VizieR Online Data Catalog: IRS spectra with features of crystalline silicates (Chen+, 2016)

Science.gov (United States)

Chen, R.; Luo, A.; Liu, J.; Jiang, B.

2018-04-01

Spectra taken by the IRS (Houck et al. 2004ApJS..154...18H) on the Spitzer space telescope (Werner et al. 2004ApJS..154....1W) are now publicly available. These spectra are produced using the bksub.tbl products from SL and LL modules of final SSC pipeline, version 18.18. From the IRS data archive, we found a collection of 16986 low-resolution spectra. The spectra are merged by four slits: SL2 (5.21-7.56 μm), SL1 (7.57-14.28 μm), LL2 (14.29-20.66 μm), and LL1 (20.67-38.00 μm). As crystalline silicates have no features in the SL2 band, we choose the spectra that include all the other three bands: SL1, LL2, and LL1 so that the object has a continuous spectrum from about 7.5-38 μm. In this way, five of the seven infrared complexes of crystalline silicates are covered, i.e., the 10, 18, 23, 28, and 33 μm complexes. (5 data files).

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.

Model and measurements of linear mixing in thermal IR ground leaving radiance spectra

Science.gov (United States)

Balick, Lee; Clodius, William; Jeffery, Christopher; Theiler, James; McCabe, Matthew; Gillespie, Alan; Mushkin, Amit; Danilina, Iryna

2007-10-01

Hyperspectral thermal IR remote sensing is an effective tool for the detection and identification of gas plumes and solid materials. Virtually all remotely sensed thermal IR pixels are mixtures of different materials and temperatures. As sensors improve and hyperspectral thermal IR remote sensing becomes more quantitative, the concept of homogeneous pixels becomes inadequate. The contributions of the constituents to the pixel spectral ground leaving radiance are weighted by their spectral emissivities and their temperature, or more correctly, temperature distributions, because real pixels are rarely thermally homogeneous. Planck's Law defines a relationship between temperature and radiance that is strongly wavelength dependent, even for blackbodies. Spectral ground leaving radiance (GLR) from mixed pixels is temperature and wavelength dependent and the relationship between observed radiance spectra from mixed pixels and library emissivity spectra of mixtures of 'pure' materials is indirect. A simple model of linear mixing of subpixel radiance as a function of material type, the temperature distribution of each material and the abundance of the material within a pixel is presented. The model indicates that, qualitatively and given normal environmental temperature variability, spectral features remain observable in mixtures as long as the material occupies more than roughly 10% of the pixel. Field measurements of known targets made on the ground and by an airborne sensor are presented here and serve as a reality check on the model. Target spectral GLR from mixtures as a function of temperature distribution and abundance within the pixel at day and night are presented and compare well qualitatively with model output.

Synoptic Mid-IR Spectra ToO Novae

Science.gov (United States)

Helton, L. Andrew; Woodward, Chick; Evans, Nye; Geballe, Tom; Spitzer Nova Team

2007-02-01

Stars are the engines of energy production and chemical evolution in our Universe, depositing radiative and mechanical energy into their environments and enriching the ambient ISM with elements synthesized in their interiors and dust grains condensed in their atmospheres. Classical novae (CN) contribute to this cycle of chemical enrichment through explosive nucleosynthesis and the violent ejection of material dredged from the white dwarf progenitor and mixed with the accreted surface layers. We propose to obtain mid-IR spectra of a new galactic CN in outburst to investigate aspects of the CN phenomenon including the in situ formation and mineralogy of nova dust and the elemental abundances resulting from thermonuclear runaway. Synoptic, high S/N Michelle spectra permit: 1) determination of the grain size distribution and mineral composition of nova dust; 2) estimation of chemical abundances of nova ejecta from coronal and other emission line spectroscopy; and 3) measurement of the density and masses of the ejecta. This Gemini `Target of Opportunity' initiative (trigger K=5- 8 mag, assuming adequate PWFS guide stars exist) complements our extensive Spitzer, Chandra, Swift, XMM-Newton CN DDT/ToO programs.

Discrimination of Chinese Sauce liquor using FT-IR and two-dimensional correlation IR spectroscopy

Science.gov (United States)

Sun, Su-Qin; Li, Chang-Wen; Wei, Ji-Ping; Zhou, Qun; Noda, Isao

2006-11-01

We applied the three-step IR macro-fingerprint identification method to obtain the IR characteristic fingerprints of so-called Chinese Sauce liquor (Moutai liquor and Kinsly liquor) and a counterfeit Moutai. These fingerprints can be used for the identification and discrimination of similar liquor products. The comparison of their conventional IR spectra, as the first step of identification, shows that the primary difference in Sauce liquor is the intensity of characteristic peaks at 1592 and 1225 cm -1. The comparison of the second derivative IR spectra, as the second step of identification, shows that the characteristic absorption in 1400-1800 cm -1 is substantially different. The comparison of 2D-IR correlation spectra, as the third and final step of identification, can discriminate the liquors from another direction. Furthermore, the method was successfully applied to the discrimination of a counterfeit Moutai from the genuine Sauce liquor. The success of the three-step IR macro-fingerprint identification to provide a rapid and effective method for the identification of Chinese liquor suggests the potential extension of this technique to the identification and discrimination of other wine and spirits, as well.

An IR investigation of solid amorphous ethanol - Spectra, properties, and phase changes

Science.gov (United States)

Hudson, Reggie L.

2017-12-01

Mid- and far-infrared spectra of condensed ethanol (CH3CH2OH) at 10-160 K are presented, with a special focus on amorphous ethanol, the form of greatest astrochemical interest, and with special attention given to changes at 155-160 K. Infrared spectra of amorphous and crystalline forms are shown. The refractive index at 670 nm of amorphous ethanol at 16 K is reported, along with three IR band strengths and a density. A comparison is made to recent work on the isoelectronic compound ethanethiol (CH3CH2SH), and several astrochemical applications are suggested for future study.

Far IR spectra of Th(IV) halide complexes of some heterocyclic bases

International Nuclear Information System (INIS)

Srivastava, A.K.; Agarwal, R.K.; Srivastava, M.; Kapoor, V.; Srivastava, T.N.

1981-01-01

The synthesis and IR spectra of Th(IV) perchlorato, nitrato and thiocyanato complexes of some heterocyclic bases have been reported. Halogens are common ligands in coordination chemistry forming coordinate bonds with metals readily. Metal halogen (M-X) stretching bands show a strong absorption in the far-IR region. Very little information is available on Th-X stretching frequencies. In the present communication, adducts of Th(IV) halide with certain nitrogen heterocyclic bases such as pyridine, α-picoline, 2-amino pyridine, 2:4-lutidine, 2:6-lutidine, quinoline, 2,2'-bipyridine and 1,10-phenanthroline were synthesised and characterised. Experimental details are given. Results are presented and discussed. (author)

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.

SPITZER IRS SPECTRA OF LUMINOUS 8 μm SOURCES IN THE LARGE MAGELLANIC CLOUD: TESTING COLOR-BASED CLASSIFICATIONS

International Nuclear Information System (INIS)

Buchanan, Catherine L.; Kastner, Joel H.; Hrivnak, Bruce J.; Sahai, Raghvendra

2009-01-01

We present archival Spitzer Infrared Spectrograph (IRS) spectra of 19 luminous 8 μm selected sources in the Large Magellanic Cloud (LMC). The object classes derived from these spectra and from an additional 24 spectra in the literature are compared with classifications based on Two Micron All Sky Survey (2MASS)/MSX (J, H, K, and 8 μm) colors in order to test the 'JHK8' (Kastner et al.) classification scheme. The IRS spectra confirm the classifications of 22 of the 31 sources that can be classified under the JHK8 system. The spectroscopic classification of 12 objects that were unclassifiable in the JHK8 scheme allow us to characterize regions of the color-color diagrams that previously lacked spectroscopic verification, enabling refinements to the JHK8 classification system. The results of these new classifications are consistent with previous results concerning the identification of the most infrared-luminous objects in the LMC. In particular, while the IRS spectra reveal several new examples of asymptotic giant branch (AGB) stars with O-rich envelopes, such objects are still far outnumbered by carbon stars (C-rich AGB stars). We show that Spitzer IRAC/MIPS color-color diagrams provide improved discrimination between red supergiants and oxygen-rich and carbon-rich AGB stars relative to those based on 2MASS/MSX colors. These diagrams will enable the most luminous IR sources in Local Group galaxies to be classified with high confidence based on their Spitzer colors. Such characterizations of stellar populations will continue to be possible during Spitzer's warm mission through the use of IRAC [3.6]-[4.5] and 2MASS colors.

Mid-IR Spectra of Refractory Minerals Relevant to Comets

Science.gov (United States)

Jauhari, Shekeab

2008-09-01

On 4 July 2005 the Spitzer Space Telescope obtained mid-IR ( 5-40 µm) spectra of the ejecta from the hypervelocity impact of the Deep Impact projectile with comet 9P/Tempel 1. Spectral modeling demonstrates that there are abundant minerals present in the ejecta including Ca/Fe/Mg-rich silicates, carbonates, phyllosilicates, water ice, amorphous carbon, and sulfides [1]. However, precise mineralogical identifications are hampered by the lack of comprehensive 5 - 40 µm spectral measurements of the emissivity for a broad compositional range of these materials. Here, we present our initial results for 2 - 50 µm transmission spectra and absorption constants for materials relevant to comets, including pyrrhotite, pyrite, and several phyllosilicate (clay) minerals. Measuring the transmission of materials over the full spectral range sensitive by Spitzer requires grinding the minerals into submicron powders and then mixing them with KBr (for the 1-25 um region) and polyethylene (16-50 um region) to form pellets. Transmission measurements of sub-micron sulfides are particularly difficult to obtain because the minerals oxidize rapidly upon grinding and subsequent handling unless special care is taken. A detailed description of our sample preparation and measurement technique will be provided to assist other researchers in their attempts to acquire similar spectra. References: [1] Lisse, C.M. et al., Science 313, 635 - 640 (2006)

Effect of second-sphere cation nature on the character of IR spectra of molybdeum(4, 5) cyanide complexes

International Nuclear Information System (INIS)

Zubritskaya, D.I.; Semenishin, D.I.; Vretsena, N.B.; Chernyak, B.I.

1989-01-01

The effect of nature of second-sphere cations on IR spectra of molybdeum (4, 5) cyanide complexes is studied. It is found that the increase in the first ionization potential (radius decrease) brings about the increase in the frequency of valent variations ν (CN). This proves the possibility of formation of bridge bonds Mo-CN-M in the compounds (M-alkali, alkaline earth or rare earth metal, Cs, Y). The conclusion is made on a considerable effect of the nature of second-sphere cations and oxidation degree of complexing agent atoms on the nature of IR spectra of octacyanomolybdates (4, 5)

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

FT-IR, FT-Raman spectra and DFT calculations of melaminium perchlorate monohydrate

Science.gov (United States)

Kanagathara, N.; Marchewka, M. K.; Drozd, M.; Renganathan, N. G.; Gunasekaran, S.; Anbalagan, G.

2013-08-01

Melaminium perchlorate monohydrate (MPM), an organic material has been synthesized by slow solvent evaporation method at room temperature. Powder X-ray diffraction analysis confirms that MPM crystal belongs to triclinic system with space group P-1. FTIR and FT Raman spectra are recorded at room temperature. Functional group assignment has been made for the melaminium cations and perchlorate anions. Vibrational spectra have also been discussed on the basis of quantum chemical density functional theory (DFT) calculations using Firefly (PC GAMESS) version 7.1 G. Vibrational frequencies are calculated and scaled values are compared with experimental values. The assignment of the bands has been made on the basis of the calculated PED. The Mulliken charges, HOMO-LUMO orbital energies are analyzed directly from Firefly program log files and graphically illustrated. HOMO-LUMO energy gap and other related molecular properties are also calculated. The theoretically constructed FT-IR and FT-Raman spectra of MPM coincide with the experimental one. The chemical structure of the compound has been established by 1H and 13C NMR spectra. No detectable signal was observed during powder test for second harmonic generation.

Manifestation of Crystal Lattice Distortions in the IR Reflection Spectra of Abrasion-Treated ZnSe Ceramics

Science.gov (United States)

Sitnikova, V. E.; Dunaev, A. A.; Mamalimov, R. I.; Pakhomov, P. M.; Khizhnyak, S. D.; Chmel, A. E.

2017-07-01

The Fourier IR reflection spectra of ZnSe ceramics prepared by hot pressing (HP), physical vapor deposition (PVD), and PVD combined with hot isostatic pressing (HIP) are presented. The optical constants of polished and dry-ground specimens were used for comparison. The grinding treatment simulated the erosion of the outer surface of optical elements made of zinc selenide under the influence of solid dust particles and deposits. In the polished specimens residual stresses showed up in the IR reflection spectra of the ZnSePVD and ZnSeHIP ceramics, which had well-defined orientation of grains, but were not present in the spectra of the ZnSeHIP ceramics as a result of mutual compensation of the stresses in the randomly oriented grains of the material. The stresses, which appeared as a shift of the absorption bands calculated by the Kramers-Kronig method, increased significantly after abrasive treatment of the specimens. For all the treated ceramics the intensity of the absorption bands resulting from the anharmonicity of the vibrations in the distorted crystal lattice increased by several times. The last effect also depends on the production prehistory of the ceramics.

Hydrogenated fullerenes in space: FT-IR spectra analysis

Energy Technology Data Exchange (ETDEWEB)

El-Barbary, A. A. [Physics Department, Faculty of Education, Ain-Shams University, Cairo, Egypt Physics Department, Faculty of Science, Jazan University, Jazan (Saudi Arabia)

2016-06-10

Fullerenes and hydrogenated fullerenes are found in circumstellar and interstellar environments. But the determination structures for the detected bands in the interstellar and circumstellar space are not completely understood so far. For that purpose, the aim of this article is to provide all possible infrared spectra for C{sub 20} and C{sub 60} fullerenes and their hydrogenated fullerenes. Density Functional theory (DFT) is applied using B3LYP exchange-functional with basis set 6–31G(d, p). The Fourier transform infrared spectroscopy (FT-IR) is found to be capable of distinguishing between fullerenes, mono hydrogenated fullerenes and fully hydrogenated fullerenes. In addition, deposition of one hydrogen atom outside the fully hydrogenated fullerenes is found to be distinguished by forming H{sub 2} molecule at peak around 4440 cm{sup −1}. However, deposition of one hydrogen atom inside the fully hydrogenated fullerenes cannot be distinguished. The obtained spectral structures are analyzed and are compared with available experimental results.

Hydrogenated fullerenes in space: FT-IR spectra analysis

International Nuclear Information System (INIS)

El-Barbary, A. A.

2016-01-01

Fullerenes and hydrogenated fullerenes are found in circumstellar and interstellar environments. But the determination structures for the detected bands in the interstellar and circumstellar space are not completely understood so far. For that purpose, the aim of this article is to provide all possible infrared spectra for C 20 and C 60 fullerenes and their hydrogenated fullerenes. Density Functional theory (DFT) is applied using B3LYP exchange-functional with basis set 6–31G(d, p). The Fourier transform infrared spectroscopy (FT-IR) is found to be capable of distinguishing between fullerenes, mono hydrogenated fullerenes and fully hydrogenated fullerenes. In addition, deposition of one hydrogen atom outside the fully hydrogenated fullerenes is found to be distinguished by forming H 2 molecule at peak around 4440 cm −1 . However, deposition of one hydrogen atom inside the fully hydrogenated fullerenes cannot be distinguished. The obtained spectral structures are analyzed and are compared with available experimental results.

Effect of low-temperature argon matrices on IR spectra and structure of flexible N-acetylglycine molecules

International Nuclear Information System (INIS)

Stepan'yan, S.G.; Ivanov, A.Yu.; Adamowicz, L.

2016-01-01

The influence of the matrix environment on structure and IR spectra of the N-acetylglycine conformers was studied. Based on the FTIR spectra of N-acetyl-glycine isolated in low temperature argon matrices we determined its conformational composition. The spectra bands of main and two minor conformers of N-acetylglycine were identified in the FTIR spectra. The structure of the observed conformers was stabilized by different intramolecular hydrogen bonds. The Gibbs free energies of the conformers (CCSD(T)/CBS method) were performed and population of the con-formers at 360 K were determined. They were 85.3% for the main conformer and 9.6 and 5.1% for the mi-nor N-acetylglycine conformers. We also determined size and shape of the cavities which were formed by embedding of the N-acetylglycine conformers in argon matrices during deposition. It was found that for the planar main conformer the most energetically preferred cavity was formed by substituting of 7 argon atoms. At the same time, bulky minor conformers were embedded in a cavity formed by substituting of 8 argon atoms. Complexation energies as well as the deformation energies of the argon crystal and conformers of N-acetylglycine were calculated. Also we determined values of the matrix shifts of vibrational frequencies of N-acetylglycine conformers.

DFT study of structure, IR and Raman spectra of the fluorescent "Janus" dendron built from cyclotriphosphazene core

Science.gov (United States)

Furer, V. L.; Vandyukova, I. I.; Vandyukov, A. E.; Fuchs, S.; Majoral, J. P.; Caminade, A. M.; Kovalenko, V. I.

2011-11-01

The FTIR and FT-Raman spectra of the zero generation dendron, possessing five fluorescent dansyl terminal groups, cyclotriphosphazene core, and one carbamate function G0v were studied. The structural optimization and normal mode analysis were performed for G0v dendron on the basis of the density functional theory (DFT). The calculated geometrical parameters and harmonic vibrational frequencies are predicted in a good agreement with the experimental data. It was found that dendron molecule G0v has a concave lens structure with slightly non-planar cyclotriphosphazene core. The experimental IR and Raman spectra of G0v dendron were interpreted by means of potential energy distributions. Relying on DFT calculations a complete vibrational assignment is proposed. The frequency of ν(N-H) band in the IR spectrum reveal the presence of H-bonds in the G0v dendron.

Volatility-dependent 2D IR correlation analysis of traditional Chinese medicine ‘Red Flower Oil’ preparation from different manufacturers

Science.gov (United States)

Wu, Yan-Wen; Sun, Su-Qin; Zhou, Qun; Tao, Jia-Xun; Noda, Isao

2008-06-01

As a traditional Chinese medicine (TCM), 'Red Flower Oil' preparation is widely used as a household remedy in China and Southeast Asia. Usually, the preparation is a mixture of several plant essential oils with different volatile features, such as wintergreen oil, turpentine oil and clove oil. The proportions of these plant essential oils in 'Red Flower Oil' vary from different manufacturers. Thus, it is important to develop a simple and rapid evaluation method for quality assurance of the preparations. Fourier transform infrared (FT-IR) was applied and two-dimensional correlation infrared spectroscopy (2D IR) based on the volatile characteristic of samples was used to enhance the resolution of FT-IR spectra. 2D IR technique could, not only easily provide the composition and their volatile sequences in 'Red flower Oil' preparations, but also rapidly discriminate the subtle differences in products from different manufacturers. Therefore, FT-IR combined with volatility-dependent 2D IR correlation analysis provides a very fast and effective method for the quality control of essential oil mixtures in TCM.

IR spectra and properties of solid acetone, an interstellar and cometary molecule

Science.gov (United States)

Hudson, Reggie L.; Gerakines, Perry A.; Ferrante, Robert F.

2018-03-01

Mid-infrared spectra of amorphous and crystalline acetone are presented along with measurements of the refractive index and density for both forms of the compound. Infrared band strengths are reported for the first time for amorphous and crystalline acetone, along with IR optical constants. Vapor pressures and a sublimation enthalpy for crystalline acetone also are reported. Positions of 13C-labeled acetone are measured. Band strengths are compared to gas-phase values and to the results of a density-functional calculation. A 73% error in previous work is identified and corrected.

Rapid discrimination of sea buckthorn berries from different H. rhamnoides subspecies by multi-step IR spectroscopy coupled with multivariate data analysis

Science.gov (United States)

Liu, Yue; Zhang, Ying; Zhang, Jing; Fan, Gang; Tu, Ya; Sun, Suqin; Shen, Xudong; Li, Qingzhu; Zhang, Yi

2018-03-01

As an important ethnic medicine, sea buckthorn was widely used to prevent and treat various diseases due to its nutritional and medicinal properties. According to the Chinese Pharmacopoeia, sea buckthorn was originated from H. rhamnoides, which includes five subspecies distributed in China. Confusion and misidentification usually occurred due to their similar morphology, especially in dried and powdered forms. Additionally, these five subspecies have vital differences in quality and physiological efficacy. This paper focused on the quick classification and identification method of sea buckthorn berry powders from five H. rhamnoides subspecies using multi-step IR spectroscopy coupled with multivariate data analysis. The holistic chemical compositions revealed by the FT-IR spectra demonstrated that flavonoids, fatty acids and sugars were the main chemical components. Further, the differences in FT-IR spectra regarding their peaks, positions and intensities were used to identify H. rhamnoides subspecies samples. The discrimination was achieved using principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA). The results showed that the combination of multi-step IR spectroscopy and chemometric analysis offered a simple, fast and reliable method for the classification and identification of the sea buckthorn berry powders from different H. rhamnoides subspecies.

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].

Anharmonic effects in IR, Raman, and Raman optical activity spectra of alanine and proline zwitterions

Czech Academy of Sciences Publication Activity Database

Daněček, Petr; Kapitán, Josef; Baumruk, V.; Bednárová, Lucie; Kopecký, V.; Bouř, Petr

2007-01-01

Roč. 126, č. 22 (2007), s. 224513-1 ISSN 0021-9606 R&D Projects: GA ČR GA203/06/0420; GA ČR GA202/07/0732; GA AV ČR IAA400550702 Institutional research plan: CEZ:AV0Z40550506 Keywords : IR * Raman * ROA spectra * Anharmonic effects Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.044, year: 2007

Effect of source encapsulation on the energy spectra of sup 192 Ir and sup 137 Cs seed sources

Energy Technology Data Exchange (ETDEWEB)

Thomason, C [Wisconsin Univ., Madison, WI (USA). Dept. of Medical Physics; Mackie, T R [Wisconsin Univ., Madison, WI (USA). Dept. of Medical Physics Wisconsin Univ., Madison, WI (USA). Dept. of Human Oncology; Lindstrom, M J [Wisconsin Univ., Madison, WI (USA). Biostatistics Center

1991-04-01

The effect of source encapsulation on the energy spectra of {sup 192}Ir and {sup 137}Cs seed sources, both with stainless steel and with platinum encapsulation, was determined from results of Monte Carlo simulation. The fractional scatter dose around these sources has also been determined from Monte Carlo simulation. The platinum-encapsulated {sup 192}Ir source exhibited greater attenuation of the primary spectrum, as expected, and, consistent with this greater attenuation, exhibited more scattered radiation. Significantly less scatter was seen with the {sup 137}Cs source than with either {sup 192}Ir source, as is consistent with the higher-energy photons from {sup 137}Cs. (author).

Temperature-dependent mid-IR absorption spectra of gaseous hydrocarbons

International Nuclear Information System (INIS)

Klingbeil, Adam E.; Jeffries, Jay B.; Hanson, Ronald K.

2007-01-01

Quantitative mid-IR absorption spectra (2500-3400 cm -1 ) for 12 pure hydrocarbon compounds are measured at temperatures ranging from 25 to 500 deg. C using an FTIR spectrometer. The hydrocarbons studied are n-pentane, n-heptane, n-dodecane, 2,2,4-trimethyl-pentane (iso-octane), 2-methyl-butane, 2-methyl-pentane, 2,4,4-trimethyl-1-pentene, 2-methyl-2-butene, propene, toluene, m-xylene, and ethylbenzene. Room-temperature measurements of neat hydrocarbon vapor were made with an instrument resolution of both 0.1 and 1 cm -1 (FWHM) to confirm that the high-resolution setting was required only to resolve the propene absorption spectrum while the spectra of the other hydrocarbons could be resolved with 1 cm -1 resolution. High-resolution (0.1 cm -1 ), room-temperature measurements of neat hydrocarbons were made at low pressure (∼1 Torr, 133 Pa) and compared to measurements of hydrocarbon/N 2 mixtures at atmospheric pressure to verify that no pressure broadening could be observed over this pressure range. The temperature was varied between 25 and 500 o C for atmospheric-pressure measurements of hydrocarbon/N 2 mixtures (X hydrocarbon ∼0.06-1.5%) and it was found that the absorption cross section shows simple temperature-dependent behavior for a fixed wavelength over this temperature range. Comparisons with previous FTIR data over a limited temperature range and with high-resolution laser absorption data over a wide temperature range show good agreement

Rotational Isomers, Intramolecular Hydrogen Bond, and IR Spectra of o-Vinylphenol Homologs

Science.gov (United States)

Glazunov, V. P.; Berdyshev, D. V.; Balaneva, N. N.; Radchenko, O. S.; Novikov, V. L.

2018-03-01

The ν(OH) stretching-mode bands in solution IR spectra of five o-vinylphenol (o-VPh) homologs in the slightly polar solvents CCl4 and n-hexane were studied. Several rotamers with free OH groups were found in solutions of o-VPh and its methyl-substituted derivatives in n-hexane. The proportion of rotamers in o-VPh homologs with intramolecular hydrogen bonds (IHBs) O-H...π varied from 22 to 97% in the gas and cyclohexane according to B3LYP/cc-pVTZ calculations. The theoretically estimated effective enthalpies -ΔH of their IHBs varied in the range 0.20-2.24 kcal/mol.

Rapid authentication and identification of different types of A. roxburghii by Tri-step FT-IR spectroscopy

Science.gov (United States)

Chen, Ying; Huang, Jinfang; Yeap, Zhao Qin; Zhang, Xue; Wu, Shuisheng; Ng, Chiew Hoong; Yam, Mun Fei

2018-06-01

Anoectochilus roxburghii (Wall.) Lindl. (Orchidaceae) is a precious traditional Chinese medicinal herb and has been perennially used to treat various illness. However, there were unethical sellers who adulterated wild A. roxburghii with tissue cultured and cultivated ones. Therefore, there is an urgent need for an effective authentication method to differentiate between these different types of A. roxburghii. In this research, the infrared spectroscopic tri-step identification approach including Fourier transform infrared spectroscopy (FT-IR), Second derivative infrared spectra (SD-IR) and two-dimensional correlation infrared spectra (2D-IR) was used to develop a simple and rapid method to discriminate between wild, cultivated and tissue cultivated A. roxburghii plant. Through this study, all three types of A. roxburghii plant were successfully identified and discriminated through the infrared spectroscopic tri-step identification method. Besides that, all the samples of wild, cultivated and tissue cultivated A. roxburghii plant were analysed with the Soft Independent Modelling of Class Analogy (SIMCA) pattern recognition technique to test and verify the experimental results. The results showed that the three types of A. roxburghii can be discriminated clearly as the recognition rate was 100% for all three types and the rejection rate was more than 60%. 70% of the validated samples were also identified correctly by the SIMCA model. The SIMCA model was also validated by comparing 70 standard herbs to the model. As a result, it was demonstrated that the macroscopic IR fingerprint method and the classification analysis could discriminate not only between the A. roxburghi samples and the standard herbs, it could also distinguish between the three different types of A. roxburghi plant in a direct, rapid and holistic manner.

IR spectroscopy at the ITO-organic interface

Energy Technology Data Exchange (ETDEWEB)

Alt, Milan [Karlsruher Institut fuer Technologie, Karlsruhe (Germany); Shazada, Ahmad [Max-Planck Institut fuer Polymerforschung, Mainz (Germany); Tamanai, Akemi; Trollmann, Jens; Glaser, Tobias; Beck, Sebastian; Tengeler, Sven; Pucci, Annemarie [Kirchhoff-Institut fuer Physik, Heidelberg (Germany)

2012-07-01

Thin films of P3HT have been prepared by spin coating and electrooxidative polymerization on platinum- and ITO-coated substrates. Additionally, P3HT-films on silicon substrates have been prepared by spin coating only. The measured IR spectra of the spin coated films allowed for an elaboration of a detailed optical model for P3HT, which has been used to simulate IR reflection-absorption spectra on ITO and Pt substrates. Comparison of simulated spectra with measurements revealed no substrate influence on the IR spectra for the spincoated films. In case of spincoated P3HT-films on ITO-substrate, the obtained IR spectra correspond to simulation data very well up to 6000 wavenumbers. In the electropolymerized P3HT films we have identified residuals of the electrolyte ionic liquid, acting as dopand for P3HT. While IR spectra of the electropolymerized P3HT films on Pt substrate could be explained reasonably well as a superposition of chemically doped P3HT and the ionic electrolyte, the IR spectra of electropolymerized P3HT films on ITO substrates showed strongly deposition-time dependent deviations. These were most likely related to varying properties of the ITO surface between reference and sample measurement due to an interaction of ITO and the electrolyte at the film-substrate interface.

The characteristics of the IR emission features in the spectra of Herbig Ae stars : evidence for chemical evolution

NARCIS (Netherlands)

Boersma, C.; Bouwman, J.; Lahuis, F.; van Kerckhoven, C.; Tielens, A. G. G. M.; Waters, L. B. F. M.; Henning, T.

Context. Infrared ( IR) spectra provide a prime tool to study the characteristics of polycyclic aromatic hydrocarbon ( PAH) molecules in regions of star formation. Herbig Ae/Be stars are a class of young pre-main sequence stellar objects of intermediate mass. They are known to have varying amounts

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.

The use of UV, FT-IR and Raman spectra for the identification of the newest penem analogs: solutions based on mathematic procedure and the density functional theory.

Science.gov (United States)

Cielecka-Piontek, J; Lewandowska, K; Barszcz, B; Paczkowska, M

2013-02-15

The application of ultraviolet, FT-IR and Raman spectra was proposed for identification studies of the newest penem analogs (doripenem, biapenem and faropenem). An identification of the newest penem analogs based on their separation from related substances was achieved after the application of first derivative of direct spectra in ultraviolet which permitted elimination of overlapping effects. A combination of experimental and theoretical studies was performed for analyzing the structure and vibrational spectra (FT-IR and Raman spectra) of doripenem, biapenem and faropenem. The calculations were conducted using the density functional theory with the B3LYP hybrid functional and 6-31G(d,p) basis set. The confirmation of the applicability of the DFT methodology for interpretation of vibrational IR and Raman spectra of the newest penem analogs contributed to determination of changes of vibrations in the area of the most labile bonds. By employing the theoretical approach it was possible to eliminate necessity of using reference standards which - considering the instability of penem analogs - require that correction coefficients are factored in. Copyright © 2012 Elsevier B.V. All rights reserved.

