or chlorides in Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) data using standard spectral search parameters for anhydrous carbonates. We present strategies for recognizing hydrous carbonates in CRISM data using combinations of spectral parameters that measure the intensity and shape of the water-related absorptions in these minerals.

  14. Signal-to-noise contribution of principal component loads in reconstructed near-infrared Raman tissue spectra.

    Science.gov (United States)

    Grimbergen, M C M; van Swol, C F P; Kendall, C; Verdaasdonk, R M; Stone, N; Bosch, J L H R

    2010-01-01

    The overall quality of Raman spectra in the near-infrared region, where biological samples are often studied, has benefited from various improvements to optical instrumentation over the past decade. However, obtaining ample spectral quality for analysis is still challenging due to device requirements and short integration times required for (in vivo) clinical applications of Raman spectroscopy. Multivariate analytical methods, such as principal component analysis (PCA) and linear discriminant analysis (LDA), are routinely applied to Raman spectral datasets to develop classification models. Data compression is necessary prior to discriminant analysis to prevent or decrease the degree of over-fitting. The logical threshold for the selection of principal components (PCs) to be used in discriminant analysis is likely to be at a point before the PCs begin to introduce equivalent signal and noise and, hence, include no additional value. Assessment of the signal-to-noise ratio (SNR) at a certain peak or over a specific spectral region will depend on the sample measured. Therefore, the mean SNR over the whole spectral region (SNR(msr)) is determined in the original spectrum as well as for spectra reconstructed from an increasing number of principal components. This paper introduces a method of assessing the influence of signal and noise from individual PC loads and indicates a method of selection of PCs for LDA. To evaluate this method, two data sets with different SNRs were used. The sets were obtained with the same Raman system and the same measurement parameters on bladder tissue collected during white light cystoscopy (set A) and fluorescence-guided cystoscopy (set B). This method shows that the mean SNR over the spectral range in the original Raman spectra of these two data sets is related to the signal and noise contribution of principal component loads. The difference in mean SNR over the spectral range can also be appreciated since fewer principal components can

  15. Effects of mercury on visible/near-infrared reflectance spectra of mustard spinach plants (Brassica rapa P.)

    International Nuclear Information System (INIS)

    Dunagan, Sarah C.; Gilmore, Martha S.; Varekamp, Johan C.

    2007-01-01

    Mustard spinach plants were grown in mercury-spiked and contaminated soils collected in the field under controlled laboratory conditions over a full growth cycle to test if vegetation grown in these soils has discernible characteristics in visible/near-infrared (VNIR) spectra. Foliar Hg concentrations (0.174-3.993 ppm) of the Mustard spinach plants were positively correlated with Hg concentration of soils and varied throughout the growing season. Equations relating foliar Hg concentration to spectral reflectance, its first derivative, and selected vegetation indices were generated using stepwise multiple linear regression. Significant correlations are found for limited wavelengths for specific treatments and dates. Ratio Vegetation Index (RVI) and Red Edge Position (REP) values of plants in Hg-spiked and field-contaminated soils are significantly lower relative to control plants during the early and middle portions of the growth cycle which may be related to lower chlorophyll abundance or functioning in Hg-contaminated plants. - Some spectral characteristics of leaves of Brassica rapa P. may be associated with foliar mercury content

  16. Classification of dry-cured hams according to the maturation time using near infrared spectra and artificial neural networks.

    Science.gov (United States)

    Prevolnik, M; Andronikov, D; Žlender, B; Font-i-Furnols, M; Novič, M; Škorjanc, D; Čandek-Potokar, M

    2014-01-01

    An attempt to classify dry-cured hams according to the maturation time on the basis of near infrared (NIR) spectra was studied. The study comprised 128 samples of biceps femoris (BF) muscle from dry-cured hams matured for 10 (n=32), 12 (n=32), 14 (n=32) or 16 months (n=32). Samples were minced and scanned in the wavelength range from 400 to 2500 nm using spectrometer NIR System model 6500 (Silver Spring, MD, USA). Spectral data were used for i) splitting of samples into the training and test set using 2D Kohonen artificial neural networks (ANN) and for ii) construction of classification models using counter-propagation ANN (CP-ANN). Different models were tested, and the one selected was based on the lowest percentage of misclassified test samples (external validation). Overall correctness of the classification was 79.7%, which demonstrates practical relevance of using NIR spectroscopy and ANN for dry-cured ham processing control. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Infrared Spectra of the n-PROPYL and i-PROPYL Radicals in Solid Para-Hydrogen

    Science.gov (United States)

    Pullen, Gregory T.; Franke, Peter R.; Douberly, Gary E.; Lee, Yuan-Pern

    2017-06-01

    We report the infrared spectra of the n-propyl and i-propyl radicals measured in solid para-hydrogen (p-H_2) matrices at 3.2 K. n-Propyl and i-propyl radicals were produced via the 248 nm irradiation of matrices formed by co-depositing p-H_2 and either 1-Iodopropane (n-propyl) or 2-Iodopropane (i-propyl). Secondary photolysis was used to group spectral lines all due to the same species. Lines in the C-H stretching region were compared to previous work using the Helium Nanodroplet Isolation (HENDI) technique, and are in excellent agreement. In addition to a few lines previously measured in Ar matrices, we observe many previously unreported bands below 2000 \\wn, which we attribute to the n-propyl and i-propyl radicals. The assignment of features below 2000 \\wn are made via comparisons to anharmonic VPT2+K frequency computations. Peter R. Franke, Daniel P. Tabor, Christopher P. Moradi, Gary E. Douberly, Jay Agarwal, Henry F. Schaefer III, and Edwin L. Sibert III, Journal of Chemical Physics 145, 224304 (2016).

  18. Theoretical Investigation of the Effect of the Rare Gas Matrices on the Vibrational Spectra of Solvated Molecular Ions: Cu+CO

    Czech Academy of Sciences Publication Activity Database

    Bludský, Ota; Šilhan, Martin; Nachtigall, Petr

    2002-01-01

    Roč. 117, č. 20 (2002), s. 9298-9305 ISSN 0021-9606 R&D Projects: GA MŠk LN00A032 Institutional research plan: CEZ:AV0Z4040901 Keywords : vibrational spectra * solvated molecular ions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.998, year: 2002

  19. Theoretical considerations and preparatory experiments for poloidal field measurements in tokamaks by far-infrared polarimetry

    Energy Technology Data Exchange (ETDEWEB)

    Kunz, W; Dodel, G [Stuttgart Univ. (TH) (Germany, F.R.). Inst. fuer Plasmaforschung

    1978-12-01

    Numerical calculations give an optimum wavelength and show the precision requirements for determining poloidal field profiles in tokamaks on the basis of the Faraday effect. The required precision of the polarimetric measurements can be achieved in the far-infrared as is verified in a model experiment using a ferrite modulated HCN laser beam.

  20. A theoretical study of the molecular structures and vibrational spectra of the N 2O⋯(HF) 2

    Science.gov (United States)

    de Lima, Nathália B.; Ramos, Mozart N.

    2012-01-01

    Theoretical calculations using both the MP2 and B3LYP levels of calculation with a 6-311++G(3df,3pd) basis set have been performed to determine stable structures and molecular properties for the H-bonded complexes involving nitrous oxide (N 2O) and two HF molecules. Five complex have been characterized as minima since no imaginary frequency was found. Three complex are predicted to be relatively more stable with binding energies varying from 14 kJ mol -1 to 23 kJ mol -1 after BSSE and ZPE corrections. Our calculations have revealed that the second complexation with HF preferably occurs with the first complexed HF molecule, i.e., forming the X⋯H sbnd F⋯H sbnd F skeleton with X = O or N instead the F sbnd H⋯N sbnd N sbnd O⋯H sbnd F one. As expected, the H sbnd F chemical bonds are increased after complexation due to intermolecular charge transfer from "n" isolated pair of the X atom (X = N, O or F) to the σ ∗ anti-bonding orbital of HF. For the strongly bounded complex, the doubly complexed HF molecule acts as a bridge between the two end molecules while transferring electrons from N 2O to HF. Both possess the same amount of residual charge but with opposite signs. The H sbnd F stretching frequency of the monoprotic acid is shifted downward after complexation whereas its IR intensity is much enhanced. This increase has been adequately interpreted in terms of equilibrium hydrogen charge and charge-flux associated to the H sbnd F stretching using the CCFOM model for infrared intensities. This procedure has also allowed to analyze the new vibrational modes arising upon H-bond formation, especially those associated with the out-of-plane and in-plane HF bending modes, which are pure rotations in the HF isolated molecule.

  1. Non-intrusive measurement of emission indices. A new approach to the evaluation of infrared spectra emitted by aircraft engine exhaust gases

    Energy Technology Data Exchange (ETDEWEB)

    Lindermeir, E.; Haschberger, P.; Tank, V. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Optoelektronik

    1997-12-31

    A non-intrusive method is used to determine the emission indices of a research aircraft`s engine in-flight. The principle is based on the Fourier Transform Infrared Spectrometer MIROR which was specifically designed and built for operation aboard aircrafts. This device measures the spectrum of the infrared radiation emitted by the hot exhaust gas under cruise conditions. From these spectra mixing ratios and emission indices can be derived. An extension to previously applied evaluation schemes is proposed: Whereas formerly the plume was assumed a homogeneous layer of gas, temperature and concentration profiles are now introduced to the evaluation procedure. (author) 5 refs.

  2. Quantitative analysis of the hydration of lithium salts in water using multivariate curve resolution of near-infrared spectra

    Energy Technology Data Exchange (ETDEWEB)

    Barba, M. Isabel [Group of Research in Applied Thermal Engineering-CREVER, Mechanical Engineering Dept. (Spain); Larrechi, M. Soledad, E-mail: mariasoledad.larrechi@urv.cat [Analytical and Organic Chemistry Dept., Universitat Rovira i Virgili, Tarragona (Spain); Coronas, Alberto [Group of Research in Applied Thermal Engineering-CREVER, Mechanical Engineering Dept. (Spain)

    2016-05-05

    The hydration process of lithium iodide, lithium bromide, lithium chloride and lithium nitrate in water was analyzed quantitatively by applying multivariate curve resolution alternating least squares (MCR-ALS) to their near infrared spectra recorded between 850 nm and 1100 nm. The experiments were carried out using solutions with a salt mass fraction between 0% and 72% for lithium bromide, between 0% and 67% for lithium nitrate and between 0% and 62% for lithium chloride and lithium iodide at 323.15 K, 333.15 K, 343.15 K and 353.15 K, respectively. Three factors were determined for lithium bromide and lithium iodide and two factors for the lithium chloride and lithium nitrate by singular value decomposition (SVD) of their spectral data matrices. These factors are associated with various chemical environments in which there are aqueous clusters containing the ions of the salts and non-coordinated water molecules. Spectra and concentration profiles of non-coordinated water and cluster aqueous were retrieved by MCR-ALS. The amount of water involved in the process of hydration of the various salts was quantified. The results show that the water absorption capacity increases in the following order LiI < LiBr < LiNO{sub 3} < LiCl. The salt concentration at which there is no free water in the medium was calculated at each one of the temperatures considered. The values ranged between 62.6 and 65.1% for LiBr, 45.5–48.3% for LiCl, 60.4–61.2% for LiI and 60.3–63.7% for LiNO{sub 3}. These values are an initial approach to determining the concentration as from which crystal formation is favored. - Highlights: • Quantitative analysis of the hydration of lithium salts in water. • The absorption capacity of the electrolytes in function of the salt is evaluated. • The lithium salt concentration is estimated when the crystal formation is favored.

  3. Quantitative analysis of the hydration of lithium salts in water using multivariate curve resolution of near-infrared spectra

    International Nuclear Information System (INIS)

    Barba, M. Isabel; Larrechi, M. Soledad; Coronas, Alberto

    2016-01-01

    The hydration process of lithium iodide, lithium bromide, lithium chloride and lithium nitrate in water was analyzed quantitatively by applying multivariate curve resolution alternating least squares (MCR-ALS) to their near infrared spectra recorded between 850 nm and 1100 nm. The experiments were carried out using solutions with a salt mass fraction between 0% and 72% for lithium bromide, between 0% and 67% for lithium nitrate and between 0% and 62% for lithium chloride and lithium iodide at 323.15 K, 333.15 K, 343.15 K and 353.15 K, respectively. Three factors were determined for lithium bromide and lithium iodide and two factors for the lithium chloride and lithium nitrate by singular value decomposition (SVD) of their spectral data matrices. These factors are associated with various chemical environments in which there are aqueous clusters containing the ions of the salts and non-coordinated water molecules. Spectra and concentration profiles of non-coordinated water and cluster aqueous were retrieved by MCR-ALS. The amount of water involved in the process of hydration of the various salts was quantified. The results show that the water absorption capacity increases in the following order LiI < LiBr < LiNO_3 < LiCl. The salt concentration at which there is no free water in the medium was calculated at each one of the temperatures considered. The values ranged between 62.6 and 65.1% for LiBr, 45.5–48.3% for LiCl, 60.4–61.2% for LiI and 60.3–63.7% for LiNO_3. These values are an initial approach to determining the concentration as from which crystal formation is favored. - Highlights: • Quantitative analysis of the hydration of lithium salts in water. • The absorption capacity of the electrolytes in function of the salt is evaluated. • The lithium salt concentration is estimated when the crystal formation is favored.

  4. A comparative study on experimental and theoretical ESR spectra of lactic acid polymers irradiated by gamma rays

    International Nuclear Information System (INIS)

    Kantoglu, Oe.; Oezbey, T.; Gueven, O.

    1998-01-01

    Homo polymers of L-Lactic acid (LLA) and D,L-Lactic acid (DLLA), being biocompatible and absorbable in body iluids have recently found wide applications in the preparation of surgical sutures, controlled drug delivery systems, burn wound coverings etc. For sometime these polymers have also been prepared in the form of plates and screws for mandibular fracture fixation, tissue implants. Their chemical sensitivities against relatively high temperatures and hydrolysis with water make them unsuitable for conventional sterilization techniques like hot water vapor and ethylene oxide. Sterilization of the devices made of these polymers is therefore possible by gamma ray irradiation. This has initiated a number of research works in order to better understand the effects of ionizing radiation on this polymer. The aim of this study is to determine the possible radical types, their location on macromolecular structure and the reasons for peak shifts in the experimental and theoretical ESR spectra. Polymer samples were irradiated in air and in vacuum (10□□ torr) to 25 kGy sterilization dose at the dose rate 0.59 kGy/h and at room temperature by 60 Co γ-irradiator. Despite being chemically the same radical type, some differences were observed in the splitting of peaks of PLLA and PDLLA samples. These differences were determined and compared by means of fitting studies. Firstly, PLLA was characterized and its g and hyperfine splitting values were found as 2.0032±0.0002 and 20.37±0.2. In the characterization study of PDLLA, it was found that one of the nearest two radicals was on the upper and the other one was on the lower plane of PDLLA chain. (author)

  5. Infrared Spectra of Novel NgBeSO2 Complexes (Ng = Ne, Ar, Kr, Xe) in Low Temperature Matrixes.

    Science.gov (United States)

    Yu, Wenjie; Liu, Xing; Xu, Bing; Xing, Xiaopeng; Wang, Xuefeng

    2016-11-03

    The novel noble-gas complexes NgBeSO 2 (Ng = Ne, Ar, Kr, Xe) have been prepared in the laser-evaporated beryllium atom reactions with SO 2 in low-temperature matrixes. Doped with heavier noble gas, the guest (Ar, Kr, Xe) atom can substitute neon to form more stable complex. Infrared spectroscopy and theoretical calculations are used to confirm the band assignment. The dissociation energies are calculated at 0.9, 4.0, 4.7, and 6.0 kcal/mol for NeBeSO 2 , ArBeSO 2 , KrBeSO 2 , and XeBeSO 2 , respectively, at the CCSD(T) level. Quantum chemical calculations demonstrate that the Ng-Be bonds in NgBeSO 2 could be formed by the combination of electron-donation and ion-induced dipole interactions. The Wiberg bond index (WBI) values of Ng-Be bonds and LOL (localized orbital locator) profile indicate that the Ng-Be bond exhibits a gradual increase in covalent character along Ne to Xe.

  6. The ground state infrared spectra of several isotopic forms of the CdH and ZnH radicals

    International Nuclear Information System (INIS)

    Urban, R.; Magg, U.; Birk, H.; Jones, H.

    1990-01-01

    The infrared spectra of six isotopic forms of cadmium monohydride, [ 116 CdH (7.6%), 114 CdH (28.9%), 113 CdH (12.3%), 112 CdH (24.1%), 111 CdH (12.7%), and 110 CdH (12.4%)] and four isotopic forms of zinc hydride [ 68 ZnH (18.6%), 67 ZnH (4.1%), 66 ZnH (27.8%), and 64 ZnH (48.9%)] have been observed in natural abundance in their ground electronic state ( 2 Σ + ) in the gas phase using a diode laser spectrometer. A number of transitions of 108 CdH (0.9%) and 106 CdH (1.2%) and 70 ZnH (0.6%) were also observed, but too little data was accumulated to allow a good analysis. The hydrides were produced by reaction of hydrogen with metal vapor at elevated temperature in an electric discharge. The analysis of the experimental data was carried out in two ways. (a) A complete set of Dunham parameters and spin--rotation parameters (γ parameters) was determined for each isotopic species of the two radicals and (b) a set of mass-independent parameters were calculated for both ZnH and CdH. Since only information over the isotopic species of the heavy atom was produced in each case, effects arising from a breakdown of the Born--Oppenheimer approximation were negligible. The effects of the strong anharmonicity present in these two molecules on the values of the parameters are discussed

  7. Infrared spectra and stability of CO and H2O sorption over Ag-exchanged ZSM-5 zeolite: DFT study

    International Nuclear Information System (INIS)

    Jiang Shujun; Huang Shiping; Tu Weixia; Zhu Jiqin

    2009-01-01

    The infrared spectra and stability of CO and H 2 O sorption over Ag-exchanged ZSM-5 zeolite were investigated by using density function theory (DFT). The changes of NBO charge show that the electron transfers from CO molecule to the Ag + cation to form an σ-bond, and it accompanies by the back donation of d-electrons from Ag + cation to the CO (π*) orbital as one and two CO molecules are adsorbed on Ag-ZSM-5. The free energy changes ΔG, -5.55 kcal/mol and 6.52 kcal/mol for one and two CO molecules, illustrate that the Ag + (CO) 2 complex is unstable at the room temperature. The vibration frequency of C-O stretching of one CO molecule bonded to Ag + ion at 2211 cm -1 is in good agreement with the experimental results. The calculated C-O symmetric and antisymmetric stretching frequencies in the Ag + (CO) 2 complex shift to 2231 cm -1 and 2205 cm -1 when the second CO molecule is adsorbed. The calculated C-O stretching frequency in CO-Ag-ZSM-5-H 2 O complex shifts to 2199 cm -1 , the symmetric and antisymmetric O-H stretching frequencies are 3390 cm -1 and 3869 cm -1 , respectively. The Gibbs free energy change (ΔG H 2 O ) is -6.58 kcal/mol as a H 2 O molecule is adsorbed on CO-Ag-ZSM-5 complex at 298 K. The results show that CO-Ag-ZSM-5-H 2 O complex is more stable at room temperature

  8. Computational study of the signature of hydrogen-bond strength on the infrared spectra of a hydrogen-bonded complex dissolved in a polar liquid

    International Nuclear Information System (INIS)

    Hanna, Gabriel; Geva, Eitan

    2010-01-01

    The signature of hydrogen-bond strength on the one- and two-dimensional infrared spectra of the hydrogen-stretch in a hydrogen-bonded complex dissolved in a polar liquid was investigated via mixed quantum-classical molecular dynamics simulations. Non-Condon effects were found to intensify with increasing hydrogen-bond strength and to shift oscillator strength from the stable configurations that correspond to the ionic and covalent tautomers into unstable configurations that correspond to the transition-state between them. The transition-state peak is observed to blue shift and increase in intensity with increasing hydrogen-bond strength, and to dominate the spectra in the case of a strong hydrogen-bond. It is argued that the application of multidimensional infrared spectroscopy in the region of the transition-state peak can provide a uniquely direct probe of the molecular events underlying breaking and forming of hydrogen-bonds in the condensed phase.

  9. New Measurements of s-Process Enrichments in Planetary Nebulae from High-Resolution Near-Infrared Spectra

    Science.gov (United States)

    Dinerstein, Harriet L.; Karakas, Amanda; Sterling, Nicholas C.; Kaplan, Kyle

    2017-06-01

    We present preliminary results from a high-spectral resolution survey of near-infrared emission lines of neutron-capture elements in planetary nebulae using the Immersion Grating Infrared Spectrometer, IGRINS (Park et al. 2014, SPIE. 9147, 1), which spans the H- and K-bands at spectral resolving power R ≈ 45,000. Both the [Kr III] and [Se IV] lines identified by Dinerstein (2001, ApJL, 550, L223) are seen in nearly all of an initial sample of ≈ 15 nebulae, with improved accuracy over earlier studies based on lower-resolution data (Sterling & Dinerstein 2008, ApJS, 174, 158; Sterling, Porter, & Dinerstein 2015, ApJS, 218, 25). Several new detections of the [Rb IV], [Cd IV], and [Ge VI] lines identified by Sterling et al. (2016, ApJL, 819, 9), as well as a [Br V] line, were made. About half the objects in this sample descend from stars with [Fe/H] = -0.7 ± 0.2 dex, while the remainder have -0.3 ≤ [Fe/H] ≤ 0. We compare the measured enhancements of Se, Kr, Rb, and Cd with predictions of their production by slow-neutron captures (the s-process) during the AGB from theoretical evolutionary models for the corresponding metallicities and various initial masses. New nucleosynthesis calculations were carried out for [Fe/H] = -0.7 for initial masses between 1.1 and 3 M⊙ using the Monash stellar evolution and post-processing codes described in Karakas & Lugaro (2016, ApJ, 825, 26), which provides the nucleosynthesis predictions for the metal-rich end of our sample. The Monash models predict enrichments larger by factors of two or more than those from FRUITY (Cristallo et al. 2015, ApJS, 219, 40) and NuGRID (Pignatari et al. 2016, ApJS, 225, 24) models for the same masses and metallicities. We find that the Monash models are in substantially better agreement than the others with the abundances derived from the IGRINS observations.This work is based on data taken at the McDonald Observatory of the University of Texas at Austin. IGRINS was developed with support from

  10. Experimental and Theoretical Analysis of Headlight Surface Temperature in an Infrared Heated Stress Relieving Oven

    Directory of Open Access Journals (Sweden)

    Mustafa MUTLU

    2016-04-01

    Full Text Available In this study, the IR heated stress relieve oven was experimentally and theoretically examined. In experimental measurements, temperature was measured on headlight surface, placed in IR oven at various conveyor speeds and various distances between IR lamps and headlight surface. In theoretical study, a mathematical model was developed for the headlights surface temperature by using heat transfer theory. The results obtained by the mathematical model and the measurement showed very good agreement with a 6.5 % average error. It is shown that mathematical models can be used to estimate the surface temperatures when the oven is operated under different conditions.

  11. Mid-infrared volume diffraction gratings in IG2 chalcogenide glass: fabrication, characterization, and theoretical verification

    Science.gov (United States)

    Butcher, Helen L.; MacLachlan, David G.; Lee, David; Brownsword, Richard A.; Thomson, Robert R.; Weidmann, Damien

    2018-02-01

    Ultrafast laser inscription (ULI) has previously been employed to fabricate volume diffraction gratings in chalcogenide glasses, which operate in transmission mode in the mid-infrared spectral region. Prior gratings were manufactured for applications in astrophotonics, at wavelengths around 2.5 μm. Rugged volume gratings also have potential use in remote atmospheric sensing and molecular spectroscopy; for these applications, longer wavelength operation is required to coincide with atmospheric transparency windows (3-5 μm) and intense ro-vibrational molecular absorption bands. We report on ULI gratings inscribed in IG2 chalcogenide glass, enabling access to the full 3-5 μm window. High-resolution broadband spectral characterization of fabricated gratings was performed using a Fourier transform spectrometer. The zeroth order transmission was characterized to derive the diffraction efficiency into higher orders, up to the fourth orders in the case of gratings optimized for first order diffraction at 3 μm. The outcomes imply that ULI in IG2 is well suited for the fabrication of volume gratings in the mid infrared, providing the impact of the ULI fabrication parameters on the grating properties are well understood. To develop this understanding, grating modeling was conducted. Parameters studied include grating thickness, refractive index modification, and aspect ratio of the modulation achieved by ULI. Knowledge of the contribution and sensitivity of these parameters was used to inform the design of a 4.3 μm grating expected to achieve > 95% first order efficiency. We will also present the characterization of these latest mid-infrared diffraction gratings in IG2.

  12. Combined volumetric, infrared spectroscopic and theoretical investigation of CO(2) adsorption on Na-A zeolite

    Czech Academy of Sciences Publication Activity Database

    Zukal, Arnošt; Areán, C. O.; Delgado, M. R.; Nachtigall, P.; Pulido, A.; Mayerová, Jana; Čejka, Jiří

    2011-01-01

    Roč. 146, 1-3 (2011), s. 97-105 ISSN 1387-1811 R&D Projects: GA ČR GA203/08/0604 Institutional research plan: CEZ:AV0Z40400503 Keywords : Na-A-zeolite * carbon dioxide * adsorption Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.285, year: 2011

  13. Rapid, nondestructive estimation of surface polymer layer thickness using attenuated total reflection fourier transform infrared (ATR FT-IR) spectroscopy and synthetic spectra derived from optical principles.

    Science.gov (United States)

    Weinstock, B André; Guiney, Linda M; Loose, Christopher

    2012-11-01

    We have developed a rapid, nondestructive analytical method that estimates the thickness of a surface polymer layer with high precision but unknown accuracy using a single attenuated total reflection Fourier transform infrared (ATR FT-IR) measurement. Because the method is rapid, nondestructive, and requires no sample preparation, it is ideal as a process analytical technique. Prior to implementation, the ATR FT-IR spectrum of the substrate layer pure component and the ATR FT-IR and real refractive index spectra of the surface layer pure component must be known. From these three input spectra a synthetic mid-infrared spectral matrix of surface layers 0 nm to 10,000 nm thick on substrate is created de novo. A minimum statistical distance match between a process sample's ATR FT-IR spectrum and the synthetic spectral matrix provides the thickness of that sample. We show that this method can be used to successfully estimate the thickness of polysulfobetaine surface modification, a hydrated polymeric surface layer covalently bonded onto a polyetherurethane substrate. A database of 1850 sample spectra was examined. Spectrochemical matrix-effect unknowns, such as the nonuniform and molecularly novel polysulfobetaine-polyetherurethane interface, were found to be minimal. A partial least squares regression analysis of the database spectra versus their thicknesses as calculated by the method described yielded an estimate of precision of ±52 nm.

  14. A new Schiff base compound N,N'-(2,2-dimetylpropane)-bis(dihydroxylacetophenone): synthesis, experimental and theoretical studies on its crystal structure, FTIR, UV-visible, 1H NMR and 13C NMR spectra.

    Science.gov (United States)

    Saheb, Vahid; Sheikhshoaie, Iran

    2011-10-15

    The Schiff base compound, N,N'-(2,2-dimetylpropane)-bis(dihydroxylacetophenone) (NDHA) is synthesized through the condensation of 2-hydroxylacetophenone and 2,2-dimethyl 1,3-amino propane in methanol at ambient temperature. The yellow crystalline precipitate is used for X-ray single-crystal determination and measuring Fourier transform infrared (FTIR), UV-visible, (1)H NMR and (13)C NMR spectra. Electronic structure calculations at the B3LYP, PBEPBE and PW91PW91 levels of theory are performed to optimize the molecular geometry and to calculate the FTIR, (1)H NMR and (13)C NMR spectra of the compound. Time-dependent density functional theory (TDDFT) method is used to calculate the UV-visible spectrum of NDHA. Vibrational frequencies are determined experimentally and compared with those obtained theoretically. Vibrational assignments and analysis of the fundamental modes of the compound are also performed. All theoretical methods can well reproduce the structure of the compound. The (1)H NMR and (13)C NMR chemical shifts calculated by all DFT methods are consistent with the experimental data. However, the NMR shielding tensors computed at the B3LYP/6-31+G(d,p) level of theory are in better agreement with experimental (1)H NMR and (13)C NMR spectra. The electronic absorption spectrum calculated at the B3LYP/6-31+G(d,p) level by using TD-DFT method is in accordance with the observed UV-visible spectrum of NDHA. In addition, some quantum descriptors of the molecule are calculated and conformational analysis is performed and the results were compared with the crystallographic data. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Spectral Irradiance Calibration in the Infrared. XVI. Improved Accuracy in the Infrared Spectra of the Secondary and Tertiary Standard Calibration Stars

    Science.gov (United States)

    2006-10-01

    resolution ( AlA ). -, 400) spectroscopy obtained on infrared standard stars by the Short Wavelength Spectrometer on the Infrared Space Observatory with high...1995): 2.1-2.4 pm Strecker et al. (1979): 1.22-2.4 pm 6 See http://vizier.hia.nrc.ca/viz-bin/VizieR. REFERENCES Alonso, A., Salaris, M., Arribas , S...Haddock, D. J., Arribas , S., Leggett, S. K., & Mountain, C. M. 1988, A&AS, 74, 127

  16. Ground and satellite-based remote sensing of mineral dust using AERI spectra and MODIS thermal infrared window brightness temperatures

    Science.gov (United States)

    Hansell, Richard Allen, Jr.

    The radiative effects of dust aerosol on our climate system have yet to be fully understood and remain a topic of contemporary research. To investigate these effects, detection/retrieval methods for dust events over major dust outbreak and transport areas have been developed using satellite and ground-based approaches. To this end, both the shortwave and longwave surface radiative forcing of dust aerosol were investigated. The ground-based remote sensing approach uses the Atmospheric Emitted Radiance Interferometer brightness temperature spectra to detect mineral dust events and to retrieve their properties. Taking advantage of the high spectral resolution of the AERI instrument, absorptive differences in prescribed thermal IR window sub-band channels were exploited to differentiate dust from cirrus clouds. AERI data collected during the UAE2 at Al-Ain UAE was employed for dust retrieval. Assuming a specified dust composition model a priori and using the light scattering programs of T-matrix and the finite difference time domain methods for oblate spheroids and hexagonal plates, respectively, dust optical depths have been retrieved and compared to those inferred from a collocated and coincident AERONET sun-photometer dataset. The retrieved optical depths were then used to determine the dust longwave surface forcing during the UAE2. Likewise, dust shortwave surface forcing is investigated employing a differential technique from previous field studies. The satellite-based approach uses MODIS thermal infrared brightness temperature window data for the simultaneous detection/separation of mineral dust and cirrus clouds. Based on the spectral variability of dust emissivity at the 3.75, 8.6, 11 and 12 mum wavelengths, the D*-parameter, BTD-slope and BTD3-11 tests are combined to identify dust and cirrus. MODIS data for the three dust-laden scenes have been analyzed to demonstrate the effectiveness of this detection/separation method. Detected daytime dust and cloud

  17. On a New Theoretical Framework for RR Lyrae Stars. II. Mid-infrared Period–Luminosity–Metallicity Relations

    Energy Technology Data Exchange (ETDEWEB)

    Neeley, Jillian R.; Marengo, Massimo; Trueba, Nicolas [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Bono, Giuseppe; Braga, Vittorio F.; Magurno, Davide [Department of Physics, Università di Roma Tor Vergara, via della Ricerca Scientifica 1, I-00133 Roma (Italy); Dall’Ora, Massimo; Marconi, Marcella [INAF-Osservatorio Astronomico di Capodimonte, Salita Moiarello 16, I-80131 Napoli (Italy); Tognelli, Emanuele; Moroni, Pier G. Prada [Dipartimento di Fisica, Università di Pisa, Lago Bruno Pontecorvo 3, I-56127, Pisa (Italy); Beaton, Rachael L.; Madore, Barry F.; Seibert, Mark [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Freedman, Wendy L. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Monson, Andrew J. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Scowcroft, Victoria [Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Stetson, Peter B., E-mail: jrneeley@iastate.edu [NRC-Herzberg, Dominion Astrophysical Observatory, 5071 West Saanich Road, Victoria BC V9E 2E7 (Canada)

    2017-06-01

    We present new theoretical period–luminosity–metallicity (PLZ) relations for RR Lyræ stars (RRLs) at Spitzer and WISE wavelengths. The PLZ relations were derived using nonlinear, time-dependent convective hydrodynamical models for a broad range of metal abundances ( Z = 0.0001–0.0198). In deriving the light curves, we tested two sets of atmospheric models and found no significant difference between the resulting mean magnitudes. We also compare our theoretical relations to empirical relations derived from RRLs in both the field and in the globular cluster M4. Our theoretical PLZ relations were combined with multi-wavelength observations to simultaneously fit the distance modulus, μ {sub 0}, and extinction, A {sub V}, of both the individual Galactic RRL and of the cluster M4. The results for the Galactic RRL are consistent with trigonometric parallax measurements from Gaia ’ s first data release. For M4, we find a distance modulus of μ {sub 0} = 11.257 ± 0.035 mag with A {sub V}= 1.45 ± 0.12 mag, which is consistent with measurements from other distance indicators. This analysis has shown that, when considering a sample covering a range of iron abundances, the metallicity spread introduces a dispersion in the PL relation on the order of 0.13 mag. However, if this metallicity component is accounted for in a PLZ relation, the dispersion is reduced to ∼0.02 mag at mid-infrared wavelengths.