SPITZER IRS SPECTRA OF DEBRIS DISKS IN THE SCORPIUS–CENTAURUS OB ASSOCIATION

Energy Technology Data Exchange (ETDEWEB)

Jang-Condell, Hannah [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Chen, Christine H.; Mittal, Tushar; Lisse, Carey M. [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Manoj, P. [Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Rd., Mumbai 400005 (India); Watson, Dan [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); Nesvold, Erika; Kuchner, Marc [NASA Goddard Space Flight Center, Greenbelt, MD (United States)

2015-08-01

We analyze spectra obtained with the Spitzer Infrared Spectrograph (IRS) of 110 B-, A-, F-, and G-type stars with optically thin infrared excess in the Scorpius–Centaurus OB association. The ages of these stars range from 11 to 17 Myr. We fit the infrared excesses observed in these sources by Spitzer IRS and the Multiband Imaging Photometer for Spitzer (MIPS) to simple dust models according to Mie theory. We find that nearly all of the objects in our study can be fit by one or two belts of dust. Dust around lower mass stars appears to be closer in than around higher mass stars, particularly for the warm dust component in the two-belt systems, suggesting a mass-dependent evolution of debris disks around young stars. For those objects with stellar companions, all dust distances are consistent with truncation of the debris disk by the binary companion. The gaps between several of the two-belt systems can place limits on the planets that might lie between the belts, potentially constraining the mass and locations of planets that may be forming around these stars.

Gas phase UV and IR absorption spectra of CxF2x+1CHO (x=1-4)

DEFF Research Database (Denmark)

Hashikawa, Y; Kawasaki, M; Waterland, RL

2004-01-01

The UV and IR spectra of CxF2x+1 CHO (x = 1-4) were investigated using computational and experimental techniques. CxF2x+1CHO (x = 1-4) have broad UV absorption features centered at 300-310 nm. The maximum absorption cross-section increases significantly and shifts slightly to the red with increased...

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.

Quantitative gas analysis with FT-IR

DEFF Research Database (Denmark)

Bak, J.; Larsen, A.

1995-01-01

Calibration spectra of CO in the 2.38-5100 ppm concentration range (22 spectra) have been measured with a spectral resolution of 4 cm(-1), in the mid-IR (2186-2001 cm(-1)) region, with a Fourier transform infrared (FT-IR) instrument. The multivariate calibration method partial least-squares (PLS1...

Rapid authentication of different ages of tissue-cultured and wild Dendrobium huoshanense as well as wild Dendrobium henanense using FTIR and 2D-COS IR

Science.gov (United States)

Chen, Nai-Dong; Chen, Nai-Fu; Li, Jun; Cao, Cai-Yun; Wang, Jin-Mei

2015-12-01

The accumulating of pharmaceutical chemicals in medicinal plants would greatly be affected by their ages and establishing a fast quality-identification method to evaluate the similarity of medicinal herbs at different cultivated ages is a critical step for assurance of quality and safety in the TCM industry. In this work, tri-step IR macro-fingerprinting and 2D-COS IR spectrum techniques combined with statistical pattern recognition were applied for discrimination and similarity evaluation of different ages of tissue-cultured and wild Dendrobium huoshanense C. Z. Tang et S. J. Cheng as well as Dendrobium henanense J.L.Lu et L.X Gao. Both tissue-cultured and wild D. huoshanense were easily differentiated from D. henanense by FTIR and SD-IR spectra, while it's quite difficult to discriminate different cultivated years of the three investigated Dendrobiums. In 2D-COS IR spectra, 1-5 auto-peaks with different indensity and positions were located in the region 1160-1030 cm-1 of the twelve Dendrobium samples and thus could be used to identify Dendrobium samples at different ages. Principle component analysis (PCA) of synchronous 2D-COS data showed that the twelve samples were effectively identified and evaluated. The results indicated that the tri-step infrared macro-fingerprinting combined with PCA method was suitable to differentiate the cultivated ages of Dendrobiums with species and orgins rapidly and nondestructively.

Analysis of Fe species in zeolites by UV-VIS-NIR, IR spectra and voltammetry. Effect of preparation, Fe loading and zeolite type

Czech Academy of Sciences Publication Activity Database

Čapek, Libor; Kreibich, Viktor; Dědeček, Jiří; Grygar, Tomáš; Wichterlová, Blanka; Sobalík, Zdeněk; Martens, J. A.; Brosius, R.; Tokarová, V.

2005-01-01

Roč. 80, 1-3 (2005), s. 279-289 ISSN 1387-1811 R&D Projects: GA MŠk OC D15.20 Grant - others:European Union(XE) G5RD-CT-2001-00595 Institutional research plan: CEZ:AV0Z40400503 Keywords : Fe-zeolites * UV-VIS spectra * IR spectra * voltammetry * Fe complexes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.355, year: 2005

Interpretation of IR and Raman spectra of dopamine neurotransmitter and effect of hydrogen bond in HCl

Science.gov (United States)

Yadav, T.; Mukherjee, V.

2018-05-01

The potential energy scanning with respect to the different dihedral angles were performed to search possible numbers of dopamine (neutral) conformers and further, fifteen conformers of dopamine were identified on the basis of energy minima. Vibrational frequencies were calculated for all the conformers of dopamine. Density functional theory was employed to carry out all the computations. The exchange correlation functional B3LYP and the basis set 6-31++G(d,p) were included in DFT calculation. The FTIR and FT-Raman spectra of dopamine hydrochloride were also recorded in the spectral region 400-4000 cm-1 and 50-4000 cm-1 respectively. The normal coordinate analysis was also performed to scale DFT calculated force constants and to calculate potential energy distributions. The detailed vibrational spectral analysis and the assignments of the bands, done on the best-fit basis comparison of the experimentally obtained and theoretically calculated IR and Raman spectra, match quite well indicating DFT calculations as very accurate source of normal mode assignments. The interaction of the most stable conformer of dopamine with HCl was also studied to know the effect of hydrogen bond on its geometry and dynamics. The stability of the dopamine in isolated and protonated forms arising from hyperconjugative interactions was also analyzed by natural bond orbital analysis.

Discrimination of edible oils and fats by combination of multivariate pattern recognition and FT-IR spectroscopy: A comparative study between different modeling methods

Science.gov (United States)

Javidnia, Katayoun; Parish, Maryam; Karimi, Sadegh; Hemmateenejad, Bahram

2013-03-01

By using FT-IR spectroscopy, many researchers from different disciplines enrich the experimental complexity of their research for obtaining more precise information. Moreover chemometrics techniques have boosted the use of IR instruments. In the present study we aimed to emphasize on the power of FT-IR spectroscopy for discrimination between different oil samples (especially fat from vegetable oils). Also our data were used to compare the performance of different classification methods. FT-IR transmittance spectra of oil samples (Corn, Colona, Sunflower, Soya, Olive, and Butter) were measured in the wave-number interval of 450-4000 cm-1. Classification analysis was performed utilizing PLS-DA, interval PLS-DA, extended canonical variate analysis (ECVA) and interval ECVA methods. The effect of data preprocessing by extended multiplicative signal correction was investigated. Whilst all employed method could distinguish butter from vegetable oils, iECVA resulted in the best performances for calibration and external test set with 100% sensitivity and specificity.

LO-TO splittings, effective charges and interactions in electro-optic meta-nitroaniline crystal as studied by polarized IR reflection and transmission spectra

Science.gov (United States)

Szostak, M. M.; Le Calvé, N.; Romain, F.; Pasquier, B.

1994-10-01

The polarized IR reflection spectra of the meta-nitroaniline ( m-NA) single crystal along the a, b and c crystallographic axes as well as the b and c polarized transmission spectra have been measured in the 100-400 cm -1 region. The LO-TO splitting values have been calculated from the reflection spectra by fitting them with the four parameter dielectric function. The dipole moment derivatives, relevant to dynamic effective charges, of the vibrations have also been calculated and used to check the applicability of the oriented gas model (OGM) to reflection spectra. The discrepancies from the OGM have been discussed in terms of vibronic couplings, weak hydrogen bondings (HB) and intramolecular charge transfer.

Vibrational investigation on FT-IR and FT-Raman spectra, IR intensity, Raman activity, peak resemblance, ideal estimation, standard deviation of computed frequencies analyses and electronic structure on 3-methyl-1,2-butadiene using HF and DFT (LSDA/B3LYP/B3PW91) calculations.

Science.gov (United States)

Ramalingam, S; Jayaprakash, A; Mohan, S; Karabacak, M

2011-11-01

FT-IR and FT-Raman (4000-100 cm(-1)) spectral measurements of 3-methyl-1,2-butadiene (3M12B) have been attempted in the present work. Ab-initio HF and DFT (LSDA/B3LYP/B3PW91) calculations have been performed giving energies, optimized structures, harmonic vibrational frequencies, IR intensities and Raman activities. Complete vibrational assignments on the observed spectra are made with vibrational frequencies obtained by HF and DFT (LSDA/B3LYP/B3PW91) at 6-31G(d,p) and 6-311G(d,p) basis sets. The results of the calculations have been used to simulate IR and Raman spectra for the molecule that showed good agreement with the observed spectra. The potential energy distribution (PED) corresponding to each of the observed frequencies are calculated which confirms the reliability and precision of the assignment and analysis of the vibrational fundamentals modes. The oscillation of vibrational frequencies of butadiene due to the couple of methyl group is also discussed. A study on the electronic properties such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The thermodynamic properties of the title compound at different temperatures reveal the correlations between standard heat capacities (C) standard entropies (S), and standard enthalpy changes (H). Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

Vibrational spectra (FT-IR, FT-Raman), frontier molecular orbital, first hyperpolarizability, NBO analysis and thermodynamics properties of Piroxicam by HF and DFT methods

Science.gov (United States)

Suresh, S.; Gunasekaran, S.; Srinivasan, S.

2015-03-01

The solid phase FT-IR and FT-Raman spectra of 4-Hydroxy-2-methyl-N-(2-pyridinyl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide (Piroxicam) have been recorded in the region 4000-400 and 4000-100 cm-1 respectively. The molecular geometry, harmonic vibrational frequencies and bonding features of piroxicam in the ground state have been calculated by Hartree-Fock (HF) and density functional theory (DFT) methods using 6-311++G(d,p) basis set. The calculated harmonic vibrational frequencies are scaled and they are compared with experimental obtained by FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of the title compound has been made on the basis of the calculated potential energy distribution (PED). The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MESP) are also performed. The linear polarizability (α) and the first order hyper polarizability (β) values of the title compound have been computed. The molecular stability arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis.

Non-LTE Stellar Population Synthesis of Globular Clusters Using Synthetic Integrated Light Spectra. I. Constructing the IL Spectra

Science.gov (United States)

Young, Mitchell. E.; Short, C. Ian

2017-02-01

We present an investigation of the globular cluster population synthesis method of McWilliam & Bernstein, focusing on the impact of non-LTE (NLTE) modeling effects and color-magnitude diagram (CMD) discretization. Johnson-Cousins-Bessel U - B, B-V, V-I, and J-K colors are produced for 96 synthetic integrated light (IL) spectra with two different discretization prescriptions and three degrees of NLTE treatment. These color values are used to compare NLTE- and LTE-derived population ages. Relative contributions of different spectral types to the IL spectra for different wavebands are measured. IL NLTE spectra are shown to be more luminous in the UV and optical than LTE spectra, but show stronger absorption features in the IR. The main features showing discrepancies between NLTE and LTE IL spectra may be attributed to light metals, primarily Fe I, Ca I, and Ti I, as well as TiO molecular bands. Main-sequence stars are shown to have negligible NLTE effects at IR wavelengths compared to more evolved stars. Photometric color values are shown to vary at the millimagnitude level as a function of CMD discretization. Finer CMD sampling for the upper main sequence and turnoff, base of the red giant branch, and the horizontal branch minimizes this variation. Differences in ages derived from LTE and NLTE IL spectra are found to range from 0.55 to 2.54 Gyr, comparable to the uncertainty in GC ages derived from color indices with observational uncertainties of 0.01 mag, the limiting precision of the Harris catalog.

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.

On the use of spectra from portable Raman and ATR-IR instruments in synthesis route attribution of a chemical warfare agent by multivariate modeling.

Science.gov (United States)

Wiktelius, Daniel; Ahlinder, Linnea; Larsson, Andreas; Höjer Holmgren, Karin; Norlin, Rikard; Andersson, Per Ola

2018-08-15

Collecting data under field conditions for forensic investigations of chemical warfare agents calls for the use of portable instruments. In this study, a set of aged, crude preparations of sulfur mustard were characterized spectroscopically without any sample preparation using handheld Raman and portable IR instruments. The spectral data was used to construct Random Forest multivariate models for the attribution of test set samples to the synthetic method used for their production. Colored and fluorescent samples were included in the study, which made Raman spectroscopy challenging although fluorescence was diminished by using an excitation wavelength of 1064 nm. The predictive power of models constructed with IR or Raman data alone, as well as with combined data was investigated. Both techniques gave useful data for attribution. Model performance was enhanced when Raman and IR spectra were combined, allowing correct classification of 19/23 (83%) of test set spectra. The results demonstrate that data obtained with spectroscopy instruments amenable for field deployment can be useful in forensic studies of chemical warfare agents. Copyright © 2018 Elsevier B.V. All rights reserved.

Library search with regular reflectance IR spectra

International Nuclear Information System (INIS)

Staat, H.; Korte, E.H.; Lampen, P.

1989-01-01

Characterisation in situ for coatings and other surface layers is generally favourable, but a prerequisite for precious items such as art objects. In infrared spectroscopy only reflection techniques are applicable here. However for attenuated total reflection (ATR) it is difficult to obtain the necessary optical contact of the crystal with the sample, when the latter is not perfectly plane or flexible. The measurement of diffuse reflectance demands a scattering sample and usually the reflectance is very poor. Therefore in most cases one is left with regular reflectance. Such spectra consist of dispersion-like feature instead of bands impeding their interpretation in the way the analyst is used to. Furthermore for computer search in common spectral libraries compiled from transmittance or absorbance spectra a transformation of the reflectance spectra is needed. The correct conversion is based on the Kramers-Kronig transformation. This somewhat time - consuming procedure can be speeded up by using appropriate approximations. A coarser conversion may be obtained from the first derivative of the reflectance spectrum which resembles the second derivative of a transmittance spectrum. The resulting distorted spectra can still be used successfully for the search in peak table libraries. Experiences with both transformations are presented. (author)

FT-IR, FT-Raman and UV-visible spectra of potassium 3-furoyltrifluoroborate salt

Science.gov (United States)

Iramain, Maximiliano A.; Davies, Lilian; Brandán, Silvia Antonia

2018-04-01

The potassium 3-furoyltrifluoroborate salt has been experimentally characterized by means of FT-IR, FT-Raman and UV-Visible spectroscopies. Here, the predicted FT-IR, FT-Raman and UV-visible spectra by using theoretical B3LYP/6-31G* and 6-311++G** calculations show very good correlations with the corresponding experimental ones. The solvation energies were predicted by using both levels of calculations. The NBO analyses reveal the high stability of the salt by using the B3LYP/6-31G* level of theory while the AIM studies evidence the ionic characteristics of the salt in both media. The strong blue colour observed on the K atom by using the molecular electrostatic potential mapped suggests that this region act as typical electrophilic site. The gap values have revealed that the salt in gas phase is more reactive than in solution, as was reported in the literature while, the F13⋯H6 interaction together with the Ksbnd O bond observed by the studies of their charges could probably modulate the reactivities of this salt in aqueous solution. The force fields were computed with the SQMFF methodology and the Molvib program to perform the complete vibrational analysis. Then, the 39 vibration normal modes classified as 26 A'+ 13 A″ were completely assigned and their force constants are also reported.

Visualizing Infrared (IR) Spectroscopy with Computer Animation

Science.gov (United States)

Abrams, Charles B.; Fine, Leonard W.

1996-01-01

IR Tutor, an interactive, animated infrared (IR) spectroscopy tutorial has been developed for Macintosh and IBM-compatible computers. Using unique color animation, complicated vibrational modes can be introduced to beginning students. Rules governing the appearance of IR absorption bands become obvious because the vibrational modes can be visualized. Each peak in the IR spectrum is highlighted, and the animation of the corresponding normal mode can be shown. Students can study each spectrum stepwise, or click on any individual peak to see its assignment. Important regions of each spectrum can be expanded and spectra can be overlaid for comparison. An introduction to the theory of IR spectroscopy is included, making the program a complete instructional package. Our own success in using this software for teaching and research in both academic and industrial environments will be described. IR Tutor consists of three sections: (1) The 'Introduction' is a review of basic principles of spectroscopy. (2) 'Theory' begins with the classical model of a simple diatomic molecule and is expanded to include larger molecules by introducing normal modes and group frequencies. (3) 'Interpretation' is the heart of the tutorial. Thirteen IR spectra are analyzed in detail, covering the most important functional groups. This section features color animation of each normal mode, full interactivity, overlay of related spectra, and expansion of important regions. This section can also be used as a reference.

DFT study of IR and Raman spectra of phosphotrihydrazone dendrimer with terminal phenolic groups

Science.gov (United States)

Furer, V. L.; Vandyukov, A. E.; Majoral, J. P.; Caminade, A. M.; Kovalenko, V. I.

2017-09-01

FT Raman and infrared spectra of phosphotrihydrazone (S)P[N(CH3)Ndbnd CHsbnd C6H4sbnd OH]3 (G0) were recorded. This compound is a zero generation phosphorus dendrimer with terminal phenolic groups. Optimal geometry and vibrational frequencies were calculated for G0 using the density functional theory (DFT). The molecule studied has C3 symmetry. In the molecule G0, each sbnd C6H4sbnd CHdbnd Nsbnd N(CH3)sbnd P arm is flat. Optimized geometric parameters correspond to experimental data. The core of the dendrimer manifests itself as a band at 647 cm-1 in the Raman spectrum of G0 related to Pdbnd S stretching. Phenolic end functions exhibit a well-defined band at 3374 cm-1 in the experimental IR spectrum of G0. The observed frequency of the OH stretching vibrations of the phenolic groups is lower than the theoretical value due to the intermolecular Osbnd H⋯O hydrogen bond. This hydrogen bond is also responsible for the higher intensity of this band in the experimental IR spectrum compared with the theoretical value. DFT calculations suggest full assignment of normal modes. Global and local descriptors characterize the reactivity of the core and end groups.

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.

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

Anisotropy in Bone Demineralization Revealed by Polarized Far-IR Spectroscopy

Directory of Open Access Journals (Sweden)

Roman Schuetz

2015-04-01

Full Text Available Bone material is composed of an organic matrix of collagen fibers and apatite nanoparticles. Previously, vibrational spectroscopy techniques such as infrared (IR and Raman spectroscopy have proved to be particularly useful for characterizing the two constituent organic and inorganic phases of bone. In this work, we tested the potential use of high intensity synchrotron-based far-IR radiation (50–500 cm−1 to gain new insights into structure and chemical composition of bovine fibrolamellar bone. The results from our study can be summarized in the following four points: (I compared to far-IR spectra obtained from synthetic hydroxyapatite powder, those from fibrolamellar bone showed similar peak positions, but very different peak widths; (II during stepwise demineralization of the bone samples, there was no significant change neither to far-IR peak width nor position, demonstrating that mineral dissolution occurred in a uniform manner; (III application of external loading on fully demineralized bone had no significant effect on the obtained spectra, while dehydration of samples resulted in clear differences. (IV using linear dichroism, we showed that the anisotropic structure of fibrolamellar bone is also reflected in anisotropic far-IR absorbance properties of both the organic and inorganic phases. Far-IR spectroscopy thus provides a novel way to functionally characterize bone structure and chemistry, and with further technological improvements, has the potential to become a useful clinical diagnostic tool to better assess quality of collagen-based tissues.

FT-IR, FT-Raman, UV spectra and DFT calculations on monomeric and dimeric structure of 2-amino-5-bromobenzoic acid.

Science.gov (United States)

Karabacak, Mehmet; Cinar, Mehmet

2012-02-01

In this work, the molecular conformation, vibrational and electronic transition analysis of 2-amino-5-bromobenzoic acid (2A5BrBA) were presented for the ground state using experimental techniques (FT-IR, FT-Raman and UV) and density functional theory (DFT) employing B3LYP exchange correlation with the 6-311++G(d,p) basis set. FT-IR and FT-Raman spectra were recorded in the regions of 400-4000 cm(-1) and 50-4000 cm(-1), respectively. There are four conformers, C1, C2, C3 and C4 for this molecule. The geometrical parameters, energies and wavenumbers have been obtained for all four conformers. The computational results diagnose the most stable conformer of 2A5BrBA as the C1 form. The complete assignments of fundamental vibrations were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. Raman activities calculated by DFT method have been converted to the corresponding Raman intensities using Raman scattering theory. The UV spectra of investigated compound were recorded in the region of 200-400 nm for ethanol and water solutions. The electronic properties were evaluated with help of time-dependent DFT (TD-DFT) theoretically and results were compared with experimental observations. The thermodynamic properties of the studied compound at different temperatures were calculated, revealing the correlations between standard heat capacity, standard entropy, standard enthalpy changes and temperatures. The observed and the calculated geometric parameters, vibrational wavenumbers and electronic transitions were compared with observed data and found to be in good agreement. Copyright © 2011 Elsevier B.V. All rights reserved.

Sensing the Structural Differences in Cellulose from Apple and Bacterial Cell Wall Materials by Raman and FT-IR Spectroscopy

Science.gov (United States)

Szymańska-Chargot, Monika; Cybulska, Justyna; Zdunek, Artur

2011-01-01

Raman and Fourier Transform Infrared (FT-IR) spectroscopy was used for assessment of structural differences of celluloses of various origins. Investigated celluloses were: bacterial celluloses cultured in presence of pectin and/or xyloglucan, as well as commercial celluloses and cellulose extracted from apple parenchyma. FT-IR spectra were used to estimate of the Iβ content, whereas Raman spectra were used to evaluate the degree of crystallinity of the cellulose. The crystallinity index (XCRAMAN%) varied from −25% for apple cellulose to 53% for microcrystalline commercial cellulose. Considering bacterial cellulose, addition of xyloglucan has an impact on the percentage content of cellulose Iβ. However, addition of only xyloglucan or only pectins to pure bacterial cellulose both resulted in a slight decrease of crystallinity. However, culturing bacterial cellulose in the presence of mixtures of xyloglucan and pectins results in an increase of crystallinity. The results confirmed that the higher degree of crystallinity, the broader the peak around 913 cm−1. Among all bacterial celluloses the bacterial cellulose cultured in presence of xyloglucan and pectin (BCPX) has the most similar structure to those observed in natural primary cell walls. PMID:22163913

Characterization and identification of microorganisms by FT-IR microspectrometry

Science.gov (United States)

Ngo-Thi, N. A.; Kirschner, C.; Naumann, D.

2003-12-01

We report on a novel FT-IR approach for microbial characterization/identification based on a light microscope coupled to an infrared spectrometer which offers the possibility to acquire IR-spectra of microcolonies containing only few hundred cells. Microcolony samples suitable for FT-IR microspectroscopic measurements were obtained by a replica technique with a stamping device that transfers spatially accurate cells of microcolonies growing on solid culture plates to a special, IR-transparent or reflecting stamping plate. High quality spectra could be recorded either by applying the transmission/absorbance or the reflectance/absorbance mode of the infrared microscope. Signal to noise ratios higher than 1000 were obtained for microcolonies as small as 40 μm in diameter. Reproducibility levels were established that allowed species and strain identification. The differentiation and classification capacity of the FT-IR microscopic technique was tested for different selected microorganisms. Cluster and factor analysis methods were used to evaluate the complex spectral data. Excellent discrimination between bacteria and yeasts, and at the same time Gram-negative and Gram-positive bacterial strains was obtained. Twenty-two selected strains of different species within the genus Staphylococcus were repetitively measured and could be grouped into correct species cluster. Moreover, the results indicated that the method allows also identifications at the subspecies level. Additionally, the new approach allowed spectral mapping analysis of single colonies which provided spatially resolved characterization of growth heterogeneity within complex microbial populations such as colonies.

Mid-Infrared Spectral Properties of IR QSOs

International Nuclear Information System (INIS)

Xia, X. Y.; Cao, C.; Mao, S.; Deng, Z. G.

2008-01-01

We analyse mid-infrared (MIR) spectroscopic properties for 19 ultra-luminous infrared quasars (IR QSOs) in the local universe based on the spectra from the Infrared Spectrograph on board the Spitzer Space Telescope. The MIR properties of IR QSOs are compared with those of optically-selected Palomar-Green QSOs (PG QSOs) and ultra-luminous infrared galaxies (ULIRGs). The average MIR spectral features from ∼5 to 30 μm, including the spectral slopes, 6.2 μm PAH emission strengths and [NeII] 12.81 μm luminosities of IR QSOs, differ from those of PG QSOs. In contrast, IR QSOs and ULIRGs have comparable PAH and [NeII] luminosities. These results are consistent with IR QSOs being at a transitional stage from ULIRGs to classical QSOs. We also find the correlation between the EW (PAH 6.2 μm) and outflow velocities suggests that star formation activities are suppressed by feedback from AGNs and/or supernovae.

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.

Isolated Gramicidin Peptides Probed by IR Spectroscopy

NARCIS (Netherlands)

Rijs, A. M.; Kabelac, M.; Abo-Riziq, A.; Hobza, P.; de Vries, M. S.

2011-01-01

We report double-resonant IR/UV ion-dip spectroscopy of neutral gramicidin peptides in the gas phase. The IR spectra of gramicidin A and C, recorded in both the 1000 cm(-1) to 1800 cm(-1) and the 2700 to 3750 cm(-1) region, allow structural analysis. By studying this broad IR range, various local

Solubility and IR studies of gamma-irradiated arabinoxylan

International Nuclear Information System (INIS)

Ebringerova, A.; Kacurakova, M.; Hromadkova, Z.; Pruzinec, J.

1989-01-01

The structural and solubility changes of a water-insoluble arabinoxylan with a low degree of branching was studied after γ-irradiation by IR spectroscopy and chemical analysis of the polysaccharide and its polymeric fractions. New functional groups like hydroperoxidic, carbonylic and endiolic ones were found after irradiation. The IR spectra shows that the structural changes involved by radiolytic treatment are reflected in the shape of the IR spectra of both polymeric fractions. The ratio of absorbance of the peaks at 1725 and 2920 cm -1 increased with radiation dose. (author) 17 refs.; 2 figs.; 2 tabs

IR and Raman spectra of nitroanthracene isomers: substitional effects based on density functional theory study.

Science.gov (United States)

Alparone, Andrea; Librando, Vito

2012-04-01

Structure, IR and Raman spectra of 1-, 2- and 9-nitroanthracene isomers (1-NA, 2-NA and 9-NA) were calculated and analyzed through density functional theory computations using the B3LYP functional with the 6-311+G** basis set. Steric and π-conjugative effects determine the characteristic ONCC dihedral angles, which vary from 0° (2-NA) to 28-29° (1-NA) and 59° (9-NA), influencing the relative order of stability along the series 9-NA3000 cm(-1) and utility to discriminate the NA isomers. Structural and spectroscopic results suggest that the unknown mutagenic activity of 1-NA is expected to be between that of 9-NA and 2-NA. Copyright © 2011 Elsevier B.V. All rights reserved.

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

, suggesting the possibility of a compact energy source and stratified interstellar medium in their nuclei. We confirm a strong correlation between the sum of the [Ne II]{sub 12.8{sub μm}} and [Ne III]{sub 15.5{sub μm}} emission, as well as [S III]{sub 33.5{sub μm}}, with both the infrared luminosity and the 24 μm warm dust emission measured from the spectra, consistent with all three lines tracing ongoing star formation. Finally, we find no correlation between the hardness of the radiation field or the emission-line width and the ratio of the total infrared to 8 μm emission (IR8), a measure of the strength of the starburst and the distance of the LIRGs from the star-forming main sequence. This may be a function of the fact that the infrared luminosity and the mid-infrared fine-structure lines are sensitive to different timescales over the starburst, or that IR8 is more sensitive to the geometry of the region emitting the warm dust than the radiation field producing the H II region emission.

FTIR measurements of mid-IR absorption spectra of gaseous fatty acid methyl esters at T=25–500 °C

International Nuclear Information System (INIS)

Campbell, M.F.; Freeman, K.G.; Davidson, D.F.; Hanson, R.K.

2014-01-01

Gas-phase mid-infrared (IR) absorption spectra (2500–3400 cm −1 ) for eleven fatty acid methyl esters (FAMEs) have been quantitatively measured at temperatures between 25 and 500 °C using an FTIR spectrometer with a resolution of 1 cm −1 . Using these spectra, the absorption cross section at 3.39 μm, corresponding to the monochromatic output of a helium–neon laser, is reported for each of these fuels as a function of temperature. The data indicate that the 3.39 μm cross section values of saturated FAMEs vary linearly with the logarithm of the number of C-H bonds in the molecule. - Highlights: • Infrared spectra of 11 fatty acid methyl esters (C 3 –C 11 ) have been measured. • A linear relationship for predicting 3.39 μm cross section values is proposed. • A molecule’s integrated area is linearly related to its number of C-H bonds. • Mono-unsaturation decreases cross section values

IR Cards: Inquiry-Based Introduction to Infrared Spectroscopy

Science.gov (United States)

Bennett, Jacqueline; Forster, Tabetha

2010-01-01

As infrared spectroscopy (IR) is frequently used in undergraduate organic chemistry courses, an inductive introduction to IR spectroscopy that uses index cards printed with spectra, structures, and chemical names is described. Groups of students are given an alphabetized deck of these "IR cards" to sort into functional groups. The students then…

FT-IR spectroscopy of lipoproteins—A comparative study

Science.gov (United States)

Krilov, Dubravka; Balarin, Maja; Kosović, Marin; Gamulin, Ozren; Brnjas-Kraljević, Jasminka

2009-08-01

FT-IR spectra, in the frequency region 4000-600 cm -1, of four major lipoprotein classes: very low density lipoprotein (VLDL), low density lipoprotein (LDL) and two subclasses of high density lipoproteins (HDL 2 and HDL 3) were analyzed to obtain their detailed spectral characterization. Information about the protein domain of particle was obtained from the analysis of amide I band. The procedure of decomposition and curve fitting of this band confirms the data already known about the secondary structure of two different apolipoproteins: apo A-I in HDL 2 and HDL 3 and apo B-100 in LDL and VLDL. For information about the lipid composition and packing of the particular lipoprotein the well expressed lipid bands in the spectra were analyzed. Characterization of spectral details in the FT-IR spectrum of natural lipoprotein is necessary to study the influence of external compounds on its structure.