  18. A novel tridentate Schiff base dioxo-molybdenum(VI) complex: synthesis, experimental and theoretical studies on its crystal structure, FTIR, UV-visible, ¹H NMR and ¹³C NMR spectra.

    Science.gov (United States)

    Saheb, Vahid; Sheikhshoaie, Iran; Stoeckli-Evans, Helen

    2012-09-01

    A new dioxo-molybdenum(VI) complex [MoO(2)(L)(H(2)O)] has been synthesized, using 5-methoxy 2-[(2-hydroxypropylimino)methyl]phenol as tridentate ONO donor Schiff base ligand (H(2)L) and MoO(2)(acac)(2). The yellow crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FTIR), UV-visible, (1)H NMR and (13)C NMR spectra. Electronic structure calculations at the B3LYP and PW91PW91 levels of theory are performed to optimize the molecular geometry and to calculate the UV-visible, FTIR, (1)H NMR and (13)C NMR spectra of the compound. Vibrational assignments and analysis of the fundamental modes of the compound are performed. Time-dependent density functional theory (TDDFT) method is used to calculate the electronic transitions of the complex. All theoretical methods can well reproduce the structure of the compound. The (1)H NMR shielding tensors computed at the B3LYP/DGDZVP level of theory is in agreement with experimental (1)H NMR spectra. However, the (13)C NMR shielding tensors computed at the B3LYP level, employing a combined basis set of DGDZVP for Mo and 6-31+G(2df,p) for other atoms, are in better agreement with experimental (13)C NMR spectra. The electronic transitions calculated at the B3LYP/DGDZVP level by using TD-DFT method is in accordance with the observed UV-visible spectrum of the compound. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Star-forming Galaxies as AGN Imposters? A Theoretical Investigation of the Mid-infrared Colors of AGNs and Extreme Starbursts

    Science.gov (United States)

    Satyapal, Shobita; Abel, Nicholas P.; Secrest, Nathan J.

    2018-05-01

    We conduct for the first time a theoretical investigation of the mid-infrared spectral energy distribution (SED) produced by dust heated by an active galactic nucleus (AGN) and an extreme starburst. These models employ an integrated modeling approach using photoionization and stellar population synthesis models in which both the line and emergent continuum is predicted from gas exposed to the ionizing radiation from a young starburst and an AGN. In this work, we focus on the infrared colors from the Wide-field Infrared Survey Explorer, predicting the dependence of the colors on the input radiation field, the interstellar medium conditions, the obscuring column, and the metallicity. We find that an extreme starburst can mimic an AGN in two band mid-infrared color cuts employed in the literature. However, the three-band color cuts employed in the literature require starbursts with extremely high ionization parameters or gas densities. We show that the extreme mid-infrared colors seen in some blue compact dwarf galaxies are not due to metallicity but rather a combination of high ionization parameters and high column densities. Based on our theoretical calculations, we present a theoretical mid-infrared color cut that will exclude even the most extreme starburst that we have modeled in this work. The theoretical AGN demarcation region presented here can be used to identify elusive AGN candidates for future follow-up studies with the James Webb Space Telescope. The full suite of simulated SEDs are available online.

  20. Parallel β-sheet vibrational couplings revealed by 2D IR spectroscopy of an isotopically labeled macrocycle: quantitative benchmark for the interpretation of amyloid and protein infrared spectra.

    Science.gov (United States)

    Woys, Ann Marie; Almeida, Aaron M; Wang, Lu; Chiu, Chi-Cheng; McGovern, Michael; de Pablo, Juan J; Skinner, James L; Gellman, Samuel H; Zanni, Martin T

    2012-11-21

    Infrared spectroscopy is playing an important role in the elucidation of amyloid fiber formation, but the coupling models that link spectra to structure are not well tested for parallel β-sheets. Using a synthetic macrocycle that enforces a two stranded parallel β-sheet conformation, we measured the lifetimes and frequency for six combinations of doubly (13)C═(18)O labeled amide I modes using 2D IR spectroscopy. The average vibrational lifetime of the isotope labeled residues was 550 fs. The frequencies of the labels ranged from 1585 to 1595 cm(-1), with the largest frequency shift occurring for in-register amino acids. The 2D IR spectra of the coupled isotope labels were calculated from molecular dynamics simulations of a series of macrocycle structures generated from replica exchange dynamics to fully sample the conformational distribution. The models used to simulate the spectra include through-space coupling, through-bond coupling, and local frequency shifts caused by environment electrostatics and hydrogen bonding. The calculated spectra predict the line widths and frequencies nearly quantitatively. Historically, the characteristic features of β-sheet infrared spectra have been attributed to through-space couplings such as transition dipole coupling. We find that frequency shifts of the local carbonyl groups due to nearest neighbor couplings and environmental factors are more important, while the through-space couplings dictate the spectral intensities. As a result, the characteristic absorption spectra empirically used for decades to assign parallel β-sheet secondary structure arises because of a redistribution of oscillator strength, but the through-space couplings do not themselves dramatically alter the frequency distribution of eigenstates much more than already exists in random coil structures. Moreover, solvent exposed residues have amide I bands with >20 cm(-1) line width. Narrower line widths indicate that the amide I backbone is solvent

  1. Theoretical study of EPR spectra in Cu2+ - and Mn2+ - doped CaCd(CH3COO)4.6H2O

    International Nuclear Information System (INIS)

    Zhou Yiyang; Zhao Minguang

    1987-08-01

    The EPR spectra of CaCd(CH 3 COO) 4 .6H 2 O doped with Cu 2+ and Mn 2+ have been studied theoretically. A comparison between the calculated results and the experimental data shows quantitatively that the Cu 2+ and Mn 2+ ions substitute for the Cd 2+ and Ca 2+ ions, respectively. This conclusion is consistent with the qualitative assumption given by previous authors. (author). 36 refs, 1 fig., 3 tabs

  2. Effects of varying environmental conditions on emissivity spectra of bulk lunar soils: Application to Diviner thermal infrared observations of the Moon

    Science.gov (United States)

    Donaldson Hanna, K. L.; Greenhagen, B. T.; Patterson, W. R.; Pieters, C. M.; Mustard, J. F.; Bowles, N. E.; Paige, D. A.; Glotch, T. D.; Thompson, C.

    2017-02-01

    Currently, few thermal infrared measurements exist of fine particulate (samples (e.g. minerals, mineral mixtures, rocks, meteorites, and lunar soils) measured under simulated lunar conditions. Such measurements are fundamental for interpreting thermal infrared (TIR) observations by the Diviner Lunar Radiometer Experiment (Diviner) onboard NASA's Lunar Reconnaissance Orbiter as well as future TIR observations of the Moon and other airless bodies. In this work, we present thermal infrared emissivity measurements of a suite of well-characterized Apollo lunar soils and a fine particulate (sample as we systematically vary parameters that control the near-surface environment in our vacuum chamber (atmospheric pressure, incident solar-like radiation, and sample cup temperature). The atmospheric pressure is varied between ambient (1000 mbar) and vacuum (radiation is varied between 52 and 146 mW/cm2, and the sample cup temperature is varied between 325 and 405 K. Spectral changes are characterized as each parameter is varied, which highlight the sensitivity of thermal infrared emissivity spectra to the atmospheric pressure and the incident solar-like radiation. Finally spectral measurements of Apollo 15 and 16 bulk lunar soils are compared with Diviner thermal infrared observations of the Apollo 15 and 16 sampling sites. This comparison allows us to constrain the temperature and pressure conditions that best simulate the near-surface environment of the Moon for future laboratory measurements and to better interpret lunar surface compositions as observed by Diviner.

  3. The influence of anharmonic and solvent effects on the theoretical vibrational spectra of the guanine-cytosine base pairs in Watson-Crick and Hoogsteen configurations.

    Science.gov (United States)

    Bende, Attila; Muntean, Cristina M

    2014-03-01

    The theoretical IR and Raman spectra of the guanine-cytosine DNA base pairs in Watson-Crick and Hoogsteen configurations were computed using DFT method with M06-2X meta-hybrid GGA exchange-correlation functional, including the anharmonic corrections and solvent effects. The results for harmonic frequencies and their anharmonic corrections were compared with our previously calculated values obtained with the B3PW91 hybrid GGA functional. Significant differences were obtained for the anharmonic corrections calculated with the two different DFT functionals, especially for the stretching modes, while the corresponding harmonic frequencies did not differ considerable. For the Hoogtseen case the H⁺ vibration between the G-C base pair can be characterized as an asymmetric Duffing oscillator and therefore unrealistic anharmonic corrections for normal modes where this proton vibration is involved have been obtained. The spectral modification due to the anharmonic corrections, solvent effects and the influence of sugar-phosphate group for the Watson-Crick and Hoogsteen base pair configurations, respectively, were also discussed. For the Watson-Crick case also the influence of the stacking interaction on the theoretical IR and Raman spectra was analyzed. Including the anharmonic correction in our normal mode analysis is essential if one wants to obtain correct assignments of the theoretical frequency values as compared with the experimental spectra.

  4. Theoretical and experimental study of high-magnetic-field XMCD spectra at the L2,3 absorption edges of mixed-valence rare-earth compounds

    International Nuclear Information System (INIS)

    Kotani, Akio; Matsuda, Yasuhiro H; Nojiri, Hiroyuki

    2009-01-01

    X-ray magnetic circular dichroism(XMCD) spectra at the L 2,3 edges of mixed-valence rare-earth compounds in high magnetic fields are studied both theoretically and experimentally. The theoretical study is based on a new framework proposed recently by Kotani. The Zeeman splitting of 4f states, the mixed-valence character of 4f states, and the 4f-5d exchange interaction are incorporated into a single impurity Anderson model. New XMCD experiments in high magnetic fields up to 40 T are carried out for the mixed-valence compounds EuNi 2 (Si 0.18 Ge 0.82 ) 2 and YbInCu 4 by using a miniature pulsed magnet, which was developed recently by Matsuda et al. The XMCD data are taken at 5 K by transmission measurements for incident X-rays with ± helicities at BL39XU in SPring-8. After giving a survey on recent developments in the theory of XMCD spectra for mixed-valence Ce and Yb compounds, we calculate the XMCD spectra of YbInCu 4 at the field-induced valence transition around 32 T by applying the recent theoretical framework and by newly introducing at 32 T a discontinuous change in the Yb 4f level and that in the hybridization strength between the Yb 4f and conduction electrons. The calculated results are compared with the experimental ones.

  5. Correlation of infrared spectra and phase transitions in annealed proton-exchanged MgO doped LiNbO3

    International Nuclear Information System (INIS)

    Sun, Jian; Xu, Chang-qing

    2015-01-01

    Infrared spectra of OH − groups in annealed proton-exchanged (APE) 5 mol. % MgO-doped LiNbO 3 (MgO:LiNbO 3 ) crystals were studied using the Fourier transform infrared spectroscopy technique. Samples were prepared by benzoic acid proton-exchange followed with thermal annealing in oxygen. Evolutions of absorption peaks in APE MgO:LiNbO 3 crystals were recorded and analyzed. Comparing with none-doped APE LiNbO 3 crystals, a different phase transition behavior was found during thermal annealing. A periodically poled MgO:LiNbO 3 slab waveguide was prepared using identical procedures, and the second harmonic generation (SHG) signals were measured. Comparing the obtained SHG results with the infrared spectra, relationships between the phase transitions and the recovery of second-order nonlinear coefficients during thermal annealing were investigated. Finally, a method for optimizing the performance of MgO:LiNbO 3 waveguides was proposed

  6. [Apply fourier transform infrared spectra coupled with two-dimensional correlation analysis to study the evolution of humic acids during composting].

    Science.gov (United States)

    Bu, Gui-jun; Yu, Jing; Di, Hui-hui; Luo, Shi-jia; Zhou, Da-zhai; Xiao, Qiang

    2015-02-01

    The composition and structure of humic acids formed during composting play an important influence on the quality and mature of compost. In order to explore the composition and evolution mechanism, municipal solid wastes were collected to compost and humic and fulvic acids were obtained from these composted municipal solid wastes. Furthermore, fourier transform infrared spectra and two-dimensional correlation analysis were applied to study the composition and transformation of humic and fulvic acids during composting. The results from fourier transform infrared spectra showed that, the composition of humic acids was complex, and several absorbance peaks were observed at 2917-2924, 2844-2852, 2549, 1662, 1622, 1566, 1454, 1398, 1351, 990-1063, 839 and 711 cm(-1). Compared to humic acids, the composition of fulvci acids was simple, and only three peaks were detected at 1725, 1637 and 990 cm(-1). The appearance of these peaks showed that both humic and fulvic acids comprised the benzene originated from lignin and the polysaccharide. In addition, humic acids comprised a large number of aliphatic and protein which were hardly detected in fulvic acids. Aliphatic, polysaccharide, protein and lignin all were degraded during composting, however, the order of degradation was different between humic and fulvci acids. The result from two-dimensional correlation analysis showed that, organic compounds in humic acids were degraded in the following sequence: aliphatic> protein> polysaccharide and lignin, while that in fulvic acids was as following: protein> polysaccharide and aliphatic. A large number of carboxyl, alcohols and ethers were formed during the degradation process, and the carboxyl was transformed into carbonates. It can be concluded that, fourier transform infrared spectra coupled with two-dimensional correlation analysis not only can analyze the function group composition of humic substances, but also can characterize effectively the degradation sequence of these

  7. Signatures of charge inhomogeneities in the infrared spectra of topological insulators Bi2Se3, Bi2Te3 and Sb2Te3

    International Nuclear Information System (INIS)

    Dordevic, S V; Wolf, M S; Stojilovic, N; Lei Hechang; Petrovic, C

    2013-01-01

    We present the results of an infrared spectroscopy study of topological insulators Bi 2 Se 3 , Bi 2 Te 3 and Sb 2 Te 3 . Reflectance spectra of all three materials look similar, with a well defined plasma edge. However, there are some important differences. Most notably, as temperature decreases the plasma edge shifts to lower frequencies in Bi 2 Se 3 , whereas in Bi 2 Te 3 and Sb 2 Te 3 it shifts to higher frequencies. In the loss function spectra we identify asymmetric broadening of the plasmon, and assign it to the presence of charge inhomogeneities. It remains to be seen if charge inhomogeneities are characteristic of all topological insulators, and whether they are of intrinsic or extrinsic nature.

  8. OMS, OM(η2-SO), and OM(η2-SO)(η2-SO2) molecules (M = Ti, Zr, Hf): infrared spectra and density functional calculations.

    Science.gov (United States)

    Liu, Xing; Wang, Xuefeng; Wang, Qiang; Andrews, Lester

    2012-07-02

    Infrared spectra of the matrix isolated OMS, OM(η(2)-SO), and OM(η(2)-SO)(η(2)-SO(2)) (M = Ti, Zr, Hf) molecules were observed following laser-ablated metal atom reactions with SO(2) during condensation in solid argon and neon. The assignments for the major vibrational modes were confirmed by appropriate S(18)O(2) and (34)SO(2) isotopic shifts, and density functional vibrational frequency calculations (B3LYP and BPW91). Bonding in the initial OM(η(2)-SO) reaction products and in the OM(η(2)-SO)(η(2)-SO(2)) adduct molecules with unusual chiral structures is discussed.

  9. Optimization of experimental conditions for the installation of an infrared spectra library for the characterization of sulfato and thio-sulfato-reducing bacteria

    International Nuclear Information System (INIS)

    Boudaud, N.; Carayon, A.; Amiel, C.; Mariey, L.; Travert, J.

    2005-01-01

    The presence of particular bacteria strains in bio-films can accelerate corrosion process or induce auspicious corrosion conditions. Bacteria most often described to be aggressive against metallic materials are Sulfato and Thio-sulfato Reducing Bacteria (SRB and TRB). Preliminary studies showed the potentialities of Fourier Transform InfraRed (FTIR) Spectroscopy for the discrimination of these two groups. The realization of a reference spectra library requires the working out of common standardized culture conditions for the whole flora studied. A first spectra library including 6 SRB and 6 TRB collection strains was achieved. Hierarchical cluster analysis of the spectra of these twelve strains allows to obtain three distinct clusters (SRB, TRB and mixed cluster), and to discriminate these strains at the genus level (11 out of 12) and at the species level (12 out of 12). Ten strains isolated from the environment were tested on this spectra library. The enrichment of the database will enable us to carry on the identification of higher number of wild SRB and TRB strains. (authors)

  10. On the Use of Fourier Transform Infrared (FT-IR) Spectroscopy and Synthetic Calibration Spectra to Quantify Gas Concentrations in a Fischer-Tropsch Catalyst System

    Science.gov (United States)

    Ferguson, Frank T.; Johnson, Natasha M.; Nuth, Joseph A., III

    2015-01-01

    One possible origin of prebiotic organic material is that these compounds were formed via Fischer-Tropsch-type (FTT) reactions of carbon monoxide and hydrogen on silicate and oxide grains in the warm, inner-solar nebula. To investigate this possibility, an experimental system has been built in which the catalytic efficiency of different grain-analog materials can be tested. During such runs, the gas phase above these grain analogs is sampled using Fourier transform infrared (FT-IR) spectroscopy. To provide quantitative estimates of the concentration of these gases, a technique in which high-resolution spectra of the gases are calculated using the high-resolution transmission molecular absorption (HITRAN) database is used. Next, these spectra are processed via a method that mimics the processes giving rise to the instrumental line shape of the FT-IR spectrometer, including apodization, self-apodization, and broadening due to the finite resolution. The result is a very close match between the measured and computed spectra. This technique was tested using four major gases found in the FTT reactions: carbon monoxide, methane, carbon dioxide, and water. For the ranges typical of the FTT reactions, the carbon monoxide results were found to be accurate to within 5% and the remaining gases accurate to within 10%. These spectra can then be used to generate synthetic calibration data, allowing the rapid computation of the gas concentrations in the FTT experiments.

  11. Infrared Spectroscopic Analyses of Sulfate, Nitrate, and Carbonate-bearing Atacama Desert Soils: Analogs for the Interpretation of Infrared Spectra from the Martian Surface

    Science.gov (United States)

    Dalton, J. B.; Dalton, J. B.; Ewing, S. A.; Amundson, R.; McKay, C. P.

    2005-01-01

    The Atacama Desert of northern Chile is the driest desert on Earth, receiving only a few mm of rain per decade. The Mars climate may, in the past, have been punctuated by short-lived episodes of aqueous activity. The paleo-Martian environment may have had aqueous conditions similar to the current conditions that exist in the Atacama, and Mars soils may have formed with soil chemistry and mineralogy similar to those found in the Atacama. Remote and in-situ analysis of the Martian surface using infrared technology has a long heritage. Future investigations of the subsurface mineralogy are likely to build upon this heritage, and will benefit from real life lessons to be learned from terrestrial analog studies. To that end, preliminary results from a near- and mid-infrared spectroscopic study of Atacama soil profiled at a range of depths are presented.

  12. Theoretical UV absorption spectra of hydrodynamically escaping O{sub 2}/CO{sub 2}-rich exoplanetary atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Gronoff, G.; Mertens, C. J.; Norman, R. B. [NASA LaRC, Hampton, VA (United States); Maggiolo, R. [BIRA-IASB, Avenue Circulaire 3, 1180 Brussels (Belgium); Wedlund, C. Simon [Aalto University School of Electrical Engineering Department of Radio Science and Engineering, P.O. Box 13000, FI-00076 Aalto (Finland); Bell, J. [National Institute of Aerospace, Hampton, VA (United States); Bernard, D. [IPAG, Grenoble (France); Parkinson, C. J. [University of Michigan, MI (United States); Vidal-Madjar, A., E-mail: Guillaume.P.Gronoff@nasa.gov [Observatoire de Paris, Paris (France)

    2014-06-20

    Characterizing Earth- and Venus-like exoplanets' atmospheres to determine if they are habitable and how they are evolving (e.g., equilibrium or strong erosion) is a challenge. For that endeavor, a key element is the retrieval of the exospheric temperature, which is a marker of some of the processes occurring in the lower layers and controls a large part of the atmospheric escape. We describe a method to determine the exospheric temperature of an O{sub 2}- and/or CO{sub 2}-rich transiting exoplanet, and we simulate the respective spectra of such a planet in hydrostatic equilibrium and hydrodynamic escape. The observation of hydrodynamically escaping atmospheres in young planets may help constrain and improve our understanding of the evolution of the solar system's terrestrial planets' atmospheres. We use the dependency of the absorption spectra of the O{sub 2} and CO{sub 2} molecules on the temperature to estimate the temperature independently of the total absorption of the planet. Combining two observables (two parts of the UV spectra that have a different temperature dependency) with the model, we are able to determine the thermospheric density profile and temperature. If the slope of the density profile is inconsistent with the temperature, then we infer the hydrodynamic escape. We address the question of the possible biases in the application of the method to future observations, and we show that the flare activity should be cautiously monitored to avoid large biases.

  13. Constructing theoretical M-shell spectra for Mg-like Au through Cl-like Au ions in gold plasma diagnostics

    International Nuclear Information System (INIS)

    Hamasha, Safeia; Alshaiub, Rania

    2012-01-01

    The theoretical atomic structure and spectra data for electric dipole transitions in six gold ions (Au 67+ through Au 62+ ) are produced using the flexible atomic code (FAC). The produced data contain energy levels, radiative transition rates and oscillator strengths with Δn≠0 (n = 3 → 4, 5, 6, 7). All M-shell strong lines for the six gold ions are also identified. The produced data and constructed spectra revealed the presence of a wide variety of ionization stages of Au with several blended spectral lines in the spectral range (1.7-4.4 Å). Calculated energy levels are compared against published values, which were calculated using the multi-reference many body perturbation theory that includes higher order quantum electrodynamics corrections effects. Favorable agreement with <0.26% difference was observed.

  14. Spectra and structure of silicon containing compounds. XXXII. Raman and infrared spectra, conformational stability, vibrational assignment and ab initio calculations of n-propylsilane-d0 and Si-d3.

    Science.gov (United States)

    Durig, James R; Pan, Chunhua; Guirgis, Gamil A

    2003-03-15

    The infrared (3100-40 cm(-1)) and Raman (3100-20 cm(-1)) spectra of gaseous and solid n-propylsilane, CH(3)CH(2)CH(2)SiH(3) and the Si-d(3) isotopomer, CH(3)CH(2)CH(2)SiD(3), have been recorded. Additionally, the Raman spectra of the liquids have been recorded and qualitative depolarization values obtained. Both the anti and gauche conformers have been identified in the fluid phases but only the anti conformer remains in the solid. Variable temperature (-105 to -150 degrees C) studies of the infrared spectra of n-propylsilane dissolved in liquid krypton have been recorded and the enthalpy difference has been determined to be 220+/-22 cm(-1) (2.63+/-0.26 kJ mol(-1)) with the anti conformer the more stable form. A similar value of 234+/-23 cm(-1) (2.80+/-0.28 kJ mol(-1)) was obtained for deltaH for the Si-d(3) isotopomer. At ambient temperature it is estimated that there is 30+/-2% of the gauche conformer present. The potential function governing the conformation interchange has been estimated from the far infrared spectral data, the enthalpy difference, and the dihedral angle of the gauche conformer, which is compared to the one predicted from ab initio MP2/6-31G(d) calculations. The barriers to conformational interchange are: 942, 970 and 716 cm(-1) for the anti to gauche, gauche to gauche, and gauche to anti conformers, respectively. Relatively complete vibrational assignments are proposed for both the n-propylsilane-d(0) and Si-d(3) molecules based on the relative infrared and Raman spectral intensities, infrared band contours, depolarization ratios, and normal coordinate calculations. The geometrical parameters, harmonic force constants, vibrational frequencies, infrared intensities, Raman activities and depolarization ratios, and energy differences have been obtained for the anti and gauche conformers from ab initio MP2/6-31G(d) calculations. Structural parameters and energy differences have also been obtained utilizing the larger 6-311 + G(d,p) and 6-311 + G(2

  15. Spectra and structure of silicon containing compounds. XXXII. Raman and infrared spectra, conformational stability, vibrational assignment and ab initio calculations of n-propylsilane-d 0 and Si-d 3

    Science.gov (United States)

    Durig, James R.; Pan, Chunhua; Guirgis, Gamil A.

    2003-03-01

    The infrared (3100-40 cm -1) and Raman (3100-20 cm -1) spectra of gaseous and solid n-propylsilane, CH 3CH 2CH 2SiH 3 and the Si-d 3 isotopomer, CH 3CH 2CH 2SiD 3, have been recorded. Additionally, the Raman spectra of the liquids have been recorded and qualitative depolarization values obtained. Both the anti and gauche conformers have been identified in the fluid phases but only the anti conformer remains in the solid. Variable temperature (-105 to -150 °C) studies of the infrared spectra of n-propylsilane dissolved in liquid krypton have been recorded and the enthalpy difference has been determined to be 220±22 cm -1 (2.63±0.26 kJ mol -1) with the anti conformer the more stable form. A similar value of 234±23 cm -1 (2.80±0.28 kJ mol -1) was obtained for Δ H for the Si-d 3 isotopomer. At ambient temperature it is estimated that there is 30±2% of the gauche conformer present. The potential function governing the conformation interchange has been estimated from the far infrared spectral data, the enthalpy difference, and the dihedral angle of the gauche conformer, which is compared to the one predicted from ab initio MP2/6-31G(d) calculations. The barriers to conformational interchange are: 942, 970 and 716 cm -1 for the anti to gauche, gauche to gauche, and gauche to anti conformers, respectively. Relatively complete vibrational assignments are proposed for both the n-propylsilane-d 0 and Si-d 3 molecules based on the relative infrared and Raman spectral intensities, infrared band contours, depolarization ratios, and normal coordinate calculations. The geometrical parameters, harmonic force constants, vibrational frequencies, infrared intensities, Raman activities and depolarization ratios, and energy differences have been obtained for the anti and gauche conformers from ab initio MP2/6-31G(d) calculations. Structural parameters and energy differences have also been obtained utilizing the larger 6-311+G(d,p) and 6-311+G(2d,2p) basis sets. From the isolated

  16. Integral parameters for the Godiva benchmark calculated by using theoretical and adjusted fission spectra of 235U

    International Nuclear Information System (INIS)

    Caldeira, A.D.

    1987-05-01

    The theoretical and adjusted Watt spectrum representations for 235 U are used as weighting functions to calculate K eff and θ f 28 /θ f 25 for the benchmark Godiva. The results obtained show that the values of K eff and θ f 28 /θ f 25 are not affected by spectrum form change. (author) [pt

  17. Influence of spectral resolution, spectral range and signal-to-noise ratio of Fourier transform infra-red spectra on identification of high explosive substances

    Science.gov (United States)

    Banas, Krzysztof; Banas, Agnieszka M.; Heussler, Sascha P.; Breese, Mark B. H.

    2018-01-01

    In the contemporary spectroscopy there is a trend to record spectra with the highest possible spectral resolution. This is clearly justified if the spectral features in the spectrum are very narrow (for example infra-red spectra of gas samples). However there is a plethora of samples (in the liquid and especially in the solid form) where there is a natural spectral peak broadening due to collisions and proximity predominately. Additionally there is a number of portable devices (spectrometers) with inherently restricted spectral resolution, spectral range or both, which are extremely useful in some field applications (archaeology, agriculture, food industry, cultural heritage, forensic science). In this paper the investigation of the influence of spectral resolution, spectral range and signal-to-noise ratio on the identification of high explosive substances by applying multivariate statistical methods on the Fourier transform infra-red spectral data sets is studied. All mathematical procedures on spectral data for dimension reduction, clustering and validation were implemented within R open source environment.

  18. Unsupervised explorative data analysis of normal human leukocytes and BCR/ABL positive leukemic cells mid-infrared spectra

    NARCIS (Netherlands)

    Bellisola, G.; Bolomini-Vittori, M.; Cinque, G.; Dumas, P.; Fiorini, Z.; Laudanna, C.; Mirenda, M.; Sandt, C.; Silvestri, G.; Tomasello, L.; Vezzalini, M.; Wehbe, K.; Sorio, C.

    2015-01-01

    We proved the ability of Fourier Transform Infrared microspectroscopy (microFTIR) complemented by Principal Component Analysis (PCA) to detect protein phosphorylation/de-phosphorylation in mammalian cells. We analyzed by microFTIR human polymorphonuclear neutrophil (PMNs) leukocytes, mouse-derived

  19. Applications of Group Theory: Infrared and Raman Spectra of the Isomers of 1,2-Dichloroethylene: A Physical Experiment

    Science.gov (United States)

    Craig, Norman C.; Lacuesta, Nanette N.

    2004-01-01

    A study of the vibrational spectroscopy of the cis and trans isomers of 1,2-dichloroethylene provides an excellent opportunity to learn the applications group theory in laboratories. The necessity of using infrared (IR) spectroscopy and Raman spectroscopy in making full vibrational assignments is illustrated.

  20. New Benchmarks from Tokamak Experiments for Theoretical Calculations of the Dielectronic Satellite Spectra of Helium-like Ions

    International Nuclear Information System (INIS)

    Bitter, M.; Gu, M.F.; Vainshtein, L.A.; Beiersdorfer, P.; Bertschinger, G.; Marchuk, O.; Bell, R.; LeBlanc, B.; Hill, K.W.; Johnson, D.; Roquemore, L.

    2003-01-01

    Dielectronic satellite spectra of helium-like argon, recorded with a high-resolution X-ray crystal spectrometer at the National Spherical Torus Experiment, were found to be inconsistent with existing predictions resulting in unacceptable values for the power balance and suggesting the unlikely existence of non-Maxwellian electron energy distributions. These problems were resolved with calculations from a new atomic code. It is now possible to perform reliable electron temperature measurements and to eliminate the uncertainties associated with determinations of non-Maxwellian distributions

  1. Spectra-structure correlations of saturated and unsaturated medium-chain fatty acids. Near-infrared and anharmonic DFT study of hexanoic acid and sorbic acid.