A high resolution photoemission study of surface core-level shifts in clean and oxygen-covered Ir(2 1 0) surfaces

Energy Technology Data Exchange (ETDEWEB)

Gladys, M.J.; Ermanoski, I.; Jackson, G.; Quinton, J.S.; Rowe, J.E.; Madey, T.E. E-mail: madey@physics.rutgers.edu

2004-04-01

High resolution soft X-ray photoemission electron spectroscopy (SXPS), using synchrotron radiation, is employed to investigate 4f core-level features of four differently-prepared Ir(2 1 0) surfaces: clean planar, oxygen-covered planar, oxygen-induced faceted, and clean faceted surfaces. Surface and bulk peak identifications are supported by measurements at different photon energies (thus probing different electron escape depths) and variable emission angles. Iridium 4f{sub 7/2} photoemission spectra are fitted with Doniach-Sunjic lineshapes. The surface components are identified with core levels positioned at lower binding energies than the bulk components, in contrast to previous reports of binding energy inversion on Ir(1 0 0) (1x1) and (5x1) surfaces. For clean planar Ir(2 1 0) three surface Ir 4f{sub 7/2} features are observed with core-level shifts of -765, -529, and -281 meV, with respect to the bulk; these are associated with the first, second and third layers of atoms, respectively, for atomically rough Ir(2 1 0). Adsorption of oxygen onto the planar Ir(2 1 0) surface is found to cause a suppression and shift of the surface features to higher binding energies. Annealing at T{>=}600 K in oxygen produces a faceted surface as verified by low energy electron diffraction (LEED). A comparison of planar and faceted oxygen-covered surfaces reveals minor differences in the normal emission SXPS spectra, while grazing emission spectra exhibit differences. The SXPS spectrum of the clean, faceted Ir(2 1 0) exhibits small differences in comparison to the clean planar case, with surface features having binding energy shifts of -710, -450, and -230 meV.

Different spectra with the same neutron source

International Nuclear Information System (INIS)

Vega C, H. R.; Ortiz R, J. M.; Hernandez D, V. M.; Martinez B, M. R.; Hernandez A, B.; Ortiz H, A. A.; Mercado, G. A.

2010-01-01

Using as source term the spectrum of a 239 Pu-Be source several neutron spectra have been calculated using Monte Carlo methods. The source term was located in the centre of spherical moderators made of light water, heavy water and polyethylene of different diameters. Also a 239 Pu-Be source was used to measure its neutron spectrum, bare and moderated by water. The neutron spectra were measured at 100 cm with a Bonner spheres spectrometer. Monte Carlo calculations were used to calculate the neutron spectra of bare and water-moderated spectra that were compared with those measured with the spectrometer. Resulting spectra are similar to those found in power plants with PWR, BWR and Candu nuclear reactors. Beside the spectra the dosimetric features were determined. Using moderators and a single neutron source can be produced neutron spectra alike those found in workplaces, this neutron fields can be utilized to calibrate neutron dosimeters and area monitors. (Author)

Anharmonic effects in IR, Raman, and Raman optical activity spectra of alanine and proline zwitterions.

Science.gov (United States)

Danecek, Petr; Kapitán, Josef; Baumruk, Vladimír; Bednárová, Lucie; Kopecký, Vladimír; Bour, Petr

2007-06-14

The difference spectroscopy of the Raman optical activity (ROA) provides extended information about molecular structure. However, interpretation of the spectra is based on complex and often inaccurate simulations. Previously, the authors attempted to make the calculations more robust by including the solvent and exploring the role of molecular flexibility for alanine and proline zwitterions. In the current study, they analyze the IR, Raman, and ROA spectra of these molecules with the emphasis on the force field modeling. Vibrational harmonic frequencies obtained with 25 ab initio methods are compared to experimental band positions. The role of anharmonic terms in the potential and intensity tensors is also systematically explored using the vibrational self-consistent field, vibrational configuration interaction (VCI), and degeneracy-corrected perturbation calculations. The harmonic approach appeared satisfactory for most of the lower-wavelength (200-1800 cm(-1)) vibrations. Modern generalized gradient approximation and hybrid density functionals, such as the common B3LYP method, provided a very good statistical agreement with the experiment. Although the inclusion of the anharmonic corrections still did not lead to complete agreement between the simulations and the experiment, occasional enhancements were achieved across the entire region of wave numbers. Not only the transitional frequencies of the C-H stretching modes were significantly improved but also Raman and ROA spectral profiles including N-H and C-H lower-frequency bending modes were more realistic after application of the VCI correction. A limited Boltzmann averaging for the lowest-frequency modes that could not be included directly in the anharmonic calculus provided a realistic inhomogeneous band broadening. The anharmonic parts of the intensity tensors (second dipole and polarizability derivatives) were found less important for the entire spectral profiles than the force field anharmonicities (third

Application of FT-IR spectroscopy on breast cancer serum analysis

Science.gov (United States)

Elmi, Fatemeh; Movaghar, Afshin Fayyaz; Elmi, Maryam Mitra; Alinezhad, Heshmatollah; Nikbakhsh, Novin

2017-12-01

Breast cancer is regarded as the most malignant tumor among women throughout the world. Therefore, early detection and proper diagnostic methods have been known to help save women's lives. Fourier Transform Infrared (FT-IR) spectroscopy, coupled with PCA-LDA analysis, is a new technique to investigate the characteristics of serum in breast cancer. In this study, 43 breast cancer and 43 healthy serum samples were collected, and the FT-IR spectra were recorded for each one. Then, PCA analysis and linear discriminant analysis (LDA) were used to analyze the spectral data. The results showed that there were differences between the spectra of the two groups. Discriminating wavenumbers were associated with several spectral differences over the 950-1200 cm- 1(sugar), 1190-1350 cm- 1 (collagen), 1475-1710 cm- 1 (protein), 1710-1760 cm- 1 (ester), 2800-3000 cm- 1 (stretching motions of -CH2 & -CH3), and 3090-3700 cm- 1 (NH stretching) regions. PCA-LDA performance on serum IR could recognize changes between the control and the breast cancer cases. The diagnostic accuracy, sensitivity, and specificity of PCA-LDA analysis for 3000-3600 cm- 1 (NH stretching) were found to be 83%, 84%, 74% for the control and 80%, 76%, 72% for the breast cancer cases, respectively. The results showed that the major spectral differences between the two groups were related to the differences in protein conformation in serum samples. It can be concluded that FT-IR spectroscopy, together with multivariate data analysis, is able to discriminate between breast cancer and healthy serum samples.

Rapid identification of Pterocarpus santalinus and Dalbergia louvelii by FTIR and 2D correlation IR spectroscopy

Science.gov (United States)

Zhang, Fang-Da; Xu, Chang-Hua; Li, Ming-Yu; Huang, An-Min; Sun, Su-Qin

2014-07-01

Since Pterocarpus santalinus and Dalbergia louvelii, which are of precious Rosewood, are very similar in their appearance and anatomy characteristics, cheaper Hongmu D. louvelii is often illegally used to impersonate valuable P. santalinus, especially in Chinese furniture manufacture. In order to develop a rapid and effective method for easy confused wood furniture differentiation, we applied tri-step identification method, i.e., conventional infrared spectroscopy (FT-IR), second derivative infrared (SD-IR) spectroscopy and two-dimensional correlation infrared (2DCOS-IR) spectroscopy to investigate P. santalinus and D. louvelii furniture. According to FT-IR and SD-IR spectra, it has been found two unconditional stable difference at 848 cm-1 and 700 cm-1 and relative stable differences at 1735 cm-1, 1623 cm-1, 1614 cm-1, 1602 cm-1, 1509 cm-1, 1456 cm-1, 1200 cm-1, 1158 cm-1, 1055 cm-1, 1034 cm-1 and 895 cm-1 between D. louvelii and P. santalinus IR spectra. The stable discrepancy indicates that the category of extractives is different between the two species. Besides, the relative stable differences imply that the content of holocellulose in P. santalinus is more than that of D. louvelii, whereas the quantity of extractives in D. louvelii is higher. Furthermore, evident differences have been observed in their 2DCOS-IR spectra of 1550-1415 cm-1 and 1325-1030 cm-1. P. santalinus has two strong auto-peaks at 1459 cm-1 and 1467 cm-1, three mid-strong auto-peaks at 1518 cm-1, 1089 cm-1 and 1100 cm-1 and five weak auto-peaks at 1432 cm-1, 1437 cm-1, 1046 cm-1, 1056 cm-1 and 1307 cm-1 while D. louvelii has four strong auto-peaks at 1465 cm-1, 1523 cm-1, 1084 cm-1 and 1100 cm-1, four mid-strong auto-peaks at 1430 cm-1, 1499 cm-1, 1505 cm-1 and 1056 cm-1 and two auto-peaks at 1540 cm-1 and 1284 cm-1. This study has proved that FT-IR integrated with 2DCOS-IR could be applicable for precious wood furniture authentication in a direct, rapid and holistic manner.

An FT-Raman, FT-IR, and Quantum Chemical Investigation of Stanozolol and Oxandrolone

Directory of Open Access Journals (Sweden)

Tibebe Lemma

2017-12-01

Full Text Available We have studied the Fourier Transform Infrared (FT-IR and the Fourier transform Raman (FT-Raman spectra of stanozolol and oxandrolone, and we have performed quantum chemical calculations based on the density functional theory (DFT with a B3LYP/6-31G (d, p level of theory. The FT-IR and FT-Raman spectra were collected in a solid phase. The consistency between the calculated and experimental FT-IR and FT-Raman data indicates that the B3LYP/6-31G (d, p can generate reliable geometry and related properties of the title compounds. Selected experimental bands were assigned and characterized on the basis of the scaled theoretical wavenumbers by their total energy distribution. The good agreement between the experimental and theoretical spectra allowed positive assignment of the observed vibrational absorption bands. Finally, the calculation results were applied to simulate the Raman and IR spectra of the title compounds, which show agreement with the observed spectra.

Regioselective aromatic substitution reactions of cyclometalated Ir(III) complexes: synthesis and photochemical properties of substituted Ir(III) complexes that exhibit blue, green, and red color luminescence emission.

Science.gov (United States)

Aoki, Shin; Matsuo, Yasuki; Ogura, Shiori; Ohwada, Hiroki; Hisamatsu, Yosuke; Moromizato, Shinsuke; Shiro, Motoo; Kitamura, Masanori

2011-02-07

In this manuscript, the regioselective halogenation, nitration, formylation, and acylation of Ir(tpy)(3) and Ir(ppy)(3) (tpy = 2-(4'-tolyl)pyridine and ppy = 2-phenylpyridine) and the subsequent conversions are described. During attempted bromination of the three methyl groups in fac-Ir(tpy)(3) using N-bromosuccinimide (NBS) and benzoyl peroxide (BPO), three protons at the 5'-position (p-position with respect to the C-Ir bond) of phenyl rings in tpy units were substituted by Br, as confirmed by (1)H NMR spectra, mass spectra, and X-ray crystal structure analysis. It is suggested that such substitution reactions of Ir complexes proceed via an ionic mechanism rather than a radical mechanism. UV-vis and luminescence spectra of the substituted Ir(III) complexes are reported. The introduction of electron-withdrawing groups such as CN and CHO groups at the 5'-position of tpy induces a blue shift of luminescence emission to about 480 nm, and the introduction of electron-donating groups such as an amino group results in a red shift to about 600 nm. A reversible change of emission for the 5'-amino derivative of Ir(tpy)(3), Ir(atpy)(3), between red and green occurs upon protonation and deprotonation.

Sugar and acid content of Citrus prediction modeling using FT-IR fingerprinting in combination with multivariate statistical analysis.

Science.gov (United States)

Song, Seung Yeob; Lee, Young Koung; Kim, In-Jung

2016-01-01

A high-throughput screening system for Citrus lines were established with higher sugar and acid contents using Fourier transform infrared (FT-IR) spectroscopy in combination with multivariate analysis. FT-IR spectra confirmed typical spectral differences between the frequency regions of 950-1100 cm(-1), 1300-1500 cm(-1), and 1500-1700 cm(-1). Principal component analysis (PCA) and subsequent partial least square-discriminant analysis (PLS-DA) were able to discriminate five Citrus lines into three separate clusters corresponding to their taxonomic relationships. The quantitative predictive modeling of sugar and acid contents from Citrus fruits was established using partial least square regression algorithms from FT-IR spectra. The regression coefficients (R(2)) between predicted values and estimated sugar and acid content values were 0.99. These results demonstrate that by using FT-IR spectra and applying quantitative prediction modeling to Citrus sugar and acid contents, excellent Citrus lines can be early detected with greater accuracy. Copyright © 2015 Elsevier Ltd. All rights reserved.

OSL, TL and IRSL emission spectra of sedimentary quartz and feldspar samples

International Nuclear Information System (INIS)

Lomax, Johanna; Mittelstraß, Dirk; Kreutzer, Sebastian; Fuchs, Markus

2015-01-01

This contribution presents a variety of different luminescence emission spectra from sedimentary feldspar and quartz samples under various stimulation modes. These are green stimulated quartz (OSL-) spectra, quartz TL spectra, feldspar IRSL and post-IR IRSL spectra. A focus was set at recording OSL and IRSL spectra at elevated stimulation temperatures such as routinely applied in luminescence dating. This was to test whether optical stimulation at elevated temperatures results in a shift of emission peaks. For OSL emissions of quartz, this has so far not been tested. In case of feldspar emissions, post-IR IRSL conditions, hence IRSL emissions at a low temperature, directly followed by high temperature post-IRSL emissions, are explicitly investigated. All spectra were recorded using a new system incorporated into a Lexsyg luminescence reader. Thus, this study, besides presenting new spectral data, also serves as a feasibility study for this new device. It is shown that (a) the new device is capable of automatically measuring different sorts of spectra, also at elevated temperatures, (b) known thermally and optically stimulated peak emissions of quartz and feldspar are confirmed, (c) obtained IRSL and OSL spectra indicate that there is no significant relation between peak emission and stimulation temperature. - Highlights: • We have measured OSL, IRSL and TL emission spectra of sedimentary quartz and feldspar samples. • Spectral analyses were performed at elevated stimulation temperatures. • Emission spectra show very little variation with stimulation temperatures.

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

2DCOS and PCMW2D analysis of FT-IR/ATR spectra measured at variable temperatures on-line to a polyurethane polymerization

Science.gov (United States)

Schuchardt, Patrick; Unger, Miriam; Siesler, Heinz W.

2018-01-01

In the present communication the potential of 2DCOS analysis and the spin-off technique perturbation-correlation moving window 2D (PCMW2D) analysis is illustrated with reference to spectroscopic changes observed in a data set recorded by in-line fiber-coupled FT-IR spectroscopy in the attenuated total reflection (ATR) mode during a polyurethane solution polymerization at different temperatures. In view of the chemical functionalities involved, hydrogen bonding plays an important role in this polymerization reaction. Based on the 2DCOS and PCMW2D analysis, the sequence of hydrogen bonding changes accompanying the progress of polymerization and precipitation of solid polymer can be determined. Complementary to the kinetic data derived from the original variable-temperature spectra in a previous publication the results provide a more detailed picture of the investigated solution polymerization.

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

BOOTES-IR: near IR follow-up GRB observations by a robotic system

International Nuclear Information System (INIS)

Castro-Tirado, A.J.; Postrigo, A. de Ugarte; Jelinek, M.

2005-01-01

BOOTES-IR is the extension of the BOOTES experiment, which operates in Southern Spain since 1998, to the near IR (NIR). The goal is to follow up the early stage of the gamma ray burst (GRB) afterglow emission in the NIR, alike BOOTES does already at optical wavelengths. The scientific case that drives the BOOTES-IR performance is the study of GRBs with the support of spacecraft like INTEGRAL, SWIFT and GLAST. Given that the afterglow emission in both, the NIR and the optical, in the instances immediately following a GRB, is extremely bright (reached V = 8.9 in one case), it should be possible to detect this prompt emission at NIR wavelengths too. The combined observations by BOOTES-IR and BOOTES-1 and BOOTES-2 will allow for real time identification of trustworthy candidates to have a high redshift (z > 5). It is expected that, few minutes after a GRB, the IR magnitudes be H ∼ 7-10, hence very high quality spectra can be obtained for objects as far as z = 10 by larger instruments

2D IR spectra of cyanide in water investigated by molecular dynamics simulations

Science.gov (United States)

Lee, Myung Won; Carr, Joshua K.; Göllner, Michael; Hamm, Peter; Meuwly, Markus

2013-01-01

Using classical molecular dynamics simulations, the 2D infrared (IR) spectroscopy of CN− solvated in D2O is investigated. Depending on the force field parametrizations, most of which are based on multipolar interactions for the CN− molecule, the frequency-frequency correlation function and observables computed from it differ. Most notably, models based on multipoles for CN− and TIP3P for water yield quantitatively correct results when compared with experiments. Furthermore, the recent finding that T 1 times are sensitive to the van der Waals ranges on the CN− is confirmed in the present study. For the linear IR spectrum, the best model reproduces the full widths at half maximum almost quantitatively (13.0 cm−1 vs. 14.9 cm−1) if the rotational contribution to the linewidth is included. Without the rotational contribution, the lines are too narrow by about a factor of two, which agrees with Raman and IR experiments. The computed and experimental tilt angles (or nodal slopes) α as a function of the 2D IR waiting time compare favorably with the measured ones and the frequency fluctuation correlation function is invariably found to contain three time scales: a sub-ps, 1 ps, and one on the 10-ps time scale. These time scales are discussed in terms of the structural dynamics of the surrounding solvent and it is found that the longest time scale (≈10 ps) most likely corresponds to solvent exchange between the first and second solvation shell, in agreement with interpretations from nuclear magnetic resonance measurements.

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.

FT-IR and FT-Raman spectra of 5-chlorocytosine: Solid state simulation and tautomerism. Effect of the chlorine substitution in the Watson-Crick base pair 5-chlorodeoxycytidine-deoxyguanosine

Science.gov (United States)

Alcolea Palafox, M.; Rastogi, V. K.; Singh, S. P.

2018-01-01

The laser Raman and IR spectra of 5-chlorocytosine have been recorded and accurately assigned in the solid state using Density functional calculations (DFT) together with the linear scaling equation procedure (LSE) and the solid state simulation of the crystal unit cell through a tetramer form. These results remarkably improve those reported previously by other authors. Several new scaling equations were proposed to be used in related molecules. The six main tautomers of the biomolecule 5-chlorocytosine were determined and optimized at the MP2 and CCSD levels, using different basis sets. The relative stabilities were compared with those obtained in cytosine and their 5-halo derivatives. Several relationships between energies, geometric parameters and NBO atomic charges were established. The effect of the chlorine substitution in the fifth position was evaluated through the stability of the Watson-Crick (WC) base pair of 5-chlorodeoxycytidine with deoxyguanosine, and through their vibrational spectra.

Completely automated open-path FT-IR spectrometry.

Science.gov (United States)

Griffiths, Peter R; Shao, Limin; Leytem, April B

2009-01-01

Atmospheric analysis by open-path Fourier-transform infrared (OP/FT-IR) spectrometry has been possible for over two decades but has not been widely used because of the limitations of the software of commercial instruments. In this paper, we describe the current state-of-the-art of the hardware and software that constitutes a contemporary OP/FT-IR spectrometer. We then describe advances that have been made in our laboratory that have enabled many of the limitations of this type of instrument to be overcome. These include not having to acquire a single-beam background spectrum that compensates for absorption features in the spectra of atmospheric water vapor and carbon dioxide. Instead, an easily measured "short path-length" background spectrum is used for calculation of each absorbance spectrum that is measured over a long path-length. To accomplish this goal, the algorithm used to calculate the concentrations of trace atmospheric molecules was changed from classical least-squares regression (CLS) to partial least-squares regression (PLS). For calibration, OP/FT-IR spectra are measured in pristine air over a wide variety of path-lengths, temperatures, and humidities, ratioed against a short-path background, and converted to absorbance; the reference spectrum of each analyte is then multiplied by randomly selected coefficients and added to these background spectra. Automatic baseline correction for small molecules with resolved rotational fine structure, such as ammonia and methane, is effected using wavelet transforms. A novel method of correcting for the effect of the nonlinear response of mercury cadmium telluride detectors is also incorporated. Finally, target factor analysis may be used to detect the onset of a given pollutant when its concentration exceeds a certain threshold. In this way, the concentration of atmospheric species has been obtained from OP/FT-IR spectra measured at intervals of 1 min over a period of many hours with no operator intervention.

Drift and transmission FT-IR spectroscopy of forest soils: an approach to determine decomposition processes of forest litter

International Nuclear Information System (INIS)

Haberhauer, G.; Gerzabek, M.H.

1999-06-01

A method is described to characterize organic soil layers using Fourier transformed infrared spectroscopy. The applicability of FT-IR, either dispersive or transmission, to investigate decomposition processes of spruce litter in soil originating from three different forest sites in two climatic regions was studied. Spectral information of transmission and diffuse reflection FT-IR spectra was analyzed and compared. For data evaluation Kubelka Munk (KM) transformation was applied to the DRIFT spectra. Sample preparation for DRIFT is simpler and less time consuming in comparison to transmission FT-IR, which uses KBr pellets. A variety of bands characteristics of molecular structures and functional groups has been identified for these complex samples. Analysis of both transmission FT-IR and DRIFT, showed that the intensity of distinct bands is a measure of the decomposition of forest litter. Interferences due to water adsorption spectra were reduced by DRIFT measurement in comparison to transmission FT-IR spectroscopy. However, data analysis revealed that intensity changes of several bands of DRIFT and transmission FT-IR were significantly correlated with soil horizons. The application of regression models enables identification and differentiation of organic forest soil horizons and allows to determine the decomposition status of soil organic matter in distinct layers. On the basis of the data presented in this study, it may be concluded that FT-IR spectroscopy is a powerful tool for the investigation of decomposition dynamics in forest soils. (author)

Communication: IR spectroscopy of neutral transition metal clusters through thermionic emission

NARCIS (Netherlands)

Lapoutre, V. J. F.; Haertelt, M.; Meijer, G.; Fielicke, A.; Bakker, J. M.

2013-01-01

The resonant multiple photon excitation of neutral niobium clusters using tunable infrared (IR) radiation leads to thermionic emission. By measuring the mass-resolved ionization yield as a function of IR wavenumber species selective IR spectra are obtained for Nb-n (n = 5-20) over the 200-350 cm(-1)

The molecular, electronic structures and vibrational spectra of metal-free, N,N'-dideuterio and magnesium tetra-2,3-pyridino-porphyrazines: Density functional calculations.

Science.gov (United States)

Liu, Zhongqiang; Zhang, Xianxi; Zhang, Yuexing; Li, Renjie; Jiang, Jianzhuang

2006-10-01

A theoretical investigation of the fully optimized geometries and electronic structures of the metal-free (TPdPzH(2)), N,N'-dideuterio (TPdPzD(2)), and magnesium (TPdPzMg) tetra-2,3-pyridino-porphyrazine has been conducted based on density functional theory. The optimized geometries at density functional theory level for these compounds are reported here for the first time. A comparison between the different molecules for the geometry, molecular orbital, and atomic charge is made. The substituent effect of the N atoms on the molecular structures of these compounds is discussed. The IR and Raman spectra for these three compounds have also been calculated at density functional B3LYP level using the 6-31G(d) basis set. Detailed assignments of the NH, NM, and pyridine ring vibrational bands in the IR and Raman spectra have been made based on assistance of animated pictures. The simulated IR spectra of TPdPzH(2) are compared with the experimental absorption spectra, and very good consistency has been found. The isotope effect on the IR and Raman spectra is also discussed.

Using Fourier transform IR spectroscopy to analyze biological materials

Science.gov (United States)

Baker, Matthew J; Trevisan, Júlio; Bassan, Paul; Bhargava, Rohit; Butler, Holly J; Dorling, Konrad M; Fielden, Peter R; Fogarty, Simon W; Fullwood, Nigel J; Heys, Kelly A; Hughes, Caryn; Lasch, Peter; Martin-Hirsch, Pierre L; Obinaju, Blessing; Sockalingum, Ganesh D; Sulé-Suso, Josep; Strong, Rebecca J; Walsh, Michael J; Wood, Bayden R; Gardner, Peter; Martin, Francis L

2015-01-01

IR spectroscopy is an excellent method for biological analyses. It enables the nonperturbative, label-free extraction of biochemical information and images toward diagnosis and the assessment of cell functionality. Although not strictly microscopy in the conventional sense, it allows the construction of images of tissue or cell architecture by the passing of spectral data through a variety of computational algorithms. Because such images are constructed from fingerprint spectra, the notion is that they can be an objective reflection of the underlying health status of the analyzed sample. One of the major difficulties in the field has been determining a consensus on spectral pre-processing and data analysis. This manuscript brings together as coauthors some of the leaders in this field to allow the standardization of methods and procedures for adapting a multistage approach to a methodology that can be applied to a variety of cell biological questions or used within a clinical setting for disease screening or diagnosis. We describe a protocol for collecting IR spectra and images from biological samples (e.g., fixed cytology and tissue sections, live cells or biofluids) that assesses the instrumental options available, appropriate sample preparation, different sampling modes as well as important advances in spectral data acquisition. After acquisition, data processing consists of a sequence of steps including quality control, spectral pre-processing, feature extraction and classification of the supervised or unsupervised type. A typical experiment can be completed and analyzed within hours. Example results are presented on the use of IR spectra combined with multivariate data processing. PMID:24992094

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

FT-Raman, FT-IR spectra and total energy distribution of 3-pentyl-2,6-diphenylpiperidin-4-one: DFT method.

Science.gov (United States)

Subashchandrabose, S; Saleem, H; Erdogdu, Y; Rajarajan, G; Thanikachalam, V

2011-11-01

FT-Raman and FT-IR spectra were recorded for 3-pentyl-2,6-diphenylpiperidin-4-one (PDPO) sample in solid state. The equilibrium geometries, harmonic vibrational frequencies, infrared and the Raman scattering intensities were computed using DFT/6-31G(d,p) level. Results obtained at this level of theory were used for a detailed interpretation of the infrared and Raman spectra, based on the total energy distribution (TED) of the normal modes. Molecular parameters such as bond lengths, bond angles and dihedral angles were calculated and compared with X-ray diffraction data. This comparison was good agreement. The intra-molecular charge transfer was calculated by means of natural bond orbital analysis (NBO). Hyperconjugative interaction energy was more during the π-π* transition. Energy gap of the molecule was found using HOMO and LUMO calculation, hence the less band gap, which seems to be more stable. Atomic charges of the carbon, nitrogen and oxygen were calculated using same level of calculation. Copyright © 2011 Elsevier B.V. All rights reserved.

IR spectra and structure of glasses in the BaO-WO3-P2O5 system

International Nuclear Information System (INIS)

Miroshnichenko, O.Ya.; Mombelli, V.V.

1979-01-01

Studied are IR absorption spectra and determined are the main structural characteristics of tungstophosphate glasses of the BaO-WO 3 -P 2 O 5 system in all the area of glass formation. It is shown that the main structural components of their anion network are phosphate chains consisting of PO 4 tetrahedrons and tungstate chains consisting of WO 4 tetrahedrons and of WO 6 octahedrons. These chains are connected by P-O-W bridges into three-dimentional tungstophosphate network, where the ratio of phosphate and tungstate structural units and their polymerization degree change without limits depending on the glass composition. Analysis of concentration frequency dependence and spectral band intensity permit to clarify the effect of each component on the glass structure in all the area of glass formation of the triple system

Visible and Near-IR Reflectance Spectra of Smectite Acquired Under Dry Conditions for Interpretation of Martian Surface Mineralogy

Science.gov (United States)

Morris, Richard V.; Achilles, Cherie N; Archer, Paul D.; Graff, Trevor G.; Agresti, David G.; Ming, Douglas W; Golden, Dadi C.; Mertzman, Stanley A.

2011-01-01

Visible and near-IR (VNIR) spectra from the MEx OMEGA and the MRO CRISM hyper-spectral imaging instruments have spectral features associated with the H2O molecule and M OH functional groups (M = Mg, Fe, Al, and Si). Mineralogical assignments of martian spectral features are made on the basis of laboratory VNIR spectra, which were often acquired under ambient (humid) conditions. Smectites like nontronite, saponite, and montmorillionite have interlayer H2O that is exchangeable with their environment, and we have acquired smectite reflectance spectra under dry environmental conditions for interpretation of martian surface mineralogy. We also obtained chemical, Moessbauer (MB), powder X-ray diffraction (XRD), and thermogravimetric (TG) data to understand variations in spectral properties. VNIR spectra were recorded in humid lab air at 25-35C, in a dynamic dry N2 atmosphere (50-150 ppmv H2O) after exposing the smectite samples (5 nontronites, 3 montmorillionites, and 1 saponite) to that atmosphere for up to approximately l000 hr each at 25-35C, approximately 105C, and approximately 215C, and after re-exposure to humid lab air. Heating at 105C and 215C for approximately 1000 hr is taken as a surrogate for geologic time scales at lower temperatures. Upon exposure to dry N2, the position and intensity of spectral features associated with M-OH were relatively insensitive to the dry environment, and the spectral features associated with H2O (e.g., approximately 1.90 micrometers) decreased in intensity and are sometimes not detectable by the end of the 215C heating step. The position and intensity of H2O spectral features recovered upon re-exposure to lab air. XRD data show interlayer collapse for the nontronites and Namontmorillionites, with the interlayer remaining collapsed for the latter after re-exposure to lab air. The interlayer did not collapse for the saponite and Ca-montmorillionite. TG data show that the concentration of H2O derived from structural OH was invariant

Visible and Near-IR Reflectance Spectra for Smectite, Sulfate And Perchlorate under Dry Conditions for Interpretation of Martian Surface Mineralogy

Science.gov (United States)

Morris, R.V.; Ming, W.; Golden, D.C.; Arvidson, R.E.; Wiseman, S.M.; Lichtenberg, K.A.; Cull, S.; Graff, T.G.