    Science.gov (United States)

    Grabska, Justyna; Beć, Krzysztof B; Ishigaki, Mika; Wójcik, Marek J; Ozaki, Yukihiro

    2017-10-05

    Quantum chemical reproduction of entire NIR spectra is a new trend, enabled by contemporary advances in the anharmonic approaches. At the same time, recent increase of the importance of NIR spectroscopy of biological samples raises high demand for gaining deeper understanding of NIR spectra of biomolecules, i.e. fatty acids. In this work we investigate saturated and unsaturated medium-chain fatty acids, hexanoic acid and sorbic acid, in the near-infrared region. By employing fully anharmonic density functional theory (DFT) calculations we reproduce the experimental NIR spectra of these systems, including the highly specific spectral features corresponding to the dimerization of fatty acids. Broad range of concentration levels from 5·10 -4 M in CCl 4 to pure samples are investigated. The major role of cyclic dimers can be evidenced for the vast majority of these samples. A highly specific NIR feature of fatty acids, the elevation of spectral baseline around 6500-4000cm -1 , is being explained by the contributions of combination bands resulting from the vibrations of hydrogen-bonded OH groups in the cyclic dimers. Based on the high agreement between the calculated and experimental NIR spectra, a detailed NIR band assignments are proposed for hexanoic acid and sorbic acid. Subsequently, the correlations between the structure and NIR spectra are elucidated, emphasizing the regions in which clear and universal traces of specific bands corresponding to saturated and unsaturated alkyl chains can be established, thus demonstrating the wavenumber regions highly valuable for structural identifications. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. An experimental and theoretical study of molecular structure and vibrational spectra of 2-methylphenyl boronic acid by density functional theory calculations

    Science.gov (United States)

    Hiremath, Sudhir M.; Hiremath, C. S.; Khemalapure, S. S.; Patil, N. R.

    2018-05-01

    This paper reports the experimental and theoretical study on the structure and vibrations of 2-Methylphenyl boronic acid (2MPBA). The different spectroscopic techniques such as FT-IR (4000-400 cm-1) and FT-Raman (4000-50 cm-1) of the title molecule in the solid phase were recorded. The geometry of the molecule was fully optimized using density functional theory (DFT) (B3LYP) with 6-311++G(d, p) basis set calculations. The vibrational wavenumbers were also corrected with scale factor to take better results for the calculated data. Vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the potential energy distribution (PED) of the vibrational modes obtained from VEDA 4 program. The calculated wavenumbers showed the best agreement with the experimental results. Whereas, it is observed that, the theoretical frequencies are more than the experimental one for O-H stretching vibration modes of the title molecule.

  3. Experimental and theoretical study on emission spectra of a nitrogen photoionized plasma induced by intense EUV pulses

    Directory of Open Access Journals (Sweden)

    Saber Ismail

    2018-01-01

    Full Text Available Spectral lines of low-temperature nitrogen photoionized plasma were investigated. The photoionized plasma was created in the result of irradiation N2 gas using laser plasma EUV radiation pulses. The source was based on a 10J/10ns Nd:YAG (λ = 1064 nm laser system and a gas puff target. The EUV radiation pulses were collected and focused using a grazing incidence multifoil EUV collector. The emission spectra were measured in the ultraviolet and visible (UV/Vis range. It was found that the plasma emission lines in the lower region of the UV range are relativley weak. Nonetheless, a part of the spectra contains strong molecular band in the 300 - 430 nm originated from second positive and first negative systems band transitions of nitrogen. These molecular band transitions were identified using a code for study the diatomic molecules, LIFBASE. The vibrational band of Δv = 0 and ±1 transitions were significantly populated than of that with Δv = ±2 and 3 transitions. A comparison of the calculated and measured spectrum is presented. With an assumption of a local thermodynamic equilibrium (LTE, the vibrational temperature was determined from the integrated band intensities with the help of the Boltzmann plot method and compared to the temperature predicted by SPECAIR and LIFBASE simulations. A summary of the results and the variations in the vibrational temperatures was discussed.

  4. Experimental and theoretical study on emission spectra of a nitrogen photoionized plasma induced by intense EUV pulses

    Science.gov (United States)

    Saber, Ismail; Bartnik, Andrzej; Skrzeczanowski, Wojciech; Wachulak, Przemyslaw; Jarocki, Roman; Fiedorowicz, Henryk; Limpouch, Jiri

    2018-01-01

    Spectral lines of low-temperature nitrogen photoionized plasma were investigated. The photoionized plasma was created in the result of irradiation N2 gas using laser plasma EUV radiation pulses. The source was based on a 10J/10ns Nd:YAG (λ = 1064 nm) laser system and a gas puff target. The EUV radiation pulses were collected and focused using a grazing incidence multifoil EUV collector. The emission spectra were measured in the ultraviolet and visible (UV/Vis) range. It was found that the plasma emission lines in the lower region of the UV range are relativley weak. Nonetheless, a part of the spectra contains strong molecular band in the 300 - 430 nm originated from second positive and first negative systems band transitions of nitrogen. These molecular band transitions were identified using a code for study the diatomic molecules, LIFBASE. The vibrational band of Δv = 0 and ±1 transitions were significantly populated than of that with Δv = ±2 and 3 transitions. A comparison of the calculated and measured spectrum is presented. With an assumption of a local thermodynamic equilibrium (LTE), the vibrational temperature was determined from the integrated band intensities with the help of the Boltzmann plot method and compared to the temperature predicted by SPECAIR and LIFBASE simulations. A summary of the results and the variations in the vibrational temperatures was discussed.

  5. Infrared and Microwave Spectra and Force Field of DBO: The Coriolis Interaction between the nu1 and nu2 + nu3 States.

    Science.gov (United States)

    Kawashima; Colarusso; Zhang; Bernath; Hirota

    1998-11-01

    The nu1 and nu3 bands of D11BO and the nu1 band of D10BO were observed by using an infrared diode laser spectrometer. The DBO molecule was generated by an ac discharge in a mixture of BCl3, D2, O2, and He. As inferred previously, a strong Coriolis interaction was in fact found to take place between the nu1 and nu2 + nu3 states, and an analysis of the observed nu1 spectra, which explicitly took into account this Coriolis interaction, predicted the pure rotational transition frequencies of DBO in the nu1 state. Pure rotational lines were then detected by microwave spectroscopy, confirming the validity of the infrared assignment. In the microwave experiment DBO molecules were generated by a discharge in a mixture of B2D6 and O2. The three fundamental bands and a hot band of D11BO, as well as the nu1 and nu3 bands of D10BO, were subsequently recorded in emission with a Fourier transform infrared spectrometer. DBO molecules were generated by the reaction of D2 with HBO at temperatures above 800 degreesC in a ceramic tube furnace. All of the observed spectra were simultaneously subjected to a least-squares analysis to obtain molecular parameters in the ground, nu1, nu2, nu3, and nu2 + nu3 states. The results thus obtained improved the force field and molecular structure of the HBO/DBO molecules reported in a previous study (Y. Kawashima, Y. Endo, and E. Hirota, 1989, J. Mol. Spectrosc. 133, 116-127). Copyright 1998 Academic Press.

  6. Infrared and Microwave Spectra and Force Field of DBO: The Coriolis Interaction between the ν 1and ν 2+ ν 3States

    Science.gov (United States)

    Kawashima, Yoshiyuki; Colarusso, Pina; Zhang, K. Q.; Bernath, Peter; Hirota, Eizi

    1998-11-01

    The ν1and ν3bands of D11BO and the ν1band of D10BO were observed by using an infrared diode laser spectrometer. The DBO molecule was generated by an ac discharge in a mixture of BCl3, D2, O2, and He. As inferred previously, a strong Coriolis interaction was in fact found to take place between the ν1and ν2+ ν3states, and an analysis of the observed ν1spectra, which explicitly took into account this Coriolis interaction, predicted the pure rotational transition frequencies of DBO in the ν1state. Pure rotational lines were then detected by microwave spectroscopy, confirming the validity of the infrared assignment. In the microwave experiment DBO molecules were generated by a discharge in a mixture of B2D6and O2. The three fundamental bands and a hot band of D11BO, as well as the ν1and ν3bands of D10BO, were subsequently recorded in emission with a Fourier transform infrared spectrometer. DBO molecules were generated by the reaction of D2with HBO at temperatures above 800°C in a ceramic tube furnace. All of the observed spectra were simultaneously subjected to a least-squares analysis to obtain molecular parameters in the ground, ν1, ν2, ν3, and ν2+ ν3states. The results thus obtained improved the force field and molecular structure of the HBO/DBO molecules reported in a previous study (Y. Kawashima, Y. Endo, and E. Hirota, 1989,J. Mol. Spectrosc.133, 116-127).

  7. Lanthanum trilactate: Vibrational spectroscopic study - infrared/Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Švecová, M.; Novák, Vít; Bartůněk, V.; Člupek, M.

    2016-01-01

    Roč. 87, Nov (2016), s. 123-128 ISSN 0924-2031 Institutional support: RVO:61388963 Keywords : lanthanum trilactate * tris(2-hydroxypropanoato-O1,O2) * lanthanum tris[2-(hydroxy-kappa O)propanoato-kappa O] * Raman spectra * infrared spectra * DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.740, year: 2016

  8. Theoretical realization of robust broadband transparency in ultrathin seamless nanostructures by dual blackbodies for near infrared light

    Science.gov (United States)

    Zhang, Lei; Hao, Jiaming; Ye, Huapeng; Yeo, Swee Ping; Qiu, Min; Zouhdi, Said; Qiu, Cheng-Wei

    2013-03-01

    We propose a counter-intuitive mechanism of constructing an ultrathin broadband transparent device with two perfect blackbodies. By introducing hybridization of plasmon modes, resonant modes with different symmetries coexist in this system. A broadband transmission spectrum in the near infrared regime is achieved through controlling their coupling strengths, which is governed by the thickness of high refractive index layer. Meanwhile, the transparency bandwidth is found to be tunable in a large range by varying the geometric dimension. More significantly, from the point view of applications, the proposed method of achieving broadband transparency can perfectly tolerate the misalignment and asymmetry of periodic nanoparticles on the top and bottom, which is empowered by the unique dual of coupling-in and coupling-out processes within the pair of blackbodies. Moreover, roughness has little influence on its transmission performance. According to the coupled mode theory, the distinguished transmittance performance is physically interpreted by the radiative decay rate of the entire system. In addition to the feature of uniquely robust broadband transparency, such a ultrathin seamless nanostructure (in the presence of a uniform silver layer) also provides polarization-independent and angle-independent operations. Therefore, it may power up a wide spectrum of exciting applications in thin film protection, touch screen techniques, absorber-emitter transformation, etc.We propose a counter-intuitive mechanism of constructing an ultrathin broadband transparent device with two perfect blackbodies. By introducing hybridization of plasmon modes, resonant modes with different symmetries coexist in this system. A broadband transmission spectrum in the near infrared regime is achieved through controlling their coupling strengths, which is governed by the thickness of high refractive index layer. Meanwhile, the transparency bandwidth is found to be tunable in a large range by

  9. Combining Partial Least Squares and the Gradient-Boosting Method for Soil Property Retrieval Using Visible Near-Infrared Shortwave Infrared Spectra

    Directory of Open Access Journals (Sweden)

    Lanfa Liu

    2017-12-01

    Full Text Available Soil spectroscopy has experienced a tremendous increase in soil property characterisation, and can be used not only in the laboratory but also from the space (imaging spectroscopy. Partial least squares (PLS regression is one of the most common approaches for the calibration of soil properties using soil spectra. Besides functioning as a calibration method, PLS can also be used as a dimension reduction tool, which has scarcely been studied in soil spectroscopy. PLS components retained from high-dimensional spectral data can further be explored with the gradient-boosted decision tree (GBDT method. Three soil sample categories were extracted from the Land Use/Land Cover Area Frame Survey (LUCAS soil library according to the type of land cover (woodland, grassland, and cropland. First, PLS regression and GBDT were separately applied to build the spectroscopic models for soil organic carbon (OC, total nitrogen content (N, and clay for each soil category. Then, PLS-derived components were used as input variables for the GBDT model. The results demonstrate that the combined PLS-GBDT approach has better performance than PLS or GBDT alone. The relative important variables for soil property estimation revealed by the proposed method demonstrated that the PLS method is a useful dimension reduction tool for soil spectra to retain target-related information.

  10. Impact effects of gamma irradiation on the optical and FT infrared absorption spectra of some Nd3+-doped soda lime phosphate glasses

    Science.gov (United States)

    Marzouk, M. A.; Elkashef, I. M.; Elbatal, H. A.

    2018-04-01

    The main aim of the present work is to study by two collective optical and FTIR spectral measurements some prepared Nd2O3-doped soda lime phosphate glasses before and after gamma irradiation with dose (9 Mrad). The spectral data reveal two strong UV absorption peaks which are correlated with unavoidable trace iron impurities beside extended additional characteristic bands due to Nd3+ ions. Gamma irradiation on the undoped glass produces slight decrease of the intensity of the UV absorption and the generation of an induced visible band and these effects are controlled with two photochemical reduction of some Fe3+ ions to Fe2+ ions together with the formation of nonbridging oxygen hole center (NBOHC) or phosphorous oxygen hole center (POHC). The impact effect of gamma irradiation on the spectra of Nd2O3-doped glasses is limited due to suggested shielding behavior of neodymium ions. FT-infrared spectra show vibrational modes due to main Q2-Q3 phosphate groups and the response of gamma irradiation of the IR spectra is low and the limited variations are related to suggested changes in some bond angles and bond lengths which cause the observed decrease to the intensities of some IR bands.

  11. Chemometric analysis of attenuated total reflectance infrared spectra of Proteus mirabilis strains with defined structures of LPS.

    Science.gov (United States)

    Zarnowiec, Paulina; Mizera, Andrzej; Chrapek, Magdalena; Urbaniak, Mariusz; Kaca, Wieslaw

    2016-07-01

    Proteus spp. strains are some of the most important pathogens associated with complicated urinary tract infections and bacteremia affecting patients with immunodeficiency and long-term urinary catheterization. For epidemiological purposes, various molecular typing methods have been developed for this pathogen. However, these methods are labor intensive and time consuming. We evaluated a new method of differentiation between strains. A collection of Proteus spp. strains was analyzed by attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy in the mid-infrared region. ATR FT-IR spectroscopy used in conjunction with a diamond ATR accessory directly produced the biochemical profile of the surface chemistry of bacteria. We conclude that a combination of ATR FT-IR spectroscopy and mathematical modeling provides a fast and reliable alternative for discrimination between Proteus isolates, contributing to epidemiological research. © The Author(s) 2016.

  12. Processing of phase pure and dense bulk EuTiO.sub.3./sub. ceramics and their infrared reflectivity spectra

    Czech Academy of Sciences Publication Activity Database

    Kachlik, M.; Máca, K.; Goian, Veronica; Kamba, Stanislav

    2012-01-01

    Roč. 74, MAY (2012), s. 16-18 ISSN 0167-577X R&D Projects: GA ČR GD202/09/H041; GA ČR(CZ) GA202/09/0682 Grant - others:GAUK(CZ) SVV-2011-263303 Institutional research plan: CEZ:AV0Z10100520 Keywords : functional ceramics, * europium titanate * sintering * infrared reflectivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.224, year: 2012

  13. Infrared Spectra and Binding Energies of Chemical Warfare Nerve Agent Simulants on the Surface of Amorphous Silica

    Science.gov (United States)

    2013-06-24

    surface that was nearly free from adsorbed water, had only trace hydrocarbon contamination, and contained a significant number of isolated SiO−H groups...are indicative of C−H stretches from a trace amount of hydrocarbon contamination within the silica sample. The three broad peaks at 1980, 1872, and...452. (13) Gay, I. D.; McFarlan, A. J.; Morrow, B. A. Trimethyl Phosphite Adsorbed on Silica - An NMR and Infrared Study. J. Phys. Chem. 1991, 95 (3

  14. Optimized geometry, vibration (IR and Raman spectra and nonlinear optical activity of p-nitroanilinium perchlorate molecule: A theoretical study

    Directory of Open Access Journals (Sweden)

    Tamer Ömer

    2016-03-01

    Full Text Available The molecular modeling of p-nitroanilinium perchlorate molecule was carried out by using B3LYP and HSEH1PBE levels of density functional theory (DFT. The IR and Raman spectra were simulated and the assignments of vibrational modes were performed on the basis of relative contribution of various internal co-ordinates. NBO analysis was performed to demonstrate charge transfer, conjugative interactions and the formation of intramolecular hydrogen bonding interactions within PNAPC. Obtained large dipole moment values showed that PNAPC is a highly polarizable complex, and the charge transfer occurs within PNAPC. Hydrogen bonding and charge transfer interactions were also displayed by small HOMO-LUMO gap and molecular electrostatic potential (MEP surface. The strong evidences that the material can be used as an efficient nonlinear optical (NLO material of PNAPC were demonstrated by considerable polarizability and hyperpolarizability values obtained at DFT levels.

  15. Analysis of energy transfer process based emission spectra of erbium doped germanate glasses for mid-infrared laser materials

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Muzhi; Wei, Tao; Zhou, Beier; Tian, Ying; Zhou, Jiajia; Xu, Shiqing, E-mail: shiqingxu@cjlu.edu.cn; Zhang, Junjie, E-mail: jjzhang@cjlu.edu.cn

    2015-03-25

    Highlights: • Er{sup 3+} doped germanate glass with good thermal stability were prepared. • Ionic boding nature was proved by bonding parameter calculation. • Mid-infrared fluorescent behaviors and energy transfer were investigated. • Rate equation and Dexter’s theory were utilized to elucidate 2.7 μm emission. - Abstract: Er{sup 3+} activated germanate glass with good thermal stability was prepared. Bonding parameters have been calculated and the nature of ionic bonding of the germanate glass has been determined. Mid-infrared fluorescence was observed and corresponding radiative properties were investigated. For Er{sup 3+}:{sup 4}I{sub 11/2}→{sup 4}I{sub 13/2} transition, high spontaneous radiative transition probability (30.09 s{sup −1}), large emission cross section ((14.84 ± 0.10) × 10{sup −21} cm{sup 2}) and superior gain performance were obtained from the prepared glass. Besides, energy transfer processes concerning the 2.7 μm emission were also discussed in detail. According to simplified rate equation and Dexter’s theory, energy transfer microscopic parameters were computed to elucidate observed 2.7 μm emissions. Results demonstrate that the prepared germanate glass possessing excellent spectroscopic properties might be an attractive candidate for mid-infrared laser or amplifier.

  16. Analysis of energy transfer process based emission spectra of erbium doped germanate glasses for mid-infrared laser materials

    International Nuclear Information System (INIS)

    Cai, Muzhi; Wei, Tao; Zhou, Beier; Tian, Ying; Zhou, Jiajia; Xu, Shiqing; Zhang, Junjie

    2015-01-01

    Highlights: • Er 3+ doped germanate glass with good thermal stability were prepared. • Ionic boding nature was proved by bonding parameter calculation. • Mid-infrared fluorescent behaviors and energy transfer were investigated. • Rate equation and Dexter’s theory were utilized to elucidate 2.7 μm emission. - Abstract: Er 3+ activated germanate glass with good thermal stability was prepared. Bonding parameters have been calculated and the nature of ionic bonding of the germanate glass has been determined. Mid-infrared fluorescence was observed and corresponding radiative properties were investigated. For Er 3+ : 4 I 11/2 → 4 I 13/2 transition, high spontaneous radiative transition probability (30.09 s −1 ), large emission cross section ((14.84 ± 0.10) × 10 −21 cm 2 ) and superior gain performance were obtained from the prepared glass. Besides, energy transfer processes concerning the 2.7 μm emission were also discussed in detail. According to simplified rate equation and Dexter’s theory, energy transfer microscopic parameters were computed to elucidate observed 2.7 μm emissions. Results demonstrate that the prepared germanate glass possessing excellent spectroscopic properties might be an attractive candidate for mid-infrared laser or amplifier

  17. Transition probabilities of Ce I obtained from Boltzmann analysis of visible and near-infrared emission spectra

    Science.gov (United States)

    Nitz, D. E.; Curry, J. J.; Buuck, M.; DeMann, A.; Mitchell, N.; Shull, W.

    2018-02-01

    We report radiative transition probabilities for 5029 emission lines of neutral cerium within the wavelength range 417-1110 nm. Transition probabilities for only 4% of these lines have been previously measured. These results are obtained from a Boltzmann analysis of two high resolution Fourier transform emission spectra used in previous studies of cerium, obtained from the digital archives of the National Solar Observatory at Kitt Peak. The set of transition probabilities used for the Boltzmann analysis are those published by Lawler et al (2010 J. Phys. B: At. Mol. Opt. Phys. 43 085701). Comparisons of branching ratios and transition probabilities for lines common to the two spectra provide important self-consistency checks and test for the presence of self-absorption effects. Estimated 1σ uncertainties for our transition probability results range from 10% to 18%.

  18. A new tridentate Schiff base Cu(II) complex: synthesis, experimental and theoretical studies on its crystal structure, FT-IR and UV-Visible spectra.

    Science.gov (United States)

    Saheb, Vahid; Sheikhshoaie, Iran; Setoodeh, Nasim; Rudbari, Hadi Amiri; Bruno, Giuseppe

    2013-06-01

    A new Cu(II) complex [Cu(L)(NCS)] has been synthesized, using 1-(N-salicylideneimino)-2-(N,N-methyl)-aminoethane as tridentate ONN donor Schiff base ligand (HL). The dark green crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FT-IR) and UV-Visible spectra. Electronic structure calculations at the B3LYP and MP2 levels of theory are performed to optimize the molecular geometry and to calculate the UV-Visible and FT-IR spectra of the compound. Vibrational assignments and analysis of the fundamental modes of the compound are performed. Time-dependent density functional theory (TD-DFT) method is used to calculate the electronic transitions of the complex. A scaling factor of 1.015 is obtained for vibrational frequencies computed at the B3LYP level using basis sets 6-311G(d,p). It is found that solvent has a profound effect on the electronic absorption spectrum. The UV-Visible spectrum of the complex recorded in DMSO and DMF solution can be correctly predicted by a model in which DMSO and DMF molecules are coordinated to the central Cu atom via their oxygen atoms. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Terrestrial analogs for interpretation of infrared spectra from the Martian surface and subsurface: Sulfate, nitrate, carbonate, and phyllosilicate-bearing Atacama Desert soils

    Science.gov (United States)

    Sutter, B.; Dalton, J. B.; Ewing, S. A.; Amundson, R.; McKay, C. P.

    2007-10-01

    Hyperarid (Mars soils have similar sulfate concentrations; possess phyllosilicates (e.g., smectite) and minor carbonate. Nitrate has not been detected on Mars, but its presence has been proposed. The similar compositions of Atacama and Mars soils have prompted the visible-infrared (0.35-25 μm) investigation of Atacama soils as Mars analogs. Results from this work determined the best infrared features for detecting sulfate, nitrate, carbonate, and phyllosilicate on Mars. The fundamental region (>6.5 μm) was not suited for salt and phyllosilicate detection because of overlapping spectra from primary silicates (e.g., feldspar), water and carbon dioxide. The visible near-infrared (0.35-2.5 μm) region was suited for detecting carbonate, nitrate, gypsum water of hydration, and phyllosilicate hydroxyls without interference from primary silicates. However, gypsum water of hydration features can obscure phyllosilicate hydroxyl, carbonate and nitrate, features if gypsum levels are high. Overtone/combination absorption features in the midinfrared were determined to be the best indicators of sulfate (4.48-4.70 μm), nitrate (4.12 μm), and carbonate (3.98 μm) because interferences from overlapping primary silicate and water features are not present in this region. Interferences from CO2 and thermal emission effects in the overtone/combination region are possible but may be minimized by corrective techniques. Infrared analysis of Atacama Desert soils can provide insight into the spectral search of sulfate, nitrate, carbonate, and phyllosilicate containing soils on Mars.

  20. Crystal and molecular structure of N-(4-nitrophenyl)-β-alanine—Its vibrational spectra and theoretical calculations

    Science.gov (United States)

    Marchewka, M. K.; Drozd, M.; Janczak, J.

    2011-08-01

    The N-(4-nitrophenyl)-β-alanine in crystalline form directly by the addition of 4-nitroaniline to the acrylic acid in aqueous solution has been obtained. The title β-alanine derivative crystallizes in the P2 1/ c space group of monoclinic system with four molecules per unit cell. The X-ray geometry of β-alanine derivative molecule has been compared with those obtained by molecular orbital calculations corresponding to the gas phase. In the crystal the molecules related by an inversion center interact via symmetrically equivalent O-H⋯O hydrogen bonds with O⋯O distance of 2.656(2) Å forming a dimeric structure. The dimers of β-alanine derivative weakly interact via N-H⋯O hydrogen bonds between the H atom of β-amine groups and one of O atom of nitro groups. The room temperature powder vibrational (infrared and Raman) measurements are in accordance with the X-ray analysis. In aqueous solution of 4-nitroaniline and acrylic acid, the double C dbnd C bond of vinyl group of acrylic acid breaks as result of 4-nitroaniline addition.

  1. Detection of Melamine in Soybean Meal Using Near-Infrared Microscopy Imaging with Pure Component Spectra as the Evaluation Criteria

    Directory of Open Access Journals (Sweden)

    Zengling Yang

    2016-01-01

    Full Text Available Soybean meal was adulterated with melamine with the purpose of boosting the protein content for unlawful interests. In recent years, the near-infrared (NIR spectroscopy technique has been widely used for guaranteeing food and feed security for its fast, nondestructive, and pollution-free characteristics. However, there are problems with using near-infrared (NIR spectroscopy for detecting samples with low contaminant concentration because of instrument noise and sampling issues. In addition, methods based on NIR are indirect and depend on calibration models. NIR microscopy imaging offers the opportunity to investigate the chemical species present in food and feed at the microscale level (the minimum spot size is a few micrometers, thus avoiding the problem of the spectral features of contaminants being diluted by scanning. The aim of this work was to investigate the feasibility of using NIR microscopy imaging to identify melamine particles in soybean meal using only the pure component spectrum. The results presented indicate that using the classical least squares (CLS algorithm with the nonnegative least squares (NNLS algorithm, without needing first to develop a calibration model, could identify soybean meal that is both uncontaminated and contaminated with melamine particles at as low a level as 50 mg kg−1.

  2. Tunneling Splittings in Vibronic Structure of CH_3F^+ ( X^2E): Studied by High Resolution Photoelectron Spectra and AB Initio Theoretical Method

    Science.gov (United States)

    Mo, Yuxiang; Gao, Shuming; Dai, Zuyang; Li, Hua

    2013-06-01

    We report a combined experimental and theoretical study on the vibronic structure of CH_3F^+. The results show that the tunneling splittings of vibrational energy levels occur in CH_3F^+ due to the Jahn-Teller effect. Experimentally, we have measured a high resolution ZEKE spectrum of CH_3F up to 3500 cm^-^1 above the ground state. Theoretically, we performed an ab initio calculation based on the diabatic model. The adiabatic potential energy surfaces (APES) of CH_3F^+ have been calculated at the MRCI/CAS/avq(t)z level and expressed by Taylor expansions with normal coordinates as variables. The energy gradients for the lower and upper APES, the derivative couplings between them and also the energies of the APES have been used to determine the coefficients in the Taylor expansion. The spin-vibronic energy levels have been calculated by accounting all six vibrational modes and their couplings. The experimental ZEKE spectra were assigned based on the theoretical calculations. W. Domcke, D. R. Yarkony, and H. Köpple (Eds.), Conical Intersections: Eletronic Structure, Dynamics and Spectroscopy (World Scientific, Singapore, 2004). M. S. Schuurman, D. E. Weinberg, and D. R. Yarkony, J. Chem. Phys. 127, 104309 (2007).

  3. The production and gas phase infrared spectra of phosphorous halides, O=P-X where X=F, CI and Br

    International Nuclear Information System (INIS)

    Allaf, A.W.

    1997-05-01

    A new route has been devised, leading to the production of Pox 3 molecules where X=F, Br and I by an on-line process using phosphoryl chloride, POCL 3 as a starting material passed over heated sodium fluoride, NaF, potassium bromide, KBr and potassium iodide, K1 at 535 Centigrade, 690 Centigrade and 480 Centigrade, respectively. The low resolution gas-phase fourier transform infrared spectra reported for the first time showed strong bands centered at 1411.6, 1322.9, 1300.8 and 1285 cm - 1, assigned to υ 1 (a 1 ), the O = P stretching fundamental of POF 3 , POCL 3 , POBR 3 and POI 3 , respectively. Attempts were made to prepare POCL 2 and POBr 2 , by an on-line process using POCL 3 again but passed over heated sodium and potassium bromide for POCL 2 and POBr 2 . (author). 16 refs., 6 figs., 2 tab

  4. Matrix photoionization and radiolysis of the fluorobromomethanes. Infrared spectra and photochemistry of CFBr2+, CF2Br+, CF3+, and the parent cations

    International Nuclear Information System (INIS)

    Prochaska, F.T.; Andrews, L.

    1978-01-01

    The molecules CFBr 3 , CF 2 Br 2 , CF 3 Br, and C-13 enriched CF 3 Br have been subjected to matrix radiolysis and argon resonance photoionization during condensation with excess argon at 15 K. Infrared spectra showed stable and free radical products and new absorptions due to charged species. The molecular ion bands exhibited different behavior on filtered high-pressure mercury arc photolysis. Absorptions reduced by 220 to 1000-nm light are assigned to CFBr 2 + , CF 2 Br + , and CF 3 + ; other bands destroyed by photolysis are assigned to the parent cations. Li and Na atom reactions with the fluorobromomethane molecules confirmed the identification of the CFBr 2 and CF 2 Br free radicals. Other product bands destroyed by mercury arc light, some of which were generated upon photolysis of the sodium-fluorobromomethane samples, are assigned to molecular anions. 5 figures, 6 tables

  5. Reactions of laser-ablated Co, Rh, and Ir with CO: Infrared spectra and density functional calculations of the metal carbonyl molecules, cations and anions in solid neon

    International Nuclear Information System (INIS)

    Zhou, M.; Andrews, L.

    1999-01-01

    Laser ablation produces metal atoms, cations, and electrons for reaction with CO during condensation in excess neon at 4 K. Infrared spectra are observed for the metal carbonyls, cations, and anions, which are identified from isotopic shifts ( 13 CO, C 18 O) and splittings using mixed isotopic precursors. Density functional calculations with pseudopotentials for Rh and Ir predict the observed carbonyl stretching frequencies within 1--2%. This characterization of the simple RhCO + , RhCO, and RhCO - (and Ir) species over a 350 cm -1 range provides a scale for comparison of larger catalytically active Rh and Ir carbonyl complexes in solution and on surfaces to estimate charge on the metal center. This work provides the first spectroscopic characterization of Rh and Ir carbonyl cations and anions except for the stable tetracarbonyl anions in solution

  6. Detection of organic compound signatures in infra-red, limb emission spectra observed by the MIPAS-B2 balloon instrument

    Directory of Open Access Journals (Sweden)

    J. J. Remedios

    2007-01-01

    Full Text Available Organic compounds play a central role in troposphere chemistry and increasingly are a viable target for remote sensing observations. In this paper, infra-red spectral features of three organic compounds are investigated in thermal emission spectra recorded on a flight on 8 May 1998 near Aire sur l'Adour by a balloon-borne instrument, MIPAS-B2, operating at high spectral resolution. It is demonstrated, for the first time, that PAN and acetone can be detected in infra-red remote sensing spectra of the upper troposphere; detection results are presented at tangent altitudes of 10.4 km and 7.5 km (not acetone. In addition, the results provide the first observation of spectral features of formic acid in thermal emission, as opposed to solar occultation, and confirm that concentrations of this gas are measurable in the mid-latitude upper troposphere, given accurate spectroscopic data. For PAN, two bands are observed centred at 794 cm−1 and 1163 cm−1. For acetone and formic acid, one band has been detected for each so far with band centres at 1218 cm−1 and 1105 cm−1 respectively. Mixing ratios inferred at 10.4 km tangent altitude are 180 pptv and 530 pptv for PAN and acetone respectively, and 200 pptv for formic acid with HITRAN 2000 spectroscopy. Accuracies are on the order of 15 to 40%. The detection technique applied here is verified by examining weak but known signatures of CFC-12 and HCFC-22 in the same spectral regions as those of the organic compounds, with results confirming the quality of both the instrument and the radiative transfer model. The results suggest the possibility of global sensing of the organic compounds studied here which would be a major step forward in verifying and interpreting global tropospheric model calculations.

  7. High resolution infrared and Raman spectra of 13C12CD2: The CD stretching fundamentals and associated combination and hot bands

    International Nuclear Information System (INIS)

    Di Lonardo, G.; Fusina, L.; Canè, E.; Tamassia, F.; Martínez, R. Z.; Bermejo, D.

    2015-01-01

    Infrared and Raman spectra of mono 13 C fully deuterated acetylene, 13 C 12 CD 2 , have been recorded and analysed to obtain detailed information on the C—D stretching fundamentals and associated combination, overtone, and hot bands. Infrared spectra were recorded at an instrumental resolution ranging between 0.006 and 0.01 cm −1 in the region 1800–7800 cm −1 . Sixty new bands involving the ν 1 and ν 3 C—D stretching modes also associated with the ν 4 and ν 5 bending vibrations have been observed and analysed. In total, 5881 transitions have been assigned in the investigated spectral region. In addition, the Q branch of the ν 1 fundamental was recorded using inverse Raman spectroscopy, with an instrumental resolution of about 0.003 cm −1 . The transitions relative to each stretching mode, i.e., the fundamental band, its first overtone, and associated hot and combination bands involving bending states with υ 4 + υ 5 up to 2 were fitted simultaneously. The usual Hamiltonian appropriate to a linear molecule, including vibration and rotation l-type and the Darling–Dennison interaction between υ 4 = 2 and υ 5 = 2 levels associated with the stretching states, was adopted for the analysis. The standard deviation for each global fit is ≤0.0004 cm −1 , of the same order of magnitude of the measurement precision. Slightly improved parameters for the bending and the ν 2 manifold have been also determined. Precise values of spectroscopic parameters deperturbed from the resonance interactions have been obtained. They provide quantitative information on the anharmonic character of the potential energy surface, which can be useful, in addition to those reported in the literature, for the determination of a general anharmonic force field for the molecule. Finally, the obtained values of the Darling–Dennison constants can be valuable for understanding energy flows between independent vibrations

  8. An experimental and theoretical investigation of the valence orbital momentum distributions and binding energy spectra of nitrogen

    International Nuclear Information System (INIS)

    Cook, J.P.D.; Pascual, R.; Weigold, E.

    1989-05-01

    A detailed electron momentum spectrosocpy (EMS) and a manybody theoretical study of the complete valence region of N 2 was carried out. The 1500eV EMS momentum distributions show that they provide a sensitive test for orbital wavefunctions of SCF calculations, and of correlation effects. The outermost 3σ g orbital is more sharply peaked at the origin than predicted by the orbital wavefunction. The inner valence 2σ g orbital is severely split, with spectroscopic strength ranging from 34eV to over 60eV in binding energy. The results of the present extended basis 1p Green's function calculations, as well as those of several previous manybody calculations, are only in semiquantitative agreement with this. There is a 2σ u pole at 25eV with a pole strength of approximately 0.067 in agreement with the results of manybody calculations. There is significant 2σ u and or 1π u strength and little 2σ g strength in the region 26-34eV. Poles observed at 29 and 32eV, previously attributed to the 2σ g orbital, are shown to be largely 2σ u in character. The manybody calculations predict too much 2σ g strength in the region 26-34eV. 29 refs., 1 tab., 16 figs

  9. Energetics of the rearrangement of neutral and ionized perfluorocyclopropane to perfluoropropylene. Use of infrared multiphoton dissociation spectra to identify structural isomers of molecular ions

    International Nuclear Information System (INIS)

    Bomse, D.S.; Berman, D.W.; Beauchamp, J.L.

    1981-01-01

    Infrared photodissociation spectroscopy is used to compare the structure of gas-phase C 3 F 6 + ions obtained by electron-impact ionization of two isomeric precursors: perfluoropropylene and perfluorocyclopropane. Photodissociation spectra are obtained by observing the extent of multiphoton dissociation as the CO 2 laser is tuned across the 925 to 1080 cm -1 wavelength range. Ions are formed, stored, and detected with the use of techniques of ion cyclotron resonance spectroscopy. Infrared multiphoton excitation is effected by using low-power, continuous-wave laser radiation. The fingerprint spectrum of the molecular ion of perfluorocyclopropane is identical with that obtained from perfluoropropylene, indicating rearrangement of the former to the latter. Photodissociation kinetics indicate that the entire perfluorocyclopropane molecular ion population isomerizes to the more stable perfluoropropylene structure. Thermochemistry of C 3 F 6 and C 3 F 6 + isomers is discussed. Comparisons are made with the analogous C 3 H 6 system. Photoionization mass spectroscopy results yield ΔH/sub f/(c-C 3 F 6 ) = -233.8 kcal/mol. 4 figures

  10. Adding a dimension to the infrared spectra of interfaces using heterodyne detected 2D sum-frequency generation (HD 2D SFG) spectroscopy.

    Science.gov (United States)

    Xiong, Wei; Laaser, Jennifer E; Mehlenbacher, Randy D; Zanni, Martin T

    2011-12-27

    In the last ten years, two-dimensional infrared spectroscopy has become an important technique for studying molecular structures and dynamics. We report the implementation of heterodyne detected two-dimensional sum-frequency generation (HD 2D SFG) spectroscopy, which is the analog of 2D infrared (2D IR) spectroscopy, but is selective to noncentrosymmetric systems such as interfaces. We implement the technique using mid-IR pulse shaping, which enables rapid scanning, phase cycling, and automatic phasing. Absorptive spectra are obtained, that have the highest frequency resolution possible, from which we extract the rephasing and nonrephasing signals that are sometimes preferred. Using this technique, we measure the vibrational mode of CO adsorbed on a polycrystalline Pt surface. The 2D spectrum reveals a significant inhomogenous contribution to the spectral line shape, which is quantified by simulations. This observation indicates that the surface conformation and environment of CO molecules is more complicated than the simple "atop" configuration assumed in previous work. Our method can be straightforwardly incorporated into many existing SFG spectrometers. The technique enables one to quantify inhomogeneity, vibrational couplings, spectral diffusion, chemical exchange, and many other properties analogous to 2D IR spectroscopy, but specifically for interfaces.

  11. Upper limits for stratospheric H2O2 and HOCl from high resolution balloon-borne infrared solar absorption spectra

    Science.gov (United States)

    Larsen, J. C.; Rinsland, C. P.; Goldman, A.; Murcray, D. G.; Murcray, F. J.

    1985-01-01

    Solar absorption spectra from two stratospheric balloon flights have been analyzed for the presence of H2O2 and HOCl absorption in the 1230.0 to 1255.0 per cm region. The data were recorded at 0.02 per cm resolution during sunset with the University of Denver interferometer system on October 27, 1978 and March 23, 1981. Selected spectral regions were analyzed with the technique of nonlinear least squares spectral curve fitting. Upper limits of 0.33 ppbv for H2O2 and 0.36 ppbv for HOCl near 28 km are derived from the 1978 flight data while upper limits of 0.44 ppbv for H2O2 and 0.43 ppbv for HOCl at 29.5 km are obtained from the 1981 flight data.

  12. [The influence of pulsed low-intensity laser radiation of the red (635 nm) and infrared (904 nm) spectra on the human mesenchymal stem cells in vitro].

    Science.gov (United States)

    Moskvin, S V; Kliuchnikov, D Iu; Antipov, E V; Volchkov, S E; Kiseleva, O N

    2014-01-01

    Mesenchymal stem cells (MSC) have for a long time been an object of investigation with a view to elucidating the prospects for their application in clinical medicine and cosmetology. One of the approaches to the non-specific regulation of the activity of these cells at the stage of preliminary in vitro combination is the treatment with low-intensity laser radiation (LILR). The objective of the present study was to evaluate the possibility of using pulsed LILR of the infrared and red spectra for this purpose. We used the 4th passage adhesive MSC cultures based at the umbilical tissue of a donor who gave the informed consent to participate in the study. The source of illumination was a Lazmik-VLOK laser therapeutic apparatus (RU No RZN 2014/1410 dated 06.02.2014) with the matrix laser infrared radiation heads (wavelength 904 nm, light pulse length 108 ns, frequency 1500 Hz). The apparatus was operated either in the multi-frequency Lazmik regime [Moskvin S.V., 2014] with mean power density 0.05 and 0.14 mW/cm2 and the red spectrum (wavelength 635 nm, light pulse length 144 ns, frequency 1500 Hz) or in the multi-frequency Lazmik regime [Moskvin S.V., 2014] with mean power density 0.03 and 0.12. The exposition was 5 min in both regimes. The study has demonstrated that neither the morphological structure nor the viability of mesenchymal stem cells changed under the influence of energy and time parameters used in experiments. The number of cells was shown to slightly increase in comparison with control. The most pronounced effect was documented after illumination with pulse infrared (904 nm) LILR in the multi-frequency Lazmik regime. The maximum effect was observed during a period between days 1 and 3 of cultivation.

  13. Acquisition of reproducible transmission near-infrared (NIR) spectra of solid samples with inconsistent shapes by irradiation with isotropically diffused radiation using polytetrafluoroethylene (PTFE) beads.

    Science.gov (United States)

    Lee, Jinah; Duy, Pham Khac; Yoon, Jihye; Chung, Hoeil

    2014-06-21

    A bead-incorporated transmission scheme (BITS) has been demonstrated for collecting reproducible transmission near-infrared (NIR) spectra of samples with inconsistent shapes. Isotropically diffused NIR radiation was applied around a sample and the surrounding radiation was allowed to interact homogeneously with the sample for transmission measurement. Samples were packed in 1.40 mm polytetrafluoroethylene (PTFE) beads, ideal diffusers without NIR absorption, and then transmission spectra were collected by illuminating the sample-containing beads using NIR radiation. When collimated radiation was directly applied, a small portion of the non-fully diffused radiation (NFDR) propagated through the void space of the packing and eventually degraded the reproducibility. Pre-diffused radiation was introduced by placing an additional PTFE disk in front of the packing to diminish NFDR, which produced more reproducible spectral features. The proposed scheme was evaluated by analyzing two different solid samples: density determination for individual polyethylene (PE) pellets and identification of mining locality for tourmalines. Because spectral collection was reproducible, the use of the spectrum acquired from one PE pellet was sufficient to accurately determine the density of nine other pellets with different shapes. The differentiation of tourmalines, which are even more dissimilar in appearance, according to their mining locality was also feasible with the help of the scheme.

  14. Diffuse Reflectance Spectroscopy of Hidden Objects, Part I: Interpretation of the Reflection-Absorption-Scattering Fractions in Near-Infrared (NIR) Spectra of Polyethylene Films.

    Science.gov (United States)

    Pomerantsev, Alexey L; Rodionova, Oxana Ye; Skvortsov, Alexej N

    2017-08-01

    Investigation of a sample covered by an interfering layer is required in many fields, e.g., for process control, biochemical analysis, and many other applications. This study is based on the analysis of spectra collected by near-infrared (NIR) diffuse reflectance spectroscopy. Each spectrum is a composition of a useful, target spectrum and a spectrum of an interfering layer. To recover the target spectrum, we suggest using a new phenomenological approach, which employs the multivariate curve resolution (MCR) method. In general terms, the problem is very complex. We start with a specific problem of analyzing a system, which consists of several layers of polyethylene (PE) film and underlayer samples with known spectral properties. To separate information originating from PE layers and the target, we modify the system versus both the number of the PE layers as well as the reflectance properties of the target sample. We consider that the interfering spectrum of the layer can be modeled using three components, which can be tentatively called transmission, absorption, and scattering contributions. The novelty of our approach is that we do not remove the reflectance and scattering effects from the spectra, but study them in detail aiming to use this information to recover the target spectrum.

  15. Theoretical modeling of deuteration-induced shifts of the 0-0 bands in absorption spectra of selected aromatic amines: the role of the double-well potential.

    Science.gov (United States)

    Andrzejak, Marcin; Kolek, Przemysław

    2013-12-05

    The harmonic approximation fails for inversion of the NH2 group in the ground state of aromatic amines as this vibration is characterized by a symmetric double-well potential with relatively small energy barrier. In such cases, the standard harmonic vibrational analysis is inapplicable: the inversion frequency calculated for the bottom of the potential well is strongly overestimated, while it attains imaginary values for the planar conformation of the molecule. The model calculations are discussed taking explicitly into account the presence of the double-well potential. The study is initially focused on reproduction of the deuteration-induced shifts of the 0-0 absorption band for anthranilic acid. The (incorrect) harmonic frequency of the NH2 inversion is replaced by a better one, obtained from numerical calculations employing a simple, quartic-quadratic model for the double-well potential, which is parametrized using just the harmonic frequency of the inversion and the height of the energy barrier. This operation brings theoretical results to qualitative agreement with experiment. A still better match is achieved with a modified version of the model that accounts for mixing of the NH2 inversion mode with other normal modes while retaining the initial simplicity of one-dimensional approach. The corrected results show surprisingly good accuracy, with deviations of the calculated shifts from the experimental values reduced to less than 5 cm(-1). In order to test the performance of the model for systems with higher energy barrier for the NH2 inversion, we have measured the LIF excitation spectra of three different amminobenzonitriles. Partial assignment of the 0-0 bands has been achieved based on their relative intensities for samples with different isotopic exchange ratios. Calculated shifts are in excellent agreement with experimental values for the identified bands. Theoretical predictions are used to complete the assignment of the 0-0 bands in the spectra of the

  16. Using visible and near-infrared diffuse reflectance spectroscopy for predicting soil properties based on regression with peaks parameters as derived from continuum-removed spectra

    Science.gov (United States)

    Vasat, Radim; Klement, Ales; Jaksik, Ondrej; Kodesova, Radka; Drabek, Ondrej; Boruvka, Lubos

    2014-05-01

    Visible and near-infrared diffuse reflectance spectroscopy (VNIR-DRS) provides a rapid and inexpensive tool for simultaneous prediction of a variety of soil properties. Usually, some sophisticated multivariate mathematical or statistical methods are employed in order to extract the required information from the raw spectra measurement. For this purpose especially the Partial least squares regression (PLSR) and Support vector machines (SVM) are the most frequently used. These methods generally benefit from the complexity with which the soil spectra are treated. But it is interesting that also techniques that focus only on a single spectral feature, such as a simple linear regression with selected continuum-removed spectra (CRS) characteristic (e.g. peak depth), can often provide competitive results. Therefore, we decided to enhance the potential of CRS taking into account all possible CRS peak parameters (area, width and depth) and develop a comprehensive methodology based on multiple linear regression approach. The eight considered soil properties were oxidizable carbon content (Cox), exchangeable (pHex) and active soil pH (pHa), particle and bulk density, CaCO3 content, crystalline and amorphous (Fed) and amorphous Fe (Feox) forms. In four cases (pHa, bulk density, Fed and Feox), of which two (Fed and Feox) were predicted reliably accurately (0.50 interestingly, in the case of particle density, the presented approach outperformed the PLSR and SVM dramatically offering a fairly accurate prediction (R2cv = 0.827) against two failures (R2cv = 0.034 and 0.121 for PLSR and SVM, resp.). In last two cases (Cox and CaCO3) a slightly worse results were achieved then with PLSR and SVM with overall fairly accurate prediction (R2cv > 0.80). Acknowledgment: Authors acknowledge the financial support of the Ministry of Agriculture of the Czech Republic (grant No. QJ1230319).

  17. Arrangement of Fibril Side Chains Studied by Molecular Dynamics and Simulated Infrared and Vibrational Circular Dichroism Spectra

    Czech Academy of Sciences Publication Activity Database

    Kessler, Jiří; Kiederling, T. A.; Bouř, Petr

    2014-01-01

    Roč. 118, č. 24 (2014), s. 6937-6945 ISSN 1520-6106 R&D Projects: GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033 Grant - others:MŠMT(CZ) LM2010005; AV ČR(CZ) M200550902; MŠMT(CZ) ED3.2.00/08.0144 Institutional support: RVO:61388963 Keywords : insulin amyloid superstructures * DFT * VCD * molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.302, year: 2014

  18. Theoretical Time Dependent Thermal Neutron Spectra and Reaction Rates in H{sub 2}O and D{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Purohit, S N

    1966-04-15

    The early theoretical and experimental time dependent neutron thermalization studies were limited to the study of the transient spectrum in the diffusion period. The recent experimental measurements of the time dependent thermal neutron spectra and reaction rates, for a number of moderators, have generated considerable interest in the study of the time dependent Boltzmann equation. In this paper we present detailed results for the time dependent spectra and the reaction rates for resonance detectors using several scattering models of H{sub 2}O and D{sub 2}O. This study has been undertaken in order to interpret the integral time dependent neutron thermalization experiments in liquid moderators which have been performed at the AB Atomenergi. The proton gas and the deuteron gas models are inadequate to explain the measured reaction rates in H{sub 2}O and D{sub 2}O. The bound models of Nelkin for H{sub 2}O and of Butler for D{sub 2}O give much better agreement with the experimental results than the gas models. Nevertheless, some disagreement between theoretical and experimental results still persists. This study also indicates that the bound model of Butler and the effective mass 3. 6 gas model of Brown and St. John give almost identical reaction rates. It is also surprising to note that the calculated reaction rate for Cd for the Butler model appears to be in better agreement with the experimental results of D{sub 2}O than of the Nelkin model with H{sub 2}O experiments. The present reaction rate studies are sensitive enough so as to distinguish between the gas model and the bound model of a moderator. However, to investigate the details of a scattering law (such as the effect of the hindered rotations in H{sub 2}O and D{sub 2}O and the weights of different dynamical modes) with the help of these studies would require further theoretical as well as experimental investigations. Theoretical results can be further improved by improving the source for thermal neutrons, the

  19. ON THE VIABILITY OF THE PAH MODEL AS AN EXPLANATION OF THE UNIDENTIFIED INFRARED EMISSION FEATURES

    International Nuclear Information System (INIS)

    Zhang, Yong; Kwok, Sun

    2015-01-01

    Polycyclic aromatic hydrocarbon (PAH) molecules are widely considered the preferred candidate for the carrier of the unidentified infrared emission bands observed in the interstellar medium and circumstellar envelopes. In this paper, we report the results of fitting a variety of non-PAH spectra (silicates, hydrogenated amorphous carbon, coal, and even artificial spectra) using the theoretical infrared spectra of PAHs from the NASA Ames PAH IR Spectroscopic Database. We show that these non-PAH spectra can be well fitted by PAH mixtures. This suggests that a general match between astronomical spectra and those of PAH mixtures does not necessarily provide definitive support for the PAH hypothesis

  20. Characterization of ionizing radiation effects on bone using Fourier Transform Infrared Spectroscopy and multivariate analysis of spectra

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Pedro Arthur Augusto de; Dias, Derly Augusto; Zezell, Denise Maria, E-mail: zezell@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2017-11-01

    Ionizing radiation has been used as an important treatment and diagnostic method for several diseases. Optical techniques provides an efficient clinical diagnostic to support an accurate evaluation of the interaction of radiation with molecules. Fourier-transform infrared spectroscopy coupled with attenuated total reflectance (ATR-FTIR) is a label-free and nondestructive optical technique that can recognize functional groups in biological samples. In this work, 30 fragments of bone were collected from bovine femur diaphysis. Samples were cut and polished until 1 cm x 1 cm x 1 mm, which were then stored properly in the refrigerated environment. Samples irradiation was performed with a Cobalt-60 Gammacell Irradiator source at doses of 0.1 kGy, 1 kGy, whereas the fragments exposed to dose of 15 kGy was irradiated in a multipurpose irradiator of Cobalt-60. Spectral data was submitted to principal component analysis followed by linear discriminant analysis. Multivariate analysis was performed with Principal component analysis(PCA) followed by Linear Discriminant Analysis(LDA) using MATLAB R2015a software (The Mathworks Inc., Natick, MA, USA). We demonstrated the feasibility of using ATR-FTIR spectroscopy associated with PCA-LDA multivariate technique to evaluate the molecular changes in bone matrix caused by different doses: 0.1 kGy, 1 kGy and 15 kGy. These alterations between the groups are mainly reported in phosphate region. Our results open up new possibilities for protein monitoring relating to dose responses. (author)

  1. Structural aspects of pressure effects on infrared spectra of mixed-chain phosphatidylcholine assemblies in D2O

    International Nuclear Information System (INIS)

    Wong, P.T.; Huang, C.H.

    1989-01-01

    The barotropic behavior of D 2 O dispersions of 1-stearoyl-2-caproyl-sn-glycero-3-phosphocholine, C(18):C(10)PC, a highly asymmetric phospholipid in which the length of the fully extended acyl chain at the sn-1 position of the glycerol backbone is twice as long as that at the sn-2 position, has been investigated by high-pressure Fourier transform infrared spectroscopy. This asymmetric phosphatidylcholine bilayer at room temperature displays a pressure-induced phase transition corresponding to the liquid-crystalline----gel phase transition at 1.4 kbar. A conformational ordering of the lipid acyl chains is observed to take place abruptly at the transition pressure of 1.4 kbar. However, the lamellar lipid molecules and their acyl chains remain to be orientationally disordered in the gel phase until the applied pressure reaches 5.5 kbar. In the gel phase of fully hydrated C(18):C(10)PC, the asymmetric lipid molecules assemble into mixed interdigitated bilayers with perpendicular orientation of the zigzag planes among neighboring acyl chains. The role of excess water played in the interchain structure and the behavior of excess water and bound water under high pressure are also discussed

  2. Characterization of ionizing radiation effects on bone using Fourier Transform Infrared Spectroscopy and multivariate analysis of spectra

    International Nuclear Information System (INIS)

    Castro, Pedro Arthur Augusto de; Dias, Derly Augusto; Zezell, Denise Maria

    2017-01-01

    Ionizing radiation has been used as an important treatment and diagnostic method for several diseases. Optical techniques provides an efficient clinical diagnostic to support an accurate evaluation of the interaction of radiation with molecules. Fourier-transform infrared spectroscopy coupled with attenuated total reflectance (ATR-FTIR) is a label-free and nondestructive optical technique that can recognize functional groups in biological samples. In this work, 30 fragments of bone were collected from bovine femur diaphysis. Samples were cut and polished until 1 cm x 1 cm x 1 mm, which were then stored properly in the refrigerated environment. Samples irradiation was performed with a Cobalt-60 Gammacell Irradiator source at doses of 0.1 kGy, 1 kGy, whereas the fragments exposed to dose of 15 kGy was irradiated in a multipurpose irradiator of Cobalt-60. Spectral data was submitted to principal component analysis followed by linear discriminant analysis. Multivariate analysis was performed with Principal component analysis(PCA) followed by Linear Discriminant Analysis(LDA) using MATLAB R2015a software (The Mathworks Inc., Natick, MA, USA). We demonstrated the feasibility of using ATR-FTIR spectroscopy associated with PCA-LDA multivariate technique to evaluate the molecular changes in bone matrix caused by different doses: 0.1 kGy, 1 kGy and 15 kGy. These alterations between the groups are mainly reported in phosphate region. Our results open up new possibilities for protein monitoring relating to dose responses. (author)

  3. An attempt at predicting blood β-hydroxybutyrate from Fourier-transform mid-infrared spectra of milk using multivariate mixed models in Polish dairy cattle.

    Science.gov (United States)

    Belay, T K; Dagnachew, B S; Kowalski, Z M; Ådnøy, T

    2017-08-01

    Fourier transform mid-infrared (FT-MIR) spectra of milk are commonly used for phenotyping of traits of interest through links developed between the traits and milk FT-MIR spectra. Predicted traits are then used in genetic analysis for ultimate phenotypic prediction using a single-trait mixed model that account for cows' circumstances at a given test day. Here, this approach is referred to as indirect prediction (IP). Alternatively, FT-MIR spectral variable can be kept multivariate in the form of factor scores in REML and BLUP analyses. These BLUP predictions, including phenotype (predicted factor scores), were converted to single-trait through calibration outputs; this method is referred to as direct prediction (DP). The main aim of this study was to verify whether mixed modeling of milk spectra in the form of factors scores (DP) gives better prediction of blood β-hydroxybutyrate (BHB) than the univariate approach (IP). Models to predict blood BHB from milk spectra were also developed. Two data sets that contained milk FT-MIR spectra and other information on Polish dairy cattle were used in this study. Data set 1 (n = 826) also contained BHB measured in blood samples, whereas data set 2 (n = 158,028) did not contain measured blood values. Part of data set 1 was used to calibrate a prediction model (n = 496) and the remaining part of data set 1 (n = 330) was used to validate the calibration models, as well as to evaluate the DP and IP approaches. Dimensions of FT-MIR spectra in data set 2 were reduced either into 5 or 10 factor scores (DP) or into a single trait (IP) with calibration outputs. The REML estimates for these factor scores were found using WOMBAT. The BLUP values and predicted BHB for observations in the validation set were computed using the REML estimates. Blood BHB predicted from milk FT-MIR spectra by both approaches were regressed on reference blood BHB that had not been used in the model development. Coefficients of determination in cross

  4. The optimum measurement precision evaluation for blood components using near-infrared spectra on 1000-2500 nm

    Science.gov (United States)

    Zhang, Ziyang; Sun, Di; Han, Tongshuai; Guo, Chao; Liu, Jin

    2016-10-01

    In the non-invasive blood components measurement using near infrared spectroscopy, the useful signals caused by the concentration variation in the interested components, such as glucose, hemoglobin, albumin etc., are relative weak. Then the signals may be greatly disturbed by a lot of noises in various ways. We improved the signals by using the optimum path-length for the used wavelength to get a maximum variation of transmitted light intensity when the concentration of a component varies. And after the path-length optimization for every wavelength in 1000-2500 nm, we present the detection limits for the components, including glucose, hemoglobin and albumin, when measuring them in a tissue phantom. The evaluated detection limits could be the best reachable precision level since it assumed the measurement uses a high signal-to-noise ratio (SNR) signal and the optimum path-length. From the results, available wavelengths in 1000-2500 nm for the three component measurements can be screened by comparing their detection limit values with their measurement limit requirements. For other blood components measurement, the evaluation their detection limits could also be designed using the method proposed in this paper. Moreover, we use an equation to estimate the absorbance at the optimum path-length for every wavelength in 1000-2500 nm caused by the three components. It could be an easy way to realize the evaluation because adjusting the sample cell's size to the precise path-length value for every wavelength is not necessary. This equation could also be referred to other blood components measurement using the optimum path-length for every used wavelength.

  5. Discovery of the Linear Region of Near Infrared Diffuse Reflectance Spectra Using the Kubelka-Munk Theory

    Directory of Open Access Journals (Sweden)

    Shengyun Dai

    2018-05-01

    Full Text Available Particle size is of great importance for the quantitative model of the NIR diffuse reflectance. In this paper, the effect of sample particle size on the measurement of harpagoside in Radix Scrophulariae powder by near infrared diffuse (NIR reflectance spectroscopy was explored. High-performance liquid chromatography (HPLC was employed as a reference method to construct the quantitative particle size model. Several spectral preprocessing methods were compared, and particle size models obtained by different preprocessing methods for establishing the partial least-squares (PLS models of harpagoside. Data showed that the particle size distribution of 125–150 μm for Radix Scrophulariae exhibited the best prediction ability with Rpre2 = 0.9513, RMSEP = 0.1029 mg·g−1, and RPD = 4.78. For the hybrid granularity calibration model, the particle size distribution of 90–180 μm exhibited the best prediction ability with Rpre2 = 0.8919, RMSEP = 0.1632 mg·g−1, and RPD = 3.09. Furthermore, the Kubelka-Munk theory was used to relate the absorption coefficient k (concentration-dependent and scatter coefficient s (particle size-dependent. The scatter coefficient s was calculated based on the Kubelka-Munk theory to study the changes of s after being mathematically preprocessed. A linear relationship was observed between k/s and absorption A within a certain range and the value for k/s was >4. According to this relationship, the model was more accurately constructed with the particle size distribution of 90–180 μm when s was kept constant or in a small linear region. This region provided a good reference for the linear modeling of diffuse reflectance spectroscopy. To establish a diffuse reflectance NIR model, further accurate assessment should be obtained in advance for a precise linear model.

  6. INFRARED SPECTRA AND PHOTOMETRY OF COMPLETE SAMPLES OF PALOMAR-GREEN AND TWO MICRON ALL SKY SURVEY QUASARS

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yong [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Rieke, G. H.; Su, K. Y. L. [Department of Astronomy And Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Ogle, P. M. [Infrared Processing and Analysis Center, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Balog, Z., E-mail: yshipku@gmail.com [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)

    2014-10-01

    As a step toward a comprehensive overview of the infrared (IR) diagnostics of the central engines and host galaxies of quasars at low redshift, we present Spitzer Space Telescope spectroscopic (5-40 μm) and photometric (24, 70, and 160 μm) measurements of all Palomar-Green (PG) quasars at z < 0.5 and Two Micron All Sky Survey (2MASS) quasars at z < 0.3. We supplement these data with Herschel measurements at 160 μm. The sample is composed of 87 optically selected PG quasars and 52 near-IR-selected 2MASS quasars. Here we present the data, measure the prominent spectral features, and separate emission due to star formation from that emitted by the dusty circumnuclear torus. We find that the mid-IR (5-30 μm) spectral shape for the torus is largely independent of quasar IR luminosity with scatter in the spectral energy distribution (SED) shape of ≲0.2 dex. Except for the silicate features, no large difference is observed between PG (unobscured—silicate emission) and 2MASS (obscured—silicate absorption) quasars. Only mild silicate features are observed in both cases. When in emission, the peak wavelength of the silicate feature tends to be longer than 9.7 μm, possibly indicating effects on grain properties near the active galactic nucleus. The IR color is shown to correlate with the equivalent width of the aromatic features, indicating that the slope of the quasar mid- to far-IR SED is to first order driven by the fraction of radiation from star formation in the IR bands.

  7. A Climatology of Tropospheric CO over the Central and Southeastern United States and the Southwestern Pacific Ocean Derived from Space, Air, and Ground-based Infrared Interferometer Spectra

    Science.gov (United States)

    McMillian, W. Wallace; Strow, L. Larrabee; Revercomb, H.; Knuteson, R.; Thompson, A.