2009-01-01

Visible and near-IR (VNIR) spectral data for the martian surface obtained from orbit by the MRO-CRISM and OMEGA instruments are interpreted as having spectral signatures of H2O/OH-bearing phases, including smectites and other phyllosilicates, sulfates, and high-SiO2 phases [e.g., 1-4]. Interpretations of martian spectral signatures are based on and constrained by spectra that are obtained in the laboratory on samples with known mineralogical compositions and other physicochemical characteristics under, as appropriate, Mars-like environmental conditions (e.g., temperature, pressure, and humidity). With respect to environmental conditions, differences in the absolute concentration of atmospheric H2O can effect the hydration state and therefore the spectra signatures of smectite phyllosilicates (solvation H2O) and certain sulfates (hydration H2O) [e.g., 5-7]. We report VNIR spectral data acquired under humid (laboratory air) and dry (dry N2 gas) environments for two natural smectites (nontronite API-33A and saponite SapCa-1) to characterize the effect of solvation H2O on spectral properties. We also report spectral data for the thermal dehydration products of (1) melanterite (FeSO4.7H2O) in both air and dry N2 gas and (2) Mg-perchlorate (Mg(ClO4)2.6H2O) in dry N2 environments. Spectral measurements for samples dehydrated in dry N2 were made without exposing them to humid laboratory air.

The vibrational spectrum of the hydrated alanine-leucine peptide in the amide region from IR experiments and first principles calculations

Science.gov (United States)

Hassan, Irtaza; Donati, Luca; Stensitzki, Till; Keller, Bettina G.; Heyne, Karsten; Imhof, Petra

2018-04-01

We have combined infrared (IR) experiments with molecular dynamics (MD) simulations in solution at finite temperature to analyse the vibrational signature of the small floppy peptide Alanine-Leucine. IR spectra computed from first-principles MD simulations exhibit no distinct differences between conformational clusters of α -helix or β -sheet-like folds with different orientations of the bulky leucine side chain. All computed spectra show two prominent bands, in good agreement with the experiment, that are assigned to the stretch vibrations of the carbonyl and carboxyl group, respectively. Variations in band widths and exact maxima are likely due to small fluctuations in the backbone torsion angles.

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.

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 NO_x 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.

Spitzer IRS (8-30 micron) Spectra of Basaltic Asteroids 1459 Magnya and 956 Elisa: Mineralogy and Thermal Properties

Science.gov (United States)

Lim, Lucy F.; Emery, J. P.; Moskovitz, N. A.

2009-01-01

We report preliminary results from Spitzer IRS (Infrared Spectrograph) spectroscopy of 956 Elisa, 1459 Magnya, and other small basaltic asteroids with the Spitzer IRS. Program targets include members of the dynamical family of the unique large differentiated asteroid 4 Vesta ("Vestoids"), several outer-main-belt basaltic asteroids whose orbits exclude them from originating on 4 Vesta, and the basaltic near-Earth asteroid 4055 Magellan. The preliminary thermal model (STM) fit to the 5--35 micron spectrum of 956 Elisa gives a radius of 5.4 +/- 0.3 km and a subsolar- point temperature of 282.2 +/- 0.5 K. This temperature corresponds to eta approximately equals 1.06 +/- 0.02, which is substantially higher than the eta approximately equals 0.756 characteristic of large main-belt asteroids. Unlike 4 Vesta and other large asteroids, therefore, 956 Elisa has significant thermal inertia in its surface layer. The wavelength of the Christiansen feature (emissivity maximum near 9 micron), the positions and shapes of the narrow maxima (10 micron, 11 micron) within the broad 9--14 micron silicate band, and the 19--20 micron minimum are consistent with features found in the laboratory spectra of diogenites and of low-Ca pyroxenes of similar composition (Wo<5, En50-En75).

IDENTIFICATION OF SOME COMPOSITE MEDICINAL DRUGS CONTAINING PARACETAMOL, WITH IR-SPECTROMETRY METHOD

Directory of Open Access Journals (Sweden)

A. S. Saushkina

2017-01-01

Full Text Available A serious threat to the health of the population is falsified medicines. In a number of cases, they are identified in the process of incoming quality control for compliancewith the requirements of regulatory documents for indicators “Description”, “Packaging”, “Marking”. However, in order to identify sophisticated counterfeits, only a visual assessment of the drug is not enough. Purpose screening evaluation of potentiallycounterfeited or poor-quality drugs using the IR spectrometry along the total spectrum.Materials and methods. The objects of research were available in freely availablecommercially available tablets produced by domestic and foreign manufacturers“Paracetamol Extratab”, “Solpadein fast”, “Citrapac”, “Citramon P”, “Ascofen-P”,  corresponding to the requirements of the current regulatory documents. The studies were carried out on a Fourier-Spectrophotometer infrared “FSM 1201”. Results and discussion. On the example of the tablets “Citramon P”, “Ascophen-P”, “Citrapac”, “Paracetamol Extratab”, “Solpadein Fast” the possibility of using the total IR spectra as a primary screening index of authenticity is shown. It was established that the total IR spectra of medicines of similar composition reflect the similarity of serial samples of the products ofone manufacturer and the difference in serial samples of products of different manufacturers.

Detector Sampling of Optical/IR Spectra: How Many Pixels per FWHM?

Science.gov (United States)

Robertson, J. Gordon

2017-08-01

Most optical and IR spectra are now acquired using detectors with finite-width pixels in a square array. Each pixel records the received intensity integrated over its own area, and pixels are separated by the array pitch. This paper examines the effects of such pixellation, using computed simulations to illustrate the effects which most concern the astronomer end-user. It is shown that coarse sampling increases the random noise errors in wavelength by typically 10-20 % at 2 pixels per Full Width at Half Maximum, but with wide variation depending on the functional form of the instrumental Line Spread Function (i.e. the instrumental response to a monochromatic input) and on the pixel phase. If line widths are determined, they are even more strongly affected at low sampling frequencies. However, the noise in fitted peak amplitudes is minimally affected by pixellation, with increases less than about 5%. Pixellation has a substantial but complex effect on the ability to see a relative minimum between two closely spaced peaks (or relative maximum between two absorption lines). The consistent scale of resolving power presented by Robertson to overcome the inadequacy of the Full Width at Half Maximum as a resolution measure is here extended to cover pixellated spectra. The systematic bias errors in wavelength introduced by pixellation, independent of signal/noise ratio, are examined. While they may be negligible for smooth well-sampled symmetric Line Spread Functions, they are very sensitive to asymmetry and high spatial frequency sub-structure. The Modulation Transfer Function for sampled data is shown to give a useful indication of the extent of improperly sampled signal in an Line Spread Function. The common maxim that 2 pixels per Full Width at Half Maximum is the Nyquist limit is incorrect and most Line Spread Functions will exhibit some aliasing at this sample frequency. While 2 pixels per Full Width at Half Maximum is nevertheless often an acceptable minimum for

Discrimination of different red wine by Fourier-transform infrared and two-dimensional infrared correlation spectroscopy

Science.gov (United States)

Zhang, Yan-ling; Chen, Jian-bo; Lei, Yu; Zhou, Qun; Sun, Su-qin; Noda, Isao

2010-06-01

Fourier-transform infrared spectroscopy (FT-IR) and two-dimensional infrared (2D IR) correlation spectroscopy were applied to analyze main components of liquid red wine with different sugar contents and volatilization residues of dry red wine from different manufactures. The infrared spectra, second derivative spectra of dry red wine show the typical peaks of alcohol, while the spectra of sweet wine are composed of the peaks of both alcohol and sugar, and the contribution of sugar enhanced as the increase of sugar content. Using principal component analysis (PCA) method, dry and sweet wine can be readily classified. Analysis of the infrared spectra of the volatilization residues of dry red wine samples from five different manufactures indicates that dry red wine may be composed of glycerol, carboxylic acids or esters and carboxyl ate, at the same time, different dry red wine show different characteristic peaks in the second derivative spectra and 2D IR correlation spectra, which can be used to discriminate the different manufactures and evaluate the quality of wine samples. The results suggested that infrared spectroscopy is a direct and effective method for the analysis of principle components of different red wines and discrimination of different red wines.

The Electronic Structure and Spectra of Triphenylamines Functionalized by Phenylethynyl Groups

Science.gov (United States)

Baryshnikov, G. V.; Minaeva, V. A.; Minaev, B. F.; Grigoras, M.

2018-01-01

We study the features of the electronic structure and the IR, UV, and visible spectra of a series of triphenylamines substituted with phenylethynyl groups. The analysis is performed at the level of the density functional theory (DFT) and its nonstationary version in comparison with the experimental data of IR and electron spectroscopy. It is shown that, in the excited state, there is a change in the alternation of single, double, and triple bonds in accordance with the character of bonding and antibonding in the lowest vacant molecular orbital. The gradual introduction of additional phenylethynyl groups does not cause frequency shifts in the IR spectra of the molecules under study, but significantly affects the intensity of the corresponding IR bands. A similar effect is also observed in the electronic-absorption spectra of these compounds. This can be used for optical tuning of triphenylamines as promising materials for organic light-emitting diodes and solar cells.

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

calibration is linear. Using samples in the calibration set that have a different OM / OC or ammonium / OC distributions than the test set leads to only a modest increase in bias and normalized error in the predicted samples. We conclude that FT-IR analysis with partial least squares regression is a robust method for accurately predicting TOR OC in IMPROVE network samples; providing complementary information to the organic functional group composition and organic aerosol mass estimated previously from the same set of sample spectra (Ruthenburg et al., 2014).

VizieR Online Data Catalog: IR-bright MSX sources in the SMC with Spitzer/IRS (Kraemer+, 2017)

Science.gov (United States)

Kraemer, K. E.; Sloan, G. C.; Wood, P. R.; Jones, O. C.; Egan, M. P.

2017-07-01

Our original set of infrared spectra of MSX SMC sources was obtained in Spitzer Cycle 1 (Program ID 3277, P.I. M. Egan). This program included 35 targets from the MSX SMC catalog. 24 targets were discussed in previous papers; this paper examines the remaining 11 sources in the sample. We also selected 4 objects in the MSX SMC catalog with similar photometric characteristics in an effort to uncover additional sources with crystalline dust. We observed these targets in Spitzer Cycle 3 (Program ID 30355, P.I. J. Houck). See tables 1 and 2 for observation data and basic properties of the targets. Table 3 lists 20 additional MSX SMC sources that were observed by other Spitzer IRS programs. Overall, 59 MSX SMC sources were observed with the IRS. The spectra were observed using the low-resolution modules of the IRS, Short-Low (SL) and Long-Low (LL), which provided spectra in the 5-14 and 14-37um ranges, respectively, at a resolution between ~60 and 120. For 10 evolved stars with oxygen-rich dust in our Cycle 1 program, we obtained spectra from 0.45 to 1.03um with the Double-Beam Spectrograph at the 2.3m telescope of the Australian National University at Siding Spring Observatory. A 0.45-0.89um spectrum for one of the stars in program 30355 was also observed. These spectra have a resolution of 10Å. Tables 5-7: catalog based on the 243 sources detected in the MSX survey of the SMC, updated with positions and photometry from more recent space-based missions and ground-based surveys. See the Appendix section for more details. The SMC catalog from MSX consists of the 243 sources in the main MSX catalog (Egan+ 2003, see V/114) that lie within the region 7°

Influence of composition and roughness on the pigment mapping of paintings using mid-infrared fiberoptics reflectance spectroscopy (mid-IR FORS) and multivariate calibration.

Science.gov (United States)

Sessa, Clarimma; Bagán, Héctor; García, Jose Francisco

2014-10-01

Mid-infrared fiberoptics reflectance spectroscopy (mid-IR FORS) is a very interesting technique for artwork characterization purposes. However, the fact that the spectra obtained are a mixture of surface (specular) and volume (diffuse) reflection is a significant drawback. The physical and chemical features of the artwork surface may produce distortions in the spectra that hinder comparison with reference databases acquired in transmission mode. Several studies attempted to understand the influence of the different variables and propose procedures to improve the interpretation of the spectra. This article is focused on the application of mid-IR FORS and multivariate calibration to the analysis of easel paintings. The objectives are the evaluation of the influence of the surface roughness on the spectra, the influence of the matrix composition for the classification of unknown spectra, and the capability of obtaining pigment composition mappings. A first evaluation of a fast procedure for spectra management and pigment discrimination is discussed. The results demonstrate the capability of multivariate methods, principal component analysis (PCA), and partial least squares discrimination analysis (PLS-DA), to model the distortions of the reflectance spectra and to delimitate and discriminate areas of uniform composition. The roughness of the painting surface is found to be an important factor affecting the shape and relative intensity of the spectra. A mapping of the major pigments of a painting is possible using mid-IR FORS and PLS-DA when the calibration set is a palette that includes the potential pigments present in the artwork mixed with the appropriate binder and that shows the different paint textures.

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.

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.

Spectroscopic studies of ozone in cryosolutions: FT-IR spectra of 16O3 in liquid nitrogen, oxygen, argon and krypton

Science.gov (United States)

Bulanin, Kirill M.; Bulanin, Michael O.; Rudakova, Aida V.; Kolomijtsova, Tatiana D.; Shchepkin, Dmitrij N.

2018-03-01

We have measured and interpreted the IR spectra of ozone dissolved in liquid nitrogen, oxygen, argon, and krypton in the 650-4700 cm-1 spectral region at 79-117 K. Frequency shifts, band intensities and bandshapes of 22 spectral features of soluted ozone were analyzed. The bands of the A1 symmetry have a complex contour and possess an excess intensity with respect to the value of the purely vibrational transition moment. It was found that this effect is related to the manifestation of the Coriolis interaction. The bandshape distortion manifests itself as an additional intensity from the side of the B1 symmetry band being an intensity source in the case of the Coriolis interaction.

EPR and IR spectral investigations on some leafy vegetables of Indian origin

Science.gov (United States)

Prasuna, C. P. Lakshmi; Chakradhar, R. P. S.; Rao, J. L.; Gopal, N. O.

2009-09-01

EPR spectral investigations have been carried out on four edible leafy vegetables of India, which are used as dietary component in day to day life. In Rumex vesicarius leaf sample, EPR spectral investigations at different temperatures indicate the presence of anti-ferromagnetically coupled Mn(IV)-Mn(IV) complexes. EPR spectra of Trigonella foenum graecum show the presence of Mn ions in multivalent state and Fe 3+ ions in rhombic symmetry. EPR spectra of Basella rubra indicate the presence of Mn(IV)-O-Mn(IV) type complexes. The EPR spectra of Basella rubra have been studied at different temperatures. It is found that the spin population for the resonance signal at g = 2.06 obeys the Boltzmann distribution law. The EPR spectra of Moringa oliefera leaves show the presence of Mn 2+ ions. Radiation induced changes in free radical of this sample have also been studied. The FT-IR spectra of Basella rubra and Moringa oliefera leaves show the evidences for the protein matrix bands and those corresponding to carboxylic C dbnd O bonds.

FT-IR, FT-Raman spectra and ab initio HF and DFT calculations of 7-chloro-5-(2-chlorophenyl)-3-hydroxy-2,3-dihydro-1H-1,4-benzodiazepin-2-one.

Science.gov (United States)

Muthu, S; Prasath, M; Paulraj, E Isac; Balaji, R Arun

2014-01-01

The Fourier Transform infrared and Fourier Transform Raman spectra of 7-chloro-5 (2-chlorophenyl)-3-hydroxy-2,3-dihydro-1H-1,4-benzodiazepin-2-one (7C3D4B) were recorded in the regions 4000-400 and 4000-100 cm(-1), respectively. The appropriate theoretical spectrograms for the IR and Raman spectra of the title molecule were also constructed. The calculated results show that the predicted geometry can well reproduce the structural parameters. Predicted vibrational frequencies have been assigned and compared with experimental IR spectra and they supported each other. Stability of the molecule arising from hyperconjugative interactions, charge delocalization and intramolecular hydrogen bond-like weak interaction has been analyzed using natural bond orbital (NBO) analysis by using B3LYP/6-31G(d,p) method. The results show that electron density (ED) in the σ* and π* antibonding orbitals and second-order delocalization energies E(2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. The first order hyperpolarizability (βtotal) of this molecular system and related properties (β, μ, and Δα) are calculated using HF/6-31G(d,p) and B3LYP/6-31G(d,p) methods based on the finite-field approach. Copyright © 2013 Elsevier B.V. All rights reserved.

MTF measurement of IR optics in different temperature ranges

Science.gov (United States)

Bai, Alexander; Duncker, Hannes; Dumitrescu, Eugen

2017-10-01

Infrared (IR) optical systems are at the core of many military, civilian and manufacturing applications and perform mission critical functions. To reliably fulfill the demanding requirements imposed on today's high performance IR optics, highly accurate, reproducible and fast lens testing is of crucial importance. Testing the optical performance within different temperature ranges becomes key in many military applications. Due to highly complex IR-Applications in the fields of aerospace, military and automotive industries, MTF Measurement under realistic environmental conditions become more and more relevant. A Modulation Transfer Function (MTF) test bench with an integrated thermal chamber allows measuring several sample sizes in a temperature range from -40 °C to +120°C. To reach reliable measurement results under these difficult conditions, a specially developed temperature stable design including an insulating vacuum are used. The main function of this instrument is the measurement of the MTF both on- and off-axis at up to +/-70° field angle, as well as measurement of effective focal length, flange focal length and distortion. The vertical configuration of the system guarantees a small overall footprint. By integrating a high-resolution IR camera with focal plane array (FPA) in the detection unit, time consuming measurement procedures such as scanning slit with liquid nitrogen cooled detectors can be avoided. The specified absolute accuracy of +/- 3% MTF is validated using internationally traceable reference optics. Together with a complete and intuitive software solution, this makes the instrument a turn-key device for today's state-of- the-art optical testing.

(Ir)reconcilable differences? The debate concerning nursing and technology.

Science.gov (United States)

Sandelowski, M

1997-01-01

To review and critique the debate concerning nursing and technology. Technology has been considered both at one and at odds with nursing. Mitcham's (1994) concepts of technological optimism and romanticism. Nursing literature since 1960. Historical analysis. Technological optimists in nursing have viewed technology as an extension of and as readily assimilable into humanistic nursing practice, and nursing as socially advantaged by technology. Technological romantics have viewed technology as irreconcilable with nursing culture, as an expression of masculine culture, and as recirculating existing gender and social inequalities. Both optimists and romantics essentialize technology and nursing, treating the two as singular and fixed entities. The (ir)reconcilability of nursing and technology may be a function of how devices are used by people in different contexts, or of the (ir)reconcilability of views of technology in nursing.

Geographic identification of Boletus mushrooms by data fusion of FT-IR and UV spectroscopies combined with multivariate statistical analysis

Science.gov (United States)

Yao, Sen; Li, Tao; Li, JieQing; Liu, HongGao; Wang, YuanZhong

2018-06-01

Boletus griseus and Boletus edulis are two well-known wild-grown edible mushrooms which have high nutrition, delicious flavor and high economic value distributing in Yunnan Province. In this study, a rapid method using Fourier transform infrared (FT-IR) and ultraviolet (UV) spectroscopies coupled with data fusion was established for the discrimination of Boletus mushrooms from seven different geographical origins with pattern recognition method. Initially, the spectra of 332 mushroom samples obtained from the two spectroscopic techniques were analyzed individually and then the classification performance based on data fusion strategy was investigated. Meanwhile, the latent variables (LVs) of FT-IR and UV spectra were extracted by partial least square discriminant analysis (PLS-DA) and two datasets were concatenated into a new matrix for data fusion. Then, the fusion matrix was further analyzed by support vector machine (SVM). Compared with single spectroscopic technique, data fusion strategy can improve the classification performance effectively. In particular, the accuracy of correct classification of SVM model in training and test sets were 99.10% and 100.00%, respectively. The results demonstrated that data fusion of FT-IR and UV spectra can provide higher synergic effect for the discrimination of different geographical origins of Boletus mushrooms, which may be benefit for further authentication and quality assessment of edible mushrooms.

DFT, FT-IR, FT-Raman and vibrational studies of 3-methoxyphenyl boronic acid

Science.gov (United States)

Patil, N. R.; Hiremath, Sudhir M.; Hiremath, C. S.

2018-05-01

The aim of this work is to study the possible stable, geometrical molecular structure, experimental and theoretical FT-IR and FT-Raman spectroscopic methods of 3-Methoxyphenyl boronic acid (3MPBA). FT-IR and FT-Raman spectra were recorded in the region of 4000-400 cm-1 and 40000-50 cm-1 respectively. The optimized geometric structure and vibrational wavenumbers of the title compound were searched by B3LYP hybrid density functional theory method with 6-311++G (d, p) basis set. The Selectedexperimentalbandswereassignedandcharacterizedonthebasisofthescaledtheoreticalwavenumbersby their potential energy distribution (PED) of the vibrational modes obtained from VEDA 4 program. Finally, the predicted calculation results were applied to simulated FT-IR and FT-Raman spectra of the title compound, which show agreement with the observed spectra. Whereas, it is observed that, the theoretical frequencies are more than the experimental one for O-H stretching vibration modes of the title molecule.

Retrieving CO concentrations from FT-IR spectra with nonmodeled interferences and fluctuating baselines using PCR model parameters

DEFF Research Database (Denmark)

Bak, J.

2001-01-01

It is demonstrated that good predictions of gas concentrations based on measured spectra can be made even if these spectra contain totally overlapping spectral features from nonidentified and non-modeled interfering compounds and fluctuating baselines. The prediction program (CONTOUR) is based...... solely on principal component regression (PCR) model parameters, CONTOUR consists of two smaller algorithms. The first of these is used to calculate pure component spectra based on the PCR model parameters at different concentrations. In the second algorithm, the calculated pure component spectra...... remains. The assumptions are that the background and analytical signals must be additive and that no accidental match between these signals takes place. The best results are obtained with the use of spectra with a high selectivity. The use of the program is demonstrated hg applying simple single...

Temperature measurements with two different IR sensors in a continuous-flow microwave heated system

Directory of Open Access Journals (Sweden)

Jonas Rydfjord

2013-10-01

Full Text Available In a continuous-flow system equipped with a nonresonant microwave applicator we have investigated how to best assess the actual temperature of microwave heated organic solvents with different characteristics. This is non-trivial as the electromagnetic field will influence most traditional methods of temperature measurement. Thus, we used a microwave transparent fiber optic probe, capable of measuring the temperature inside the reactor, and investigated two different IR sensors as non-contact alternatives to the internal probe. IR sensor 1 measures the temperature on the outside of the reactor whilst IR sensor 2 is designed to measure the temperature of the fluid through the borosilicate glass that constitutes the reactor wall. We have also, in addition to the characterization of the before mentioned IR sensors, developed statistical models to correlate the IR sensor reading to a correct value of the inner temperature (as determined by the internal fiber optic probe, thereby providing a non-contact, indirect, temperature assessment of the heated solvent. The accuracy achieved with these models lie well within the range desired for most synthetic chemistry applications.

IR spectral analysis for the diagnostics of crust earthquake precursors

Science.gov (United States)

Umarkhodgaev, R. M.; Liperovsky, V. A.; Mikhailin, V. V.; Meister, C.-V.; Naumov, D. Ju

2012-04-01

In regions of future earthquakes, a few days before the seismic shock, the emanation of radon and hydrogen is being observed, which causes clouds of increased ionisation in the atmosphere. In the present work the possible diagnostics of these clouds using infrared (IR) spectroscopy is considered, which may be important and useful for the general geophysical system of earthquake prediction and the observation of industrial emissions of radioactive materials into the atmosphere. Some possible physical processes are analysed, which cause, under the condition of additional ionisation in a pre-breakdown electrical field, emissions in the IR interval. In doing so, the transparency region of the IR spectrum at wavelengths of 7-15 μm is taken into account. This transparency region corresponds to spectral lines of small atmospheric constituents like CH4, CO2, N2O, NO2, NO, and O3. The possible intensities of the IR emissions observable in laboratories and in nature are estimated. The acceleration process of the electrons in the pre-breakdown electrical field before its adhesion to the molecules is analysed. The laboratory equipment for the investigation of the IR absorption spectrum is constructed for the cases of normal and decreased atmospheric pressures. The syntheses of ozone and nitrous oxides are performed in the barrier discharge. It is studied if the products of the syntheses may be used to model atmospheric processes where these components take part. Spectra of products of the syntheses in the wavelength region of 2-10 μm are observed and analysed. A device is created for the syntheses and accumulation of nitrous oxides. Experiments to observe the IR-spectra of ozone and nitrous oxides during the syntheses and during the further evolution of these molecules are performed. For the earthquake prediction, practically, the investigation of emission spectra is most important, but during the laboratory experiments, the radiation of the excited molecules is shifted by a

Analysis and identification of two similar traditional Chinese medicines by using a three-stage infrared spectroscopy: Ligusticum chuanxiong, Angelica sinensis and their different extracts

Science.gov (United States)

Xiang, Li; Wang, Jingjuan; Zhang, Guijun; Rong, Lixin; Wu, Haozhong; Sun, Suqin; Guo, Yizhen; Yang, Yanfang; Lu, Lina; Qu, Lei

2016-11-01

Rhizoma Chuanxiong (CX) and Radix Angelica sinensis (DG) are very important Traditional Chinese Medicine (TCM) and usually used in clinic. They both are from the Umbelliferae family, and have almost similar chemical constituents with each other. It is complicated, time-consuming and laborious to discriminate them by using the chromatographic methods such as high performance liquid chromatography (HPLC) and gas chromatography (GC). Therefore, to find a fast, applicable and effective identification method for two herbs is urged in quality research of TCM. In this paper, by using a three-stage infrared spectroscopy (Fourier transform infrared spectroscopy (FT-IR), the second derivative infrared spectroscopy (SD-IR) and two-dimensional correlation infrared spectroscopy (2D-IR)), we analyzed and discriminated CX, DG and their different extracts (aqueous extract, alcoholic extract and petroleum ether extract). In FT-IR, all the CX and DG samples' spectra seemed similar, but they had their own unique macroscopic fingerprints to identify. Through comparing with the spectra of sucrose and the similarity calculation, we found the content of sucrose in DG raw materials was higher than in CX raw materials. The significant differences in alcoholic extract appeared that in CX alcoholic extract, the peaks at 1743 cm-1 was obviously stronger than the peak at same position in DG alcoholic extract. Besides in petroleum ether extract, we concluded CX contained much more ligustilide than DG by the similarity calculation. With the function of SD-IR, some tiny differences were amplified and overlapped peaks were also unfolded in FT-IR. In the range of 1100-1175 cm-1, there were six peaks in the SD-IR spectra of DG and the intensity, shape and location of those six peaks were similar to that of sucrose, while only two peaks could be observed in that of CX and those two peaks were totally different from sucrose in shape and relative intensity. This result was consistent with that of the

Quantum-chemical, NMR, FT IR, and ESI MS studies of complexes of colchicine with Zn(II).

Science.gov (United States)

Jankowski, Wojciech; Kurek, Joanna; Barczyński, Piotr; Hoffmann, Marcin

2017-04-01

Colchicine is a tropolone alkaloid from Colchicinum autumnale. It shows antifibrotic, antimitotic, and anti-inflammatory activities, and is used to treat gout and Mediterranean fever. In this work, complexes of colchicine with zinc(II) nitrate were synthesized and investigated using DFT, 1 H and 13 C NMR, FT IR, and ESI MS. The counterpoise-corrected and uncorrected interaction energies of these complexes were calculated. We also calculated their 1 H, 13 C NMR, and IR spectra and compared them with the corresponding experimentally obtained data. According to the ESI MS mass spectra, colchicine forms stable complexes with zinc(II) nitrate that have various stoichiometries: 2:1, 1:1:1, and 2:1:1 with respect to colchichine, Zn(II), and nitrate ion. All of the complexes were investigated using the quantum theory of atoms in molecules (QTAIM). The calculated and the measured spectra showed differences before and after the complexation process. Calculated electron densities and bond critical points indicated the presence of bonds between the ligands and the central cation in the investigated complexes that satisfied the quantum theory of atoms in molecules. Graphical Abstract DFT, NMR, FT IR, ESI MS, QTAIM and puckering studies of complexes of colchicine with Zn(II).

Multi-pollutants sensors based on near-IR telecom lasers and mid-IR difference frequency generation: development and applications

International Nuclear Information System (INIS)

Cousin, J.

2006-12-01

At present the detection of VOC and other anthropic trace pollutants is an important challenge in the measurement of air quality. Infrared spectroscopy, allowing spectral regions rich in molecular absorption to be probed, is a suitable technique for in-situ monitoring of the air pollution. Thus the aim of this work was to develop instruments capable of detecting multiple pollutants for in-situ monitoring by IR spectroscopy. A first project benefited from the availability of the telecommunications lasers emitting in near-IR. This instrument was based on an external cavity diode laser (1500 - 1640 nm) in conjunction with a multipass cell (100 m). The detection sensitivity was optimised by employing a balanced detection and a sweep integration procedure. The instrument developed is deployable for in-situ measurements with a sensitivity of -8 cm -1 Hz -1/2 and allowed the quantification of chemical species such as CO 2 , CO, C 2 H 2 , CH 4 and the determination of the isotopic ratio 13 CO 2 / 12 CO 2 in combustion environment The second project consisted in mixing two near-IR fiber lasers in a non-linear crystal (PPLN) in order to produce a laser radiation by difference frequency generation in the middle-IR (3.15 - 3.43 μm), where the absorption bands of the molecules are the most intense. The first studies with this source were carried out on detection of ethylene (C 2 H 4 ) and benzene (C 6 H 6 ). Developments, characterizations and applications of these instruments in the near and middle IR are detailed and the advantages of the 2 spectral ranges is highlighted. (author)

IR spectral analysis for the diagnostics of crust earthquake precursors

Directory of Open Access Journals (Sweden)

R. M. Umarkhodgaev

2012-11-01

Full Text Available Some possible physical processes are analysed that cause, under the condition of additional ionisation in a pre-breakdown electric field, emissions in the infrared (IR interval. The atmospheric transparency region of the IR spectrum at wavelengths of 7–15 μm is taken into account. This transparency region corresponds to spectral lines of small atmospheric constituents like CH₄, CO₂, N₂O, NO₂, NO, and O₃. The possible intensities of the IR emissions observable in laboratories and in nature are estimated. The acceleration process of the electrons in the pre-breakdown electrical field before its adhesion to the molecules is analyzed. For daytime conditions, modifications of the adsorption spectra of the scattered solar emissions are studied; for nighttime, variations of emission spectra may be used for the analysis.

Polarized IR spectra of resonance assisted hydrogen bond (RAHB) in 2-hydroxyazobenzenes

International Nuclear Information System (INIS)

Rospenk, Maria; Majewska, Paulina; Czarnik-Matusewicz, Boguslawa; Sobczyk, Lucjan

2006-01-01

The polarized IR spectra in the region 4000-400 cm -1 over the temperature range 298-370 K of liquid crystalline (LC) 4-chloro-2'-hydroxy-4'-pentyloxyazobenzene (CHPAB) containing strong O-H...N RAHBs were studied. It has been established that molecules of this compound undergoes a spontaneous ordering in thin layers (10-20 μm) between the KRS-5 plates. The order degree expressed by the S parameter exceeds 0.6 for the Smectic A and crystalline phases. The best indicator of orientation is the mode at 1084 cm -1 as its transition dipole moment is oriented parallel to the long axis of the molecule. A good marker is also the γ(OH) band with the transition dipole moment nearly perpendicular to the long axis. The intramolecular O-H...N hydrogen bonding shows features characteristic of RAHB. The transition dipole moment of the ν(OH) vibrations forms with the long axis of the molecule the angle equal to 43 ± 3 deg. (the OH bond is oriented to this axis at the angle of 9 deg.) that convincingly speaks in favour of a coupling between the proton and π-electron motions. Similar behaviour is manifested by a broad absorption in the finger print region that can be interpreted in terms of the modification of the potential energy shape due to the plane-to-plane intermolecular interaction and appearance of the second minimum. A marked ordering of molecules in the isotropic phase is also observed evidencing some alignment of molecules extended far beyond the monomolecular layers on the surfaces of the KRS-5 windows

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.

Quantitative Interpretation of Polarization SFG Vibrational Spectra of Air/Methanol Interface

Science.gov (United States)

Wu, Hui; Zhang, Wen-kai; Gan, Wei; Cui, Zhi-feng; Wang, Hong-fei

2006-06-01

Even though in IR and Raman spectra of liquid methanol there is always an apparent feature for the asymmetric stretching mode of the CH3 group around 2970 cm-1, this feature has not been observed in the Sum Frequency Generation Vibrational Spectroscopy (SFG-VS) in any polarizations from the air/methanol interface. Here we present a treatment based on a corrected bond additivity model to quantitatively interpret the SFG-VS of the air/methanol interface from the IR and Raman spectra of liquid methanol.

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

divided into calibration and test sets by OC mass and by OM / OC ratio, which reflects the organic composition of the particulate matter and is obtained from organic functional group composition; these divisions 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 calibration is linear. Using samples in the calibration set that have different OM / OC or ammonium / OC distributions than the test set leads to only a modest increase in bias and normalized error in the predicted samples. We conclude that FT-IR analysis with partial least-squares regression is a robust method for accurately predicting TOR OC in IMPROVE network samples - providing complementary information to the organic functional group composition and organic aerosol mass estimated previously from the same set of sample spectra (Ruthenburg et al., 2014).

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.

Ammonia IR Absorbance Measurements with an Equilibrium Vapor Cell

National Research Council Canada - National Science Library

Field, Paul

2004-01-01

Infrared (IR) absorbance spectra were acquired for 18 ammonia vapor pressures. The vapor pressures were generated with 15 gravimetrically prepared aqueous solutions and three commercial aqueous solutions using a dynamic method I.E...

Analysis of cosmetic residues on a single human hair by ATR FT-IR microspectroscopy.

Science.gov (United States)

Pienpinijtham, Prompong; Thammacharoen, Chuchaat; Naranitad, Suwimol; Ekgasit, Sanong

2018-05-15

In this work, ATR FT-IR spectra of single human hair and cosmetic residues on hair surface are successfully collected using a homemade dome-shaped Ge μIRE accessary installed on an infrared microscope. By collecting ATR spectra of hairs from the same person, the spectral patterns are identical and superimposed while different spectral features are observed from ATR spectra of hairs collected from different persons. The spectral differences depend on individual hair characteristics, chemical treatments, and cosmetics on hair surface. The "Contact-and-Collect" technique that transfers remarkable materials on the hair surface to the tip of the Ge μIRE enables an identification of cosmetics on a single hair. Moreover, the differences between un-split and split hairs are also studied in this report. These highly specific spectral features can be employed for unique identification or for differentiation of hairs based on the molecular structures of hairs and cosmetics on hairs. Copyright © 2018 Elsevier B.V. All rights reserved.

Analysis of cosmetic residues on a single human hair by ATR FT-IR microspectroscopy

Science.gov (United States)

Pienpinijtham, Prompong; Thammacharoen, Chuchaat; Naranitad, Suwimol; Ekgasit, Sanong

2018-05-01

In this work, ATR FT-IR spectra of single human hair and cosmetic residues on hair surface are successfully collected using a homemade dome-shaped Ge μIRE accessary installed on an infrared microscope. By collecting ATR spectra of hairs from the same person, the spectral patterns are identical and superimposed while different spectral features are observed from ATR spectra of hairs collected from different persons. The spectral differences depend on individual hair characteristics, chemical treatments, and cosmetics on hair surface. The "Contact-and-Collect" technique that transfers remarkable materials on the hair surface to the tip of the Ge μIRE enables an identification of cosmetics on a single hair. Moreover, the differences between un-split and split hairs are also studied in this report. These highly specific spectral features can be employed for unique identification or for differentiation of hairs based on the molecular structures of hairs and cosmetics on hairs.

Temperature-dependent absorption cross-section measurements of 1-butene (1-C4H8) in VUV and IR

KAUST Repository

Es-sebbar, Et-touhami

2013-01-01

Vacuum ultraviolet (VUV) and infrared (IR) absorption cross-section measurements of 1-butene (1-C4H8; CH2=CHCH2CH3; Butylene) are reported over the temperature range of 296-529K. The VUV measurements are performed between 115 and 205nm using synchrotron radiation as a tunable VUV light source. Fourier Transform Infrared (FTIR) spectroscopy is employed to measure absorption cross-section and band strengths in the IR region between 1.54 and 25μm (~6500-400cm-1). The measured room-temperature VUV and IR absorption cross-sections are compared with available literature data and are found to be in good agreement. The oscillator strength for the electronic transition (A1A\\'→X1A\\') around 150-205nm is determined to be 0.32±0.01.The gas temperature has a strong effect on both VUV and IR spectra. Measurements made in the VUV region show that the peak value of the band cross-section decreases and the background continuum increases with increasing gas temperature. This behavior is due to a change in the rotational and vibrational population distribution of 1-butene molecule. Similar changes in rotational population are observed in the IR spectra. Moreover, variation of the IR spectra with temperature is used to measure the enthalpy difference between syn and skew conformations of 1-butene and is found to be 0.24±0.03. kcal/mol, which is in excellent agreement with values reported in the literature. The measurements reported in this work will provide the much-needed spectroscopic information for the development of high-temperature quantitative diagnostics in combustion applications and validation of atmospheric chemistry models of extra-solar planets. © 2012 Elsevier Ltd.

Ab initio and density functional force field studies on the IR spectra and structure of diazonium dicyanomethylide (diazodicyanomethane)

Science.gov (United States)

Georgieva, Miglena K.

2004-03-01

The structure of diazonium dicyanomethylide (diazodicyanomethane) +N 2-C(CN) 2-↔N 2C(CN) 2 has been studied on the basis of ab initio HF, MP2 and DFT BLYP force field calculations, as well as of literature IR spectra and X-ray diffraction structural data. The results have been compared with those obtained for a series of chemical relatives of the title compound, i.e. molecules, push-pull molecules, anions and zwitterions, containing α-dicyano or diazo fragments, and especially substituted ammonium dicyanomethylides and diazomethane +N 2-CH 2-↔N 2CH 2. It has been found on the basis of spectral, bond length, bond order and electric charge analyses that the diazonium (or carbanionic, left) canonical form is much more important for the title zwitterion, than the corresponding one for diazomethane. So, the title compound can be named (and considered as) both diazonium dicyanomethylide and dicyanodiazomethane.

Vibrational spectra, powder X-ray diffractions and physical properties of cyanide complexes with 1-ethylimidazole

Science.gov (United States)

Kürkçüoğlu, Güneş Süheyla; Kiraz, Fulya Çetinkaya; Sayın, Elvan

2015-10-01

The heteronuclear tetracyanonickelate(II) complexes of the type [M(etim)Ni(CN)4]n (hereafter, abbreviated as M-Ni-etim, M = Mn(II), Fe(II) or Co(II); etim = 1-ethylimidazole, C5H8N2) were prepared in powder form and characterized by FT-IR and Raman spectroscopy, powder X-ray diffraction (PXRD), thermal (TG; DTG and DTA), and elemental analysis techniques. The structures of these complexes were elucidated using vibrational spectra and powder X-ray diffraction patterns with the peak assignment to provide a better understanding of the structures. It is shown that the spectra are consistent with a proposed crystal structure for these compounds derived from powder X-ray diffraction measurements. Vibrational spectra of the complexes were presented and discussed with respect to the internal modes of both the etim and the cyanide ligands. The C, H and N analyses were carried out for all the complexes. Thermal behaviors of these complexes were followed using TG, DTG and DTA curves in the temperature range 30-700 °C in the static air atmosphere. The FT-IR, Raman spectra, thermal and powder X-ray analyses revealed no significant differences between the single crystal and powder forms. Additionally, electrical and magnetic properties of the complexes were investigated. The FT-IR and Raman spectroscopy, PXRD, thermal and elemental analyses results propose that these complexes are similar in structure to the Hofmann-type complexes.

Complementary online aerosol mass spectrometry and offline FT-IR spectroscopy measurements: Prospects and challenges for the analysis of anthropogenic aerosol particle emissions

Science.gov (United States)

Faber, Peter; Drewnick, Frank; Bierl, Reinhard; Borrmann, Stephan

2017-10-01

The aerosol mass spectrometer (AMS) is well established in investigating highly time-resolved dynamics of submicron aerosol chemical composition including organic aerosol (OA). However, interpretation of mass spectra on molecular level is limited due to strong fragmentation of organic substances and potential reactions inside the AMS ion chamber. Results from complementary filter-based FT-IR absorption measurements were used to explain features in high-resolution AMS mass spectra of different types of OA (e.g. cooking OA, cigarette smoking OA, wood burning OA). Using this approach some AMS fragment ions were validated in this study as appropriate and rather specific markers for a certain class of organic compounds for all particle types under investigation. These markers can therefore be used to get deeper insights in the chemical composition of OA based on AMS mass spectra in upcoming studies. However, the specificity of other fragment ions such as C2H4O2+ (m/z 60.02114) remains ambiguous. In such cases, complementary FT-IR measurements allow the interpretation of highly time-resolved AMS mass spectra at the level of molecular functional groups. Furthermore, this study discusses the challenges in reducing inorganic interferences (e.g. from water and ammonium salts) in FT-IR spectra of atmospheric aerosols to decrease spectral uncertainties for better comparisons and, thus, to get more robust results.

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.

Study on Angelica and its different extracts by Fourier transform infrared spectroscopy and two-dimensional correlation IR spectroscopy

Science.gov (United States)

Liu, Hong-xia; Sun, Su-qin; Lv, Guang-hua; Chan, Kelvin K. C.

2006-05-01

In order to develop a rapid and effective analysis method for studying integrally the main constituents in the medicinal materials and their extracts, discriminating the extracts from different extraction process, comparing the categories of chemical constituents in the different extracts and monitoring the qualities of medicinal materials, we applied Fourier transform infrared spectroscopy (FT-IR) associated with second derivative infrared spectroscopy and two-dimensional correlation infrared spectroscopy (2D-IR) to study the main constituents in traditional Chinese medicine Angelica and its different extracts (extracted by petroleum ether, ethanol and water in turn). The findings indicated that FT-IR spectrum can provide many holistic variation rules of chemical constituents. Use of the macroscopical fingerprint characters of FT-IR and 2D-IR spectrum can not only identify the main chemical constituents in medicinal materials and their different extracts, but also compare the components differences among the similar samples. This analytical method is highly rapid, effective, visual and accurate for pharmaceutical research.

ESR investigation of NR and IR rubber vulcanized with different cross-link agents

Directory of Open Access Journals (Sweden)

P. Posadas

2016-01-01

Full Text Available This study evaluates the formation of radical species in natural rubber (NR and poly-isoprene rubber (IR during the vulcanization process and the uniaxial deformation of the formed networks by means of Electron Spin Resonance (ESR. Vulcanization of NR and IR always shows a radical pathway, where the different vulcanization systems dictate the concentration of radical species in the course of this complex process. The greatest concentration of radicals were detected during the vulcanization with sulfur/accelerator based on efficient systems (EV, followed by conventional (CV and sulfur donor systems, whereas azide and organic peroxide agents showed smaller concentration of radicals. Independently of the vulcanization system, certain amount of radicals was detected on the vulcanized samples after the end of the vulcanization process. Comparison between different matrices demonstrates that NR always shows higher concentration of radicals than IR in the vulcanization process as well as during uniaxial deformation, fact that could be associated to the presence of nonrubber components in NR.

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.

Distinguishing Vaccinium species by chemical fingerprinting based on NMR spectra, validated with spectra collected in different laboratories.

Science.gov (United States)

Markus, Michelle A; Ferrier, Jonathan; Luchsinger, Sarah M; Yuk, Jimmy; Cuerrier, Alain; Balick, Michael J; Hicks, Joshua M; Killday, K Brian; Kirby, Christopher W; Berrue, Fabrice; Kerr, Russell G; Knagge, Kevin; Gödecke, Tanja; Ramirez, Benjamin E; Lankin, David C; Pauli, Guido F; Burton, Ian; Karakach, Tobias K; Arnason, John T; Colson, Kimberly L

2014-06-01

A method was developed to distinguish Vaccinium species based on leaf extracts using nuclear magnetic resonance spectroscopy. Reference spectra were measured on leaf extracts from several species, including lowbush blueberry (Vaccinium angustifolium), oval leaf huckleberry (Vaccinium ovalifolium), and cranberry (Vaccinium macrocarpon). Using principal component analysis, these leaf extracts were resolved in the scores plot. Analysis of variance statistical tests demonstrated that the three groups differ significantly on PC2, establishing that the three species can be distinguished by nuclear magnetic resonance. Soft independent modeling of class analogies models for each species also showed discrimination between species. To demonstrate the robustness of nuclear magnetic resonance spectroscopy for botanical identification, spectra of a sample of lowbush blueberry leaf extract were measured at five different sites, with different field strengths (600 versus 700 MHz), different probe types (cryogenic versus room temperature probes), different sample diameters (1.7 mm versus 5 mm), and different consoles (Avance I versus Avance III). Each laboratory independently demonstrated the linearity of their NMR measurements by acquiring a standard curve for chlorogenic acid (R(2) = 0.9782 to 0.9998). Spectra acquired on different spectrometers at different sites classifed into the expected group for the Vaccinium spp., confirming the utility of the method to distinguish Vaccinium species and demonstrating nuclear magnetic resonance fingerprinting for material validation of a natural health product. Georg Thieme Verlag KG Stuttgart · New York.

DFT Calculation of IR Absorption Spectra for PCE-nH2O, TCE-nH2O, DCE-nH2O, VC-nH2O for Small and Water-Dominated Molecular Clusters

Science.gov (United States)

2017-10-31

VC-nH2O for Small and Water-Dominated Molecular Clusters October 31, 2017 Approved for public release; distribution is unlimited. L. Huang S.g...Calculation of IR Absorption Spectra for PCE-nH2O, TCE-nH2O, DCE-nH2O, VC-nH2O for Small and Water-Dominated Molecular Clusters L. Huang,1 S.G...nH2O molecular clusters using density function theory (DFT). DFT can provide interpretation of absorption spectra with respect to molecular

Numerical analysis of alpha spectra using two different codes

International Nuclear Information System (INIS)

Hurtado, S.; Jimenez-Ramos, M.C.; Villa, M.; Vioque, I.; Manjon, G.; Garcia-Tenorio, R.

2008-01-01

This work presents an intercomparison between commercial software for alpha-particle spectrometry, Genie 2000, and the new free available software, Winalpha, developed by International Atomic Energy Agency (IAEA). In order to compare both codes, different environmental spectra containing plutonium, uranium, thorium and polonium have been analyzed, together with IAEA test alpha spectra. A statistical study was performed in order to evaluate the precision and accuracy in the analyses, and to enhance the confidence in using the software on alpha spectrometric studies

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

Analytical investigation of different mathematical approaches utilizing manipulation of ratio spectra

Science.gov (United States)

Osman, Essam Eldin A.

2018-01-01

This work represents a comparative study of different approaches of manipulating ratio spectra, applied on a binary mixture of ciprofloxacin HCl and dexamethasone sodium phosphate co-formulated as ear drops. The proposed new spectrophotometric methods are: ratio difference spectrophotometric method (RDSM), amplitude center method (ACM), first derivative of the ratio spectra (1DD) and mean centering of ratio spectra (MCR). The proposed methods were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical formulation containing the cited drugs. The proposed methods were validated according to the ICH guidelines. A comparative study was conducted between those methods regarding simplicity, limitations and sensitivity. The obtained results were statistically compared with those obtained from the reported HPLC method, showing no significant difference with respect to accuracy and precision.

AXION DECAY AND ANISOTROPY OF NEAR-IR EXTRAGALACTIC BACKGROUND LIGHT

Energy Technology Data Exchange (ETDEWEB)

Gong, Yan; Chen, Xuelei [National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 (China); Cooray, Asantha; Mitchell-Wynne, Ketron [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Zemcov, Michael [Center for Detectors, School of Physics and Astronomy, Rochester Institute of Technology, Rochester, NY 14623 (United States); Smidt, Joseph [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2016-07-10

The extragalactic background light (EBL) is composed of the cumulative radiation from all galaxies and active galactic nuclei over cosmic history. In addition to point sources, the EBL also contains information from diffuse sources of radiation. The angular power spectra of the near-infrared intensities could contain additional signals, and a complete understanding of the nature of the infrared (IR) background is still lacking in the literature. Here we explore the constraints that can be placed on particle decays, especially candidate dark matter (DM) models involving axions that trace DM halos of galaxies. Axions with a mass around a few electronvolts will decay via two photons with wavelengths in the near-IR band and will leave a signature in the IR background intensity power spectrum. Using recent power spectra measurements from the Hubble Space Telescope and the Cosmic Infrared Background Experiment, we find that the 0.6–1.6 μ m power spectra can be explained by axions with masses around 4 eV. The total axion abundance Ω{sub a} ≃ 0.05, and it is comparable to the baryon density of the universe. The suggested mean axion mass and abundance are not ruled out by existing cosmological observations. Interestingly, the axion model with a mass distribution is preferred by the data, which cannot be explained by the standard quantum chromodynamics theory and needs further discussion.

Rotation-vibration interactions in the spectra of polycyclic aromatic hydrocarbons: Quinoline as a test-case species

International Nuclear Information System (INIS)

Pirali, O.; Gruet, S.; Kisiel, Z.; Goubet, M.; Martin-Drumel, M. A.; Cuisset, A.; Hindle, F.; Mouret, G.

2015-01-01

Polycyclic aromatic hydrocarbons (PAHs) are highly relevant for astrophysics as possible, though controversial, carriers of the unidentified infrared emission bands that are observed in a number of different astronomical objects. In support of radio-astronomical observations, high resolution laboratory spectroscopy has already provided the rotational spectra in the vibrational ground state of several molecules of this type, although the rotational study of their dense infrared (IR) bands has only recently become possible using a limited number of experimental set-ups. To date, all of the rotationally resolved data have concerned unperturbed spectra. We presently report the results of a high resolution study of the three lowest vibrational states of quinoline C 9 H 7 N, an N-bearing naphthalene derivative. While the pure rotational ground state spectrum of quinoline is unperturbed, severe complications appear in the spectra of the ν 45 and ν 44 vibrational modes (located at about 168 cm −1 and 178 cm −1 , respectively). In order to study these effects in detail, we employed three different and complementary experimental techniques: Fourier-transform microwave spectroscopy, millimeter-wave spectroscopy, and Fourier-transform far-infrared spectroscopy with a synchrotron radiation source. Due to the high density of states in the IR spectra of molecules as large as PAHs, perturbations in the rotational spectra of excited states should be ubiquitous. Our study identifies for the first time this effect and provides some insights into an appropriate treatment of such perturbations

Rotation-vibration interactions in the spectra of polycyclic aromatic hydrocarbons: Quinoline as a test-case species

Science.gov (United States)

Pirali, O.; Kisiel, Z.; Goubet, M.; Gruet, S.; Martin-Drumel, M. A.; Cuisset, A.; Hindle, F.; Mouret, G.

2015-03-01

Polycyclic aromatic hydrocarbons (PAHs) are highly relevant for astrophysics as possible, though controversial, carriers of the unidentified infrared emission bands that are observed in a number of different astronomical objects. In support of radio-astronomical observations, high resolution laboratory spectroscopy has already provided the rotational spectra in the vibrational ground state of several molecules of this type, although the rotational study of their dense infrared (IR) bands has only recently become possible using a limited number of experimental set-ups. To date, all of the rotationally resolved data have concerned unperturbed spectra. We presently report the results of a high resolution study of the three lowest vibrational states of quinoline C9H7N, an N-bearing naphthalene derivative. While the pure rotational ground state spectrum of quinoline is unperturbed, severe complications appear in the spectra of the ν45 and ν44 vibrational modes (located at about 168 cm-1 and 178 cm-1, respectively). In order to study these effects in detail, we employed three different and complementary experimental techniques: Fourier-transform microwave spectroscopy, millimeter-wave spectroscopy, and Fourier-transform far-infrared spectroscopy with a synchrotron radiation source. Due to the high density of states in the IR spectra of molecules as large as PAHs, perturbations in the rotational spectra of excited states should be ubiquitous. Our study identifies for the first time this effect and provides some insights into an appropriate treatment of such perturbations.

Rotation-vibration interactions in the spectra of polycyclic aromatic hydrocarbons: Quinoline as a test-case species

Energy Technology Data Exchange (ETDEWEB)

Pirali, O.; Gruet, S. [AILES Beamline, Synchrotron SOLEIL, l’Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette cedex (France); Institut des Sciences Moléculaires d’Orsay, UMR8214 CNRS – Université Paris-Sud, Bât. 210, 91405 Orsay cedex (France); Kisiel, Z. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Goubet, M. [Laboratoire de Physique des Lasers, Atomes et Molécules, UMR 8523 CNRS - Université Lille 1, Bâtiment P5, F-59655 Villeneuve d’Ascq Cedex (France); Martin-Drumel, M. A.; Cuisset, A.; Hindle, F.; Mouret, G. [Laboratoire de Physico-Chimie de l’Atmosphère, EA-4493, Université du Littoral – Côte d’Opale, 59140 Dunkerque (France)

2015-03-14

Polycyclic aromatic hydrocarbons (PAHs) are highly relevant for astrophysics as possible, though controversial, carriers of the unidentified infrared emission bands that are observed in a number of different astronomical objects. In support of radio-astronomical observations, high resolution laboratory spectroscopy has already provided the rotational spectra in the vibrational ground state of several molecules of this type, although the rotational study of their dense infrared (IR) bands has only recently become possible using a limited number of experimental set-ups. To date, all of the rotationally resolved data have concerned unperturbed spectra. We presently report the results of a high resolution study of the three lowest vibrational states of quinoline C{sub 9}H{sub 7}N, an N-bearing naphthalene derivative. While the pure rotational ground state spectrum of quinoline is unperturbed, severe complications appear in the spectra of the ν{sub 45} and ν{sub 44} vibrational modes (located at about 168 cm{sup −1} and 178 cm{sup −1}, respectively). In order to study these effects in detail, we employed three different and complementary experimental techniques: Fourier-transform microwave spectroscopy, millimeter-wave spectroscopy, and Fourier-transform far-infrared spectroscopy with a synchrotron radiation source. Due to the high density of states in the IR spectra of molecules as large as PAHs, perturbations in the rotational spectra of excited states should be ubiquitous. Our study identifies for the first time this effect and provides some insights into an appropriate treatment of such perturbations.

Photodissociation Spectroscopy of Cold Protonated Synephrine: Surprising Differences between IR-UV Hole-Burning and IR Photodissociation Spectroscopy of the O-H and N-H Modes.

Science.gov (United States)

Nieuwjaer, N; Desfrançois, C; Lecomte, F; Manil, B; Soorkia, S; Broquier, M; Grégoire, G

2018-04-19

We report the UV and IR photofragmentation spectroscopies of protonated synephrine in a cryogenically cooled Paul trap. Single (UV or IR) and double (UV-UV and IR-UV) resonance spectroscopies have been performed and compared to quantum chemistry calculations, allowing the assignment of the lowest-energy conformer with two rotamers depending on the orientation of the phenol hydroxyl (OH) group. The IR-UV hole burning spectrum exhibits the four expected vibrational modes in the 3 μm region, i.e., the phenol OH, C β -OH, and two NH 2 + stretches. The striking difference is that, among these modes, only the free phenol OH mode is active through IRPD. The protonated amino group acts as a proton donor in the internal hydrogen bond and displays large frequency shifts upon isomerization expected during the multiphoton absorption process, leading to the so-called IRMPD transparency. More interestingly, while the C β -OH is a proton acceptor group with moderate frequency shift for the different conformations, this mode is still inactive through IRPD.

Olivine Composition of the Mars Trojan 5261 Eureka: Spitzer IRS Data

Science.gov (United States)

Lim, L. F.; Burt, B. J.; Emery, J. P.; Mueller, M.; Rivkin, A. S.; Trilling, D.

2011-01-01

The largest Mars trojan, 5261 Eureka, is one of two prototype "Sa" asteroids in the Bus-Demeo taxonomy. Analysis of its visible/near-IR spectrum led to the conclusion that it might represent either an angritic analog or an olivine-rich composition such as an R chondrite. Spitzer IRS data (5-30 micrometers) have enabled us to resolve this ambiguity. The thermal-IR spectrum exhibits strong olivine reststrahlen features consistent with a composition of approximately equals Fo60-70. Laboratory spectra of R chondrites, brachinites, and chassignites are dominated by similar features.

FT-IR microscopical analysis with synchrotron radiation: The microscope optics and system performance

International Nuclear Information System (INIS)

Reffner, J.A.; Martoglio, P.A.; Williams, G.P.

1995-01-01

When a Fourier transform infrared (FT-IR) microspectrometer was first interfaced with the National Synchrotron Light Source (NSLS) in September 1993, there was an instant realization that the performance at the diffraction limit had increased 40-100 times. The synchrotron source transformed the IR microspectrometer into a true IR microprobe, providing high-quality IR spectra for probe diameters at the diffraction limit. The combination of IR microspectroscopy and synchrotron radiation provides a powerful new tool for molecular spectroscopy. The ability to perform IR microspectroscopy with synchrotron radiation is still under development at Brookhaven National Laboratory, but several initial studies have been completed that demonstrate the broad-ranging applications of this technology and its potential for materials characterization

FT-IR microscopical analysis with synchrotron radiation: The microscope optics and system performance

Energy Technology Data Exchange (ETDEWEB)

Reffner, J.A.; Martoglio, P.A. [Spectra-Tech, Inc., Shelton, CT (United States); Williams, G.P. [Brookhaven National Lab., Upton, NY (United States)

1995-01-01

When a Fourier transform infrared (FT-IR) microspectrometer was first interfaced with the National Synchrotron Light Source (NSLS) in September 1993, there was an instant realization that the performance at the diffraction limit had increased 40-100 times. The synchrotron source transformed the IR microspectrometer into a true IR microprobe, providing high-quality IR spectra for probe diameters at the diffraction limit. The combination of IR microspectroscopy and synchrotron radiation provides a powerful new tool for molecular spectroscopy. The ability to perform IR microspectroscopy with synchrotron radiation is still under development at Brookhaven National Laboratory, but several initial studies have been completed that demonstrate the broad-ranging applications of this technology and its potential for materials characterization.

Spectroelectrochemical study of polyphenylene by in situ external reflection FT-IR spectroscopy. Pt. 2

International Nuclear Information System (INIS)

Kvarnstroem, C.; Ivaska, A.

1994-01-01

In situ external reflection FT-IR measurements are performed during cyclic voltammetric scans on electrochemically polymerized polyphenylene films. The films are polymerized either in 0.1 or 0.8 M biphenyl in 0.1 M TBABF 4 in acetonitrile. Changes in the IR spectrum of films of different thicknesses are studied when the films are potentially cycled from the neutral to the oxidized states of the polymer. No differences between films made in high or low dimer concentration can be observed in the spectra. The potential-dependent insertion and expulsion of solvent, residual water, anions and cations in and out of the film have different behaviour in films of different thicknesses. Changes in the structure of the segments in the film, from the benzenoid form into the quinoid form, can be followed. Differences between the first and subsequent cyclic potential scans are observed. (orig.)

Chemical profiling and adulteration screening of Aquilariae Lignum Resinatum by Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy

Science.gov (United States)

Qu, Lei; Chen, Jian-bo; Zhang, Gui-Jun; Sun, Su-qin; Zheng, Jing

2017-03-01

As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p = 0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR.

Avaliação do uso de técnicas PIR-G/FT-IR para caracterização de elastômeros Evaluation of PIR-G/FT-IR techniques for characterization of elastomers

Directory of Open Access Journals (Sweden)

Natália B. Sanches

2006-01-01

Full Text Available A técnica de pirólise gasosa, em bico de Bunsen, para análise por espectroscopia no infravermelho com transformada de Fourier (PIR-G/FT-IR foi aplicada a diferentes borrachas, incluindo algumas misturas. Foi observado que é possível diferenciar os tipos de elastômeros por meio de análise de produtos gasosos de pirólise, inclusive aqueles que apresentam espectros IR de pirolisados líquidos similares, como é o caso de CIIR e BIIR, NR/SBR e EPDM/SBR, SBR/BR e SBR.Pyrolysis and infrared spectroscopy (PIR-G/FT-IR were used for investigating gaseous products of rubber. The results show that this method was suitable to identify different elastomers and elastomer blends, including rubbers that present similar IR spectra of pyrolysed liquid products such as CIIR and BIIR, NR/SBR and EPDM/SBR, SBR/BR and SBR.

Ir-Driven Dynamics of the 3-AMINOPHENOL-AMMONIA Complex

Science.gov (United States)

Heid, Cornelia G.; Merrill, W. G.; Case, Amanda; Crim, Fleming

2014-06-01

We report on gas-phase experiments investigating the predissociation and possible IR-driven isomerization of the 3-aminophenol-ammonia complex (3-AP-NH3). A molecular beam of 3-AP-NH3 is vibrationally excited with pulsed IR light, initiating an intramolecular vibrational redistribution and subsequent dissociation. The 3-AP fragment is then probed state-selectively via multiphoton ionization (REMPI) and time-of-flight mass spectrometry. Of particular interest is an IR-driven feature which we associate tentatively with a trans-cis isomerization process. We see clear correlation between the excitation of specific vibrational modes (namely the NH3 symmetric and OH stretches) and the presence of this feature, as evidenced by IR-action and IR-depletion spectra. The feature persists atop a broader signal which we assign to the predissociation of the complex and whose cutoff in REMPI-action experiments provides an upper bound on the dissociation energy for 3-AP-NH3.