    2003-01-01

    This final report summarizes all research activities and publications undertaken as part of NASA Atmospheric Chemistry and Modeling Analysis Program (ACMAP) Grant NAG-1-2022, 'A Climatology of Tropospheric CO over the Central and Southeastern United States and the Southwestern Pacific Ocean Derived from Space, Air, and Ground-based Infrared Interferometer Spectra'. Major project accomplishments include: (1) analysis of more than 300,000 AERI spectra from the ARM SGP site yielding a 5-year (1998-2002) timeseries of CO retrievals from the Lamont, OK AERI; (2) development of a prototype CO profile retrieval algorithm for AERI spectra; (3) validation and publication of the first CO retrievals from the Scanning High-resolution Interferometer Sounder (SHIS); and (4) development of a prototype AERI tropospheric O3 retrieval algorithm. Compilation and publication of the 5-year Lamont, OK timeseries is underway including a new collaboration with scientists at the Lawrence Berkeley National Laboratory. Public access to this data will be provided upon article submission. A comprehensive CO analysis of the archive of HIS spectra of remains as the only originally proposed activity with little progress. The greatest challenge faced in this project was motivating the University of Wisconsin Co-Investigators to deliver their archived HIS and AERIOO data along with the requisite temperature and water vapor profiles in a timely manner. Part of the supplied HIS dataset from ASHOE may be analyzed as part of a Master s Thesis under a separate project. Our success with the SAFARI 2000 SHIS CO analysis demonstrates the utility of such aircraft remote sensing data given the proper support from the instrument investigators. In addition to the PI and Co-I s, personnel involved in this CO climatology project include one Post Doctoral Fellow, one Research Scientist, two graduate students, and two undergraduate students. A total of fifteen presentations regarding research related to this

  8. Predicting ambient aerosol thermal-optical reflectance (TOR) measurements from infrared spectra: extending the predictions to different years and different sites

    Science.gov (United States)

    Reggente, Matteo; Dillner, Ann M.; Takahama, Satoshi

    2016-02-01

    Organic carbon (OC) and elemental carbon (EC) are major components of atmospheric particulate matter (PM), which has been associated with increased morbidity and mortality, climate change, and reduced visibility. Typically OC and EC concentrations are measured using thermal-optical methods such as thermal-optical reflectance (TOR) from samples collected on quartz filters. In this work, we estimate TOR OC and EC using Fourier transform infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE Teflon) filters using partial least square regression (PLSR) calibrated to TOR OC and EC measurements for a wide range of samples. The proposed method can be integrated with analysis of routinely collected PTFE filter samples that, in addition to OC and EC concentrations, can concurrently provide information regarding the functional group composition of the organic aerosol. We have used the FT-IR absorbance spectra and TOR OC and EC concentrations collected in the Interagency Monitoring of PROtected Visual Environments (IMPROVE) network (USA). We used 526 samples collected in 2011 at seven sites to calibrate the models, and more than 2000 samples collected in 2013 at 17 sites to test the models. Samples from six sites are present both in the calibration and test sets. The calibrations produce accurate predictions both for samples collected at the same six sites present in the calibration set (R2 = 0.97 and R2 = 0.95 for OC and EC respectively), and for samples from 9 of the 11 sites not included in the calibration set (R2 = 0.96 and R2 = 0.91 for OC and EC respectively). Samples collected at the other two sites require a different calibration model to achieve accurate predictions. We also propose a method to anticipate the prediction error; we calculate the squared Mahalanobis distance in the feature space (scores determined by PLSR) between new spectra and spectra in the calibration set. The squared Mahalanobis distance provides a crude method for assessing the

  9. Within tree variation of lignin, extractives, and microfibril angle coupled with the theoretical and near infrared modeling of microfibril angle

    Science.gov (United States)

    Brian K. Via; chi L. So; Leslie H. Groom; Todd F. Shupe; michael Stine; Jan. Wikaira

    2007-01-01

    A theoretical model was built predicting the relationship between microfibril angle and lignin content at the Angstrom (A) level. Both theoretical and statistical examination of experimental data supports a square root transformation of lignin to predict microfibril angle. The experimental material used came from 10 longleaf pine (Pinus palustris)...

  10. Genetic parameters of blood β-hydroxybutyrate predicted from milk infrared spectra and clinical ketosis, and their associations with milk production traits in Norwegian Red cows.

    Science.gov (United States)

    Belay, T K; Svendsen, M; Kowalski, Z M; Ådnøy, T

    2017-08-01

    The aim of this study was to estimate genetic parameters for blood β-hydroxybutyrate (BHB) predicted from milk spectra and for clinical ketosis (KET), and to examine genetic association of blood BHB with KET and milk production traits (milk, fat, protein, and lactose yields, and milk fat, protein, and lactose contents). Data on milk traits, KET, and milk spectra were obtained from the Norwegian Dairy Herd Recording System with legal permission from TINE SA (Ås, Norway), the Norwegian Dairy Association that manages the central database. Data recorded up to 120 d after calving were considered. Blood BHB was predicted from milk spectra using a calibration model developed based on milk spectra and blood BHB measured in Polish dairy cows. The predicted blood BHB was grouped based on days in milk into 4 groups and each group was considered as a trait. The milk components for test-day milk samples were obtained by Fourier transform mid-infrared spectrometer with previously developed calibration equations from Foss (Hillerød, Denmark). Veterinarian-recorded KET data within 15 d before calving to 120 d after calving were used. Data were analyzed using univariate or bivariate linear animal models. Heritability estimates for predicted blood BHB at different stages of lactation were moderate, ranging from 0.250 to 0.365. Heritability estimate for KET from univariate analysis was 0.078, and the corresponding average estimate from bivariate analysis with BHB or milk production traits was 0.002. Genetic correlations between BHB traits were higher for adjacent lactation intervals and decreased as intervals were further apart. Predicted blood BHB at first test day was moderately genetically correlated with KET (0.469) and milk traits (ranged from -0.367 with protein content to 0.277 with milk yield), except for milk fat content from across lactation stages that had near zero genetic correlation with BHB (0.033). These genetic correlations indicate that a lower BHB is genetically

  11. Application of the Polynomial-Based Least Squares and Total Least Squares Models for the Attenuated Total Reflection Fourier Transform Infrared Spectra of Binary Mixtures of Hydroxyl Compounds.

    Science.gov (United States)

    Shan, Peng; Peng, Silong; Zhao, Yuhui; Tang, Liang

    2016-03-01

    An analysis of binary mixtures of hydroxyl compound by Attenuated Total Reflection Fourier transform infrared spectroscopy (ATR FT-IR) and classical least squares (CLS) yield large model error due to the presence of unmodeled components such as H-bonded components. To accommodate these spectral variations, polynomial-based least squares (LSP) and polynomial-based total least squares (TLSP) are proposed to capture the nonlinear absorbance-concentration relationship. LSP is based on assuming that only absorbance noise exists; while TLSP takes both absorbance noise and concentration noise into consideration. In addition, based on different solving strategy, two optimization algorithms (limited-memory Broyden-Fletcher-Goldfarb-Shanno (LBFGS) algorithm and Levenberg-Marquardt (LM) algorithm) are combined with TLSP and then two different TLSP versions (termed as TLSP-LBFGS and TLSP-LM) are formed. The optimum order of each nonlinear model is determined by cross-validation. Comparison and analyses of the four models are made from two aspects: absorbance prediction and concentration prediction. The results for water-ethanol solution and ethanol-ethyl lactate solution show that LSP, TLSP-LBFGS, and TLSP-LM can, for both absorbance prediction and concentration prediction, obtain smaller root mean square error of prediction than CLS. Additionally, they can also greatly enhance the accuracy of estimated pure component spectra. However, from the view of concentration prediction, the Wilcoxon signed rank test shows that there is no statistically significant difference between each nonlinear model and CLS. © The Author(s) 2016.

  12. Infrared absorption spectra of gaseous HD. II. Collision-induced fundamental band of HD in HD--Ne and HD--Ar mixtures at room temperature

    International Nuclear Information System (INIS)

    Prasad, R.D.G.; Reddy, S.P.

    1976-01-01

    The collision-induced infrared absorption spectra of the fundamental band of HD in binary mixtures of HD with Ne and Ar at room temperature have been studied with an absorption path length of 105.2 cm for different base densities of HD in the range 8--20 amagat and a number of total gas densities up to 175 amagat. The observed features of the profiles of the enhancement of absorption in these mixtures resemble closely those of the corresponding profiles of the fundamental band of H 2 in binary mixtures with Ne and Ar. The binary absorption coefficients of the band obtained from the measured integrated intensities are (1.84 +- 0.06) x 10 -35 and (4.41 +- 0.06) x 10 -35 cm 6 s -1 for HD--Ne and HD--Ar, respectively. The characteristic half-width parameters, delta/subd/ and delta/subc/ of the overlap transitions and delta/subq/ (and delta/subq//sub prime/) of the quadrupolar transitions, are obtained from an analysis of the profiles of the enhancement of absorption in both these mixtures. The quantity delta/subc/ which is the half-width of the intercollisional interference dip of the Q branch increases with the density of the perturbing gas Ne or Ar, and for HD--Ne it varies in a manner similar to that for HD--He as described in Paper I of this series

  13. Effects of anisotropic interaction-induced properties of hydrogen-rare gas compounds on rototranslational Raman scattering spectra: Comprehensive theoretical and numerical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Głaz, Waldemar, E-mail: glaz@kielich.amu.edu.pl; Bancewicz, Tadeusz [Nonlinear Optics Division, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Godet, Jean-Luc [Laboratoire de Photonique d’Angers, Université d’Angers, 2 Boulevard Lavoisier, 49045 Angers (France); Gustafsson, Magnus [Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-97187 Luleå (Sweden); Haskopoulos, Anastasios; Maroulis, George [Department of Chemistry, University of Patras, GR-26500 Patras (Greece)

    2016-07-21

    A comprehensive study is presented of many aspects of the depolarized anisotropic collision induced (CI) component of light scattered by weakly bound compounds composed of a dihydrogen molecule and a rare gas (Rg) atom, H{sub 2}–Rg. The work continues a series of earlier projects marking the revival of interest in linear light scattering following the development of new highly advanced tools of quantum chemistry and other theoretical, computational, and experimental means of spectral analyses. Sophisticated ab initio computing procedures are applied in order to obtain the anisotropic polarizability component’s dependence on the H{sub 2}–Rg geometry. These data are then used to evaluate the CI spectral lines for all types of Rg atoms ranging from He to Xe (Rn excluded). Evolution of the properties of CI spectra with growing polarizability/masses of the complexes studied is observed. Special attention is given to the heaviest, Kr and Xe based, scatterers. The influence of specific factors shaping the spectral lines (e.g., bound and metastable contribution, potential anisotropy) is discussed. Also the share of pressure broadened allowed rotational transitions in the overall spectral profile is taken into account and the extent to which it is separable from the pure CI contribution is discussed. We finish with a brief comparison between the obtained results and available experimental data.

  14. The Infrared Spectra of Polycyclic Aromatic Hydrocarbons with Excess Peripheral H Atoms (H(sub n)-PAHs) and their Relation to the 3.4 and 6.9 Micrometer PAH Emission Features

    Science.gov (United States)

    Sandford, Scott A.; Bernstein, Max P.; Materese, Christopher K.

    2013-01-01

    A population of polycyclic aromatic hydrocarbons (PAHs) and related materials are thought to be responsible for the family of infrared emission features that are seen towards a wide variety of astrophysical environments. A potentially important subclass of these materials are polycyclic aromatic hydrocarbons whose edges contain excess H atoms (H(sub n)-PAHs). While it has been suggested that this type of compound may be present in the interstellar population, it has been difficult to properly assess this possibility because of a lack of suitable infrared laboratory spectra to assist with analysis of the astronomical data. We present the 4000-500 cm(exp -1) (2.5-20 micrometers) infrared spectra of 23 H(sub n)-PAHs and related molecules isolated in argon matrices, under conditions suitable for use in the interpretation of astronomical data. The spectra of molecules with mixed aromatic and aliphatic domains show unique characteristics that distinguish them from their fully aromatic PAH equivalents. We discuss the changes to the spectra of these types of molecules as they transition from fully aromatic to fully aliphatic forms. The implications for the interpretation of astronomical spectra are discussed with specific emphasis on the 3.4 and 6.9 micrometer features. Laboratory data is compared with emission spectra from IRAS 21282+5050, an object with normal PAH emission features, in addition to IRAS 22272+5435 and IRAS 0496+3429, two protoplanetary nebulae with abnormally large 3.4 micrometer features. We show that 'normal' PAH emission objects contain relatively few H(sub n)-PAHs in their emitter populations, but less evolved protoplanetary nebulae may contain significant abundances of these molecules.

  15. INFRARED SPECTRA, THERMOGRAVIMETRIC ANALYSIS AND ...

    African Journals Online (AJOL)

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    2Department of Pesticides Formulation, Central Agricultural Pesticides ... a number of other Fusarium species are able to degrade benzoxazolinone compounds to products which are less inhibitory to fungal growth and also important ...

  16. Molecular structure and infrared spectra of the monomeric 3-(methoxy)-1,2-benzisothiazole 1,1-dioxide (methyl pseudosaccharyl ether)

    Science.gov (United States)

    Kaczor, Agnieszka; Almeida, Rui; Gómez-Zavaglia, Andrea; Cristiano, Maria de Lurdes S.; Fausto, Rui

    2008-03-01

    The computational description of saccharin (1,2-benzisothiazol-3(2 H)-one-1,1-dioxide) and its derivatives is difficult due to the presence of hypervalent S dbnd O bonds in their structures. Therefore, in this investigation, the HF, DFT/B3LYP and MP2 methods were used to predict the geometry and the infrared spectrum of the saccharyl derivative 3-(methoxy)-1,2-benzisothiazole 1,1-dioxide (MBID). Their relative predictive capabilities were then evaluated by comparing the obtained results with experimentally available data, namely the newly obtained IR spectra of MBID isolated in low-temperature inert matrices. For each method, different basis sets [6-31++G(d,p), 6-31++G(3df,3pd), 6-311++G(d,p), 6-311++G(2df,2pd), 6-311++G(3df,3pd), aug-cc-pVDZ and aug-cc-pVTZ] were considered. The best overall agreement has been achieved at the B3LYP/6-311++G(3df,3pd) and B3LYP/6-31++G(3df,3pd) levels of theory, showing the adequacy of the B3LYP functional to describe the investigated properties in this type of compounds and stressing the relevance of including high-order polarization functions in the basis set. The chosen level of theory [B3LYP/6-311++G(3df,3pd)] was applied to analyze the vibrational spectra and the geometry of the title molecule. In agreement with the experiment, the C sbnd O sbnd C linkage in MBID is predicted by these calculations to exhibit considerably short (1.320 Å) and long (1.442 Å) (N dbnd )C sbnd O and (H 3)C sbnd O bonds, respectively, and a hybridization of the central oxygen atom close to sp 2 (the C sbnd O sbnd C angle is predicted to be ca. 117°). This C sbnd O sbnd C bonding pattern fits the well-known high reactivity of MBID upon thermal rearrangement, which has been shown to result in easy selective [1,3']-isomerization of the compound.

  17. Induced absorption spectra of the infrared fundamental band of molecular deuterium at 77 K: S1( J)+S0( J) transitions

    International Nuclear Information System (INIS)

    Gillard, P.G.; Prasad, R.D.G.; Reddy, S.P.

    1984-01-01

    The collision-induced spectra of the fundamental band of normal D 2 in the high frequency region 3200--3700 cm -1 were recorded for gas densities in the range 80--140 amagat at 77 K with a 2 m absorption cell. The contribution to the intensity of the band in this region comes from the high frequency wings of quadrupolar transitions S 1 ( J) and Q 1 ( J)+S 0 ( J) with J = 0 and 1, and from the group of transitions S 1 (2) and Q 1 ( J)+S 0 (2) with J = 0, 1, and 2 as well as from the relatively weaker double rotational transitions of the type S 1 ( J)+S 0 ( J); the latter transitions arise from the intermolecular interaction between the anisotropic component of the polarizability of one of the colliding pairs of molecules and the quadrupole field of the other. The experimental profiles were analyzed by assuming appropriate line shape functions and using the theoretical matrix elements of the quadrupole moment, isotropic polarizability, and anisotropy of polarizability of the D 2 molecule. From this analysis the characteristic half-width parameters delta/sub q/2 and delta/sub q/4 of the quadrupolar transitions and the binary and ternary absorption coefficients of the S 1 ( J)+S 0 ( J) transitions have been obtained. The experimental value of the binary absorption coefficient of S 1 (0)+S 0 (0) is (2.2 +- 0.1) x 10 -9 cm -1 amagat -2 and the corresponding theoretical value is 1.53 x 10 -9 cm -1 amagat -2

  18. Theoretical evaluation of accuracy in position and size of brain activity obtained by near-infrared topography

    International Nuclear Information System (INIS)

    Kawaguchi, Hiroshi; Hayashi, Toshiyuki; Kato, Toshinori; Okada, Eiji

    2004-01-01

    Near-infrared (NIR) topography can obtain a topographical distribution of the activated region in the brain cortex. Near-infrared light is strongly scattered in the head, and the volume of tissue sampled by a source-detector pair on the head surface is broadly distributed in the brain. This scattering effect results in poor resolution and contrast in the topographic image of the brain activity. In this study, a one-dimensional distribution of absorption change in a head model is calculated by mapping and reconstruction methods to evaluate the effect of the image reconstruction algorithm and the interval of measurement points for topographic imaging on the accuracy of the topographic image. The light propagation in the head model is predicted by Monte Carlo simulation to obtain the spatial sensitivity profile for a source-detector pair. The measurement points are one-dimensionally arranged on the surface of the model, and the distance between adjacent measurement points is varied from 4 mm to 28 mm. Small intervals of the measurement points improve the topographic image calculated by both the mapping and reconstruction methods. In the conventional mapping method, the limit of the spatial resolution depends upon the interval of the measurement points and spatial sensitivity profile for source-detector pairs. The reconstruction method has advantages over the mapping method which improve the results of one-dimensional analysis when the interval of measurement points is less than 12 mm. The effect of overlapping of spatial sensitivity profiles indicates that the reconstruction method may be effective to improve the spatial resolution of a two-dimensional reconstruction of topographic image obtained with larger interval of measurement points. Near-infrared topography with the reconstruction method potentially obtains an accurate distribution of absorption change in the brain even if the size of absorption change is less than 10 mm

  19. Comparison of human skin opto-thermal response to near-infrared and visible laser irradiations: a theoretical investigation

    Energy Technology Data Exchange (ETDEWEB)

    Dai Tianhong [Department of Bioengineering, Rice University, Houston, TX 77251 (United States); Pikkula, Brian M [Department of Bioengineering, Rice University, Houston, TX 77251 (United States); Wang, Lihong V [Department of Biomedical Engineering, Texas A and M University, College Station, TX 77843 (United States); Anvari, Bahman [Department of Bioengineering, Rice University, Houston, TX 77251 (United States)

    2004-11-07

    Near-infrared wavelengths are absorbed less by epidermal melanin, and penetrate deeper into human skin dermis and blood than visible wavelengths. Therefore, laser irradiation using near-infrared wavelengths may improve the therapeutic outcome of cutaneous hyper-vascular malformations in moderately to heavily pigmented skin patients and those with large-sized blood vessels or blood vessels extending deeply into the skin. A mathematical model composed of a Monte Carlo algorithm to estimate the distribution of absorbed light, numerical solution of a bio-heat diffusion equation to calculate the transient temperature distribution, and a damage integral based on an empirical Arrhenius relationship to quantify the tissue damage was utilized to investigate the opto-thermal response of human skin to near-infrared and visible laser irradiations in conjunction with cryogen spray cooling. In addition, the thermal effects of a single continuous laser pulse and micropulse-composed laser pulse profiles were compared. Simulation results indicated that a 940 nm wavelength induces improved therapeutic outcome compared with a 585 and 595 nm wavelengths for the treatment of patients with large-sized blood vessels and moderately to heavily pigmented skin. On the other hand, a 585 nm wavelength shows the best efficacy in treating small-sized blood vessels, as characterized by the largest laser-induced blood vessel damage depth compared with 595 and 940 nm wavelengths. Dermal blood content has a considerable effect on the threshold incident dosage for epidermal damage, while the effect of blood vessel size is minimal. For the same macropulse duration and incident dosage, a micropulse-composed pulse profile results in higher peak temperature at the basal layer of skin epidermis than an ideal single continuous pulse profile.

  20. Probing the spin multiplicity of gas-phase polycyclic aromatic hydrocarbons through their infrared emission spectrum: a theoretical study.

    Science.gov (United States)

    Falvo, Cyril; Calvo, Florent; Parneix, Pascal

    2012-08-14

    The anharmonic infrared emission spectrum following an optical excitation has been calculated for a variety of polycyclic aromatic hydrocarbon molecules in their ground singlet electronic state or in their triplet state. The computational protocol relies on second-order perturbation theory and involves a quartic vibrational Hamiltonian, the vibrational quantum numbers being sampled according to a Monte Carlo procedure. In the case of neutral naphthalene, the IR spectrum obtained in the (ground) singlet state differs significantly from the spectrum in the triplet state, especially for out-of-plane CH bending modes. Although not as prominent, spectral differences in larger molecules are still observable.

  1. Preparation and infrared spectra of the Schiff base solid complexes [UO2(sal-O-phdn)(H2O)] and [UO2(sal-O-phdn) (Et3N)] (sal-O-phdn=n, n'-o-phenylenebissalicylideniminato)

    International Nuclear Information System (INIS)

    Sadeek, S.A.; Teleb, S.M.; Al-Kority, A.M.

    1993-01-01

    In the present communication, we report the preparation of the related two new complexes, [UO 2 (sal-o-phdn)(H 2 O)] and LUO 2 (sal-o-phdn)(Et 3 N)], where sal-o-phdn=N, N'-o-phenylenebis (salicylideneiminato); here U VI is seven-coordinate. The infrared spectra of these two complexes are recorded and assigned. (author). 10 refs., 1 tab

  2. Laboratory Gas-phase Infrared Spectra of Two Astronomically Relevant PAH Cations: Diindenoperylene, {{\\rm{C}}}_{32}{{\\rm{H}}}_{16}^{+} and Dicoronylene, {{\\rm{C}}}_{48}{{\\rm{H}}}_{20}^{+}

    Science.gov (United States)

    Zhen, Junfeng; Candian, Alessandra; Castellanos, Pablo; Bouwman, Jordy; Linnartz, Harold; Tielens, Alexander G. G. M.

    2018-02-01

    The first gas-phase infrared spectra of two isolated astronomically relevant and large polycyclic aromatic hydrocarbon (PAH) cations—diindenoperylene (DIP) and dicoronylene (DC)—in the 530–1800 cm‑1 (18.9‑5.6 μm) range—are presented. Vibrational band positions are determined for comparison to the aromatic infrared bands. The spectra are obtained via infrared multiphoton dissociation spectroscopy of ions stored in a quadrupole ion trap using the intense and tunable radiation of the free electron laser for infrared experiments (FELIX). DIP+ shows its main absorption peaks at 737 (13.57), 800 (12.50), 1001 (9.99), 1070 (9.35), 1115 (8.97), 1152 (8.68), 1278 (7.83), 1420 (7.04), and 1550 (6.45) cm‑1(μm), in good agreement with density functional theory (DFT) calculations that are uniformly scaled to take anharmonicities into account. DC+ has its main absorption peaks at 853 (11.72), 876 (11.42), 1032 (9.69), 1168 (8.56), 1300 (7.69), 1427 (7.01), and 1566 (6.39) cm‑1(μm), which also agree well with the scaled DFT results presented here. The DIP+ and DC+ spectra are compared with the prominent infrared features observed toward NGC 7023. This results both in matches and clear deviations. Moreover, in the 11.0–14.0 μm region, specific bands can be linked to CH out-of-plane (oop) bending modes of different CH edge structures in large PAHs. The molecular origin of these findings and their astronomical relevance are discussed.

  3. Thermodynamics of reversible gas adsorption on alkali-metal exchanged zeolites - the interplay of infrared spectroscopy and theoretical calculations

    Czech Academy of Sciences Publication Activity Database

    Otero Areán, C.; Nachtigallová, Dana; Nachtigall, Petr; Garrone, E.; Rodríguez Delgado, M.

    2007-01-01

    Roč. 9, č. 12 (2007), s. 1421-1437 ISSN 1463-9076 R&D Projects: GA MŠk LC512; GA ČR GA203/06/0324 Grant - others:UIB(ES) MAT2006-05350 Institutional research plan: CEZ:AV0Z40550506 Keywords : adsorption * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.343, year: 2007

  4. Predicting enteric methane emission of dairy cows with milk Fourier-transform infrared spectra and gas chromatography-based milk fatty acid profiles.

    Science.gov (United States)

    van Gastelen, S; Mollenhorst, H; Antunes-Fernandes, E C; Hettinga, K A; van Burgsteden, G G; Dijkstra, J; Rademaker, J L W

    2018-06-01

    The objective of the present study was to compare the prediction potential of milk Fourier-transform infrared spectroscopy (FTIR) for CH 4 emissions of dairy cows with that of gas chromatography (GC)-based milk fatty acids (MFA). Data from 9 experiments with lactating Holstein-Friesian cows, with a total of 30 dietary treatments and 218 observations, were used. Methane emissions were measured for 3 consecutive days in climate respiration chambers and expressed as production (g/d), yield (g/kg of dry matter intake; DMI), and intensity (g/kg of fat- and protein-corrected milk; FPCM). Dry matter intake was 16.3 ± 2.18 kg/d (mean ± standard deviation), FPCM yield was 25.9 ± 5.06 kg/d, CH 4 production was 366 ± 53.9 g/d, CH 4 yield was 22.5 ± 2.10 g/kg of DMI, and CH 4 intensity was 14.4 ± 2.58 g/kg of FPCM. Milk was sampled during the same days and analyzed by GC and by FTIR. Multivariate GC-determined MFA-based and FTIR-based CH 4 prediction models were developed, and subsequently, the final CH 4 prediction models were evaluated with root mean squared error of prediction and concordance correlation coefficient analysis. Further, we performed a random 10-fold cross validation to calculate the performance parameters of the models (e.g., the coefficient of determination of cross validation). The final GC-determined MFA-based CH 4 prediction models estimate CH 4 production, yield, and intensity with a root mean squared error of prediction of 35.7 g/d, 1.6 g/kg of DMI, and 1.6 g/kg of FPCM and with a concordance correlation coefficient of 0.72, 0.59, and 0.77, respectively. The final FTIR-based CH 4 prediction models estimate CH 4 production, yield, and intensity with a root mean squared error of prediction of 43.2 g/d, 1.9 g/kg of DMI, and 1.7 g/kg of FPCM and with a concordance correlation coefficient of 0.52, 0.40, and 0.72, respectively. The GC-determined MFA-based prediction models described a greater part of the observed variation in CH 4 emission than did the

  5. HIRS-AMTS satellite sounding system test - Theoretical and empirical vertical resolving power. [High resolution Infrared Radiation Sounder - Advanced Moisture and Temperature Sounder

    Science.gov (United States)

    Thompson, O. E.

    1982-01-01

    The present investigation is concerned with the vertical resolving power of satellite-borne temperature sounding instruments. Information is presented on the capabilities of the High Resolution Infrared Radiation Sounder (HIRS) and a proposed sounding instrument called the Advanced Moisture and Temperature Sounder (AMTS). Two quite different methods for assessing the vertical resolving power of satellite sounders are discussed. The first is the theoretical method of Conrath (1972) which was patterned after the work of Backus and Gilbert (1968) The Backus-Gilbert-Conrath (BGC) approach includes a formalism for deriving a retrieval algorithm for optimizing the vertical resolving power. However, a retrieval algorithm constructed in the BGC optimal fashion is not necessarily optimal as far as actual temperature retrievals are concerned. Thus, an independent criterion for vertical resolving power is discussed. The criterion is based on actual retrievals of signal structure in the temperature field.

  6. Theoretical and experimental investigation of near-infrared light propagation in a model of the adult head.

    Science.gov (United States)

    Okada, E; Firbank, M; Schweiger, M; Arridge, S R; Cope, M; Delpy, D T

    1997-01-01

    Near-infrared light propagation in various models of the adult head is analyzed by both time-of-flight measurements and mathematical prediction. The models consist of three- or four-layered slabs, the latter incorporating a clear cerebrospinal fluid (CSF) layer. The most sophisticated model also incorporates slots that imitate sulci on the brain surface. For each model, the experimentally measured mean optical path length as a function of source-detector spacing agrees well with predictions from either a Monte Carlo model or a finite-element method based on diffusion theory or a hybrid radiosity-diffusion theory. Light propagation in the adult head is shown to be highly affected by the presence of the clear CSF layer, and both the optical path length and the spatial sensitivity profile of the models with a CSF layer are quite different from those without the CSF layer. However, the geometry of the sulci and the boundary between the gray and the white matter have little effect on the detected light distribution.

  7. Absorption infrared spectra of interaction products of cyclic polyethers 18-crown-6 and dibenzo-18-crown-6 with uranyl dinitrate hexahydrate

    International Nuclear Information System (INIS)

    Chumaevskij, N.A.; Belomestnykh, V.I.; Razgonyaeva, G.A.; Shabel'nik, K.S.; Afanas'eva, E.E.

    1988-01-01

    Using the method of IR spectroscopy it is established that during interaction of uranyl nitrate hexahydrate (UNH) with crown-ethers under investigation macrocycles adhere to UO 2 2+ via hydrogen bonds between water molecules and oxygen of polyethers. Interaction of UNH with the above-mentioned crowns leads to conformational rearrangement of cycles of polyethers and improvement of their symmetry, reflecting in noticeable simplification of IR spectra of interaction products as compared to spectra of initial cyclic polyethers

  8. Infrared laser spectroscopy of H2 and D2 Rydberg states. II. Diode laser spectra and assignment of 5g--4f, 6h--5g, and 8i--6h systems

    International Nuclear Information System (INIS)

    Davies, P.B.; Guest, M.A.; Stickland, R.J.

    1990-01-01

    Infrared diode laser absorption spectra of portions of the 5g--4f, 6h--5g, and 8i--6h Rydberg bands of H 2 and D 2 have been measured at Doppler limited resolution in low pressure A. C. discharges. The spectra, arising from L uncoupled states of H 2 and D 2 , are assigned using an ab initio polarization model supported by intensity calculations. Details of the different implementations of this polarization model are given in the preceding paper. The most useful was the single channel vibrationally extended (1)/(2) V 6 model which became progressively better at higher n (and L). Results of multichannel calculations for a selected set of transitions are also reported

  9. Theoretical modeling of Comptonized X-ray spectra of super-Eddington accretion flow: Origin of hard excess in ultraluminous X-ray sources

    Science.gov (United States)

    Kitaki, Takaaki; Mineshige, Shin; Ohsuga, Ken; Kawashima, Tomohisa

    2017-12-01

    X-ray continuum spectra of super-Eddington accretion flow are studied by means of Monte Carlo radiative transfer simulations based on the radiation hydrodynamic simulation data, in which both thermal- and bulk-Compton scatterings are taken into account. We compare the calculated spectra of accretion flow around black holes with masses of MBH = 10, 102, 103, and 104 M⊙ for a fixed mass injection rate (from the computational boundary at 103 rs) of 103 LEdd/c2 (with rs, LEdd, and c being the Schwarzschild radius, the Eddington luminosity, and the speed of light, respectively). The soft X-ray spectra exhibit mass dependence in accordance with the standard-disk relation; the maximum surface temperature is scaled as T ∝ M_{ BH}^{ -1/4}. The spectra in the hard X-ray band, by contrast with soft X-ray, look to be quite similar among different models, if we normalize the radiation luminosity by MBH. This reflects that the hard component is created by thermal- and bulk-Compton scatterings of soft photons originating from an accretion flow in the overheated and/or funnel regions, the temperatures of which have no dependence on mass. The hard X-ray spectra can be reproduced by a Wien spectrum with the temperature of T ˜ 3 keV accompanied by a hard excess at photon energy above several keV. The excess spectrum can be fitted well with a power law with a photon index of Γ ˜ 3. This feature is in good agreement with that of the recent NuSTAR observations of ULXs (ultra-luminous X-ray sources).