Honey bee odorant-binding protein 14: effects on thermal stability upon odorant binding revealed by FT-IR spectroscopy and CD measurements.

Science.gov (United States)

Schwaighofer, Andreas; Kotlowski, Caroline; Araman, Can; Chu, Nam; Mastrogiacomo, Rosa; Becker, Christian; Pelosi, Paolo; Knoll, Wolfgang; Larisika, Melanie; Nowak, Christoph

2014-03-01

In the present work, we study the effect of odorant binding on the thermal stability of honey bee (Apis mellifera L.) odorant-binding protein 14. Thermal denaturation of the protein in the absence and presence of different odorant molecules was monitored by Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD). FT-IR spectra show characteristic bands for intermolecular aggregation through the formation of intermolecular β-sheets during the heating process. Transition temperatures in the FT-IR spectra were evaluated using moving-window 2D correlation maps and confirmed by CD measurements. The obtained results reveal an increase of the denaturation temperature of the protein when bound to an odorant molecule. We could also discriminate between high- and low-affinity odorants by determining transition temperatures, as demonstrated independently by the two applied methodologies. The increased thermal stability in the presence of ligands is attributed to a stabilizing effect of non-covalent interactions between odorant-binding protein 14 and the odorant molecule.

Identification of the traditional Tibetan medicine "Shaji" and their different extracts through tri-step infrared spectroscopy

Science.gov (United States)

Liu, Yue; Li, Jingyi; Fan, Gang; Sun, Suqin; Zhang, Yuxin; Zhang, Yi; Tu, Ya

2016-11-01

Hippophae rhamnoides subsp. sinensis Rousi, Hippophae gyantsensis (Rousi) Y. S. Lian, Hippophae neurocarpa S. W. Liu & T. N. He and Hippophae tibetana Schlechtendal are typically used under one name "Shaji", to treat cardiovascular diseases and lung disorders in Tibetan medicine (TM). A complete set of infrared (IR) macro-fingerprints of these four Hippophae species should be characterized and compared simply, accurately, and in detail for identification. In the present study, tri-step IR spectroscopy, which included Fourier transform IR (FT-IR) spectroscopy, second derivative IR (SD-IR) spectroscopy and two-dimensional correlation IR (2D-IR) spectroscopy, was employed to discriminate the four Hippophae species and their corresponding extracts using different solvents. The relevant spectra exhibited the holistic chemical compositions and variations. Flavonoids, fatty acids and sugars were found to be the main chemical components. Characteristic peak positions, intensities and shapes derived from FT-IR, SD-IR and 2D-IR spectra provided valuable information for sample discrimination. Principal component analysis (PCA) of spectral differences was performed to illustrate the objective identification. Results showed that the species and their extracts can be clearly distinguished. Thus, a quick, precise and effective tri-step IR spectroscopy combined with PCA can be applied to identify and discriminate medicinal materials and their extracts in TM research.

Uranyl oxalate hydrates: structures and IR spectra

International Nuclear Information System (INIS)

Giesting, P.A.; Porter, N.J.; Burns, P.C.

2006-01-01

The novel compound (UO 2 ) 2 C 2 O 4 (OH) 2 (H 2 O) 2 (UrOx2A) and the previously studied compound UO 2 C 2 O 4 (H 2 O) 3 (UrOx3) have been synthesized by mild hydrothermal methods. Single crystal diffraction data collected at 125 K using MoK α radiation and a CCD-based area detector were used to solve and refine the crystal structures by full-matrix least-squares techniques to agreement indices (UrOx2A, UrOx3) wR 2 = 0.037, 0.049 for all data, and R1 0.015, 0.024 calculated for 1285, 2194 unique reflections respectively. The compound UrOx2A is triclinic, space group P1, Z = 1, a = 5.5353(4), b 6.0866(4), c = 7.7686(6) Aa, α = 85.6410(10) , β = 89.7740(10) , γ = 82.5090(10) , V = 258.74(3) Aa 3 . The compound UrOx3 is monoclinic, space group P2 1 /c, Z = 4, a = 5.5921(4), b = 16.9931(13), c = 9.3594(7) Aa, β = 99.5330(10) , V = 877.11(11) Aa 3 . The structures consist of chains of uranyl pentagonal bipyramids connected by oxalate groups and, in UrOx2A, hydroxyl groups; UrOx2A is also notable for its high (2:1) ratio of uranyl to oxalate groups, higher than any observed in other published structures of uranyl oxalates. The structure determined for UrOx3, previously studied by Jayadevan and Chackraburtty (1972); Mikhailov et al. (1999) is in agreement with the previous results; however, the increased precision of the present low-temperature structure refinement allows for the assignment of H atom positions based on the difference Fourier map of electron density. The infrared spectra of these two materials collected at room temperature are also presented and compared with previous work on uranyl oxalate systems. (orig.)

Critical Dispersion-Theory Tests of Silicon's IR Refractive Index

Science.gov (United States)

Karstens, William; Smith, D. Y.

Silicon strongly absorbs both visible and UV light, but is highly transparent in the IR. Hence, it is a common choice for infrared windows and lenses. However, optical design is hindered by literature index values that disagree by up to 1%. In contrast optical-glass indices are known to 0.01% or better. The most widely available silicon IR indices are based on bulk measurements using either Snell's-Law refraction by a prism or channel-spectra interference of front- and backsurface reflections from a planar sample. To test the physical acceptability of these data, we have developed criteria based on a Taylor expansion of the Kramers-Kronig relation for the index at energies below strong inter-band transitions. These tests require that the coefficients of the series in powers of energy squared must be positive within the region of transparency. This is satisfied by essentially all prism measurements; their small scatter arises primarily from impurities and doping. In contrast, channel-spectra data fail in the second and third coefficients. A review of the experimental analysis indicates three problems besides purity: incorrect channel number arising from a channel-spectra model that neglects spectrum distortion by the weak lattice absorption; use of a series expansion of mixed parity in photon energy to describe the even-parity index; and use of an incorrect absorption energy in the Li-Sellmeier dispersion formula. Recommendations for IR index values for pure silicon will be discussed. Supported in part by the US Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC02-06CH11357.

IR-IR Conformation Specific Spectroscopy of Na+(Glucose) Adducts

Science.gov (United States)

Voss, Jonathan M.; Kregel, Steven J.; Fischer, Kaitlyn C.; Garand, Etienne

2018-01-01

We report an IR-IR double resonance study of the structural landscape present in the Na+(glucose) complex. Our experimental approach involves minimal modifications to a typical IR predissociation setup, and can be carried out via ion-dip or isomer-burning methods, providing additional flexibility to suit different experimental needs. In the current study, the single-laser IR predissociation spectrum of Na+(glucose), which clearly indicates contributions from multiple structures, was experimentally disentangled to reveal the presence of three α-conformers and five β-conformers. Comparisons with calculations show that these eight conformations correspond to the lowest energy gas-phase structures with distinctive Na+ coordination. [Figure not available: see fulltext.

The discrimination of 72 nitrate, chlorate and perchlorate salts using IR and Raman spectroscopy

Science.gov (United States)

Zapata, Félix; García-Ruiz, Carmen

2018-01-01

Inorganic oxidizing energetic salts including nitrates, chlorates and perchlorates are widely used in the manufacture of not only licit pyrotechnic compositions, but also illicit homemade explosive mixtures. Their identification in forensic laboratories is usually accomplished by either capillary electrophoresis or ion chromatography, with the disadvantage of dissociating the salt into its ions. On the contrary, vibrational spectroscopy, including IR and Raman, enables the non-invasive identification of the salt, i.e. avoiding its dissociation. This study focuses on the discrimination of all nitrate, chlorate and perchlorate salts that are commercially available, using both Raman and IR spectroscopy, with the aim of testing whether every salt can be unequivocally identified. Besides the visual spectra comparison by assigning every band with the corresponding molecular vibrational mode, a statistical analysis based on Pearson correlation was performed to ensure an objective identification, either using Raman, IR or both. Positively, 25 salts (out of 72) were unequivocally identified using Raman, 30 salts when using IR and 44 when combining both techniques. Negatively, some salts were undistinguishable even using both techniques demonstrating there are some salts that provide very similar Raman and IR spectra.

Prediction of the oversulphated chondroitin sulphate contamination of unfractionated heparin by ATR-IR spectrophotometry.

Science.gov (United States)

Norwig, J; Beyer, T; Brinz, D; Holzgrabe, U; Diller, M; Manns, D

2009-03-01

The detection of a contamination of heparin with oversulphated chondroitin sulphate (OSCS) was first analysed in an unfractionated heparin batch supplied to the US API-market in April 2006. OSCS is a semi-synthetic derivative of the natural occuring glycosaminoglycan chondroitin sulphate. Moreover some spectroscopic characteristics of the substance overlap with those of heparin, so that the infrared (IR) spectra are visually difficult to distinguish whereas (1)H-NMR (Nuclear Magnetic Resonance) spectroscopy or capillary electrophoresis (CE) provides identification by a simple visual inspection of either the spectrum or the electropherogram respectively. However, applying special tools of Multivariate Data Analysis (MVA) to the IR spectra an identification of the contaminated samples is possible. In detail a rapid Attenuation Total Reflectance-Infrared (ATR-IR) measurement was selected, which does not require any sample preparation. The result (contaminated or not contaminated) is predicted within a few minutes. A method transfer to mobile ATR-IR spectrometers seems to be possible. The analysis is based on the fact that the fingerprint of the OSCS IR spectrum (1st derivative) complies with a theoretically calculated principal component in the MVA.

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.

Mid IR-fiber spectroscopy in the 2-17μm range

Science.gov (United States)

Artyushenko, Viatcheslav G.; Bocharnikov, A.; Colquhoun, Gary; Leach, Clive A.; Lobachov, Vladimir; Pirogova, Lyudmila; Sakharova, Tatjana; Savitskij, Dmitrij; Ezhevskaya, Tatjana; Bublikov, Alexandr

2007-10-01

The latest development in IR-fibre optics enables us to expand the spectral range of process spectroscopy from 2μm out to 17μm (5000 to 600cm-1) i.e. into the most informative "finger-print" part of the spectrum. Mid-IR wavelength ranges from 2 to 6-10μm may be covered by Chalcogenide IR-glass CIR-fibres while Polycrystalline PIR-fibres made of Silver Halides solid solutions transmit 4-17 μm wavelength radiation. PIR-fibre immersion ATR probes and Transmission/Reflection probes had been manufactured and successfully tested with different FTIR spectrometers in the field of remote spectroscopy for forensic substances identification, chemical reaction control, and monitoring of exhaust or exhalation gases. Using these techniques no sample preparation is necessary for fibre probes to measure evanescent, reflection and transmission spectra, in situ and in real time. QCL spectrometer may be used as a portable device for multispectral gas analysis at 1ppb level of detectivity for various applications in environmental pollution monitoring.

Binding water to a PEG-linked flexible bichromophore: IR spectra of diphenoxyethane-(H{sub 2}O){sub n} clusters, n = 2-4

Energy Technology Data Exchange (ETDEWEB)

Walsh, Patrick S.; Buchanan, Evan G.; Gord, Joseph R.; Zwier, Timothy S., E-mail: zwier@purdue.edu [Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084 (United States)

2015-04-21

The single-conformation infrared (IR) and ultraviolet (UV) spectroscopies of neutral 1,2-diphenoxyethane-(H{sub 2}O){sub n} clusters with n = 2-4 (labeled henceforth as 1:n) have been studied in a molecular beam using a combination of resonant two-photon ionization, IR-UV holeburning, and resonant ion-dip infrared (RIDIR) spectroscopies. Ground state RIDIR spectra in the OH and CH stretch regions were used to provide firm assignments for the structures of the clusters by comparing the experimental spectra with the predictions of calculations carried out at the density functional M05-2X/6-31+G(d) level of theory. At all sizes in this range, the water molecules form water clusters in which all water molecules engage in a single H-bonded network. Selective binding to the tgt monomer conformer of 1,2-diphenoxyethane (C{sub 6}H{sub 5}-O-CH{sub 2}-CH{sub 2}-O-C{sub 6}H{sub 5}, DPOE) occurs, since this conformer provides a binding pocket in which the two ether oxygens and two phenyl ring π clouds can be involved in stabilizing the water cluster. The 1:2 cluster incorporates a water dimer “chain” bound to DPOE much as it is in the 1:1 complex [E. G. Buchanan et al., J. Phys. Chem. Lett. 4, 1644 (2013)], with primary attachment via a double-donor water that bridges the ether oxygen of one phenoxy group and the π cloud of the other. Two conformers of the 1:3 cluster are observed and characterized, one that extends the water chain to a third molecule (1:3 chain) and the other incorporating a water trimer cycle (1:3 cycle). A cyclic water structure is also observed for the 1:4 cluster. These structural characterizations provide a necessary foundation for studies of the perturbations imposed on the two close-lying S{sub 1}/S{sub 2} excited states of DPOE considered in the adjoining paper [P. S. Walsh et al., J. Chem. Phys. 142, 154304 (2015)].

Chemical profiling and adulteration screening of Aquilariae Lignum Resinatum by Fourier transform infrared (FT-IR) spectroscopy and two-dimensional correlation infrared (2D-IR) spectroscopy.

Science.gov (United States)

Qu, Lei; Chen, Jian-Bo; Zhang, Gui-Jun; Sun, Su-Qin; Zheng, Jing

2017-03-05

As a kind of expensive perfume and valuable herb, Aquilariae Lignum Resinatum (ALR) is often adulterated for economic motivations. In this research, Fourier transform infrared (FT-IR) spectroscopy is employed to establish a simple and quick method for the adulteration screening of ALR. First, the principal chemical constituents of ALR are characterized by FT-IR spectroscopy at room temperature and two-dimensional correlation infrared (2D-IR) spectroscopy with thermal perturbation. Besides the common cellulose and lignin compounds, a certain amount of resin is the characteristic constituent of ALR. Synchronous and asynchronous 2D-IR spectra indicate that the resin (an unstable secondary metabolite) is more sensitive than cellulose and lignin (stable structural constituents) to the thermal perturbation. Using a certified ALR sample as the reference, the infrared spectral correlation threshold is determined by 30 authentic samples and 6 adulterated samples. The spectral correlation coefficient of an authentic ALR sample to the standard reference should be not less than 0.9886 (p=0.01). Three commercial adulterated ALR samples are identified by the correlation threshold. Further interpretation of the infrared spectra of the adulterated samples indicates the common adulterating methods - counterfeiting with other kind of wood, adding ingredient such as sand to increase the weight, and adding the cheap resin such as rosin to increase the content of resin compounds. Results of this research prove that FT-IR spectroscopy can be used as a simple and accurate quality control method of ALR. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of Space Weathering on Reflectance Spectra of Ureilites: A Proof-of-Concept Study

Science.gov (United States)

Goodrich, C. A.; Gillis-Davis, J.; Cloutis, E.; Applin, D.; Hibbits, C.; Klima, R.; Christoffersen, R.; Fries, M.; Decker, S.

2017-07-01

Space weathering and spectral studies of three ureilitic samples show that space weathering causes significant changes in UV-VIS-IR spectra and Raman spectra. Changes due to amorphization of carbon could disguise ureilitic asteroids as CC-like.

Spectra calculations in central and wing regions of CO2 IR bands between 10 and 20 μm. III: atmospheric emission spectra

International Nuclear Information System (INIS)

Niro, F.; Clarmann, T. von; Jucks, K.; Hartmann, J.-M.

2005-01-01

A theoretical model for the prediction of CO 2 absorption in both central and wing regions of infrared absorption bands was presented in the companion paper I. It correctly accounts for line-mixing effects and was validated by comparisons with laboratory spectra in the 600-1000 cm -1 region. This quality was confirmed using atmospheric transmissions measured by solar occultation experiments in the second paper. The present work completes these studies by now considering atmospheric emission in the 10-20 μm range. Comparisons are made between computed atmospheric radiances and measurements obtained using four different Fourier transform experiments collecting spectra for nadir, up-looking, as well as limb (from balloon and satellite) geometries. Our results confirm that using a Voigt model can lead to very large errors that affect the spectrum more than 300 cm -1 away from the center of the CO 2 ν 2 band. They also demonstrate the capability of our model to represent accurately the radiances in the entire region for a variety of atmospheric paths. This success opens interesting perspectives for the sounding of pressure and temperature profiles, particularly at low altitudes. Another benefit of the quality of the model should be an increased accuracy in the retrieval of atmospheric state parameters from broad features in the measured spectra (clouds, aerosols, heavy trace gases)

A conformational study of protonated noradrenaline by UV-UV and IR dip double resonance laser spectroscopy combined with an electrospray and a cold ion trap method.

Science.gov (United States)

Wako, Hiromichi; Ishiuchi, Shun-Ichi; Kato, Daichi; Féraud, Géraldine; Dedonder-Lardeux, Claude; Jouvet, Christophe; Fujii, Masaaki

2017-05-03

The conformer-selected ultraviolet (UV) and infrared (IR) spectra of protonated noradrenaline were measured using an electrospray/cryogenic ion trap technique combined with photo-dissociation spectroscopy. By comparing the UV photo dissociation (UVPD) spectra with the UV-UV hole burning (HB) spectra, it was found that five conformers coexist under ultra-cold conditions. Based on the spectral features of the IR dip spectra of each conformer, two different conformations on the amine side chain were identified. Three conformers (group I) were assigned to folded and others (group II) to extended structures by comparing the observed IR spectra with the calculated ones. Observation of the significantly less-stable extended conformers strongly suggests that the extended structures are dominant in solution and are detected in the gas phase by kinetic trapping. The conformers in each group are assignable to rotamers of OH orientations in the catechol ring. By comparing the UV-UV HB spectra and the calculated Franck-Condon spectra obtained by harmonic vibrational analysis of the S 1 state, with the aid of relative stabilization energies of each conformer in the S 0 state, the absolute orientations of catechol OHs of the observed five conformers were successfully determined. It was found that the 0-0 transition of one folded conformer is red-shifted by about 1000 cm -1 from the others. The significant red-shift was explained by a large contribution of the πσ* state to S 1 in the conformer in which an oxygen atom of the meta-OH group is close to the ammonium group.

Attenuated total reflectance-FT-IR spectroscopy for gunshot residue analysis: potential for ammunition determination.

Science.gov (United States)

Bueno, Justin; Sikirzhytski, Vitali; Lednev, Igor K

2013-08-06

The ability to link a suspect to a particular shooting incident is a principal task for many forensic investigators. Here, we attempt to achieve this goal by analysis of gunshot residue (GSR) through the use of attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FT-IR) combined with statistical analysis. The firearm discharge process is analogous to a complex chemical process. Therefore, the products of this process (GSR) will vary based upon numerous factors, including the specific combination of the firearm and ammunition which was discharged. Differentiation of FT-IR data, collected from GSR particles originating from three different firearm-ammunition combinations (0.38 in., 0.40 in., and 9 mm calibers), was achieved using projection to latent structures discriminant analysis (PLS-DA). The technique was cross (leave-one-out), both internally and externally, validated. External validation was achieved via assignment (caliber identification) of unknown FT-IR spectra from unknown GSR particles. The results demonstrate great potential for ATR-FT-IR spectroscopic analysis of GSR for forensic purposes.

Retrieval of Tropospheric Profiles from IR Emission Spectra: Field Experiment and Sensitivity Study

National Research Council Canada - National Science Library

Theriault, J

1993-01-01

.... The goal of this project was the retrieval of atmospheric temperature and water vapor profiles and possibly over relevant information on clouds and aerosol properties from high resolution IR emission...

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

Acquisition of Infrared Variable Angle Spectroscopic Ellipsometer (IR-VASE)

Science.gov (United States)

2016-04-22

biomaterials , and nanocomposites. Based on this base user group it is estimated that...Engineering; and Barbara Calcagno, Department of General Engineering) 5. The Role of Mechanical Stimulus on Collagen Expression During Bone Repair (Paul...Polymeric Biomaterials Laboratory Principal Investigator: Jorge Almodóvar, PhD - The IR spectra

IR and NMR spectroscopic correlation of enterobactin by DFT

Science.gov (United States)

Moreno, M.; Zacarias, A.; Porzel, A.; Velasquez, L.; Gonzalez, G.; Alegría-Arcos, M.; Gonzalez-Nilo, F.; Gross, E. K. U.

2018-06-01

Emerging and re-emerging epidemic diseases pose an ongoing threat to global health. Currently, Enterobactin and Enterobactin derivatives have gained interest, owing to their potential application in the pharmaceutical field. As it is known [J. Am. Chem. Soc (1979) 101, 20, 6097-6104], Enterobactin (H6EB) is an efficient iron carrier synthesized and secreted by many microbial species. In order to facilitate the elucidation of enterobactin and its analogues, here we propose the creation of a H6EB standard set using Density Functional Theory Infrared (IR) and NMR spectra. We used two exchange-correlation (xc) functionals (PBE including long-range corrections sbnd LC-PBEsbnd and mPW1), 2 basis sets (QZVP and 6-31G(d)) and 2 grids (fine and ultrafine) for most of the H6EB structures dependent of dihedral angles. The results show a significant difference between the Osbnd H and Nsbnd H bands, while the Cdbnd O amide and Osbnd (Cdbnd O)sbnd IR bands are often found on top of each other. The NMR DFT calculations show a strong dependence on the xc functional, basis set, and grid used for the H6EB structure. Calculated 1H and 13C NMR spectra enable the effect of the solvent to be understood in the context of the experimental measurements. The good agreement between the experimental and the calculated spectra using LC-PBE/QZVP and ultrafine grid suggest the possibility of the systems reported here to be considered as a standard set. The dependence of electrostatic potential and frontier orbitals with the catecholamide dihedral angles of H6EB is described. The matrix-assisted laser desorption/ionization time of the flight mass spectrometry (MALDI-TOF MS) of H6EB is also reported of manner to enrich the knowledge about its reactivity.

Structural Changes Induced in Grapevine (Vitis vinifera L. DNA by Femtosecond IR Laser Pulses: A Surface-Enhanced Raman Spectroscopic Study

Directory of Open Access Journals (Sweden)

Nicoleta E. Dina

2016-05-01

Full Text Available In this work, surface-enhanced Raman spectra of ten genomic DNAs extracted from leaf tissues of different grapevine (Vitis vinifera L. varieties, respectively, are analyzed in the wavenumber range 300–1800 cm−1. Furthermore, structural changes induced in grapevine genomic nucleic acids upon femtosecond (170 fs infrared (IR laser pulse irradiation (λ = 1100 nm are discussed in detail for seven genomic DNAs, respectively. Surface-enhanced Raman spectroscopy (SERS signatures, vibrational band assignments and structural characterization of genomic DNAs are reported for each case. As a general observation, the wavenumber range between 1500 and 1660 cm−1 of the spectra seems to be modified upon laser treatment. This finding could reflect changes in the base-stacking interactions in DNA. Spectral shifts are mainly attributed to purines (dA, dG and deoxyribose. Pyrimidine residues seem to be less affected by IR femtosecond laser pulse irradiation. Furthermore, changes in the conformational properties of nucleic acid segments are observed after laser treatment. We have found that DNA isolated from Feteasca Neagra grapevine leaf tissues is the most structurally-responsive system to the femtosecond IR laser irradiation process. In addition, using unbiased computational resources by means of principal component analysis (PCA, eight different grapevine varieties were discriminated.

FT-Raman and FT-IR studies of 1:2.5 piroxicam: β-cyclodextrin inclusion compound

Science.gov (United States)

Bertoluzza, A.; Rossi, M.; Taddei, P.; Redenti, E.; Zanol, M.; Ventura, P.

1999-05-01

The FT-Raman and FT-IR spectra of amorphous 1:2.5 piroxicam (P): β-cyclodextrin (βCD) inclusion compound (PβCD) are presented and discussed in comparison with the spectra of the three main modifications of piroxicam (α,β and monohydrate). In the 1700-1200 cm -1 FT-Raman spectrum of 1:2.5 PβCD inclusion compound the bands of βCD are weak and covered by those stronger of piroxicam, differently from the FT-IR spectrum where the bands of βCD are stronger, so covering a large part of the spectrum. Typical FT-Raman marker bands are assigned for the characterization of the three modifications of piroxicam. The FT-Raman spectrum of 1:2.5 PβCD inclusion compound predominantly shows the bands at about 1465 and 1400 cm -1 of the monohydrate, indicating that piroxicam assumes the zwitterionic structure stabilized by interaction with βCD via electrostatic and hydrogen bonds. The dipolar character of 1:2.5 PβCD inclusion compound improves the solubility and the dissolution rate of piroxicam and thus its rate of absorption.

IR and NMR characterisation of extraction products of radioactively deuteromethylated coals

Energy Technology Data Exchange (ETDEWEB)

Kozlowski, M.; Wachowska, H.; Adriaensens, P.; Gelan, J. [Adam Mickiewicz University, Poznan (Poland). Faculty of Chemistry

1999-12-01

Products of reductive methylation and deuteromethylation of two Polish coals of different rank performed in the potassium/liquid ammonia system were subjected to extraction by dichloromethane. Spectral analysis of the extracts was made. A comparison of {sup 1}H and {sup 2}H NMR spectra indicated that the cleavage of C-C bonds in methylene bridges is of substantial importance for the fragmentation of the coal structure taking place under the effect of potassium in liquid ammonia. This finding was confirmed by results of IR analysis. 25 refs., 3 figs., 2 tabs.

Influence of two different IR radiators on the antioxidative potential of the human skin

International Nuclear Information System (INIS)

Darvin, M E; Patzelt, A; Meinke, M; Sterry, W; Lademann, J

2009-01-01

Resonance Raman spectroscopy was used for the fast in vivo detection of the concentration of carotenoid antioxidant substances such as beta-carotene and lycopene in human skin and for the measurement of their degradation dynamics, subsequent to infrared (IR) irradiation emitted by two different IR radiators applied at the same power density. One of the radiators was equipped with a water filter in front of the radiation source (WIRA) and the other was a usual broadband system without a water filter (standard IR radiator – SIR). It was found that the SIR exerted a higher influence on the degradation of carotenoids in the skin than the WIRA. Furthermore, all twelve volunteers who participated in the study felt that the irradiation with the SIR was disagreeably warmer on the skin surface compared to the WIRA, in spite of the same power density values for both radiators on the skin surface. The average degradation magnitude of the carotenoids in the skin of all volunteers after an IR irradiation was determined at 23% for WIRA and 33% for the SIR. A correlation (R 2 ∼ 0.6) was found between the individual level of carotenoids in the skin of the volunteers and the magnitude of degradation of the carotenoids for both IR radiators. Taking the previous investigations into consideration, which clearly showed production of free radicals in the skin subsequent to IR irradiation, it can be concluded that during the application of WIRA irradiation on the skin, fewer radicals are produced in comparison to the SIR

Organic Spectroscopy Laboratory: Utilizing IR and NMR in the Identification of an Unknown Substance

Science.gov (United States)

Glagovich, Neil M.; Shine, Timothy D.

2005-01-01

A laboratory experiment that emphasizes the interpretation of both infrared (IR) and nuclear magnetic resonance (NMR) spectra in the elucidation of the structure of an unknown compound was developed. The method helps students determine [to the first power]H- and [to the thirteenth power]C-NMR spectra from the structures of compounds and to…

A Rapid Method of Crude Oil Analysis Using FT-IR Spectroscopy

African Journals Online (AJOL)

HP USER

Nigerian Journal of Basic and Applied Science (June,2016), 24(1): 47-55 ... ABSTRACT: This study determines the viability of the use of Fourier Transform ... IR spectra of Crude oil sample containing a mixture of both degraded (sample 151).

Vibrational spectra study of fluorescent dendrimers built from the cyclotriphosphazene core with terminal dansyl and carbamate groups

Science.gov (United States)

Furer, V. L.; Vandyukova, I. I.; Vandyukov, A. E.; Fuchs, S.; Majoral, J. P.; Caminade, A. M.; Kovalenko, V. I.

2011-08-01

The FTIR and FT Raman spectra of the "Janus"-type dendrimers, possessing five carbamate groups on one side and five fluorescent dansyl derivatives on the other side, with amide G1 and hydrazone G2 central linkages were studied. These surface-block dendrimers are obtained by the coupling of two different dendrons. The FTIR and FT-Raman spectra of the zero generation dendrons, built from the hexafunctional cyclotriphosphazene core, with five dansyl terminal groups and one carbamate G0 v and one oxybenzaldehyde function G0v have been recorded. The structural optimization and normal mode analysis were performed for dendron G0v on the basis of the density functional theory (DFT). The calculated geometrical parameters and harmonic vibrational frequencies are predicted in a good agreement with the experimental data. It was found that dendron molecule G0v has a concave lens structure with planar -O-C6H4-CHdbnd O fragments and slightly non-planar cyclotriphosphazene core. The experimental IR and Raman spectra of dendron G0v were interpreted by means of potential energy distributions. Relying on DFT calculations a complete vibrational assignment is proposed. The strong band 1597 cm -1 show marked changes of the optical density in dependence of substituents in the aromatic ring. The frequencies of ν(N-H) bands in the IR spectra reveal the presence of the different types of H-bonds in the dendrimers.

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...

Characterization of additives typically employed in EPDM formulations by using FT-IR of gaseous pyrolyzates

Directory of Open Access Journals (Sweden)

Natália Beck Sanches

2014-06-01

Full Text Available In this study, Fourier transform infrared spectroscopy (FT-IR was employed to investigate the gaseous pyrolysis products of ethylene - propylene - diene rubber (EPDM. The objective was to evaluate the potential of FT-IR analysis of gaseous pyrolyzates (PY-G/FT-IR for characterization of EPDM additives. Two EPDM formulations, containing additives typically employed in EPDM rubbers, were analyzed. Initially, gaseous pyrolysis products from paraffin oil, stearic acid, 2,2,4-trimethyl-1,2-dihydroquinoline, tetramethylthiuram monosulfide (TMTM, tetramethylthiuram disulfide (TMTD, and 2-mercaptobenzothiazole (MBT were characterized separately, and their main absorptions were identified. Subsequently, the gaseous pyrolysis products of raw, unvulcanized, and vulcanized EPDM formulations were analyzed. The similarities observed in the FT-IR spectra of unvulcanized and vulcanized EPDM show that the vulcanization process does not interfere with the pyrolysis products. The identification of the functional groups of the studied additives was possible in both unvulcanized and vulcanized EPDM samples, without solvent extraction. Results also demonstrate that the PY-G/FT-IR technique can identify additives containing sulfur in concentrations as low as 1.4 phr (1.26% in both unvulcanized and vulcanized EPDM. However, the method showed some limitation due to overlapping and to similarities of TMTM and TMTD PY-G/FT-IR spectra, which could not be distinguished from each other. The PY-G/FT-IR technique is a faster and cheaper alternative to the sophisticated techniques usually applied to detection of additives in rubbers.