  10. Theoretical predictions of the two-dimensional solid-state NMR spectra: a case study of the 13C-1H correlations in metergoline

    Czech Academy of Sciences Publication Activity Database

    Czernek, Jiří; Brus, Jiří

    2013-01-01

    Roč. 586, 24 October (2013), s. 56-60 ISSN 0009-2614 Institutional support: RVO:61389013 Keywords : NMR * shielding * metergoline Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.991, year: 2013

  11. THEORETICAL SPECTRA OF THE AM CANUM VENATICORUM BINARY SYSTEM SDSS J0926+3624: EFFECTS OF IRRADIATION ONTO THE DONOR STAR

    International Nuclear Information System (INIS)

    Sengupta, Sujan; Taam, Ronald E.

    2011-01-01

    Taking into account a range of parameters determined from evolutionary models and available observational data, the detailed non-LTE spectrum for the primary star and the irradiated donor star in the AM Canum Venaticorum system SDSS J0926+3624 are constructed based on the TLUSTY stellar atmosphere code. The combined spectrum of the primary and the donor stars along with a multicolor blackbody spectrum of the accretion disk that reproduces a detailed numerical model is compared to the Sloan Digital Sky Survey optical spectrum of the system. The photometric flux of the primary star inferred from eclipse observations is compared with the synthetic spectrum. The model fit of the two independent observations provides an upper limit on the distance of the system for different effective temperatures of the primary. In addition, an upper limit on the combined flux of the disk and the donor in the infrared region wherein the contribution of the primary is negligible is also determined. It is shown that the spectrum of a sufficiently cool donor can exhibit emission lines due to irradiation from a hot primary and the emission features should be detectable in the infrared even though the contribution of the flux from the disk dominates. Thus, it is pointed out that infrared observations of the system would provide important information on the thermal state of the donor as well as useful insight into the thermal properties of the primary star and the accretion disk.

  12. Theoretical investigations of the optical and EPR spectra for trivalent cerium and ytterbium ions in orthorhombic YF{sub 3} crystal

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hong-Gang, E-mail: kezhouliu@163.com; Zheng, Wen-Chen

    2016-09-01

    The optical spectra and electron paramagnetic resonance (EPR) parameters (g factors and hyperfine structure constants A) for trivalent cerium and ytterbium ions in YF{sub 3} crystal with orthorhombic structure are investigated together by the complete diagonalization (of energy matrix) method (CDM). The obtained results are in reasonable agreement with the experimental ones. More importantly, two magnetically nonequivalent centers in YF{sub 3} crystal observed in EPR experiments are confirmed and ascribed to their specific positions in a unit cell by our calculations based on superposition model (SPM) analysis. Such identification of local sites with different magnetic properties would help us to understand not only the EPR spectra and magnetic susceptibility of other lanthanide ions doped in crystals with the same structure as YF{sub 3} but also the energy transfer scheme between two lanthanide ions occupying such two sites. All results are discussed carefully.

  13. Polarised IR-microscope spectra of guanidinium hydrogensulphate single crystal.

    Science.gov (United States)

    Drozd, M; Baran, J

    2006-07-01

    Polarised IR-microscope spectra of C(NH(2))(3)*HSO(4) small single crystal samples were measured at room temperature. The spectra are discussed on the basis of oriented gas model approximation and group theory. The stretching nuOH vibration of the hydrogen bond with the Ocdots, three dots, centeredO distance of 2.603A gives characteristic broad AB-type absorption in the IR spectra. The changes of intensity of the AB bands in function of polariser angle are described. Detailed assignments for bands derived from stretching and bending modes of sulphate anions and guanidinium cations were performed. The observed intensities of these bands in polarised infrared spectra were correlated with theoretical calculation of directional cosines of selected transition dipole moments for investigated crystal. The vibrational studies seem to be helpful in understanding of physical and chemical properties of described compound and also in design of new complexes with exactly defined behaviors.

  14. Polarized IR-microscope spectra of guanidinium hydrogenselenate single crystal.

    Science.gov (United States)

    Drozd, M; Baran, J

    2005-10-01

    The polarized IR-microscope spectra of C(NH2)3.HSeO4 small single crystal samples were measured at room temperature. The spectra are discussed with the framework of oriented gas model approximation and group theory. The stretching nuOH vibration of the hydrogen bond with the O...O distance of 2.616 A gives characteristic broad AB-type absorption in the IR spectra. The changes of intensity of the AB bands in function of polarizer angle are described. Detailed assignment for bands derived from stretching and bending modes of selenate anions and guanidinium cations were performed. The observed intensities of these bands in polarized infrared spectra were correlated with theoretical calculation of directional cosines of selected transition dipole moments for investigated crystal. The vibrational studies seem to be helpful in understanding of physical and chemical properties of described compound and also in design of new complexes with exactly defined behaviors.

  15. Development of program package for investigation and modeling of carbon nanostructures in diamond like carbon films with the help of Raman scattering and infrared absorption spectra line resolving

    Science.gov (United States)

    Hayrapetyan, David B.; Hovhannisyan, Levon; Mantashyan, Paytsar A.

    2013-04-01

    The analysis of complex spectra is an actual problem for modern science. The work is devoted to the creation of a software package, which analyzes spectrum in the different formats, possesses by dynamic knowledge database and self-study mechanism, performs automated analysis of the spectra compound based on knowledge database by application of certain algorithms. In the software package as searching systems, hyper-spherical random search algorithms, gradient algorithms and genetic searching algorithms were used. The analysis of Raman and IR spectrum of diamond-like carbon (DLC) samples were performed by elaborated program. After processing the data, the program immediately displays all the calculated parameters of DLC.

  16. COMPARISON OF AN INNOVATIVE NONLINEAR ALGORITHM TO CLASSICAL LEAST SQUARES FOR ANALYZING OPEN-PATH FOURIER TRANSFORM INFRARED SPECTRA COLLECTED AT A CONCENTRATED SWINE PRODUCTION FACILITY

    Science.gov (United States)

    Open-path Fourier transform infrared (OP/FTIR) spectrometry was used to measure the concentrations of ammonia, methane, and other atmospheric gases at an integrated swine production facility. The concentration-pathlength products of the target gases at this site often exceeded th...

  17. The covariance of the differences between experimental and theoretical chemical shifts as an aid for assigning two-dimensional heteronuclear correlation solid-state NMR spectra

    Czech Academy of Sciences Publication Activity Database

    Czernek, Jiří; Brus, Jiří

    2014-01-01

    Roč. 608, 21 July (2014), s. 334-339 ISSN 0009-2614 R&D Projects: GA ČR(CZ) GA14-03636S Institutional support: RVO:61389013 Keywords : NMR * DFT * covariance Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.897, year: 2014

  18. A comparison of telescopic and Phobos-2 ISM spectra of Mars in the short-wave near-infrared (0.76-1.02 microns)

    Science.gov (United States)

    Bell, James F., III; Mustard, John F.

    1993-01-01

    Recent analyses of near-IR (0.76-3.16 microns) Mars surface reflectance spectra obtained by the Phobos-2 ISM instrument during early 1989 have revealed the presence of substantial variability in surface spectral properties. Strong absorption features seen in the 0.85-1.05 micron region are up to 10-15 percent deep relative to the local continuum and have been interpreted as evidence of Fe(2+) and Fe(3+) bearing minerals (pyroxenes and iron oxides, respectively). Though these observed band depths are comparable to those seen in laboratory reflectance spectra, they are up to three times larger than most previously reported band depths for Mars spectra at these wavelengths. Six regions of variable albedo and geologic setting were identified where ISM and 1988 opposition telescopic coverage either overlapped physically or sampled the same surface geologic unit. The areal sizes and positions of the regions measured telescopically were compiled by Bell et al. ISM pixels falling within these spots were averaged to produce a spatially convolved spectrum that simulates what would have been seen telescopically. To facilitate comparisons of absorption band positions and relative strengths, the convolved ISM data and the 1988 telescopic spectra were scaled to unity at 0.81 microns and are presented. The data have also been convolved to equivalent band pass normalized reflectances in the region of spectral overlap. A scatter diagram of telescopic vs. ISM reflectances is shown. The results from the investigation are discussed.

  19. Size Effect on the Infrared Spectra of Condensed Media under Conditions of 1D, 2D, and 3D Dielectric Confinement

    KAUST Repository

    Shaganov, Igor I.; Perova, Tatiana S.; Melnikov, Vasily; Dyakov, Sergey A.; Berwick, Kevin

    2010-01-01

    with the calculated data. It is shown using simulations of the absorption spectrum of MgO powder that the approach suggested can be applied under certain conditions to the modeling of the spectra of microcrystalline particles of nonspheroidal shape. © 2010 American

  20. Surface-Enhanced Infrared Spectra of Nicotinic Acid and Pyridoxine on Copper Substrates: What Is the Effect of Temperature and Deposition Conditions?

    Czech Academy of Sciences Publication Activity Database

    Kokaislová, A.; Parchaňský, Václav; Matějka, P.

    2015-01-01

    Roč. 119, č. 47 (2015), s. 26526-26539 ISSN 1932-7447 Institutional support: RVO:61388963 Keywords : absorption spectroscopy SEIRAS * Raman scattering * in situ Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.509, year: 2015

  1. Comparison of theoretically predicted and observed Solar Maximum Mission X-ray spectra for the 1980 April 13 and May 9 flares

    International Nuclear Information System (INIS)

    Smith, D.F.; Orwig, L.E.

    1982-01-01

    A method for predicting the hard X-ray spectrum in the 10--100 keV range for compact flares during their initial rise is developed on the basis of a thermal model. Observations of the flares of 1980 April 13, 4:05 U.T., and 1980 May 9, 7:12 U.T. are given and their combined spectra from the Hard X-ray Burst Spectrometer and Hard X-ray Imaging Spectrometer on the Solar Maximum Mission are deduced. Constraints on the cross sectional area of the supposed emitting arch are obtained from data from the Hard X-ray Imaging Spectrometer. A power-law spectrum is predicted for the rise of the flare of April 13 for initial arch densities less than 10 10 cm -3 and also for the flare of May 9 for initial arch densities less than 5.4 x 10 10 cm -3 . In both cases power-law spectra are observed. Limitations and implications of these results are discussed

  2. Investigating the optical modes of InxGa1xN alloy and In0.5Ga0.5N/GaN MQW in far-infrared reflectivity spectra

    International Nuclear Information System (INIS)

    Mirjalili, G.; Amraei, R.

    2006-01-01

    Optical properties of In x Ga 1 x N alloy and In 0 .5Ga 0 .5N/GaN multi quantum wells have been investigated in the region of far infrared. Far-IR reflectivity spectra of In 0 .5Ga 0 .5N/GaN multi quantum wells on GaAs substrate have been obtained by oblique incidence p- and s- polarization light using effective medium approximation. The spectra and the dielectric functions response give a good information about the phonon and plasmon contribution in doped MQW as well as the mole fraction of compounds in the alloys. The changes in position of optical modes are good tools for measurement of the amount of free carrier and the amount of mole fraction in the samples. During study of In x Ga 1 x N reflectivity spectra, two distinct reststrahl bands with frequency near those of pure InN and GaN were observed over entire composition range. Each band shifts to lower frequencies and decreases in amplitude as the concentration of corresponding compound in alloy decreased. Analysis of dielectric function gives the TO-like and LO-like mode frequencies. The changes in LO mode frequencies, due to coupling of phonon-plasmon, have been observed

  3. The Rovibronic Spectra of the Cyclopentadienyl Radical

    Science.gov (United States)

    Sharma, Ketan; Miller, Terry A.; Stanton, John F.; Nesbitt, David

    2017-06-01

    Cyclopentadienyl (Cp) radical has been subject to numerous studies for the greater part of half a century. Experimental work has involved photo-electron spectroscopy, laser induced fluorescence excitation and emission, infrared absorption spectroscopy, and recently rotationally resolved spectra in the CH stretch region taken at JILA. Even more theoretical works appear in the literature, but substantial advances in computation have occurred since their completion. Cp's highly symmetric (D_{5h}) structure and doubly degenerate electronic ground (˜{X}^2E_1^{''}), which is subject to linear Jahn-Teller distortion, have been a great motivation for work on it. We have commenced new computational work to obtain a broad understanding of the electronic, vibrational, and rotational, i.e. rovibronic, structure of the Cp radical as revealed by its spectra, with particular emphasis on the new infrared spectra. The goal is to guide experiments and their analyses and reconcile results from spectroscopy and quantum chemistry calculations. T. Ichino, et al. J. Chem. Phys. 129, 084310 (2008) L. Yu, S. C. Foster, J. M. Williamson, M. C. Heaven and T. A. Miller J. Phys. Chem. 92, 4263 (1988) B. E. Applegate, A. J. Bezant and T. A. Miller J. Chem. Phys 114, 4869 (2001) D. Leicht, M. Kaufmann, G. Schwaab, and M. Havenith J. Chem. Phys. 145, 7 (2016), 074304.

  4. Behaviour of 29Si NMR and infrared spectra of aqueous sodium and potassium silica solutions as a function of (SiO2/M2+O) ratio

    International Nuclear Information System (INIS)

    Couty, R.; Fernandez, L.

    1996-01-01

    Sodium and potassium solutions of silica with silica concentration of 1,4 mo/kg and R ms = SiO 2 /M + 2 O ratios of 4.56 to 1.6 were obtained by depolymerization of amorphous silica gel in sodium and potassium hydroxide. Solutions have been characterized by 29 Si NMR and infrared spectroscopy. The results indicated that Na + and K + exhibit the same behaviour during the depolymerization of silica. (authors). 11 refs., 4 figs., 2 tabs

  5. Atmospheric lifetimes, infrared absorption spectra, radiative forcings and global warming potentials of NF3 and CF3CF2Cl (CFC-115

    Directory of Open Access Journals (Sweden)

    A. Totterdill

    2016-09-01

    Full Text Available Fluorinated compounds such as NF3 and C2F5Cl (CFC-115 are characterised by very large global warming potentials (GWPs, which result from extremely long atmospheric lifetimes and strong infrared absorptions in the atmospheric window. In this study we have experimentally determined the infrared absorption cross sections of NF3 and CFC-115, calculated the radiative forcing and efficiency using two radiative transfer models and identified the effect of clouds and stratospheric adjustment. The infrared cross sections are within 10 % of previous measurements for CFC-115 but are found to be somewhat larger than previous estimates for NF3, leading to a radiative efficiency for NF3 that is 25 % larger than that quoted in the Intergovernmental Panel on Climate Change Fifth Assessment Report. A whole atmosphere chemistry–climate model was used to determine the atmospheric lifetimes of NF3 and CFC-115 to be (509 ± 21 years and (492 ± 22 years, respectively. The GWPs for NF3 are estimated to be 15 600, 19 700 and 19 700 over 20, 100 and 500 years, respectively. Similarly, the GWPs for CFC-115 are 6030, 7570 and 7480 over 20, 100 and 500 years, respectively.

  6. Theoretical energy level spectra and transition data for 4p64d, 4p64f and 4p54d2 configurations of W37+ ion

    International Nuclear Information System (INIS)

    Bogdanovich, P.; Kisielius, R.

    2012-01-01

    The ab initio quasirelativistic Hartree–Fock method developed specifically for the calculation of spectral parameters of heavy atoms and highly charged ions was applied to determine atomic data for tungsten ions. The correlation effects were included by adopting the configuration interaction method. The Breit–Pauli approximation for quasirelativistic Hartree–Fock radial orbitals was employed to take into account relativistic effects. The energy level spectra, radiative lifetimes, Lande factors g were calculated for the 4p 6 4d, 4p 6 4f and 4p 5 4d 2 configurations of W 37+ ion. The atomic data, namely, the transition wavelengths, spontaneous emission rates and oscillator strengths for the electric dipole, electric quadrupole and magnetic dipole transitions among and within the levels of these configurations are tabulated.

  7. Theoretical studies of the optical and EPR spectra for VO^{2+} in Na_3C_6H_5O_7·2H_2O single crystal

    Directory of Open Access Journals (Sweden)

    Ch.-Y. Li

    2015-06-01

    Full Text Available On the basis of the perturbation formulas for a d^1 configuration ion in a tetragonal crystal field, the three optical absorption bands and electron paramagnetic resonance (EPR parameters (g factors g_i and hyperfine structure constants A_i for i = || and ⊥, respectively of VO^{2+} in Na_3C_6H_5O_7·2H_2O (TSCD single crystals were studied using the perturbation theory method. By simulating the calculated optical and EPR spectra to the observed values, local structure parameters and negative signs of the hyperfine structure constants A_i of the octahedral (VO_6^{8-} cluster in TSCD single crystal can be obtained.

  8. Ab initio potential energy surface, electric-dipole moment, polarizability tensor, and theoretical rovibrational spectra in the electronic ground state of {sup 14}NH{sub 3}{sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Yurchenko, Sergei N. [Technische Universitaet Dresden, Institut fuer Physikalische Chemie und Elektrochemie, D-01062 Dresden (Germany); Thiel, Walter [Max-Planck-Institut fuer Kohlenforschung, Kaiser-Wilhelm-Platz 1, D-45470 Muelheim an der Ruhr (Germany); Carvajal, Miguel [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Avenida de las Fuerzas Armadas s/n, Universidad de Huelva, E-21071 Huelva (Spain); Jensen, Per [Theoretische Chemie, Bergische Universitaet, D-42097 Wuppertal (Germany)], E-mail: jensen@uni-wuppertal.de

    2008-05-04

    We report the calculation of a six-dimensional CCSD(T)/aug-cc-pVQZ potential energy surface for the electronic ground state of NH{sub 3}{sup +} together with the corresponding CCSD(T)/aug-cc-pVTZ dipole moment and polarizability surface of {sup 14}NH{sub 3}{sup +}. These electronic properties have been computed on a large grid of molecular geometries. A number of newly calculated band centers are presented along with the associated electric-dipole transition moments. We further report the first calculation of vibrational matrix elements of the polarizability tensor components for {sup 14}NH{sub 3}{sup +}; these matrix elements determine the intensities of Raman transitions. In addition, the rovibrational absorption spectra of the {nu}{sub 2}, {nu}{sub 3}, {nu}{sub 4}, 2{nu}{sub 2}-{nu}{sub 2}, and {nu}{sub 2}+{nu}{sub 3}-{nu}{sub 2} bands have been simulated.

  9. Intelligent evaluation of color sensory quality of black tea by visible-near infrared spectroscopy technology: A comparison of spectra and color data information

    Science.gov (United States)

    Ouyang, Qin; Liu, Yan; Chen, Quansheng; Zhang, Zhengzhu; Zhao, Jiewen; Guo, Zhiming; Gu, Hang

    2017-06-01

    Instrumental test of black tea samples instead of human panel test is attracting massive attention recently. This study focused on an investigation of the feasibility for estimation of the color sensory quality of black tea samples using the VIS-NIR spectroscopy technique, comparing the performances of models based on the spectra and color information. In model calibration, the variables were first selected by genetic algorithm (GA); then the nonlinear back propagation-artificial neural network (BPANN) models were established based on the optimal variables. In comparison with the other models, GA-BPANN models from spectra data information showed the best performance, with the correlation coefficient of 0.8935, and the root mean square error of 0.392 in the prediction set. In addition, models based on the spectra information provided better performance than that based on the color parameters. Therefore, the VIS-NIR spectroscopy technique is a promising tool for rapid and accurate evaluation of the sensory quality of black tea samples.

  10. Updated database plus software for line-mixing in CO2 infrared spectra and their test using laboratory spectra in the 1.5-2.3 μm region

    International Nuclear Information System (INIS)

    Lamouroux, J.; Tran, H.; Laraia, A.L.; Gamache, R.R.; Rothman, L.S.; Gordon, I.E.; Hartmann, J.-M.

    2010-01-01

    In a previous series of papers, a model for the calculation of CO 2 -air absorption coefficients taking line-mixing into account and the corresponding database/software package were described and widely tested. In this study, we present an update of this package, based on the 2008 version of HITRAN, the latest currently available. The spectroscopic data for the seven most-abundant isotopologues are taken from HITRAN. When the HITRAN data are not complete up to J''=70, the data files are augmented with spectroscopic parameters from the CDSD-296 database and the high-temperature CDSD-1000 if necessary. Previously missing spectroscopic parameters, the air-induced pressure shifts and CO 2 line broadening coefficients with H 2 O, have been added. The quality of this new database is demonstrated by comparisons of calculated absorptions and measurements using CO 2 high-pressure laboratory spectra in the 1.5-2.3 μm region. The influence of the imperfections and inaccuracies of the spectroscopic parameters from the 2000 version of HITRAN is clearly shown as a big improvement of the residuals is observed by using the new database. The very good agreements between calculated and measured absorption coefficients confirm the necessity of the update presented here and further demonstrate the importance of line-mixing effects, especially for the high pressures investigated here. The application of the updated database/software package to atmospheric spectra should result in an increased accuracy in the retrieval of CO 2 atmospheric amounts. This opens improved perspectives for the space-borne detection of carbon dioxide sources and sinks.

  11. X-ray absorption spectra and emission spectra of plasmas

    International Nuclear Information System (INIS)

    Peng Yonglun; Yang Li; Wang Minsheng; Li Jiaming

    2002-01-01

    The author reports a theoretical method to calculate the resolved absorption spectra and emission spectra (optically thin) of hot dense plasmas. Due to its fully relativistic treatment incorporated with the quantum defect theory, it calculates the absorption spectra and emission spectra for single element or multi-element plasmas with little computational efforts. The calculated absorption spectra of LTE gold plasmas agree well with the experimental ones. It also calculates the optical thin emission spectra of LTE gold plasmas, which is helpful to diagnose the plasmas of relevant ICF plasmas. It can also provide the relevant parameters such as population density of various ionic stages, precise radiative properties for ICF studies

  12. Resonant photoionization absorption spectra of spherical quantum dots

    CERN Document Server

    Bondarenko, V

    2003-01-01

    We study theoretically the mid-infrared photon absorption spectra due to bound-free transitions of electrons in individual spherical quantum dots. It is established that change of the dot size in one or two atomic layers or/and number of electrons by one or two can change the peak value of the absorption spectra in orders of magnitude and energy of absorbed photons by tens of millielectronvolts. The reason for this is the formation of specific free states, called resonance states. Numerical calculations are performed for quantum dots (QDs) with radius varying up to 200 A, and one to eight electrons occupying the two lowest bound states. It is supposed that realistic QD systems with resonance states would be of much advantage to design novel infrared QD photo-detectors.

  13. Novel poly(triphenylamine-alt-fluorene) with asymmetric hexaphenylbenzene and pyrene moieties: synthesis, fluorescence, flexible near-infrared electrochromic devices and theoretical investigation

    KAUST Repository

    Wang, Po-I.

    2016-01-13

    © The Royal Society of Chemistry 2016. In this study, a new triphenylamine-alt-fluorene conjugated copolymer, HPBPYFL6, with hexaphenylbenzene (HPB) and pyrene as asymmetrical pendant groups was synthesized via Suzuki coupling polymerization. The conjugated polymer had a weight-average molecular weight of 5.8 × 104 g mol-1 with a polydispersity index of 2.5 characterized by gel permeation chromatography (GPC). HPBPYFL6 showed good solubility in common organic solvents such as NMP, THF, toluene and dichloromethane at 25°C. In addition, HPBPYFL6 possessed a high glass transition temperature of 260°C and a 10% weight-loss temperature of 503°C in nitrogen. HPBPYFL6 bearing a pyrene moiety had a solvatochromic fluorescence shift from a green to an orange emission as the polarity of the solvent increased. Cyclic voltammetry of HPBPYFL6 films cast onto indium-tin oxide-coated glass (ITO-glass) exhibited two oxidation redox couples at an E1/2 value of 0.82 and 1.17 V versus Ag/Ag+ in an acetonitrile solution. The HPBPYFL6 film on graphene-coated PET had an E1/2 value of 0.24 and 1.12 V. Conjugated polymer films exhibited reversible electrochromic behaviour with a colour change from pale yellow to deep blue upon electrochemical oxidation and high absorbance in the near-infrared (NIR) region. The switching and bleaching times were 5.16 s and 3.12 s for 1231 nm and were 3.30 s and 3.74 s for 1030 nm of HPBPYFL6 on ITO-glass. The strong NIR electrochromic absorbance of HPBPYFL6 was attributed to intervalence charge transfer by the incorporation of the HPB moiety. This phenomenon was confirmed by chemical oxidation as the oxidant contents increased in the solution state. Furthermore, the electrochromic mechanism was interpreted by DFT calculation and the simulated NIR electrochromic spectra of model compound HPBPYFL are in good agreement with the experimental data.

  14. Theoretical calculation of the spectra, the EPR g-factors and the magnetic susceptibilities of Cu2+ ion in Cs2CuCl4

    International Nuclear Information System (INIS)

    Shuen Wei Li.

    1991-08-01

    The crystal-field and spin-orbit matrix for d 1 or d 9 configuration with D 2 symmetry has been derived. By diagonalizing the matrix, the energy level of C 2+ u in Cs 2 CuCl 4 and its eigenfunctions have been obtained with the aid of the approximate SCF d-orbit. Furthermore, by suing the eigenfunctions, the EPR g-factors and the magnetic susceptibilities at different temperatures have been calculated. The calculated results are in good agreement with the experimental findings. The calculation only needs two adjustable parameters and can give more theoretical results than those of previous work which introduced 11 adjustable parameters. (author). 16 refs, 3 tabs

  15. 1H NMR spectra of N-methyl-4-tolyl-1-(4-bromonaphthylamine and N-phenyl-1-(4-bromonaphthylamine: a combined experimental and theoretical study

    Directory of Open Access Journals (Sweden)

    Sergiy I. Okovytyy

    2014-03-01

    Full Text Available Theoretical investigations of the conformational properties and 1H NMR chemical shifts for N-methyl-4-tolyl-1-(4-bromonaphthylamine and N-phenyl-1-(4-bromonaphthylamine are reported. The calculations were performed at the DFT level (PBE1PBE functional using magnetically consistent 6-31G## and STO##-3Gmag basis sets. Conformational properties of the amines were studied using potential energy surface scanning. Chemical shifts were calculated using the GIAO and CSGT methods and averaged in proportion to the population of the corresponding conformations. Solvent effects (CDCl3 were accounted via PCM method. The obtained results allowed to assign the 1H NMR signals for the naphthalene moiety, which could not be done based on the experimental data alone.

  16. Vibrational spectra of aminoacetonitrile

    International Nuclear Information System (INIS)

    Bak, B.; Hansen, E.L.; Nicolaisen, F.M.; Nielsen, O.F.

    1975-01-01

    The preparation of pure, stable aminoacetonitrile(1-amino, 1'-cyanomethane)CH 2 NH 2 CN (1) is described. The Raman spectrum, now complete, and a novel infrared spectrum extending over the 50-3600 cm -1 region are reported. A tentative normal vibration analysis is presented and supported by Raman and infrared data from the spectra of CH 2 NHDCN (2) and CH 2 ND 2 CN (3). The predominance of the trans rotamer may be attributed to intramolecular hydrogen bonding but this is too unimportant to influence the vibrational frequencies of gaseous 1, 2, and 3. However, large gas/liquid frequency shifts occur. (author)

  17. Laser ablation of an indium target: time-resolved Fourier-transform infrared spectra of In I in the 700–7700 cm−1 range

    Czech Academy of Sciences Publication Activity Database

    Civiš, Svatopluk; Kubelík, Petr; Ferus, Martin; Chernov, Vladislav E.; Zanozina, Ekaterina M.; Juha, Libor

    2014-01-01

    Roč. 29, č. 12 (2014), s. 2275-2283 ISSN 0267-9477 R&D Projects: GA MŠk LD14115; GA MŠk(CZ) LG13029 Institutional support: RVO:61388955 ; RVO:68378271 Keywords : time-resolved fluorescence * Fourier transform infra reds * Laser-induced breakdown spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.466, year: 2014

  18. A theoretical and spectroscopic study of co-amorphous naproxen and indomethacin

    DEFF Research Database (Denmark)

    Löbmann, Korbinian; Laitinen, Riikka; Grohganz, Holger

    2013-01-01

    . In this study, the co-amorphous drug mixture containing naproxen (NAP) and indomethacin (IND) was investigated using infrared spectroscopy (IR) and quantum mechanical calculations. The structures of both drugs were optimized as monomer, homodimer and heterodimer using density functional theory and used...... for the calculation of IR spectra. Conformational analysis confirmed that the optimized structures were suitable for the theoretical prediction of the spectra. Vibrational modes from the calculation could be matched with experimentally observed spectra for crystalline and amorphous NAP and IND, and it could be shown...... that both drugs exist as homodimers in their respective individual amorphous form. With the results from the experimental single amorphous drugs and theoretical homodimers, a detailed analysis of the experimental co-amorphous and theoretical heterodimer spectra was performed and evaluated. It is suggested...

  19. Quantitative analysis of the effect of zidovudine, efavirenz, and ritonavir on insulin aggregation by multivariate curve resolution alternating least squares of infrared spectra

    International Nuclear Information System (INIS)

    Martí-Aluja, Idoia; Ruisánchez, Itziar; Larrechi, M. Soledad

    2013-01-01

    Highlights: ► The structure of insulin can be changed via interaction with antiretroviral drugs. ► The chemical interaction promotes the formation of aggregates. ► This drug effect was evaluated by MCR-ALS coupled to IR spectroscopy. ► Formation of aggregates was favourable if drugs were able to form hydrogen bonds. ► Higher drug concentrations favoured formation of amorphous aggregates. - Abstract: Quantification of the effect of antiretroviral drugs on the insulin aggregation process is an important area of research due to the serious metabolic diseases observed in AIDS patients after prolonged treatment with these drugs. In this work, multivariate curve resolution alternating least squares (MCR-ALS) was applied to infrared monitoring of the insulin aggregation process in the presence of three antiretroviral drugs to quantify their effect. To evidence concentration dependence in this process, mixtures at two different insulin:drug molar ratios were used. The interaction between insulin and each drug was analysed by 1 H NMR spectroscopy. In all cases, the aggregation process was monitored during 45 min by infrared spectroscopy. The aggregates were further characterised by scanning electron microscopy (SEM). MCR-ALS provided the spectral and concentration profiles of the different insulin–drug conformations that are involved in the process. Their feasible band boundaries were calculated using the MCR-BANDS methodology. The kinetic profiles describe the aggregation pathway and the spectral profiles characterise the conformations involved. The retrieved results show that each of the three drugs modifies insulin conformation in a different way, promoting the formation of aggregates. Ritonavir shows the strongest promotion of aggregation, followed by efavirenz and zidovudine. In the studied concentration range, concentration dependence was only observed for zidovudine, with shorter aggregation time obtained as the amount of zidovudine increased. This factor

  20. Forecast of physicochemical properties and chemical composition of gasoline from infrared spectra, using multivariate calibration; Previsao de propriedades fisico-quimicas e composicao quimica da gasolina a partir de espectros infravermelhos, utilizando calibracao multivariada

    Energy Technology Data Exchange (ETDEWEB)

    Cocco, Lilian Cristina; Yamamoto, Carlos Itsuo [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Lab. de Analise de Combustiveis Automotivos (LACAUTets)

    2008-07-01

    This work describes the attainment of mathematical models, applying multivariate calibration in infrared spectrum with ATR, from 128 gasoline samples with diverse chemical compositions, collected in a period of two and a half years. Infrared spectra had been used to assemble the input matrix for the modeling, whereas the standardized assays and gaseous chromatography had supplied the output matrices. Ninety samples were been used for training and 38 for testing. In order to calibrate chemical composition from chromatography, the techniques of mass spectrometry and chemical ionization were used to identify unknown substances and improve the fitting of the mathematical models. Two hundred and ninety substances were detected and identified, from which 100 were unknown. Six PLS/PCR models were attained to predict some properties as specific mass, Reid vapor pressure, T10, T50, T90 and PFE from distillation curve. Another six PLS/PCR models were attained to predict the amount of aromatics, paraffins, isoparaffins, naphthenes, olefins and oxygenates. In general, mathematical models were attained with good training fit, with correlation coefficients higher than 0,975 (T10) and reaching a maximum of 0,998 (naphthenes) and they are able to forecast an average chemical percentage and properties of interest from gasoline, with acceptable prediction errors. (author)

  1. Vibrational Spectroscopy of Intramolecular Hydrogen Bonds in the Infrared and Near-Infrared Regions

    DEFF Research Database (Denmark)

    Schrøder, Sidsel Dahl

    and 1,4-diaminobutane). Experimentally, the hydrogen bonds have been studied with vibrational spectroscopy in the infrared and near-infrared regions. The focus is primarily on spectra recorded in the near-infrared regions, which in these studies are dominated by O-H and N-H stretching overtones....... Overtone spectra have been recorded with intracavity laser photoacoustic laser spectroscopy and conventional long path absorption spectroscopy. Theoretically, a combination of electronic structure calculations and local mode models have been employed to guide the assignment of bands in the vibrational......,4-diaminobutane, no sign of intramolecular N-H···N hydrogen bonds were identified in the overtone spectra. However, theoretical analyzes indicate that intramolecular N-H···N hydrogen bonds are present in all three diamines if two hydrogen atoms on one of the methylene groups are substituted with triuoromethyl...