Synthesis and photophysical studies of blue phosphorescent Ir(III) complexes with dimethylphenylphospine.

Science.gov (United States)

Ham, Ho-Wan; Jung, Kyung-Yoon; Kim, Young-Sik

2012-02-01

New blue emitting mixed ligand iridium(III) complexes comprising one cyclometalating, two phosphines trans to each other such as Ir{(CF3)2Meppy}(PPhMe3)2(H)(L) [L = CI, NCMe, CN] [(CF3)2Meppy = 2-(3', 5'-bis-trifluoromethylphenyl)-4-methylpyridine] were synthesized and studied to tune the phosphorescence wavelength to the deep blue region and to enhance the luminescence efficiencies. To achieve deep blue emission, the trifluoromethyl group substituted on the phenyl ring and the methyl group substituted on the pyridyl ring increased HOMO-LUMO gap and achieved the hypsochromic shift. To gain insight into the factors responsible for the emission color change and the different luminescence efficiency, we investigate the electron-withdrawing capabilities of ancillary ligands using the DFT and TD-DFT calculations on the ground and excited states of the complexes. From these results, we discuss how the ancillary ligand influences the emission peak as well as the metal to ligand charge transfer (MLCT) transition efficiency. The maximum emission spectra of Ir{(CF3)2Meppy}(PPhMe3)2(H)(Cl), [Ir{(CF3),Meppy)(PPhMe3),(H)(NCMe)]+ and Ir{(CF3)2Meppy}(PPhMe3)2(H)(CN) were in the ranges of 441, 435, 434 nm, respectively.

IR, Raman and SERS studies of methyl salicylate

Science.gov (United States)

Varghese, Hema Tresa; Yohannan Panicker, C.; Philip, Daizy; Mannekutla, James R.; Inamdar, S. R.

2007-04-01

The IR and Raman spectra of methyl salicylate (MS) were recorded and analysed. Surface enhanced Raman scattering (SERS) spectrum was recorded in silver colloid. The vibrational wave numbers of the compound have been computed using the Hartree-Fock/6-31G * basis and compared with the experimental values. SERS studies suggest a flat orientation of the molecule at the metal surface.

Electronic structure, local magnetism, and spin-orbit effects of Ir(IV)-, Ir(V)-, and Ir(VI)-based compounds

Energy Technology Data Exchange (ETDEWEB)

Laguna-Marco, M. A.; Kayser, P.; Alonso, J. A.; Martínez-Lope, M. J.; van Veenendaal, M.; Choi, Y.; Haskel, D.

2015-06-01

Element- and orbital-selective x-ray absorption and magnetic circular dichroism measurements are carried out to probe the electronic structure and magnetism of Ir 5d electronic states in double perovskite Sr2MIrO6 (M = Mg, Ca, Sc, Ti, Ni, Fe, Zn, In) and La2NiIrO6 compounds. All the studied systems present a significant influence of spin-orbit interactions in the electronic ground state. In addition, we find that the Ir 5d local magnetic moment shows different character depending on the oxidation state despite the net magnetization being similar for all the compounds. Ir carries an orbital contribution comparable to the spin contribution for Ir4+ (5d(5)) and Ir5+ (5d(4)) oxides, whereas the orbital contribution is quenched for Ir6+ (5d(3)) samples. Incorporation of a magnetic 3d atom allows getting insight into the magnetic coupling between 5d and 3d transition metals. Together with previous susceptibility and neutron diffractionmeasurements, the results indicate that Ir carries a significant local magnetic moment even in samples without a 3d metal. The size of the (small) net magnetization of these compounds is a result of predominant antiferromagnetic interactions between local moments coupled with structural details of each perovskite structure

Infrared Spectroscopy of Gas-Phase M+(CO2)n (M = Co, Rh, Ir) Ion-Molecule Complexes.

Science.gov (United States)

Iskra, Andreas; Gentleman, Alexander S; Kartouzian, Aras; Kent, Michael J; Sharp, Alastair P; Mackenzie, Stuart R

2017-01-12

The structures of gas-phase M + (CO 2 ) n (M = Co, Rh, Ir; n = 2-15) ion-molecule complexes have been investigated using a combination of infrared resonance-enhanced photodissociation (IR-REPD) spectroscopy and density functional theory. The results provide insight into fundamental metal ion-CO 2 interactions, highlighting the trends with increasing ligand number and with different group 9 ions. Spectra have been recorded in the region of the CO 2 asymmetric stretch around 2350 cm -1 using the inert messenger technique and their interpretation has been aided by comparison with simulated infrared spectra of calculated low-energy isomeric structures. All vibrational bands in the smaller complexes are blue-shifted relative to the asymmetric stretch in free CO 2 , consistent with direct binding to the metal center dominated by charge-quadrupole interactions. For all three metal ions, a core [M + (CO 2 ) 2 ] structure is identified to which subsequent ligands are less strongly bound. No evidence is observed in this size regime for complete activation or insertion reactions.

Pressure-modulation dynamic attenuated-total-reflectance (ATR) FT-IR spectroscopy

Science.gov (United States)

Marcott, C.; Story, G. M.; Noda, I.; Bibby, A.; Manning, C. J.

1998-06-01

A single-reflectance attenuated-total-reflectance (ATR) accessory with a diamond internal-reflection element was modified by the addition of a piezoelectric transducer. Initial dynamic pressure-modulation experiments have been performed in the sample compartment of a step-scanning FT-IR spectrometer. A sinusoidal pressure modulation applied to samples of isotactic polypropylene and linear low density polyethylene resulted in dynamic responses which appear to be similar to those observed in previous dynamic 2D IR experiments. Preliminary pressure-modulation dynamic ATR results are also reported for a styrene-butadiene-styrene triblock copolymer. The new method has the advantages that a much wider variety of sample types and geometries can be studied and less sample preparation is required. Dynamic 2D IR experiments carried out by ATR no longer require thin films of large area and sufficient strength to withstand the dynamic strain applied by a rheometer. The ability to obtain dynamic IR spectroscopic information from a wider variety of sample types and thicknesses would greatly expand the amount of useful information that could be extracted from normally complicated, highly overlapped IR spectra.

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

Molecular orbital calculations of the unpaired electron distribution and electric field gradients in divalent paramagnetic Ir complexes

International Nuclear Information System (INIS)

Nogueira, S.R.; Vugman, N.V.; Guenzburger, D.

1988-01-01

Semi-empirical Molecular Orbital calculations were performed for the paramagnetic complex ions [Ir(CN) 5 ] 3- , [Ir(CN) 5 Cl] 4- and [Ir(CN) 4 Cl 2 ] 4- . Energy levels schemes and Mulliken-type populations were obtained. The distribution of the unpaired spin over the atoms in the complexes was derived, and compared to data obtained from Electron Paramagnetic Resonance spectra with the aid of a Ligand Field model. The electric field gradients at the Ir nucleus were calculated and compared to experiment. The results are discussed in terms of the chemical bonds formed by Ir and the ligands. (author) [pt

Electronic and oscillation absorption spectra of blood plamsa at surgical diseases of thyroid gland

Science.gov (United States)

Guminetskiy, S. G.; Motrich, A. V.; Poliansky, I. Y.; Hyrla, Ya. V.

2012-01-01

The results of investigating the absorption spectra of blood plasma in the visible and infrared parts of spectra obtained using the techniques of spherical photometer and spectrophotometric complex "Specord IR75" are presented. The possibility of using these spectra for diagnoses the cases of diffuse toxic goiter and nodular goiter and control of treatment process in postsurgical period in the cases of thyroid gland surgery is estimated.

High-resolution TNG spectra of T Tauri stars. Near-IR GIANO observations of the young variables XZ Tauri and DR Tauri

Science.gov (United States)

Antoniucci, S.; Nisini, B.; Biazzo, K.; Giannini, T.; Lorenzetti, D.; Sanna, N.; Harutyunyan, A.; Origlia, L.; Oliva, E.

2017-10-01

Aims: We aim to characterise the star-disk interaction region in T Tauri stars that show photometric and spectroscopic variability. Methods: We used the GIANO instrument at the Telescopio Nazionale Galileo to obtain near-infrared high-resolution spectra (R 50 000) of XZ Tau and DR Tau, which are two actively accreting T Tauri stars classified as EXors. Equivalent widths and profiles of the observed features are used to derive information on the properties of the inner disk, the accretion columns, and the winds. Results: Both sources display composite H I line profiles, where contributions from both accreting gas and high-velocity winds can be recognised. These lines are progressively more symmetric and narrower with increasing upper energy which may be interpreted in terms of two components with different decrements or imputed to self-absorption effects. XZ Tau is observed in a relatively high state of activity with respect to literature observations. The variation of the He I 1.08 μm line blue-shifted absorption, in particular, suggests that the inner wind has undergone a dramatic change in its velocity structure, connected with a recent accretion event. DR Tau has a more stable wind as its He I 1.08 μm absorption does not show variations with time in spite of strong variability of the emission component. The IR veiling in the two sources can be interpreted as due to blackbody emission at temperatures of 1600 K and 2300 K for XZ Tau and DR Tau, respectively, with emitting areas 30 times larger than the central star. While for XZ Tau these conditions are consistent with emission from the inner rim of the dusty disk, the fairly high temperature inferred for DR Tau might suggest that its veiling originates from a thick gaseous disk located within the dust sublimation radius. Strong and broad metallic lines, mainly from C I and Fe I, are detected in XZ Tau, similar to those observed in other EXor sources during burst phases. At variance, DR Tau shows weaker and

Role of the antiferromagnetic pinning layer on spin wave properties in IrMn/NiFe based spin-valves

Energy Technology Data Exchange (ETDEWEB)

Gubbiotti, G., E-mail: gubbiotti@fisica.unipg.it; Tacchi, S. [Istituto Officina dei Materiali del CNR (IOM-CNR), Unità di Perugia, I-06123 Perugia (Italy); Del Bianco, L. [Department of Physics and Astronomy, University of Bologna, I-40127 Bologna (Italy); Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Bonfiglioli, E.; Giovannini, L.; Spizzo, F.; Zivieri, R. [Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Tamisari, M. [Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Dipartimento di Fisica e Geologia, Università di Perugia, I-06123 Perugia (Italy)

2015-05-07

Brillouin light scattering (BLS) was exploited to study the spin wave properties of spin-valve (SV) type samples basically consisting of two 5 nm-thick NiFe layers (separated by a Cu spacer of 5 nm), differently biased through the interface exchange coupling with an antiferromagnetic IrMn layer. Three samples were investigated: a reference SV sample, without IrMn (reference); one sample with an IrMn underlayer (10 nm thick) coupled to the bottom NiFe film; one sample with IrMn underlayer and overlayer of different thickness (10 nm and 6 nm), coupled to the bottom and top NiFe film, respectively. The exchange coupling with the IrMn, causing the insurgence of the exchange bias effect, allowed the relative orientation of the NiFe magnetization vectors to be controlled by an external magnetic field, as assessed through hysteresis loop measurements by magneto-optic magnetometry. Thus, BLS spectra were acquired by sweeping the magnetic field so as to encompass both the parallel and antiparallel alignment of the NiFe layers. The BLS results, well reproduced by the presented theoretical model, clearly revealed the combined effects on the spin dynamic properties of the dipolar interaction between the two NiFe films and of the interface IrMn/NiFe exchange coupling.

Synthesis and Fluorescence Spectra of Triazolylcoumarin Fluorescent Dyes

Institute of Scientific and Technical Information of China (English)

PENG Xian-fu; LI Hong-qi

2009-01-01

Much attention is devoted to fluorescent dyes especially those with potential in versatile applications. Reactions under "click" conditions between nonfluorescent 3 - azidocoumarins and terminal alkynes produced 3 -(1, 2, 3- triazol- 1 - yl)cournarins, a novel type of fluorescent dyes with intense fluorescence. The structures of the new coumarins were characterized by 1H NMR, MS, and IR spectra. Fluorescence spectra measurement demonstrated excellent fluorescence performance of the triazolylcoumarins and this click reaction is a promising candidate for bioconjugation and bioimaging applications since both azide and alkynes are quite inert to biological systems.

Computer analysis of ATR-FTIR spectra of paint samples for forensic purposes

Science.gov (United States)

Szafarska, Małgorzata; Woźniakiewicz, Michał; Pilch, Mariusz; Zięba-Palus, Janina; Kościelniak, Paweł

2009-04-01

A method of subtraction and normalization of IR spectra (MSN-IR) was developed and successfully applied to extract mathematically the pure paint spectrum from the spectrum of paint coat on different bases, both acquired by the Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) technique. The method consists of several stages encompassing several normalization and subtraction processes. The similarity of the spectrum obtained with the reference spectrum was estimated by means of the normalized Manhattan distance. The utility and performance of the method proposed were tested by examination of five different paints sprayed on plastic (polyester) foil and on fabric materials (cotton). It was found that the numerical algorithm applied is able - in contrast to other mathematical approaches conventionally used for the same aim - to reconstruct a pure paint IR spectrum effectively without a loss of chemical information provided. The approach allows the physical separation of a paint from a base to be avoided, hence a time and work-load of analysis to be considerably reduced. The results obtained prove that the method can be considered as a useful tool which can be applied to forensic purposes.

[The radial velocity measurement accuracy of different spectral type low resolution stellar spectra at different signal-to-noise ratio].

Science.gov (United States)

Wang, Feng-Fei; Luo, A-Li; Zhao, Yong-Heng

2014-02-01

The radial velocity of the star is very important for the study of the dynamics structure and chemistry evolution of the Milky Way, is also an useful tool for looking for variable or special objects. In the present work, we focus on calculating the radial velocity of different spectral types of low-resolution stellar spectra by adopting a template matching method, so as to provide effective and reliable reference to the different aspects of scientific research We choose high signal-to-noise ratio (SNR) spectra of different spectral type stellar from the Sloan Digital Sky Survey (SDSS), and add different noise to simulate the stellar spectra with different SNR. Then we obtain theradial velocity measurement accuracy of different spectral type stellar spectra at different SNR by employing a template matching method. Meanwhile, the radial velocity measurement accuracy of white dwarf stars is analyzed as well. We concluded that the accuracy of radial velocity measurements of early-type stars is much higher than late-type ones. For example, the 1-sigma standard error of radial velocity measurements of A-type stars is 5-8 times as large as K-type and M-type stars. We discuss the reason and suggest that the very narrow lines of late-type stars ensure the accuracy of measurement of radial velocities, while the early-type stars with very wide Balmer lines, such as A-type stars, become sensitive to noise and obtain low accuracy of radial velocities. For the spectra of white dwarfs stars, the standard error of radial velocity measurement could be over 50 km x s(-1) because of their extremely wide Balmer lines. The above conclusion will provide a good reference for stellar scientific study.

Computing the Absorption and Emission Spectra of 5-Methylcytidine in Different Solvents: A Test-Case for Different Solvation Models.

Science.gov (United States)

Martínez-Fernández, L; Pepino, A J; Segarra-Martí, J; Banyasz, A; Garavelli, M; Improta, R

2016-09-13

The optical spectra of 5-methylcytidine in three different solvents (tetrahydrofuran, acetonitrile, and water) is measured, showing that both the absorption and the emission maximum in water are significantly blue-shifted (0.08 eV). The absorption spectra are simulated based on CAM-B3LYP/TD-DFT calculations but including solvent effects with three different approaches: (i) a hybrid implicit/explicit full quantum mechanical approach, (ii) a mixed QM/MM static approach, and (iii) a QM/MM method exploiting the structures issuing from molecular dynamics classical simulations. Ab-initio Molecular dynamics simulations based on CAM-B3LYP functionals have also been performed. The adopted approaches all reproduce the main features of the experimental spectra, giving insights on the chemical-physical effects responsible for the solvent shifts in the spectra of 5-methylcytidine and providing the basis for discussing advantages and limitations of the adopted solvation models.

New approach for determination of the influence of long-range order and selected ring oscillations on IR spectra in zeolites

Science.gov (United States)

Mikuła, Andrzej; Król, Magdalena; Mozgawa, Włodzimierz; Koleżyński, Andrzej

2018-04-01

Vibrational spectroscopy can be considered as one of the most important methods used for structural characterization of various porous aluminosilicate materials, including zeolites. On the other hand, vibrational spectra of zeolites are still difficult to interpret, particularly in the pseudolattice region, where bands related to ring oscillations can be observed. Using combination of theoretical and computational approach, a detailed analysis of these regions of spectra is possible; such analysis should be, however, carried out employing models with different level of complexity and simultaneously the same theory level. In this work, an attempt was made to identify ring oscillations in vibrational spectra of selected zeolite structures. A series of ab initio calculations focused on S4R, S6R, and as a novelty, 5-1 isolated clusters, as well as periodic siliceous frameworks built from those building units (ferrierite (FER), mordenite (MOR) and heulandite (HEU) type) have been carried out. Due to the hierarchical structure of zeolite frameworks it can be expected that the total envelope of the zeolite spectra should be with good accuracy a sum of the spectra of structural elements that build each zeolite framework. Based on the results of HF calculations, normal vibrations have been visualized and detailed analysis of pseudolattice range of resulting theoretical spectra have been carried out. Obtained results have been applied for interpretation of experimental spectra of selected zeolites.

Gaz Phase IR and UV Spectroscopy of Neutral Contact Ion Pairs

Science.gov (United States)

Habka, Sana; Brenner, Valerie; Mons, Michel; Gloaguen, Eric

2016-06-01

Cations and anions, in solution, tend to pair up forming ion pairs. They play a crucial role in many fundamental processes in ion-concentrated solutions and living organisms. Despite their importance and vast applications in physics, chemistry and biochemistry, they remain difficult to characterize namely because of the coexistence of several types of pairing in solution. However, an interesting alternative consists in applying highly selective gas phase spectroscopy which can offer new insights on these neutral ion pairs. Our study consists in characterizing contact ion pairs (CIPs) in isolated model systems (M+, Ph-(CH2)n-COO- with M=Li, Na, K, Rb, Cs, and n=1-3), to determine their spectral signatures and compare them to ion pairs in solution. We have used laser desorption to vaporize a solid tablet containing the desired salt. Structural information for each system was obtained by mass-selective, UV and IR laser spectroscopy combined with high level quantum chemistry calculations1. Evidence of the presence of neutral CIPs was found by scanning the π-π* transition of the phenyl ring using resonant two-photon ionization (R2PI). Then, conformational selective IR/UV double resonance spectra were recorded in the CO2- stretch region for each conformation detected. The good agreement between theoretical data obtained at the BSSE-corrected-fullCCSD(T)/dhf-TZVPP//B97-D3/dhf-TZVPP level and experimental IR spectra led us to assign the 3D structure for each ion pair formed. Spectral signatures of (M+, Ph-CH2-COO-) pairs, were assigned to a bidentate CIPs between the alkali cation and the carboxylate group. In the case of (Li+, Ph-(CH2)3-COO-) pairs, the presence of a flexible side chain promotes a cation-π interaction leading to a tridentate O-O-π structure with its unique IR and UV signatures. IR spectra obtained on isolated CIPs were found very much alike the ones published on lithium and sodium acetate in solution2. However, in the case of sodium acetate, solution

Hydrogen-Bonding Network and OH Stretch Vibration of Cellulose: Comparison of Computational Modeling with Polarized IR and SFG Spectra.

Science.gov (United States)

Lee, Christopher M; Kubicki, James D; Fan, Bingxin; Zhong, Linghao; Jarvis, Michael C; Kim, Seong H

2015-12-10

Hydrogen bonds play critical roles in noncovalent directional interactions determining the crystal structure of cellulose. Although diffraction studies accurately determined the coordinates of carbon and oxygen atoms in crystalline cellulose, the structural information on hydrogen atoms involved in hydrogen-bonding is still elusive. This could be complemented by vibrational spectroscopy; but the assignment of the OH stretch peaks has been controversial. In this study, we performed calculations using density functional theory with dispersion corrections (DFT-D2) for the cellulose Iβ crystal lattices with the experimentally determined carbon and oxygen coordinates. DFT-D2 calculations revealed that the OH stretch vibrations of cellulose are highly coupled and delocalized through intra- and interchain hydrogen bonds involving all OH groups in the crystal. Additionally, molecular dynamics (MD) simulations of a single cellulose microfibril showed that the conformations of OH groups exposed at the microfibril surface are not well-defined. Comparison of the computation results with the experimentally determined IR dichroism of uniaxially aligned cellulose microfibrils and the peak positions of various cellulose crystals allowed unambiguous identification of OH stretch modes observed in the vibrational spectra of cellulose.

Deposition and characterization of IrOx nanofoils on carbon nanotube templates by reactive magnetron sputtering

International Nuclear Information System (INIS)

Chen, Yi-Min; Cai, Jhen-Hong; Huang, Ying-Sheng; Lee, Kuei-Yi; Tsai, Dah-Shyang; Tiong, Kwong-Kau

2012-01-01

Large surface area IrO x nanofoils (IrO x NF) were deposited on multi-wall carbon nanotube (MWCNT) templates, forming IrO x /MWCNT nanocomposites, by reactive radio frequency magnetron sputtering using Ir metal target. The structural and spectroscopic properties of IrO x NF were characterized. The micrographs of field emission scanning electron microscopy showed the formation of foil-like structure for the as-deposited samples. Transmission electron microscopy analysis revealed the contiguous presence of glassy iridium oxide, iridium metal, and iridium dioxide nanocrystals in the foil. X-ray photoelectron spectroscopy analysis provided the information of the oxidation states and the stoichiometry of IrO x NF. Raman spectra revealed the amorphous-like phase of the as-deposited IrO x NF. The nanofoil structure provided ultra-high surface area for electrical charge storage which made the IrO x /MWCNT nanocomposites as an attractive candidate for the supercapacitor applications.

Acid-base titrations of functional groups on the surface of the thermophilic bacterium Anoxybacillus flavithermus: comparing a chemical equilibrium model with ATR-IR spectroscopic data.

Science.gov (United States)

Heinrich, Hannah T M; Bremer, Phil J; Daughney, Christopher J; McQuillan, A James

2007-02-27

Acid-base functional groups at the surface of Anoxybacillus flavithermus (AF) were assigned from the modeling of batch titration data of bacterial suspensions and compared with those determined from in situ infrared spectroscopic titration analysis. The computer program FITMOD was used to generate a two-site Donnan model (site 1: pKa = 3.26, wet concn = 2.46 x 10(-4) mol g(-1); site 2: pKa = 6.12, wet concn = 6.55 x 10(-5) mol g(-1)), which was able to describe data for whole exponential phase cells from both batch acid-base titrations at 0.01 M ionic strength and electrophoretic mobility measurements over a range of different pH values and ionic strengths. In agreement with information on the composition of bacterial cell walls and a considerable body of modeling literature, site 1 of the model was assigned to carboxyl groups, and site 2 was assigned to amino groups. pH difference IR spectra acquired by in situ attenuated total reflection infrared (ATR-IR) spectroscopy confirmed the presence of carboxyl groups. The spectra appear to show a carboxyl pKa in the 3.3-4.0 range. Further peaks were assigned to phosphodiester groups, which deprotonated at slightly lower pH. The presence of amino groups could not be confirmed or discounted by IR spectroscopy, but a positively charged group corresponding to site 2 was implicated by electrophoretic mobility data. Carboxyl group speciation over a pH range of 2.3-10.3 at two different ionic strengths was further compared to modeling predictions. While model predictions were strongly influenced by the ionic strength change, pH difference IR data showed no significant change. This meant that modeling predictions agreed reasonably well with the IR data for 0.5 M ionic strength but not for 0.01 M ionic strength.

Study of wide band-gap crystal LiCaAlF6 by IR-reflection spectroscopy and ab initio calculations

International Nuclear Information System (INIS)

Novikova, N.N.; Klimin, S.A.; Mavrin, B.N.

2017-01-01

Polarized IR-reflection spectra and results of ab initio calculations of vibrational and electronic properties of LiCaAlF6 single crystal are presented. It is shown that the crystal band gap is direct. Experimental and theoretical parameters are obtained for dipole-active and all phonons, respectively, including silent modes. Experimental IR-reflection and Raman spectra are well described in the frame of results obtained by ab initio calculations. The peculiarities are discussed concerning the structure of electronic bands, the interatomic interactions, the character of lattice vibrations, and the phonon dispersion.

Density functional study of the L10-αIrV transition in IrV and RhV

International Nuclear Information System (INIS)

Mehl, Michael J.; Hart, Gus L.W.; Curtarolo, Stefano

2011-01-01

Research highlights: → The computational determination of the ground state of a material can be a difficult task, particularly if the ground state is uncommon and so not found in usual databases. In this paper we consider the alpha-IrV structure, a low temperature structure found only in two compounds, IrV and RhV. In both cases this structure can be considered as a distorted tetragonal structure, and the tetragonal 'L1 0 ' structure is the high temperature structure for both compounds. We show, however, that the logical path for the transition from the L1 0 to the alpha-IrV structure is energetically forbidden, and find a series of unstable and metastable structures which have a lower energy than the L1 0 phase, but are higher in energy than the alpha-IrV phase. We also consider the possibility of the alpha-IrV structure appearing in neighboring compounds. We find that both IrTi and RhTi are candidates. - Abstract: Both IrV and RhV crystallize in the αIrV structure, with a transition to the higher symmetry L1 0 structure at high temperature, or with the addition of excess Ir or Rh. Here we present evidence that this transition is driven by the lowering of the electronic density of states at the Fermi level of the αIrV structure. The transition has long been thought to be second order, with a simple doubling of the L1 0 unit cell due to an unstable phonon at the R point (0 1/2 1/2). We use first-principles calculations to show that all phonons at the R point are, in fact, stable, but do find a region of reciprocal space where the L1 0 structure has unstable (imaginary frequency) phonons. We use the frozen phonon method to examine two of these modes, relaxing the structures associated with the unstable phonon modes to obtain new structures which are lower in energy than L1 0 but still above αIrV. We examine the phonon spectra of these structures as well, looking for instabilities, and find further instabilities, and more relaxed structures, all of which have

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.

The ir emission features: Emission from PAH (Polycyclic Aromatic Hydrocarbons) molecules and amorphous carbon particles

Energy Technology Data Exchange (ETDEWEB)

Allamandola, L.J.; Tielens, A.G.G.M.; Barker, J.R.

1986-01-01

PAHs can have several forms in the interstellar medium. To assess the importance of each requires the availability of a collection of high quality, complete mid-ir interstellar emission spectra, a collection of laboratory spectra of PAH samples prepared under realistic conditions and a firm understanding of the microscopic emission mechanism. Given what we currently know about PAHs, the spectroscopic data suggests that there are at least two components which contribute to the interstellar emission spectrum: free molecule sized PAHs producing the narrow features and amorphous carbon particles (which are primarily made up of an irregular ''lattice'' of PAHs) contributing to the broad underlying components. An exact treatment of the ir fluorescence from highly vibrationally excited large molecules shows that species containing between 20 and 30 carbon atoms are responsible for the narrow features, although the spectra match more closely with the spectra of amorphous carbon particles. Since little is known about the spectroscopic properties of free PAHs and PAH clusters, much laboratory work is called for in conjunction with an observational program which focuses on the spatial characteristics of the spectra. In this way the distribution and evolution of carbon from molecule to particle can be traced. 38 refs., 9 figs.

The ir emission features: Emission from PAH [Polycyclic Aromatic Hydrocarbons] molecules and amorphous carbon particles

International Nuclear Information System (INIS)

Allamandola, L.J.; Tielens, A.G.G.M.; Barker, J.R.

1986-01-01

PAHs can have several forms in the interstellar medium. To assess the importance of each requires the availability of a collection of high quality, complete mid-ir interstellar emission spectra, a collection of laboratory spectra of PAH samples prepared under realistic conditions and a firm understanding of the microscopic emission mechanism. Given what we currently know about PAHs, the spectroscopic data suggests that there are at least two components which contribute to the interstellar emission spectrum: free molecule sized PAHs producing the narrow features and amorphous carbon particles (which are primarily made up of an irregular ''lattice'' of PAHs) contributing to the broad underlying components. An exact treatment of the ir fluorescence from highly vibrationally excited large molecules shows that species containing between 20 and 30 carbon atoms are responsible for the narrow features, although the spectra match more closely with the spectra of amorphous carbon particles. Since little is known about the spectroscopic properties of free PAHs and PAH clusters, much laboratory work is called for in conjunction with an observational program which focuses on the spatial characteristics of the spectra. In this way the distribution and evolution of carbon from molecule to particle can be traced. 38 refs., 9 figs

The Cheshire-cat-like Behavior of 2nu(sub 3) Overtone of Co2 near 2.134 micron: NIR Lab Spectra of Solid CO2 in H2O and CH3OH

Science.gov (United States)

Bernstein, Max; Sandford, Scott; Cruikshank, Dale

2005-01-01

Infrared (IR) spectra have demonstrated that solid H2O is very common in the outer Solar System, and solid carbon dioxide (CO2) has been detected on icy satellites, comets, and planetismals throughout the outer Solar System. In such environments, CO2 and H2O must sometimes be mixed at a molecular level, changing their IR absorption features. In fact, the IR spectra of CO2-H2O mixtures are not equivalent to a linear combination of the spectra of the pure materials. Laboratory IR spectra of pure CO2 and H2O have been published but a lack of near-IR spectra of CO2-H2O mixtures has made the interpretation of outer Solar System spectra more difficult. We present near infrared (IR) spectra of CO2 in H2O and in CH3OH compared to that of pure solid CO2 and find significant differences. Peaks not present in either pure H2O or pure CO2 spectra become evident. First, the CO2 (2nu(sub 3)) overtone near 2.134 micron (4685/ cm) that is not seen in pure solid CO2 is prominent in the spectrum of a CO2/H2O = 25 mixture. Second, a 2.74 micron (3650/ cm) dangling OH feature of water (and a potentially related peak at 1.89 micron) appear in the spectra of CO2-H2O ice mixtures, but may not be specific to the presence of CO2. Other CO2 peaks display shifts in position and increased width because of intermolecular interactions with water. Changes in CO2 peak positions and profiles on warming of a CO2/H2O = 5 mixture are consistent with 'segregation' of the ice into nearly pure separate components. Absolute strengths for absorptions of CO2 in solid H2O are estimated. Similar results are observed for CO2 in solid CH3OH. Since the CO2 ( 2nu(sub 3)) overtone near 2.134 micron (4685/ cm) is not present in pure CO2 but prominent in mixtures it may be a good observational indicator of whether solid CO2 is a pure material or intimately mixed with other molecules. Significant changes in the near IR spectrum of solid CO2 in the presence of H2O and CH3OH means that the abundance of solid CO2 in the

Automatic frequency and phase alignment of in vivo J-difference-edited MR spectra by frequency domain correlation.