  2. The Born-Oppenheimer molecular simulations of infrared spectra of crystalline poly-(R)-3-hydroxybutyrate with analysis of weak Csbnd H⋯Odbnd C hydrogen bonds

    Science.gov (United States)

    Brela, Mateusz Z.; Boczar, Marek; Wójcik, Marek J.; Sato, Harumi; Nakajima, Takahito; Ozaki, Yukihiro

    2017-06-01

    In this letter we present results of study of weak Csbnd H⋯Odbnd C hydrogen bonds of crystalline poly-(R)-3-hydroxybutyrate (PHB) by using Born-Oppenheimer molecular dynamics. The polymeric structure and IR spectra of PHB result from the presence of the weak hydrogen bonds. We applied the post-molecular dynamics analysis to consider a Cdbnd O motion as indirectly involved in the hydrogen bonds. Quantization of the nuclear motion of the oxygens was done to perform detailed analysis of the strength and properties of the Cdbnd O bands involved in the weak hydrogen bonds. We have also shown the dynamic character of the weak hydrogen bond interactions.

  3. The Effects of Moisture Conditions—From Wet to Hyper dry—On Visible Near-Infrared Spectra of Danish Reference Soils

    DEFF Research Database (Denmark)

    Knadel, Maria; Deng, Fan; Alinejadian, Afsaneh

    2014-01-01

    Changes in soil water content are known to affect soil reflectance. Even though it was suggested some time ago that the phenomenon of increased forward scattering due to the presence of water in the soil is related to water film thickness and matric potential, there has been no detailed...... investigation of this in any studies. The effects of moisture conditions on visible nearinfrared (vis-NIR) spectra of four representative soils in Denmark have been assessed as a function of both water film thickness (expressed as the number of molecular layers) and matric potential. Complete water retention...... curves, from wet (pF 0.3, pF = log(|j|), where j is the matric potential in cm) to hyper dry end (oven-dried and freeze-dried soil), were obtained by initial wetting followed by successive draining and drying of soil samples, performing NIR measurements at each step. Soil reflectance was found...

  4. Infrared spectroscopy of different phosphates structures.

    Science.gov (United States)

    Jastrzębski, W; Sitarz, M; Rokita, M; Bułat, K

    2011-08-15

    Infrared (IR) spectroscopic studies of mineral and synthetic phosphates have been presented. The interpretation of the spectra has been preceded by the isolated [PO(4)](3-) tetrahedron spectra analyse. The K(3)PO(4) saturated aqueous solution was measured in the special cell for liquids. The obtained IR results have been compared with the theoretical number of IR-active modes. The number and positions of the bands due to P-O vibrations have been established. The phase composition of the phosphates has been determined using XRD and IR spectroscopy methods. The influence of non-tetrahedral cations on the shape of the spectra and the positions of bands has been analysed and the crystalline field splitting effect has been discussed. Copyright © 2010 Elsevier B.V. All rights reserved.

  5. Opacity of iron, nickel, and copper plasmas in the x-ray wavelength range: Theoretical interpretation of 2p-3d absorption spectra

    International Nuclear Information System (INIS)

    Blenski, T.; Loisel, G.; Poirier, M.; Thais, F.; Arnault, P.; Caillaud, T.; Fariaut, J.; Gilleron, F.; Pain, J.-C.; Porcherot, Q.; Reverdin, C.; Silvert, V.; Villette, B.; Bastiani-Ceccotti, S.; Turck-Chieze, S.; Foelsner, W.; Gaufridy de Dortan, F. de

    2011-01-01

    This paper deals with theoretical studies on the 2p-3d absorption in iron, nickel, and copper plasmas related to LULI2000 (Laboratoire pour l'Utilisation des Lasers Intenses, 2000J facility) measurements in which target temperatures were of the order of 20 eV and plasma densities were in the range 0.004-0.01 g/cm 3 . The radiatively heated targets were close to local thermodynamic equilibrium (LTE). The structure of 2p-3d transitions has been studied with the help of the statistical superconfiguration opacity code sco and with the fine-structure atomic physics codes hullac and fac. A new mixed version of the sco code allowing one to treat part of the configurations by detailed calculation based on the Cowan's code rcg has been also used in these comparisons. Special attention was paid to comparisons between theory and experiment concerning the term features which cannot be reproduced by sco. The differences in the spin-orbit splitting and the statistical (thermal) broadening of the 2p-3d transitions have been investigated as a function of the atomic number Z. It appears that at the conditions of the experiment the role of the term and configuration broadening was different in the three analyzed elements, this broadening being sensitive to the atomic number. Some effects of the temperature gradients and possible non-LTE effects have been studied with the help of the radiative-collisional code scric. The sensitivity of the 2p-3d structures with respect to temperature and density in medium-Z plasmas may be helpful for diagnostics of LTE plasmas especially in future experiments on the Δn=0 absorption in medium-Z plasmas for astrophysical applications.

  6. Thermoluminescence spectra of amethyst

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Q. [Suzhou Railway Teachers College (China). Dept. of Physics; Yang, B. [Beijing Normal University (China). Dept. of Physics; Wood, R.A.; White, D.R.R.; Townsend, P.D.; Luff, B.J. [Sussex Univ., Brighton (United Kingdom). School of Mathematical and Physical Sciences

    1994-04-01

    Thermoluminescence and cathodoluminescence data from natural and synthetic amethyst and synthetic quartz samples are compared. The spectra include features from the quartz host lattice and from impurity-generated recombination sites. Emission features exist throughout the wavelength range studied, 250-800 nm. The near infrared emission at 740-750 nm appears to be characteristic of the amethyst and is proposed to be due to Fe ion impurity. (Author).

  7. A multi-model fusion strategy for multivariate calibration using near and mid-infrared spectra of samples from brewing industry

    Science.gov (United States)

    Tan, Chao; Chen, Hui; Wang, Chao; Zhu, Wanping; Wu, Tong; Diao, Yuanbo

    2013-03-01

    Near and mid-infrared (NIR/MIR) spectroscopy techniques have gained great acceptance in the industry due to their multiple applications and versatility. However, a success of application often depends heavily on the construction of accurate and stable calibration models. For this purpose, a simple multi-model fusion strategy is proposed. It is actually the combination of Kohonen self-organizing map (KSOM), mutual information (MI) and partial least squares (PLSs) and therefore named as KMICPLS. It works as follows: First, the original training set is fed into a KSOM for unsupervised clustering of samples, on which a series of training subsets are constructed. Thereafter, on each of the training subsets, a MI spectrum is calculated and only the variables with higher MI values than the mean value are retained, based on which a candidate PLS model is constructed. Finally, a fixed number of PLS models are selected to produce a consensus model. Two NIR/MIR spectral datasets from brewing industry are used for experiments. The results confirms its superior performance to two reference algorithms, i.e., the conventional PLS and genetic algorithm-PLS (GAPLS). It can build more accurate and stable calibration models without increasing the complexity, and can be generalized to other NIR/MIR applications.

  8. Infrared Absorption Spectra, Radiative Efficiencies, and Global Warming Potentials of Newly-Detected Halogenated Compounds: CFC-113a, CFC-112 and HCFC-133a

    Directory of Open Access Journals (Sweden)

    Maryam Etminan

    2014-07-01

    Full Text Available CFC-113a (CF3CCl3, CFC-112 (CFCl2CFCl2 and HCFC-133a (CF3CH2Cl are three newly detected molecules in the atmosphere that are almost certainly emitted as a result of human activity. It is important to characterise the possible contribution of these gases to radiative forcing of climate change and also to provide information on the CO2-equivalence of their emissions. We report new laboratory measurements of absorption cross-sections of these three compounds at a resolution of 0.01 cm−1 for two temperatures 250 K and 295 K in the spectral range of 600–1730 cm−1. These spectra are then used to calculate the radiative efficiencies and global warming potentials (GWP. The radiative efficiencies are found to be between 0.15 and 0.3 W∙m−2∙ppbv−1. The GWP for a 100 year time horizon, relative to carbon dioxide, ranges from 340 for the relatively short-lived HCFC-133a to 3840 for the longer-lived CFC-112. At current (2012 concentrations, these gases make a trivial contribution to total radiative forcing; however, the concentrations of CFC-113a and HCFC-133a are continuing to increase. The 2012 CO2-equivalent emissions, using the GWP (100, are estimated to be about 4% of the current global CO2-equivalent emissions of HFC-134a.

  9. New investigation of the ν3 C-H stretching region of 12CH4 through the analysis of high temperature infrared emission spectra

    Science.gov (United States)

    Amyay, Badr; Gardez, Aline; Georges, Robert; Biennier, Ludovic; Vander Auwera, Jean; Richard, Cyril; Boudon, Vincent

    2018-04-01

    The ν3 C-H stretching region of methane was reinvestigated in this work using high temperature (620-1715 K) emission spectra recorded in Rennes at Doppler limited resolution. This work follows our recent global analysis of the Dyad system Δn = ±1 (1000-1500 cm-1), with n being the polyad number [B. Amyay et al., J. Chem. Phys. 144, 24312 (2016)]. Thanks to the high temperature, new assignments of vibration-rotation methane line positions have been achieved successfully in the Pentad system and some associated hot bands (Δn = ±2) observed in the spectral region 2600-3300 cm-1. In particular, rotational assignments in the cold band [Pentad-ground state (GS)] and in the first related hot band (Octad-Dyad) were extended up to J = 30 and 27, respectively. In addition, 1525 new transitions belonging to the Tetradecad-Pentad hot band system were assigned for the first time, up to J = 20. The effective global model used to deal with the new assignments was developed to the 6th order for the first three polyads (Monad, Dyad, and Pentad), and to the 5th order for both the Octad and the Tetradecad. 1306 effective parameters were fitted with a dimensionless standard deviation σ = 2.64. The root mean square deviations dRMS obtained are 4.18 × 10-3 cm-1 for the Pentad-GS cold band, 2.48 × 10-3 cm-1 for the Octad-Dyad, and 1.43 × 10-3 cm-1 for the Tetradecad-Pentad hot bands.

  10. Comparability of red/near-infrared reflectance and NDVI based on the spectral response function between MODIS and 30 other satellite sensors using rice canopy spectra.

    Science.gov (United States)

    Huang, Weijiao; Huang, Jingfeng; Wang, Xiuzhen; Wang, Fumin; Shi, Jingjing

    2013-11-26

    Long-term monitoring of regional and global environment changes often depends on the combined use of multi-source sensor data. The most widely used vegetation index is the normalized difference vegetation index (NDVI), which is a function of the red and near-infrared (NIR) spectral bands. The reflectance and NDVI data sets derived from different satellite sensor systems will not be directly comparable due to different spectral response functions (SRF), which has been recognized as one of the most important sources of uncertainty in the multi-sensor data analysis. This study quantified the influence of SRFs on the red and NIR reflectances and NDVI derived from 31 Earth observation satellite sensors. For this purpose, spectroradiometric measurements were performed for paddy rice grown under varied nitrogen levels and at different growth stages. The rice canopy reflectances were convoluted with the spectral response functions of various satellite instruments to simulate sensor-specific reflectances in the red and NIR channels. NDVI values were then calculated using the simulated red and NIR reflectances. The results showed that as compared to the Terra MODIS, the mean relative percentage difference (RPD) ranged from -12.67% to 36.30% for the red reflectance, -8.52% to -0.23% for the NIR reflectance, and -9.32% to 3.10% for the NDVI. The mean absolute percentage difference (APD) compared to the Terra MODIS ranged from 1.28% to 36.30% for the red reflectance, 0.84% to 8.71% for the NIR reflectance, and 0.59% to 9.32% for the NDVI. The lowest APD between MODIS and the other 30 satellite sensors was observed for Landsat5 TM for the red reflectance, CBERS02B CCD for the NIR reflectance and Landsat4 TM for the NDVI. In addition, the largest APD between MODIS and the other 30 satellite sensors was observed for IKONOS for the red reflectance, AVHRR1 onboard NOAA8 for the NIR reflectance and IKONOS for the NDVI. The results also indicated that AVHRRs onboard NOAA7-17 showed

  11. Microsolvation of the water cation in neon: Infrared spectra and potential energy surface of the H2O+-Ne open-shell ionic complex

    Science.gov (United States)

    Dopfer, Otto; Roth, Doris; Maier, John P.

    2001-04-01

    The intermolecular potential of the H2O+-Ne open-shell ionic dimer in its doublet electronic ground state has been investigated by infrared spectroscopy in the vicinity of the O-H stretch vibrations (ν1 and ν3) and ab initio calculations at the unrestricted Møller-Plesset second-order (MP2) level with a basis set of aug-cc-pVTZ quality. The rovibrational structure of the photodissociation spectrum is consistent with a proton-bound planar H-O-H-Ne structure and a Ne-H separation of R0=1.815(5) Å. The complexation-induced redshifts are Δν1=-69 cm-1 and Δν3=-6 cm-1, respectively. Tunneling splittings observed in the perpendicular component of the ν3 hybrid band of H2O+-Ne are attributed to hindered internal rotation between the two equivalent proton-bound equilibrium structures. The interpretation of the H2O+-Ne spectrum is supported by the spectrum of the monodeuterated species, for which both the proton-bound and the deuteron-bound isomers are observed (DOH+-Ne, HOD+-Ne). The equilibrium structure of the calculated potential energy surface of H2O+-Ne has a slightly translinear proton bond, which is characterized by a Ne-H separation of Re=1.77 Å, a bond angle of φe=174°, and dissociation energies of De=756 cm-1 and D0=476 cm-1. According to the calculated potential, the exchange tunneling between the two equivalent minima occurs via the planar bridged transition state with C2v symmetry and a barrier of 340 cm-1. In general, the calculated properties of H2O+-Ne show good agreement with the experimental data. Initial steps in the microsolvation of the water cation in neon are discussed by comparing the calculated and experimental properties of H2O+-Nen (n=0-2) with neon matrix isolation data (n→∞).

  12. BETA SPECTRA. I. Negatrons spectra

    International Nuclear Information System (INIS)

    Grau Malonda, A.; Garcia-Torano, E.

    1978-01-01

    Using the Fermi theory of beta decay, the beta spectra for 62 negatrons emitters have been computed introducing a correction factor for unique forbidden transitions. These spectra are plotted vs. energy, once normal i sed, and tabulated with the related Fermi functions. The average and median energies are calculated. (Author)

  13. Simultaneous observations of electromagnetically induced transparency (EIT) and absorption (EIA) in a multi-level V-type system of 87Rb and theoretical simulation of the observed spectra using a multi-mode approach.

    Science.gov (United States)

    Das, Bankim Chandra; Bhattacharyya, Dipankar; Das, Arpita; Chakrabarti, Shrabana; De, Sankar

    2016-12-14

    We report here simultaneous experimental observation of Electromagnetically Induced Transparency (EIT) and Electromagnetically Induced Absorption (EIA) in a multi-level V-type system in D 2 transition of Rb87, i.e., F=2→F ' with a strong pump and a weak probe beam. We studied the probe spectrum by locking the probe beam to the transition F=2→F ' =2 while the pump is scanned from F=2→F ' . EIA is observed for the open transition (F=2→F ' =2) whereas EIT is observed in the closed transition (F=2→F ' =3). Sub natural line-width is observed for the EIA. To simulate the observed spectra theoretically, Liouville equation for the three-level V-type system is solved analytically with a multi-mode approach for the density matrix elements. We assumed both the pump and the probe beams can couple the excited states. A multi-mode approach for the coherence terms facilitates the study of all the frequency contributions due to the pump and the probe fields. Since the terms contain higher harmonics of the pump and the probe frequencies, we expressed them in Fourier transformed forms. To simulate the probe spectrum, we have solved inhomogeneous difference equations for the coherence terms using the Green's function technique and continued fraction theory. The experimental line-widths of the EIT and the EIA are compared with our theoretical model. Our system can be useful in optical switching applications as it can be precisely tuned to render the medium opaque and transparent simultaneously.

  14. Molecular Structure, Vibrational Spectra, Quantum Chemical Calculations and Photochemistry of Picolinamide and Isonicotinamide Isolated in Cryogenic Inert Matrixes and in the Neat Low-Temperature Solid Phases

    OpenAIRE

    Borba, Ana; Gómez-Zavaglia, Andrea; Fausto, R.

    2007-01-01

    Picolinamide (PA) and isonicotinamide (INA), two structural isomers of pyridinecarboxamide, have been investigated by matrix isolation and low-temperature solid-state infrared spectroscopy, combined with UV (λ > 235 nm) photoexcitation and density functional theory and ab initio (MP2) theoretical studies. In consonance with the theoretical data, both PA and INA were found to exist in a single conformation in cryogenic rare gas matrixes. Comparison between the experimental spectra of the matri...

  15. HARDERSEN IRTF ASTEROID NIR REFLECTANCE SPECTRA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset includes average near-infrared (NIR) reflectance spectra for 68 main-belt asteroids that were observed at the NASA Infrared Telescope Facility (IRTF),...

  16. Raman spectra of lithium compounds

    Science.gov (United States)

    Gorelik, V. S.; Bi, Dongxue; Voinov, Y. P.; Vodchits, A. I.; Gorshunov, B. P.; Yurasov, N. I.; Yurasova, I. I.

    2017-11-01

    The paper is devoted to the results of investigating the spontaneous Raman scattering spectra in the lithium compounds crystals in a wide spectral range by the fibre-optic spectroscopy method. We also present the stimulated Raman scattering spectra in the lithium hydroxide and lithium deuteride crystals obtained with the use of powerful laser source. The symmetry properties of the lithium hydroxide, lithium hydroxide monohydrate and lithium deuteride crystals optical modes were analyzed by means of the irreducible representations of the point symmetry groups. We have established the selection rules in the Raman and infrared absorption spectra of LiOH, LiOH·H2O and LiD crystals.

  17. Lattice vibration spectra. 16

    International Nuclear Information System (INIS)

    Lutz, H.D.; Willich, P.

    1977-01-01

    The FIR absorption spectra of pyrite type compounds RuS 2 , RuSsub(2-x)Sesub(x), RuSe 2 , RuTe 2 , OsS 2 , OsSe 2 , and PtP 2 as well as loellingite type phosphides FeP 2 , RuP 2 , and OsP 2 are reported. For RuS 2 , RuSe 2 , RuTe 2 , OsS 2 , and PtP 2 all of the five infrared allowed modes (k = 0) are observed. As a first result of a numerical normal coordinate treatment vibration forms of pyrite structure are communicated. The spectra show that lattice forces of corresponding sulfides, tellurides, and phosphides are about the same strength, but increase strongly by substitution of iron by ruthenium and especially of ruthenium by osmium. The lattice constants of the RuSsub(2-x)Sesub(x) solid solution obey Vegard's rule. (author)

  18. Evaluation of hybrid theoretical approaches for structural determination of a glycine-linked cisplatin derivative via infrared multiple photon dissociation (IRMPD) action spectroscopy

    NARCIS (Netherlands)

    He, C.C.; Kimutai, B.; Bao, X.; Hamlow, L.; Zhu, Y.; Strobehn, S.F.; Gao, J.; Berden, G.; Oomens, J.; Chow, C.S.; Rodgers, M.T.

    2015-01-01

    To gain a better understanding of the binding mechanism and assist in the optimization of chemical probing and drug design applications, experimental and theoretical studies of a series of amino acid-linked cisplatin derivatives are being pursued. Glyplatin (glycine-linked cisplatin) was chosen for

  19. A high-resolution atlas of the infrared spectrum of the Sun and the Earth atmosphere from space: A compilation of ATMOS spectra of the region from 650 to 4800 cm (2.3 to 16 micron). Volume 1: The Sun

    Science.gov (United States)

    Farmer, Crofton B.; Norton, Robert H.

    1989-01-01

    During the period April 29 through May 2, 1985, the Atmospheric Trace Molecular Spectroscopy experiment was operated as part of the Spacelab-3 payload of the shuttle Challenger. The instrument, a modified Michelson Interferometer covering the frequency range from 600 to 5000/cm, at a spectral resolution of 0.01/cm, recorded infrared spectra of the Sun and of the Earth's atmosphere at times close to entry into and exit from occultation by the Earth's limb as seen from the shuttle orbit of 360 km. Spectra were obtained that are free from absorptions due to constituents of the atmosphere (i.e., solar pure spectra), as well as spectra of the atmosphere itself, covering line-of-sight tangent altitudes that span the range from the lower thermosphere to the bottom of the troposphere. This atlas, believed to be the first record of observations of the continuous high resolution infrared spectrum of the Sun and the Earth's atmosphere from space, provides a compilation of these spectra arranged in a hardcopy format suitable for quick-look reference purposes; the data are also available in digital form.

  20. Infrared Spectra of the 10-μm Bands of 1,2-Difluoroethane and 1,1,2-Trifluoroethane: Vibrationally Mediated Torsional Tunneling in 1,1,2-Trifluoroethane

    Science.gov (United States)

    Stone, Stephen C.; Miller, C. Cameron; Philips, Laura A.; Andrews, A. M.; Fraser, G. T.; Pate, B. H.; Xu, Li-Hong

    1995-12-01

    The 3-MHz-resolution infrared spectra of the 10-μm bands of thegaucheconformer of 1,2-difluoroethane (HFC152) and theC1-symmetry conformer of 1,1,2-trifluoroethane (HFC143) have been measured using a molecular-beam electric-resonance optothermal spectrometer with a tunable microwave-sideband CO2laser source. For 1,2-difluoroethane, two bands have been studied, the ν17B-symmetry C-F stretch at 1077.3 cm-1and the ν13B-symmetry CH2rock at 896.6 cm-1. Both bands are well fit to a asymmetric-rotor Hamiltonian to better than 0.5 MHz. The ν13band is effectively unperturbed, while the ν17band is weakly perturbed, as shown by the large change in centrifugal distortion constants from the ground state values. Two bands have also been studied for 1,1,2-trifluoroethane, the ν11symmetric CF2stretch at 1077.2 cm-1and the ν13C-C stretch at 905.1 cm-1. One of the two bands, ν11, is unperturbed and fit to near the experimental precision. The ν13vibration, on the other hand, is weakly perturbed by an interaction with a nearby state. This perturbation leads to a doubling or splitting of the lines, due to a perturbation-induced lifting of the degeneracy of the symmetric and antisymmetric tunneling states associated with tunneling between the two equivalentC1forms. For theJ,Kastates studied, the splittings are as large as 37 MHz. Combining this observation with published low-resolution far-infrared measurements of torsional sequence-band and hot-band frequencies and calculations from an empirical torsional potential allows us to identify the perturbing state as ν17+ 6ν18. Here, ν17is the CF2twist and ν18is the torsion. The matrix element responsible for this interaction exchanges eight vibrational quanta!

  1. Iterative maximum a posteriori (IMAP-DOAS for retrieval of strongly absorbing trace gases: Model studies for CH4 and CO2 retrieval from near infrared spectra of SCIAMACHY onboard ENVISAT

    Directory of Open Access Journals (Sweden)

    C. Frankenberg

    2005-01-01

    Full Text Available In the past, differential optical absorption spectroscopy (DOAS has mostly been employed for atmospheric trace gas retrieval in the UV/Vis spectral region. New spectrometers such as SCIAMACHY onboard ENVISAT also provide near infrared channels and thus allow for the detection of greenhouse gases like CH4, CO2, or N2O. However, modifications of the classical DOAS algorithm are necessary to account for the idiosyncrasies of this spectral region, i.e. the temperature and pressure dependence of the high resolution absorption lines. Furthermore, understanding the sensitivity of the measurement of these high resolution, strong absorption lines by means of a non-ideal device, i.e. having finite spectral resolution, is of special importance. This applies not only in the NIR, but can also prove to be an issue for the UV/Vis spectral region. This paper presents a modified iterative maximum a posteriori-DOAS (IMAP-DOAS algorithm based on optimal estimation theory introduced to the remote sensing community by rodgers76. This method directly iterates the vertical column densities of the absorbers of interest until the modeled total optical density fits the measurement. Although the discussion in this paper lays emphasis on satellite retrieval, the basic principles of the algorithm also hold for arbitrary measurement geometries. This new approach is applied to modeled spectra based on a comprehensive set of atmospheric temperature and pressure profiles. This analysis reveals that the sensitivity of measurement strongly depends on the prevailing pressure-height. The IMAP-DOAS algorithm properly accounts for the sensitivity of measurement on pressure due to pressure broadening of the absorption lines. Thus, biases in the retrieved vertical columns that would arise in classical algorithms, are obviated. Here, we analyse and quantify these systematic biases as well as errors due to variations in the temperature and pressure profiles, which is indispensable for

  2. Near infrared and ultraviolet spectra of TLEs

    Czech Academy of Sciences Publication Activity Database

    Gordillo-Vázquez, F.J.; Luque, A.; Šimek, Milan

    2012-01-01

    Roč. 117, č. 5 (2012), s. 1-7 ISSN 0148-0227 Institutional research plan: CEZ:AV0Z20430508 Keywords : sprites * halos * spectroscopy Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.174, year: 2012

  3. Espectro Vibracional no Infravermelho Próximo dos Polímeros Poliestireno, Poli(Metacrilato de Metila e Policarbonato Near-Infrared Spectra of Polystyrene, Poly(Methyl Methacrylate and Polycarbonate

    Directory of Open Access Journals (Sweden)

    Sérgio C. de Araújo

    2001-01-01

    Full Text Available Os espectros no infravermelho próximo (NIR dos polímeros amorfos poliestireno (PS, poli(metacrilato de metila (PMMA e policarbonato (PC foram estudados. A tentativa de atribuição das bandas harmônicas e de combinação dos modos vibracionais do PS, PMMA e PC foi realizada baseando-se na teoria de modos locais e pelo uso do método matemático de ajuste de curvas. A correção de anarmonicidade e freqüência mecânica foi determinada em um gráfico de Birge-Sponer. Uma correção de anarmonicidade de 57 e 58 cm-1 foi obtida para os modos de estiramento dos grupos CH2 e CH do PS; 59 e 9 cm-1 para os modos de estiramento dos grupos CH3 e CO do PMMA e 53, 59 e 10 cm-1 para os modos de estiramento dos grupos CH, CH3 e CO do PC, respectivamente.The near-infrared (NIR spectra of the amorphous polymers polystyrene (PS, poly(methyl methacrylate (PMMA, and polycarbonate (PC have been studied. The tentative assignment of the overtone and combination frequencies is made using the curve fitting calculations and the local mode theory. Anharmonicity correction and mechanical frequency were determined from a Birge-Sponer plot. A tentative assignment of stretch overtone frequency of CH2 and CH functional groups of PS; CH3 and CO functional groups of PMMA and CH, CH3 and CO functional groups of PC has been made. An anharmonicity correction of 57 and 58 cm-1 was obtained for CH2 and CH stretch modes of PS; 59 and 9 cm-1 for CH3 and CO stretch modes of PMMA and 53, 59 and 10 cm-1 for CH, CH3 and CO stretch modes of PC, respectively.

  4. Theoretical and experimental drying of a cylindrical sample by applying hot air and infrared radiation in an inert medium fluidized bed

    Directory of Open Access Journals (Sweden)

    B. Honarvar

    2012-06-01

    Full Text Available Drying of a cylindrical sample in a fluidized bed dryer containing inert particles was studied. For this purpose, a pilot-scaled fluidized bed dryer was constructed in which two different heat sources, hot air and infrared radiation were applied, and pieces of carrot were chosen as test samples. The heat transfer coefficient for cylindrical objects in a fluidized bed was also measured. The heat absorption coefficient for carrot was studied. The absorption coefficient can be computed by dividing the absorbed heat by the carrot to the heat absorbed for the water and black ink. In this regard, absorbed heat values by the carrot, water and black ink were used A mathematical model was proposed based on the mass and heat transfer phenomena within the drying sample. The results obtained by the proposed model were in favorable agreement with the experimental data.

  5. Thermal Infrared and Visible to Near-Infrared Spectral Analysis of Chert and Amorphous Silica

    Science.gov (United States)

    McDowell, M. L.; Hamilton, V. E.; Cady, S. L.; Knauth, P.

    2009-03-01

    We look in detail at the thermal infrared and visible to near-infrared spectra of various forms of chert and amorphous silica and compare the spectral variations between samples with variations in physical and chemical characteristics.

  6. Theoretical evaluation of a continues-wave Ho3+:BaY2F8 laser with mid-infrared emission

    Science.gov (United States)

    Rong, Kepeng; Cai, He; An, Guofei; Han, Juhong; Yu, Hang; Wang, Shunyan; Yu, Qiang; Wu, Peng; Zhang, Wei; Wang, Hongyuan; Wang, You

    2018-01-01

    In this paper, we build a theoretical model to study a continues-wave (CW) Ho3+:BaY2F8 laser by considering both energy transfer up-conversion (ETU) and cross relaxation (CR) processes. The influences of the pump power, reflectance of an output coupler (OC), and crystal length on the output features are systematically analyzed for an end-pumped configuration, respectively. We also investigate how the processes of ETU and CR in the energy-level system affect the output of a Ho3+:BaY2F8 laser by use of the kinetic evaluation. The simulation results show that the optical-to-optical efficiency can be promoted by adjusting the parameters such as the reflectance of an output coupler, crystal length, and pump power. It has been theoretically demonstrated that the threshold of a Ho3+:BaY2F8 laser is very high for the lasing operation in a CW mode.

  7. Mid-infrared upconversion spectroscopy

    DEFF Research Database (Denmark)

    Tidemand-Lichtenberg, Peter; Dam, Jeppe Seidelin; Andersen, H. V.

    2016-01-01

    Mid-infrared (MIR) spectroscopy is emerging as an attractive alternative to near-infrared or visible spectroscopy. MIR spectroscopy offers a unique possibility to probe the fundamental absorption bands of a large number of gases as well as the vibrational spectra of complex molecules. In this paper...

  8. Manifestation of surface phonons in far infrared reflectivity of diamond-type semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Sanchez, F.L.; Perez-Rodriguez, F. [Instituto de Fisica, Universidad Autonoma de Puebla, Apdo. Post. J-48, Puebla, Pue. 72570 (Mexico)

    2004-11-01

    The coupling of surface phonons with light at (001) surfaces of diamond-structure crystals and its manifestation in far-infrared anisotropy spectra are theoretically studied. We apply the adiabatic bond charge model to describe short-range mechanical interactions together with long-range Coulomb forces and radiation fields, and we solve the corresponding system of coupled equations for the electromagnetic field and the lattice vibrations. We calculate far-infrared normal reflectance spectra of (001) surfaces of semi-infinite diamond-type crystals. In particular, we analyse reflectance spectra for the Si(001) (2 x 1) surface, which exhibit a resonance structure associated with the excitation of surface phonon modes. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Automatic defects recognition in composite aerospace structures from experimental and theoretical analysis as part of an intelligent infrared thermographic inspection system

    Science.gov (United States)

    David, Denis G. F.; Marin, J. Y.; Tretout, Herve R.

    An original concept for IR thermography nondestructive testing is validated. The principles of image and data processing investigated and developed as well as the utilization of AI should be transposable to other nondestructive techniques such as ultrasounds and X-rays. It is shown that modeling can be used in different ways to play a great part in the detection, the interpretation, and the sizing of the defects. The original concept lies in the comparison of experimental data with theoretical ones in order to identify regions of abnormal behavior related to defects. A Laplace transforms analytical method is successfully implemented in the case of composite materials such as graphite epoxy to identify a set of thermal parameters which contributes to the expertise. This approach is extended to a more complicated composite material such as Kevlar, which presents semitransparent characteristics. This modeling technique, which expresses experimental data in terms of thermal parameters, makes it possible to increase SNR and reduce the number of thermal images to be processed.

  10. Ultraviolet spectra of planetary nebulae

    International Nuclear Information System (INIS)

    Adams, S.; Seaton, M.J.

    1982-01-01

    Features observed in infrared spectra suggest that certain very low excitation (VLE) nebulae have low C/O abundance ratios (Cohen and Barlow 1980; Aitken and Roche 1982). Fluxes in the multiplets [O II] lambda 2470 and C II] lambda 2326 have been measured for the VLE nebula He He 2-131 = HD 138403 using IUE high-dispersion spectra. An analysis similar to that of Harrington et al. (1980) for IC 418 gives C/O = 0.3 for He 2-131, compared with C/O = 1.3 for IC 418 and 0.6 for the Sun. (author)

  11. Raman spectra studies of dipeptides

    International Nuclear Information System (INIS)

    Blanchard, Simone.

    1977-10-01

    This work deals with the homogenous and heterogeneous dipeptides derived from alanine and glycine, in the solid state or in aqueous solutions, in the zwitterions or chlorhydrates form. The Raman spectra comparative study of these various forms of hydrogenated or deuterated compounds allows to specify some of the attributions which are necessary in the conformational study of the like tripeptides. These compounds contain only one peptidic group; therefore there is no possibility of intramolecular hydrogen bond which caracterise vibrations of non bonded peptidic groups and end groups. Infrared spectra of solid dipeptides will be presented and discussed in the near future [fr

  12. PCA: Principal Component Analysis for spectra modeling

    Science.gov (United States)

    Hurley, Peter D.; Oliver, Seb; Farrah, Duncan; Wang, Lingyu; Efstathiou, Andreas

    2012-07-01

    The mid-infrared spectra of ultraluminous infrared galaxies (ULIRGs) contain a variety of spectral features that can be used as diagnostics to characterize the spectra. However, such diagnostics are biased by our prior prejudices on the origin of the features. Moreover, by using only part of the spectrum they do not utilize the full information content of the spectra. Blind statistical techniques such as principal component analysis (PCA) consider the whole spectrum, find correlated features and separate them out into distinct components. This code, written in IDL, classifies principal components of IRS spectra to define a new classification scheme using 5D Gaussian mixtures modelling. The five PCs and average spectra for the four classifications to classify objects are made available with the code.

  13. A high-resolution atlas of the infrared spectrum of the sun and the earth atmosphere from space. A compilation of ATMOS spectra of the region from 650 to 4800 cm-1 (2.3 to 16 microns). Volume 2: Stratosphere and mesosphere, 650 to 3350 cm-1

    Science.gov (United States)

    Farmer, Crofton B.; Norton, Robert H.

    1989-01-01

    During the period April 29 to May 2, 1985, the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment was operated for the first time, as part of the Spacelab-3 payload of the shuttle Challenger. The principal purpose of this experiment was to study the distributions of the atmosphere's minor and trace molecular constituents. The instrument, a modified Michelson interferometer covering the frequency range from 600 to 5000/cm-1 at a spectral resolution of 0.01/cm-1, recorded infrared absorption spectra of the sun and of the earth's atmosphere at times close to entry into and exit from occultation by the earth's limb. Spectra were obtained that are free from absorptions due to constituents of the atmosphere (i.e., they are pure solar spectra), as well as spectra of the atmosphere itself, covering line-of-sight tangent altitudes that span the range from the lower thermosphere to the bottom of the troposphere. This atlas presents a compilation of these spectra arranged in a hardcopy format suitable for quick-look reference purposes. Volume 2 covers the stratosphere and mesosphere (i.e., tangent altitudes from 20 to 80 km) for frequencies from 650 to 3350/cm-1.

  14. Theoretical Characterizaiton of Visual Signatures (Muzzle Flash)

    Science.gov (United States)

    Kashinski, D. O.; Scales, A. N.; Vanderley, D. L.; Chase, G. M.; di Nallo, O. E.; Byrd, E. F. C.

    2014-05-01

    We are investigating the accuracy of theoretical models used to predict the visible, ultraviolet and infrared spectra of product materials ejected from the muzzle of currently fielded systems. Recent advances in solid propellants has made the management of muzzle signature (flash) a principle issue in weapons development across the calibers. A priori prediction of the electromagnetic spectra of formulations will allow researchers to tailor blends that yield desired signatures and determine spectrographic detection ranges. We are currently employing quantum chemistry methods at various levels of sophistication to optimize molecular geometries, compute vibrational frequencies, and determine the optical spectra of specific gas-phase molecules and radicals of interest. Electronic excitations are being computed using Time Dependent Density Functional Theory (TD-DFT). A comparison of computational results to experimental values found in the literature is used to assess the affect of basis set and functional choice on calculation accuracy. The current status of this work will be presented at the conference. Work supported by the ARL, and USMA.

  15. Low-excited f-, g- and h-states in Au, Ag and Cu observed by Fourier-transform infrared spectroscopy in the 1000-7500 cm(-1) region

    Czech Academy of Sciences Publication Activity Database

    Civiš, Svatopluk; Matulková, Irena; Cihelka, Jaroslav; Kubelík, Petr; Kawaguchi, K.; Chernov, V. E.

    2011-01-01

    Roč. 44, č. 10 (2011), s. 105002 ISSN 0953-4075 R&D Projects: GA AV ČR IAA400400705 Institutional research plan: CEZ:AV0Z40400503 Keywords : spectroscopy * infrared emission spectra * physical chemistry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.875, year: 2011

  16. Auger spectra of alkanes

    International Nuclear Information System (INIS)

    Rye, R.R.; Jennison, D.R.; Houston, J.E.

    1980-01-01

    The gas-phase Auger line shapes of the linear alkanes C 1 through C 6 and of neopentane are presented and analyzed. The general shape of the spectra are characteristic of carbon in a tetrahedral environment with the major feature in all cases occurring at approx.249 eV. The relatively large spectral changes found between methane and ethane results from the direct interaction of the terminal methyl groups in ethane, and the spectra of the higher alkanes are shown to be a composite of contributions from terminal methyl and interior methylene group carbon atoms. Theoretical analysis based on a one-electron approximation is shown to be capable of making a molecular orbital assignment by comparing calculated vertical transitions to features in the Auger spectra of ethane and propane, and, in the case of ethane, of differentiating between the 2 E/sub g/ and 2 A/sub 1g/ assignment of the ground state of (C 2 H 6 ) + . A one-electron based molecular orbital treatment, however, is shown to partially break down in propane and neopentane. Analysis of neopentane and the observed absence of any noticeable major peak energy shift with increasing molecular size (as predicted by the one-electron treatment) suggests that some Auger final states occur in which both valence holes are localized on the same subunit of the molecule

  17. Infrared spectroscopic study of the synthetic Mg-Ni talc series

    Science.gov (United States)

    Blanchard, Marc; Méheut, Merlin; Delon, Louise; Poirier, Mathilde; Micoud, Pierre; Le Roux, Christophe; Martin, François

    2018-05-01

    Five talc samples [(Mg,Ni)3Si4O10(OH)2] covering the entire Mg-Ni solid solution were synthesized following a recently developed and patented process (Dumas et al., Process for preparing a composition comprising synthetic mineral particles and composition, 2013a; Procédé de préparation d'une composition comprenant des particules minérales synthétiques et composition, 2013b), which produces sub-micron talc particles replying to industrial needs. Near- and mid-infrared spectra were collected and compared to infrared spectra modeled from first-principles calculations based on density functional theory. The good agreement between experimental and theoretical spectra allowed assigning unambiguously all absorption bands. We focused in particular on the four main OH stretching bands, which represent good probes of their local physical and chemical environment. The description of the vibrational modes at the origin of these absorption bands and the theoretical determination of absorption coefficients provide a firm basis for quantifying the talc chemical composition from infrared spectroscopy and for discussing the distribution of divalent cations in the octahedral sheet. Results confirm that these synthetic talc samples have a similar structure as natural talc, with a random distribution of Mg and Ni atoms. They only differ from natural talc by their hydrophilic character, which is due to their large proportion of reactive sites on sheet edges due to sub-micronic size of the particles. Therefore, the contribution on infrared spectra of hydroxyls adsorbed on edge sites has also been investigated by computing the infrared signature of hydroxyls of surface models.

  18. Experimental and theoretical studies of the VUV emission and absorption spectra of H{sub 2}, HD and D{sub 2} molecules; Etude experimentale et theorique des spectres d'emission et d'absorption VUV des molecules H{sub 2}, D{sub 2} et HD

    Energy Technology Data Exchange (ETDEWEB)

    Roudjane, M

    2007-12-15

    The aim of this thesis is to carry out an experimental study of the absorption and emission spectra of the D{sub 2} and HD isotopes, with high resolution, in the VUV domain and to supplement it by a theoretical study of the excited electronic states involved in the observed transitions. The emission spectra of HD and D{sub 2} are produced by Penning discharge source operating under low pressure and are recorded in the spectral range 78 - 170 nm. The recorded spectra contains more than 20.000 lines. The analysis of the spectrum consists in identifying and assigning the lines to the electronic transitions between energy levels of the molecule. The present analysis is based on our theoretical calculations of the ro-vibrational energy levels of the excited electronic states and the transition probabilities from these states towards the energy levels of the fundamental state. The theoretical results are obtained by resolving the coupled equations between the excited electronic states B{sup 1}{sigma}{sub u}{sup 1}, B'{sup 1}{sigma}{sub u}{sup 1}, C{sup 1}{pi}{sub u}{sup 1} and D{sup 1}{pi}{sub u}{sup 1}, taking into account the nonadiabatic couplings between these states, and they are obtained in the adiabatic approximation for the excited electronic states B''B-bar{sup 1}{sigma}{sub u}{sup +}, D'{sup 1}{pi}{sub u}{sup 1} and D''{sup 1}{pi}{sub u}{sup 1}. The equations are resolved using a modern method based on the discretization variables representation method. In addition, we have carried out a study of the absorption spectra of the HD and D{sub 2} molecules.

  19. FTIR spectra of whey and casein hydrolysates in relation to their functional properties

    NARCIS (Netherlands)

    Ven, van der C.; Muresan, S.; Gruppen, H.; Bont, D.B.A.; Merck, K.B.; Voragen, A.G.J.

    2002-01-01

    Mid-infrared spectra of whey and casein hydrolysates were recorded using Fourier transform infrared (FTIR) spectroscopy. Multivariate data analysis techniques were used to investigate the capacity of FTIR spectra to classify hydrolysates and to study the ability of the spectra to predict bitterness,

  20. Effect of deuteration on the vibrational spectra of organic molecules

    International Nuclear Information System (INIS)

    Billes, Ferenc; Endredi, Henrietta; Varady, Balazs

    2001-01-01

    The stable isotope substitution of organic compounds deforms their vibrational spectra. The modifications of the spectra appear as band shifts and changes in intensities and shapes of the bands. The magnitude of the effect depends on the ratio of the masses of the new and old isotopes and on the atom active position. According to these mentioned reasons large effects can be observed only if hydrogen atoms are substituted. With the effect of the substitution we dealt already in a former lecture. In this lecture we concentrate on the effect of the change of hydrogen to deuterium. We investigate the changes both experimentally and theoretically. There are two possibilities: - the hydrogen atom is in an active position, its interaction with the environment is strong, either it can dissociate or move on the skeleton of the molecule (tautomerism, resonance) and it can build hydrogen bond, (e.g. it is connected to nitrogen and oxygen atoms); - the hydrogen atom is in an indifferent position in the molecule, its interaction with the environment is weak (e.g. it joins carbon atom). When building the hydrogen bond besides the hydrogen donors also acceptors exist, namely, oxygen and nitrogen atoms having non-bonded electron pairs. When comparing the experimental and theoretical (calculated) effects of this type of isotope changes one must take into account that the calculations refer to the isolated molecule while the experimental spectra characterize the compound. The hydrogen bond is a very strong intermolecular interaction and produces tremendous changes in the infrared spectrum of the molecule in comparison to the imagined theoretical spectrum of the molecule. Some bands disappear, appear, or shift and deform drastically. The H/D change diminishes these effects. Of course, these changes entail the shift of several bands. The Raman spectrum is less sensitive to the large dipole moment changes therefore the deuteration effect is there less dramatic. Deuteration of hydrogen

  1. Far infrared spectroscopy of H II regions

    International Nuclear Information System (INIS)

    Ward, D.B.

    1976-01-01

    A fully liquid helium cooled grating spectrometer has been developed for far infrared observations from the NASA Lear Jet. This instrument has been used in observations of the galactic HII regions M42 and M17. The instrument is described, and the results of various performance tests and calibrations are presented. The methods employed in observations from the Lear Jet are described, and the data analysis procedures are discussed. The results of a search for the (O III) 88.16 micron fine structure line are presented. The intensity of the line in M17 is reported, and an upper limit given for the intensity in M42. These results are compared with theoretical predictions, and future applications of infrared line observations are discussed. Coarse resolution spectra of M42 and M17 from 45 to 115 microns are also presented. The emission from M42 is shown to be a very smooth function of wavelength, closely fitting the wavelength dependence of a 105 0 K graybody. The spectrum of M17 is very different, having a bump at approximately 75 microns and a general far infrared excess. The observed spectrum is compared to the predictions of models for M17

  2. Near IR spectra of symbiotic stars

    International Nuclear Information System (INIS)

    Andrillat, Y.

    1982-01-01

    The author reports on recent observations from the near IR spectra of symbiotic stars. The helium and oxygen lines useful for the construction of theoretical models are identified. Observations for cool stars and novae (nebular phase) are outlined and the spectra of specific symbiotic stars between lambdalambda 8000-11000 are presented and discussed. (Auth./C.F.)

  3. Infrared and Raman spectroscopy: principles and spectral interpretation

    National Research Council Canada - National Science Library

    Larkin, Peter

    2011-01-01

    .... The book reviews basic principles, instrumentation, sampling methods, quantitative analysis, origin of group frequencies and qualitative interpretation using generalized Infrared (IR) and Raman spectra...

  4. Infrared emission from protostars

    International Nuclear Information System (INIS)

    Adams, F.C.; Shu, F.H.

    1985-01-01

    The emergent spectral energy distribution at infrared to radio wavelengths is calculated for the simplest theoretical construct of a low-mass protostar. It is shown that the emergent spectrum in the infrared is insensitive to the details assumed for the temperature profile as long as allowance is made for a transition from optically thick to optically thin conditions and luminosity conservation isenforced at the inner and outer shells. The radiation in the far infrared and submillimeter wavelengths depends on the exact assumptions made for grain opacities at low frequencies. An atlas of emergent spectral energy distributions is presented for a grid of values of the instantaneous mass of the protostar and the mass infall rate. The attenuated contribution of the accretion shock to the near-infrared radiation is considered. 50 references

  5. Astrophysical interpretation of molecular spectra

    International Nuclear Information System (INIS)

    Scoville, N.Z.

    1984-01-01

    As sensitive, high resolution spectrometers are developed throughout the infrared great progress is anticipated in understanding not only the young-stellar objects but also the active galaxy nuclei so luminous in the far-infrared. In the infrared the variety of atomic and molecular spectroscopic transitions is capable of probing conditions ranging from hot circumstellar HII regions, molecular envelopes, and shock fronts at > 2000 K down to cold, low density interstellar gas at < 10 K. The ability to measure both physical conditions and kinematics aids in the separation of the physical regimes and in the building of a coherent dynamic/evolutionary model. The author briefly reviews the characteristics of some of the observed molecular transitions and theoretical considerations important for understanding their excitation. (Auth.)

  6. Comparisons of theoretical and experimental neutron spectra, 115In(n,n') and fission rates, in the centre of three spherical natural uranium and iron shell configurations, located at BR1

    International Nuclear Information System (INIS)

    De Leeuw-Gierts, G.; De Leeuw, S.; Gilliam, D.M.

    1984-01-01

    Three spherical configurations of iron and uranium shells have been studied. The configurations were a 1-cm thick natural uranium shell, a 1-cm thick natural uranium shell with an inner 7-cm thick iron shell and a 1-cm thick natural uranium shell with an inner iron shell of 14-cm thickness. For the measurements, the shells were located at the centre of a hollow cavity, 100-cm in diameter, in the vertical graphite thermal column of the BR1 reactor. The central neutron spectra were calculated by means of the DTF-IV code, using the 208-group KEDAK-3 library, and by means of the ANISN code, using the 171-group VITAMIN-C library. Central neutron spectra, measured by the proton-recoil and 6 Li(n,α)t spectrometry techniques, are compared to the theory between ∼ 100 keV and 5 MeV. Mean fission cross-sections of 240 Pu, 237 Np, 234 U, 235 U, 236 U and 238 U were deduced from the calculations. Their ratios with respect to 238 U are compared to measurements made with NBS dual fission chambers. (Auth.)

  7. EPOXI EARTH OBS - HRII CALIBRATED SPECTRA V2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset contains calibrated, 1.05- to 4.8-micron spectra of Earth acquired by the High Resolution Infrared Spectrometer (HRII) during the EPOCh and Cruise 2...

  8. REDDY MAIN BELT ASTEROID SPECTRA V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains low-resolution (R~150) near-infrared (0.7-2.5 microns) spectra of 90 main belt asteroids observed with the SpeX instrument on the NASA...

  9. Theoretical and Experimental Spectroscopic Analysis of Cyano-Substituted Styrylpyridine Compounds

    Directory of Open Access Journals (Sweden)

    Jorge Lopez-Cruz

    2013-02-01

    Full Text Available A combined theoretical and experimental study on the structure, infrared, UV-Vis and 1H NMR data of trans-2-(m-cyanostyrylpyridine, trans-2-[3-methyl-(m-cyanostyryl]pyridine and trans-4-(m-cyanostyrylpyridine is presented. The synthesis was carried out with an efficient Knoevenagel condensation using green chemistry conditions. Theoretical geometry optimizations and their IR spectra were carried out using the Density Functional Theory (DFT in both gas and solution phases. For theoretical UV-Vis and 1H NMR spectra, the Time-Dependent DFT (TD-DFT and the Gauge-Including Atomic Orbital (GIAO methods were used, respectively. The theoretical characterization matched the experimental measurements, showing a good correlation. The effect of cyano- and methyl- substituents, as well as of the N-atom position in the pyridine ring on the UV-Vis, IR and NMR spectra, was evaluated. The UV-Vis results showed no significant effect due to electron-withdrawing cyano- and electron-donating methyl-substituents. The N-atom position, however, caused a slight change in the maximum absorption wavelengths. The IR normal modes were assigned for the cyano- and methyl-groups. 1H NMR spectra showed the typical doublet signals due to protons in the trans position of a double bond. The theoretical characterization was visibly useful to assign accurately the signals in IR and 1H NMR spectra, as well as to identify the most probable conformation that could be present in the formation of the styrylpyridine-like compounds.

  10. Study of GeSn Alloy for Low Cost Monolithic Mid Infrared Quantum Well Sensor

    Directory of Open Access Journals (Sweden)

    Prakash PAREEK

    2017-02-01

    Full Text Available This paper focuses on theoretical study of Tin incorporated group IV alloys particularly GeSn and design of quantum well sensor for mid infrared sensing applications. Initially, the physics behind the selection of material for midinfrared sensor is explained. The importance of controlling strain in GeSn alloy is also explained. The physical background and motivation for incorporation of Tin(Sn in Germanium is briefly narrated. Eigen energy states for different Sn concentrations are obtained for strain compensated quantum well in G valley conduction band (GCB, heavy hole (HH band and light hole (LH band by solving coupled Schrödinger and Poisson equations simultaneously. Sn concentration dependent absorption spectra for HH- GCB transition reveals that significant absorption observed in mid infrared range (3-5 µm. So, Ge1-x Snx quantum well can be used for mid infrared sensing applications.

  11. Ar 3p photoelectron sideband spectra in two-color XUV + NIR laser fields

    Science.gov (United States)

    Minemoto, Shinichirou; Shimada, Hiroyuki; Komatsu, Kazma; Komatsubara, Wataru; Majima, Takuya; Mizuno, Tomoya; Owada, Shigeki; Sakai, Hirofumi; Togashi, Tadashi; Yoshida, Shintaro; Yabashi, Makina; Yagishita, Akira

    2018-04-01

    We performed photoelectron spectroscopy using femtosecond XUV pulses from a free-electron laser and femtosecond near-infrared pulses from a synchronized laser, and succeeded in measuring Ar 3p photoelectron sideband spectra due to the two-color above-threshold ionization. In our calculations of the first-order time-dependent perturbation theoretical model based on the strong field approximation, the photoelectron sideband spectra and their angular distributions are well reproduced by considering the timing jitter between the XUV and the NIR pulses, showing that the timing jitter in our experiments was distributed over the width of {1.0}+0.4-0.2 ps. The present approach can be used as a method to evaluate the timing jitter inevitable in FEL experiments.

  12. UV and infrared absorption spectra, atmospheric lifetimes, and ozone depletion and global warming potentials for CCl2FCCl2F (CFC-112, CCl3CClF2 (CFC-112a, CCl3CF3 (CFC-113a, and CCl2FCF3 (CFC-114a

    Directory of Open Access Journals (Sweden)

    M. E. Davis

    2016-07-01

    Full Text Available The potential impact of CCl2FCF3 (CFC-114a and the recently observed CCl2FCCl2F (CFC-112, CCl3CClF2 (CFC-112a, and CCl3CF3 (CFC-113a chlorofluorocarbons (CFCs on stratospheric ozone and climate is presently not well characterized. In this study, the UV absorption spectra of these CFCs were measured between 192.5 and 235 nm over the temperature range 207–323 K. Precise parameterizations of the UV absorption spectra are presented. A 2-D atmospheric model was used to evaluate the CFC atmospheric loss processes, lifetimes, ozone depletion potentials (ODPs, and the associated uncertainty ranges in these metrics due to the kinetic and photochemical uncertainty. The CFCs are primarily removed in the stratosphere by short-wavelength UV photolysis with calculated global annually averaged steady-state lifetimes (years of 63.6 (61.9–64.7, 51.5 (50.0–52.6, 55.4 (54.3–56.3, and 105.3 (102.9–107.4 for CFC-112, CFC-112a, CFC-113a, and CFC-114a, respectively. The range of lifetimes given in parentheses is due to the 2σ uncertainty in the UV absorption spectra and O(1D rate coefficients included in the model calculations. The 2-D model was also used to calculate the CFC ozone depletion potentials (ODPs with values of 0.98, 0.86, 0.73, and 0.72 obtained for CFC-112, CFC-112a, CFC-113a, and CFC-114a, respectively. Using the infrared absorption spectra and lifetimes determined in this work, the CFC global warming potentials (GWPs were estimated to be 4260 (CFC-112, 3330 (CFC-112a, 3650 (CFC-113a, and 6510 (CFC-114a for the 100-year time horizon.

  13. Theoretical study on photon-phonon coupling at (001)-(2 x 1) surfaces of Ge and {alpha}-Sn

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Sanchez, F.L. [Escuela de Ciencias, Universidad Autonoma ' ' Benito Juarez' ' de Oaxaca, Av. Universidad S/N, Ex-Hacienda de Cinco Senores, Ciudad Universitaria, Oaxaca de Juarez, Oax., 68120 (Mexico); Perez-Rodriguez, F. [Instituto de Fisica, Benemerita Universidad Autonoma de Puebla, Apdo. Post. J-48, Puebla, Pue. 72570 (Mexico)

    2011-06-15

    We present a study of the far-infrared reflectance anisotropy spectra for (001) surfaces of Ge and {alpha}-Sn in the (2 x 1) asymmetric dimer geometry, which exhibit a resonance structure associated with the excitation of surface phonon modes. We have employed a theoretical formalism, based on the adiabatic bond-charge model (ABCM), for computing the far-infrared reflectance anisotropy spectra. In comparison with previous theoretical results for silicon and diamond surfaces, the resonance structure in the reflectance anisotropy spectrum for Ge(001)-(2 x 1) turns out to be similar to that observed in the spectrum for the Si(001)-(2 x 1) surface, whereas the spectrum for {alpha}-Sn(001)-(2 x 1) surface is noticeably different from the others. We have established a trend of far-infrared reflectance anisotropy spectra for IV(001) surfaces: the weaker dimer strength, the stronger resonances of low-frequency surface phonons. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Density functional theory for prediction of far-infrared vibrational frequencies: molecular crystals of astrophysical interest

    Science.gov (United States)

    Ennis, C.; Auchettl, R.; Appadoo, D. R. T.; Robertson, E. G.

    2017-11-01

    Solid-state density functional theory code has been implemented for the structure optimization of crystalline methanol, acetaldehyde and acetic acid and for the calculation of infrared frequencies. The results are compared to thin film spectra obtained from low-temperature experiments performed at the Australian Synchrotron. Harmonic frequency calculations of the internal modes calculated at the B3LYP-D3/m-6-311G(d) level shows higher deviation from infrared experiment than more advanced theory applied to the gas phase. Importantly for the solid-state, the simulation of low-frequency molecular lattice modes closely resembles the observed far-infrared features after application of a 0.92 scaling factor. This allowed experimental peaks to be assigned to specific translation and libration modes, including acetaldehyde and acetic acid lattice features for the first time. These frequency calculations have been performed without the need for supercomputing resources that are required for large molecular clusters using comparable levels of theory. This new theoretical approach will find use for the rapid characterization of intermolecular interactions and bonding in crystals, and the assignment of far-infrared spectra for crystalline samples such as pharmaceuticals and molecular ices. One interesting application may be for the detection of species of prebiotic interest on the surfaces of Kuiper-Belt and Trans-Neptunian Objects. At such locations, the three small organic molecules studied here could reside in their crystalline phase. The far-infrared spectra for their low-temperature solid phases are collected under planetary conditions, allowing us to compile and assign their most intense spectral features to assist future far-infrared surveys of icy Solar system surfaces.

  15. INFRARED AND RAMAN SPECTROSCOPIC STUDY OF ION ...

    African Journals Online (AJOL)

    Infrared and Raman spectroscopy techniques have been used to study the ionic interactions of strontium(II) and barium(II) with thiocyanate ion in liquid ammonia. A number of bands were observed in both n (CN) and n (CS) regions of infrared and Raman spectra and these were assigned to 1:1 contact ion pair, ...

  16. Studies of the tautomeric equilibrium of 1,3-thiazolidine-2-thione: Theoretical and experimental approaches

    Energy Technology Data Exchange (ETDEWEB)

    Abbehausen, Camilla; Paiva, Raphael E.F. de [Institute of Chemistry, University of Campinas - UNICAMP, P.O. Box 6154, 13083-970 Campinas, SP (Brazil); Formiga, Andre L.B., E-mail: formiga@iqm.unicamp.br [Institute of Chemistry, University of Campinas - UNICAMP, P.O. Box 6154, 13083-970 Campinas, SP (Brazil); Corbi, Pedro P. [Institute of Chemistry, University of Campinas - UNICAMP, P.O. Box 6154, 13083-970 Campinas, SP (Brazil)

    2012-10-26

    Highlights: Black-Right-Pointing-Pointer Tautomeric equilibrium in solution. Black-Right-Pointing-Pointer Spectroscopic and theoretical studies. Black-Right-Pointing-Pointer UV-Vis theoretical and experimental spectra. Black-Right-Pointing-Pointer {sup 1}H NMR theoretical and experimental spectra. -- Abstract: The tautomeric equilibrium of the thione/thiol forms of 1,3-thiazolidine-2-thione was studied by nuclear magnetic resonance, infrared and ultraviolet-visible spectroscopies. Density functional theory was used to support the experimental data and indicates the predominance of the thione tautomer in the solid state, being in agreement with previously reported crystallographic data. In solution, the tautomeric equilibrium was evaluated using {sup 1}H NMR at different temperatures in four deuterated solvents acetonitrile, dimethylsulfoxide, chloroform and methanol. The equilibrium constants, K = (thiol)/(thione), and free Gibbs energies were obtained by integration of N bonded hydrogen signals at each temperature for each solvent, excluding methanol. The endothermic tautomerization is entropy-driven and the combined effect of solvent and temperature can be used to achieve almost 50% thiol concentrations in solution. The nature of the electronic transitions was investigated theoretically and the assignment of the bands was made using time-dependent DFT as well as the influence of solvent on the energy of the most important bands of the spectra.

  17. Infrared astronomy

    International Nuclear Information System (INIS)

    Setti, G.; Fazio, G.

    1978-01-01

    This volume contains lectures describing the important achievements in infrared astronomy. The topics included are galactic infrared sources and their role in star formation, the nature of the interstellar medium and galactic structure, the interpretation of infrared, optical and radio observations of extra-galactic sources and their role in the origin and structure of the universe, instrumental techniques and a review of future space observations. (C.F.)

  18. Vibrational spectroscopic and quantum theoretical study of host-guest interactions in clathrates: I. Hofmann type clathrates

    Directory of Open Access Journals (Sweden)

    VLADIMIR M. PETRUSEVSKI

    2000-06-01

    Full Text Available Hofmann type clatharates are host-guest compounds with the general formula M(NH32M'(CN4·2G, in which M(NH32M'(CN4 is the host lattice and G is benzene, the guest molecule. In previous studies, host-guest interactions have been investigated by analyzing the RT and LNT vibrational (infrared, far infrared and Raman spectra of these clathrates. All the observed changes in the vibrational spectra of these clathrates are referred to a host-guest interaction originating from weak hydrogen bonding between the ammonia hydrogen atoms from the host lattice and the p electron cloud of the guest (benzene molecules. In order to obtain an insight into the relative importance of the local crystalline field vs. the anharmonicity effects on the spectroscopic properties of the guest species upon enclathration, as well as to explain the observed band shifts and splittings, several quantum theoretical approaches are proposed.

  19. Tips for deciphering and quick calculation of radiation spectra

    Science.gov (United States)

    Bondarenco, M. V.

    2018-04-01

    Radiation spectra from ultra-relativistic electrons in thin [Tll lf(ω)] and thick [Tgg lf(ω)] targets are discussed. The method of simplified averaging is described by examples of Landau-Pomeranchuk-Migdal effect and radiation at doughnut scattering. General infrared and ultraviolet asymptotic properties of radiation spectra are discussed.

  20. Beta spectra. II-Positron spectra

    International Nuclear Information System (INIS)

    Grau, A.; Garcia-Torano, E.

    1981-01-01

    Using the Fermi theory of beta decay, the beta spectra for 30 positron emitters have been computed, introducing a correction factor for unique forbidden transitions. The spectra are ploted vs. energy, once normalised, and tabulated with the related Fermi functions. The average and median energies are calculated. (author)