Science.gov (United States)

Wiegers, Evita C; Philips, Bart W J; Heerschap, Arend; van der Graaf, Marinette

2017-12-01

J-difference editing is often used to select resonances of compounds with coupled spins in 1 H-MR spectra. Accurate phase and frequency alignment prior to subtracting J-difference-edited MR spectra is important to avoid artefactual contributions to the edited resonance. In-vivo J-difference-edited MR spectra were aligned by maximizing the normalized scalar product between two spectra (i.e., the correlation over a spectral region). The performance of our correlation method was compared with alignment by spectral registration and by alignment of the highest point in two spectra. The correlation method was tested at different SNR levels and for a broad range of phase and frequency shifts. In-vivo application of the proposed correlation method showed reduced subtraction errors and increased fit reliability in difference spectra as compared with conventional peak alignment. The correlation method and the spectral registration method generally performed equally well. However, better alignment using the correlation method was obtained for spectra with a low SNR (down to ~2) and for relatively large frequency shifts. Our correlation method for simultaneously phase and frequency alignment is able to correct both small and large phase and frequency drifts and also performs well at low SNR levels.

Possible superconductivity in Sr₂IrO₄ probed by quasiparticle interference.

Science.gov (United States)

Gao, Yi; Zhou, Tao; Huang, Huaixiang; Wang, Qiang-Hua

2015-03-18

Based on the possible superconducting (SC) pairing symmetries recently proposed, the quasiparticle interference (QPI) patterns in electron- and hole-doped Sr₂IrO₄ are theoretically investigated. In the electron-doped case, the QPI spectra can be explained based on a model similar to the octet model of the cuprates while in the hole-doped case, both the Fermi surface topology and the sign of the SC order parameter resemble those of the iron pnictides and there exists a QPI vector resulting from the interpocket scattering between the electron and hole pockets. In both cases, the evolution of the QPI vectors with energy and their behaviors in the nonmagnetic and magnetic impurity scattering cases can well be explained based on the evolution of the constant-energy contours and the sign structure of the SC order parameter. The QPI spectra presented in this paper can be compared with future scanning tunneling microscopy experiments to test whether there are SC phases in electron- and hole-doped Sr₂IrO₄ and what the pairing symmetry is.

Monitoring wine aging with Fourier transform infrared spectroscopy (FT-IR

Directory of Open Access Journals (Sweden)

Basalekou Marianthi

2015-01-01

Full Text Available Oak wood has commonly been used in wine aging but recently other wood types such as Acacia and Chestnut, have attracted the interest of the researchers due to their possible positive contribution to wine quality. However, only the use of oak and chestnut woods is approved by the International Enological Codex of the International Organisation of Vine and Wine. In this study Fourier Transform (FT-mid-infrared spectroscopy combined with Discriminant Analysis was used to differentiate wines aged in barrels made from French oak, American oak, Acacia and Chestnut and in tanks with oak chips, over a period of 12 months. Two red (Mandilaria, Kotsifali and two white (Vilana, Dafni native Greek grape varieties where used to produce four wines. The Fourier Transform Infrared (FT-IR spectra of the samples were recorded on a Zinc Selenide (ZnSe window after incubation at 40 °C for 30 min. A complete differentiation of the samples according to both the type of wood used and the contact time was achieved based on their FT-IR spectra.

Surface core level shifts of clean and oxygen covered Ir(111)

Energy Technology Data Exchange (ETDEWEB)

Bianchi, M; Cassese, D; Cavallin, A; Comin, R; Orlando, F; Postregna, L [Universita degli Studi di Trieste, Via A Valerio 2, 34127, Trieste (Italy); Golfetto, E; Baraldi, A [Dipartimento di Fisica e CENMAT, Universita degli Studi di Trieste, Via A Valerio 2, 34127, Trieste (Italy); Lizzit, S [Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34012 Trieste (Italy)], E-mail: alessandro.baraldi@elettra.trieste.it

2009-06-15

We present the results of high resolution core level photoelectron spectroscopy employed to investigate the electronic structure of clean and oxygen covered Ir(111) surface. Ir 4f{sub 7/2} core level spectra are shown to be very sensitive to the local atomic environment. For the clean surface we detected two distinct components shifted by 550 meV, originated by surface and bulk atoms. The larger Gaussian width of the bulk component is explained as due to experimentally unresolved subsurface components. In order to determine the relevance of the phonon contribution we examined the thermal behaviour of the core level lineshape using the Hedin-Rosengren theory. From the phonon-induced spectral broadening we found the Debye temperature of bulk and surface atoms to be 298 and 181 K, respectively, which confirms the softening of the vibrational modes at the surface. Oxygen adsorption leads to the appearance of new surface core level components at -200 meV and +230 meV, which are interpreted as due to first-layer Ir atoms differently coordinated with oxygen. The coverage dependence of these components demonstrates that the oxygen saturation corresponds to 0.38 ML, in good agreement with recent density functional theory calculations.

Satellite Atmospheric Sounder IRFS-2 1. Analysis of Outgoing Radiation Spectra Measurements

Science.gov (United States)

Polyakov, A. V.; Timofeyev, Yu. M.; Virolainen, Ya. A.; Uspensky, A. B.; Zavelevich, F. S.; Golovin, Yu. M.; Kozlov, D. A.; Rublev, A. N.; Kukharsky, A. V.

2017-12-01

The outgoing radiation spectra measured by the IRFS-2 spectrometer onboard Meteor-M no. 2 satellite have been analyzed. Some statistical parameters of more than 106 spectra measured in spring in 2015 have been calculated. The radiation brightness temperature varied from ˜300 K (surface temperature) up to ˜210 K (tropopause temperature). The quite high variability of the longwave measured radiation has been demonstrated. The signal-to-noise ratio distinctively decreases in the shortwave region (higher than 1300 cm-1). Intercomparisons of IR sounders IRFS-2 with IASI and CrIS spectra showed that the discrepancies in the average spectra and their variability do not exceed measurement errors in the spectral region 660-1300 cm-1. A comparison of specially chosen pairs of the simultaneously measured spectra showed that the differences between IRFS-2 and European instruments in the region of the 15-μm CO2 band and the transparency windows 8-12 μm are less than 1 mW/(m2 sr cm-1) and no more than the differences between the two IASI instruments (-A and -B). The differences between measured and simulated spectra are less than 1 mW/(m2 sr cm-1) in the mean part of CO2 band. However, starting from 720 cm-1, values appear that reach 2-4 mW/(m2 sr cm-1). This is caused by the absence of precise information about the surface temperature. Further investigations into the possible reasons for the observed disagreements are required in order to improve both the method of initial processing and the radiative model of the atmosphere.

HIGH RESOLUTION OPTICAL AND NIR SPECTRA OF HBC 722

Energy Technology Data Exchange (ETDEWEB)

Lee, Jeong-Eun; Park, Sunkyung [School of Space Research, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Green, Joel D.; Cochran, William D. [Department of Astronomy, University of Texas at Austin, TX (United States); Kang, Wonseok; Lee, Sang-Gak [National Youth Space Center, 200 Deokheungyangjjok-gil, Dongil-myeon, Goheung-gun, Jeollanam-do 548-951 (Korea, Republic of); Sung, Hyun-Il, E-mail: jeongeun.lee@khu.ac.kr, E-mail: sunkyung@khu.ac.kr, E-mail: joel@astro.as.utexas.edu, E-mail: wdc@astro.as.utexas.edu, E-mail: wskang@kywa.or.kr, E-mail: sanggak@kywa.or.kr, E-mail: hisung@kasi.re.kr [Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon 305-348 (Korea, Republic of)

2015-07-01

We present the results of high resolution (R ≥ 30,000) optical and near-IR spectroscopic monitoring observations of HBC 722, a recent FU Orionis object that underwent an accretion burst in 2010. We observed HBC 722 in the optical/near-IR with the Bohyunsan Optical Echelle Spectrograph, Hobby–Eberly Telescope-HRS, and Immersion Grating Infrared Spectrograph, at various points in the outburst. We found atomic lines with strongly blueshifted absorption features or P Cygni profiles, both evidence of a wind driven by the accretion. Some lines show a broad double-peaked absorption feature, evidence of disk rotation. However, the wind-driven and disk-driven spectroscopic features are anti-correlated in time; the disk features became strong as the wind features disappeared. This anti-correlation might indicate that the rebuilding of the inner disk was interrupted by the wind pressure during the first 2 years. The half-width at half-depth of the double-peaked profiles decreases with wavelength, indicative of the Keplerian rotation; the optical spectra with the disk feature are fitted by a G5 template stellar spectrum convolved with a rotation velocity of 70 km s{sup −1} while the near-IR disk features are fitted by a K5 template stellar spectrum convolved with a rotation velocity of 50 km s{sup −1}. Therefore, the optical and near-IR spectra seem to trace the disk at 39 and 76 R{sub ⊙}, respectively. We fit a power-law temperature distribution in the disk, finding an index of 0.8, comparable to optically thick accretion disk models.

[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

Attenuated total reflection design for in situ FT-IR spectroelectrochemical studies

International Nuclear Information System (INIS)

Visser, Hendrik; Curtright, Aimee E.; McCusker, James K.; Sauer, Kenneth

2000-01-01

A versatile spectroelectrochemical apparatus is introduced to study the changes in IR spectra of organic and inorganic compounds upon oxidation or reduction. The design is based on an attenuated total reflection (ATR) device, which permits the study of a wide spectral range of 16,700 cm-1 (600 nm) - 250 cm-1 with a small opaque region of 2250 - 1900 cm-1. In addition, an IR data collection protocol is introduced to deal with electrochemically non-reversible background signals. This method is tested with ferrocene in acetonitrile, producing results that agree with those in the literature

The nature of hydrogen-bonding interactions in nonsteroidal anti-inflammatory drugs revealed by polarized IR spectroscopy

Science.gov (United States)

Hachuła, Barbara

2018-01-01

The influence of hydrogen-bonding interactions in the solid phase on the IR spectroscopic pattern of the νOsbnd H band of nonsteroidal anti-inflammatory drugs (NSAIDs) was studied experimentally by IR spectroscopy with the use of polarized light at two temperatures (293 K and 77 K) and in isotopic dilution. The neat and deuterated crystals of (S)-naproxen ((S)-NPX), (R)-flurbiprofen ((R)-FBP), (RS)-flurbiprofen ((RS)-FBP) and (RS)-ketoprofen ((RS)-KTP) were obtained by melt crystallization between the two squeezed CaF2 plates. The vibrational spectra of selected α-aryl propionic acid derivatives (2APAs) reflected the characteristics of their hydrogen-bond networks, i.e., 2APAs were characterized by the chain ((S)-NPX, (R)-FBP) and by dimeric ((RS)-FBP, (RS)-KTP) arrangement of hydrogen bonds in the crystal lattice. Spectroscopic results showed that the interchain (through-space) exciton coupling, between two laterally-spaced hydrogen bonds, dominates in the crystals of four NSAIDs. The same exciton coupled hydrogen bonds were also responsible for the H/D isotopic recognition mechanism in the crystalline spectra of deuterated 2APAs. The presented spectral results may help to predict the hydrogen bond motifs in the crystalline NSAIDs, which structures are not yet known, based on their IR spectra of hydrogen bond in the crystals.

Preparation and Characterization of cis- and trans-[Ir(tn)2Cl2]CF3SO3 and of [Ir(tn)3]Cl3 (tn=propane-1,3-diamine)

DEFF Research Database (Denmark)

Brorson, Michael; Galsbøl, Frode; Simonsen, Kim

1998-01-01

for the preparation of [Rh(tn)3]Cl3 in quantitative yield from Rh(thtp)3Cl3 is also given. The complexes were characterized by 1H and 13C NMR and by UV/VIS spectroscopy. The conformation of the six-membered chelate rings of [Ir(tn)3]3+ in the solid state was determined by single-crystal X-ray diffraction of [Ir(tn)3......Procedures are given for the preparation and isolation of cis- and trans-[Ir(tn)2Cl2]CF3SO3 and of [Ir(tn)3]Cl3, (tn=propane-1,3-diamine). The compounds were prepared by the use of Ir(thtp)3Cl3 (thtp=tetrahydrothiophene) as starting material, using either DMSO or neat tn as solvent. A procedure......] [Co(CN)6] x 5H2O. The three chelate rings all adopt the energetically favoured chair conformation; however, the overall idealized symmetry is C1. A comparative ligand field analysis, based on Gaussian resolution of the solution UV/VIS spectra for a number of homoleptic [M(N6)]3+ (M=CoIII, RhIII, Ir...

Structure and linear spectroscopic properties of near IR polymethine dyes

International Nuclear Information System (INIS)

Webster, Scott; Padilha, Lazaro A.; Hu Honghua; Przhonska, Olga V.; Hagan, David J.; Van Stryland, Eric W.; Bondar, Mikhail V.; Davydenko, Iryna G.; Slominsky, Yuriy L.; Kachkovski, Alexei D.

2008-01-01

We performed a detailed experimental investigation and quantum-chemical analysis of a new series of near IR polymethine dyes with 5-butyl-7,8-dihydrobenzo[cd]furo[2,3-f]indolium terminal groups. We also synthesized and studied two neutral dyes, squaraine and tetraone, with the same terminal groups and performed a comparison of the spectroscopic properties of this set of 'near IR' dyes (polymethine, squaraine, and tetraone) with an analogous set of 'visible' dyes with simpler benzo[e]indolium terminal groups. From these measurements, we find that the dyes with dihydrobenzo[cd]furo[2,3-f]indolium terminal groups are characterized by a remarkably large shift ∼300 nm (∼200 nm for tetraone) of their absorption bands towards the red region. We discuss the difference in electronic structure for these molecules and show that the 'near IR' dyes are characterized by an additional weak fluorescence band from the higher lying excited states connected with the terminal groups. Absorption spectra for the longest polymethines are solvent-dependent and are characterized by a broadening of the main band in polar solvents, which is explained by ground state symmetry breaking and reduced charge delocalization within the polymethine chromophore. The results of these experiments combined with the agreement of quantum chemical calculations moves us closer to a predictive capability for structure-property relations in cyanine-like molecules

FT-IR spectroscopic studies of protein secondary structures for breast cancer diagnosis

International Nuclear Information System (INIS)

Karamancheva, I; Simonova, D.; Milev, A.

2013-01-01

Full text: Roughly 14 million new cancer cases and 8 million cancer deaths have occurred worldwide in 2012. At least 30 % of all cancer cases and 40 % of the cancer deaths should be avoided by improving the early detection. Fourier transform infrared (FT-IR) spectroscopy has shown many advantages as a tool for the detection of cancer over the traditional methods such as histopathological analysis, X-ray transmission, ultrasonic and computer tomography techniques. With the aim to establish the FT-IR spectroscopy as an alternative method for the diagnosis of human cancers, we have made several studies to examine in details the spectroscopic properties of normal and carcinomatous tissues. Human breast tissues were obtained immediately after surgical breast resection with the informed patient's consent. In our studies we made extensive use of Fourier self-deconvolution, second-order derivatization, difference spectra, curve-fitting procedures and quantitative determinations according to Beer's law. Cancer is a multi-step process. Characteristic differences in both the frequencies and the intensity ratios of several bands have been revealed. Considerable differences have been found in the spectral patterns. The most important and informative region in the mid-IR for determination of protein secondary structure is the amide I and amide II region. The bands between 1730 and 1600 cm -1 are highly sensitive to conformational changes. Considerable changes were observed in the A1735/A1652 absorbance ratio, which provides a measure for the content of a- helix and P-sheet domains. Our investigations have shown that the major biomarker peaks are in the amide I and amide II regions. In the so called 'fingerprint region' many molecular constituents such as lipids, phospholipids, proteins, DNA and RNA, carbohydrates and metabolites may overlap and the quantitative interpretation is impossible. The spectrum may therefore reflect only the average biochemical composition.; key words

Polar phonons in β-Ga2O3 studied by IR reflectance spectroscopy and first-principle calculations

Science.gov (United States)

Azuhata, Takashi; Shimada, Kazuhiro

2017-08-01

IR reflectance spectra of β-Ga2O3 are measured in the range from 400 to 1100 cm-1 using the (\\bar{2}01) and (010) planes for pure transverse Au- and Bu-mode phonons, respectively. The spectra measured using the (010) plane depend remarkably on the polarization direction of the incident light because of the monoclinic symmetry. Reflectance spectra simulated using parameters obtained from first-principle calculations are in good agreement with the experimental spectra. By adjusting the calculated phonon parameters so as to reproduce the experimental spectra, the polar phonon parameters were determined for six modes above 400 cm-1.

Sensitivity of NMR spectra properties to different inversion algorithms. Abstract 97

International Nuclear Information System (INIS)

Bryan, J.; Wang, G.; Vargas, S.; Kantzas, A.

2004-01-01

'Full text:' Low field NMR technology has many applications in the petroleum industry. NMR spectra obtained from logging tools or laboratory instruments can be used to provide an incredible wealth of useful information for formation evaluation and reservoir fluid characterization purposes. In recent years, research performed at the University of Calgary has been instrumental in developing this technology for heavy oil and bitumen related problems. Specifically, low field NMR has been used in several niche applications: in-situ viscosity estimates of heavy oil and bitumen, water-in-oil emulsion and solvent-bitumen mixture viscosity, water cut in produced fluid streams, and oil-water-solids content in oil sands mining samples. The majority of all NMR analyses are based on the interpretation of NMR spectra. These spectra are inverted numerically from the measured NMR decay data. The mathematics of the inversion is generally assumed to be correct, and the analyses revolve around interpretations of how the spectra relate to physical properties of the samples. However, when measuring high viscosity fluids or clay-bound water, the NMR signal relaxes very quickly and it becomes extremely important to ensure that the spectrum obtained is accurate before relating its properties to physics. This work investigates the effect of different inversion algorithms on the generated spectra, and attempts to quantify the magnitude of the errors that can be associated with the mathematics of inversion. This leads to a better understanding of the accuracy of NMR estimates of rock and fluid properties. (author)

Differentiation of Leishmania species by FT-IR spectroscopy

Science.gov (United States)

Aguiar, Josafá C.; Mittmann, Josane; Ferreira, Isabelle; Ferreira-Strixino, Juliana; Raniero, Leandro

2015-05-01

Leishmaniasis is a parasitic infectious disease caused by protozoa that belong to the genus Leishmania. It is transmitted by the bite of an infected female Sand fly. The disease is endemic in 88 countries Desjeux (2001) [1] (16 developed countries and 72 developing countries) on four continents. In Brazil, epidemiological data show the disease is present in all Brazilian regions, with the highest incidences in the North and Northeast. There are several methods used to diagnose leishmaniasis, but these procedures have many limitations, are time consuming, have low sensitivity, and are expensive. In this context, Fourier Transform Infrared Spectroscopy (FT-IR) analysis has the potential to provide rapid results and may be adapted for a clinical test with high sensitivity and specificity. In this work, FT-IR was used as a tool to investigate the promastigotes of Leishmaniaamazonensis, Leishmaniachagasi, and Leishmaniamajor species. The spectra were analyzed by cluster analysis and deconvolution procedure base on spectra second derivatives. Results: cluster analysis found four specific regions that are able to identify the Leishmania species. The dendrogram representation clearly indicates the heterogeneity among Leishmania species. The band deconvolution done by the curve fitting in these regions quantitatively differentiated the polysaccharides, amide III, phospholipids, proteins, and nucleic acids. L. chagasi and L. major showed a greater biochemistry similarity and have three bands that were not registered in L. amazonensis. The L. amazonensis presented three specific bands that were not recorded in the other two species. It is evident that the FT-IR method is an indispensable tool to discriminate these parasites. The high sensitivity and specificity of this technique opens up the possibilities for further studies about characterization of other microorganisms.

Impaired Insulin Signaling is Associated with Hepatic Mitochondrial Dysfunction in IR+/−-IRS-1+/− Double Heterozygous (IR-IRS1dh Mice

Directory of Open Access Journals (Sweden)

Andras Franko

2017-05-01

Full Text Available Mitochondria play a pivotal role in energy metabolism, but whether insulin signaling per se could regulate mitochondrial function has not been identified yet. To investigate whether mitochondrial function is regulated by insulin signaling, we analyzed muscle and liver of insulin receptor (IR+/−-insulin receptor substrate-1 (IRS-1+/− double heterozygous (IR-IRS1dh mice, a well described model for insulin resistance. IR-IRS1dh mice were studied at the age of 6 and 12 months and glucose metabolism was determined by glucose and insulin tolerance tests. Mitochondrial enzyme activities, oxygen consumption, and membrane potential were assessed using spectrophotometric, respirometric, and proton motive force analysis, respectively. IR-IRS1dh mice showed elevated serum insulin levels. Hepatic mitochondrial oxygen consumption was reduced in IR-IRS1dh animals at 12 months of age. Furthermore, 6-month-old IR-IRS1dh mice demonstrated enhanced mitochondrial respiration in skeletal muscle, but a tendency of impaired glucose tolerance. On the other hand, 12-month-old IR-IRS1dh mice showed improved glucose tolerance, but normal muscle mitochondrial function. Our data revealed that deficiency in IR/IRS-1 resulted in normal or even elevated skeletal muscle, but impaired hepatic mitochondrial function, suggesting a direct cross-talk between insulin signaling and mitochondria in the liver.

Synchrotron far-IR RAIRS studies of interfaces created by polyfunctional organic molecules at defined metal surfaces

International Nuclear Information System (INIS)

Raval, R.; Williams, J.; Roberts, A.J.; Nunney, T.S.; Surman, M.

1998-01-01

Far-IR Reflection Absorption Infrared Spectroscopy (RAIRS) has been used to probe sub monolayers and multilayers of polyfunctional organic ad layers deposited under clean controlled conditions on small-area single-crystal surfaces, using the newly commissioned Daresbury 13.3 far-IR synchrotron beamline. It's shown that the current performance of the beamline allows to monitor fractions of monolayers of formate species on Cu(110), formed at 300 K from the deprotonation of formic acid. Two distinct vCu-O vibrations are observed for coverages up to 0.25 monolayer. The paper attributes the two bands to at least two chemically distinct species, each possessing a local site symmetry of C 2v and bonded to the metal surface via the two oxygen atoms. The two types of formate species are thought to arise from local density fluctuations in formate coverage across the ad layer which leads to local changes in the Cu-O bond. In additions, it's reported far-IR RAIRS spectra of bio molecule/metal interfaces created by depositing thin films (3-10 layers) of the chiral amino-acid, L-methionine, on Cu(110) at 300 K. The multilayer spectra closely resemble the far-IR spectra obtained from crystalline L-methionine, suggesting that the thin layer consists of the zwitterionic species. These thin bio films are stable on the surface to >330 K. No growth of metal-ligand vibrations in the multilayer phase is observed, demonstrating that corrosive chemisorption processes that create Cu-methionine complexes in the multilayer by leaching of surface Cu atoms do not occur in these conditions

Combined IR-Raman vs vibrational sum-frequency heterospectral correlation spectroscopy

Science.gov (United States)

Roy, Sandra; Beutier, Clémentine; Hore, Dennis K.

2018-06-01

Vibrational sum-frequency generation spectroscopy is a valuable probe of surface structure, particularly when the same molecules are present in one of the adjacent bulk solid or solution phases. As a result of the non-centrosymmetric requirement of SFG, the signal generated is a marker of the extent to which the molecules are ordered in an arrangement that breaks the up-down symmetry at the surface. In cases where the accompanying changes in the bulk are of interest in understanding and interpreting the surface structure, simultaneous analysis of the bulk IR absorption or bulk Raman scattering is helpful, and may be used in heterospectral surface-bulk two-dimensional correlation. We demonstrate that, in such cases, generating a new type of bulk spectrum that combines the IR and Raman amplitudes is a better candidate than the individual IR and Raman spectra for the purpose of correlation with the SFG signal.

Dual emitter IrQ(ppy)2 for OLED applications: Synthesis and spectroscopic analysis

International Nuclear Information System (INIS)

Ciobotaru, I.C.; Polosan, S.; Ciobotaru, C.C.

2014-01-01

The synthesis of organometallic compound with iridium and two types of ligands, quinoline and phenylpyridine, was done successfully. The absorption spectra of this compound have shown broad peaks in a visible region assigned to metal-to-ligands charge transfer and in UV region assigned to intraligand absorptions. The photoluminescence spectra exhibit dual character in which the red emission is more intense than the green one. In cathodoluminescence measurements, under electron beam, the powder obtained after recrystallization from dichloromethane, shows similar behaviors with photoluminescence spectra. The cathodoluminescence images have shown a luminescent crystalline powder with triclinic structure. This compound exhibits combined vibrational modes, which proves the presence in the same molecule of both ligands. Density Functional Theory calculation was involved in order to identify the main vibrations of this compound. Highlights: • Mixed-ligand of IrQ(ppy) 2 synthesis which gives green and red phosphorescence due to the MCLT processes coming from two types of ligands. • Absorption, photoluminescence, infrared spectroscopy and cathodoluminescence measurements for characterization of IrQ(ppy) 2 organometallic compound. • Experimental results have been compared with the output files obtained from Density Functional Theory by using the Gaussian 03W software

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…

Effects of Space Weathering on Reflectance Spectra of Ureilites: First Studies

Science.gov (United States)

Goodrich, C. A.; Gillis-Davis, J.; Cloutis, E.; Applin, D.; Takir, D.; Hibbitts, C.; Christoffersen, R.; Fries, M.; Klima, R.; Decker, S.

2018-01-01

Ureilites are differentiated meteorites (ultramafic rocks interpreted to be mantle residues) that contain as much carbon as the most carbon-rich carbonaceous chondrites (CCs). Reflectance spectra of ureilites are similar to those of some CCs. Hence, ureilitic asteroids may accidentally be categorized as primitive because their spectra could resemble those of C-complex asteroids, which are thought to be CC-like. We began spectral studies of progressively laser-weathered ureilites with the goals of predicting UV-VIS-IR spectra of ureilitic asteroids, and identifying features that could distinguish differentiated from primitive dark asteroids. Space weathering has not previously been studied for ureilites, and, based on space weathering studies of CCs and other C-rich materials, it could significantly alter their reflectance spectra.

Spectra of Earth-like Planets through Geological Evolution around FGKM Stars

Science.gov (United States)

Rugheimer, S.; Kaltenegger, L.

2018-02-01

Future observations of terrestrial exoplanet atmospheres will occur for planets at different stages of geological evolution. We expect to observe a wide variety of atmospheres and planets with alternative evolutionary paths, with some planets resembling Earth at different epochs. For an Earth-like atmospheric time trajectory, we simulate planets from the prebiotic to the current atmosphere based on geological data. We use a stellar grid F0V to M8V ({T}{eff}=7000–2400 K) to model four geological epochs of Earth's history corresponding to a prebiotic world (3.9 Ga), the rise of oxygen at 2.0 Ga and at 0.8 Ga, and the modern Earth. We show the VIS–IR spectral features, with a focus on biosignatures through geological time for this grid of Sun-like host stars and the effect of clouds on their spectra. We find that the observability of biosignature gases reduces with increasing cloud cover and increases with planetary age. The observability of the visible O2 feature for lower concentrations will partly depend on clouds, which, while slightly reducing the feature, increase the overall reflectivity, and thus the detectable flux of a planet. The depth of the IR ozone feature contributes substantially to the opacity at lower oxygen concentrations, especially for the high near-UV stellar environments around F stars. Our results are a grid of model spectra for atmospheres representative of Earth's geological history to inform future observations and instrument design and are available online at http://carlsaganinstitute.org/data/.

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

Aplicación de las espectroscopias IR/ATR y Raman al estudio de la superficie de vidrios sometidos a molturación

Directory of Open Access Journals (Sweden)

Pérez-Villar, S.

2008-04-01

Full Text Available The grinding process of vítreous silica and a conventional glass has been studied by means of Raman and IR/ATR spectroscopies. By using the obtained spectra, the positions and areas of the different bands have been calculated. The Raman spectra have been analysed using the Polymerisation Index (PI that indicates the depolymerization degree achieved on the particle surface after grinding. On the other hand, the IR/ATR spectra have been used to follow the positions of the symmetric and antisymmetric Si-O-Si bands. It has been observed that both techniques give similar results. These indicate that the depolymerisation degree increases with the grinding process. This depolymerisation is due to the broke of Si-O-Si bonds.

El proceso de molienda de sílice vítrea y un vidrio convencional se ha estudiado mediante espectroscopias IR/ATR y Raman. A partir de los espectros obtenidos para diferentes tamaños de partícula se calcularon tanto las posiciones como las áreas de las bandas que aparecían en cada espectro. Utilizando los espectros Raman se ha hecho uso del denominado Índice de Polimerización (IP el cual es indicativo del grado de despolimerización producido en la superficie de las partículas tras el proceso de molienda. Por otro lado, mediante los espectros IR/ATR y analizando las posiciones de las bandas de tensión simétrica y asimétrica de los enlaces Si-O-Si se ha podido seguir el citado proceso de molturación. Se ha observado, mediante ambas técnicas, como la superficie de las partículas se despolimeriza al disminuir el tamaño de partícula. Esta despolimerización es debida a la rotura de los enlaces Si-O-Si.

Diogenite-like Features in the Spitzer IRS (5-35 micrometers) Spectrum of 956 ELISA

Science.gov (United States)

Lim, Lucy F.; Emery, Joshua P.; Moskovitz, Nicholas A.

2009-01-01

We report preliminary results from the Spitzer Infrared Spectrograph (IRS) observations of the V-type asteroid 956 Elisa. Elisa was observed as part of a campaign to measure the 5.2-38 micron spectra of small basaltic asteroids with the Spitzer IRS. Targets include members of the dynamical family of the unique large differentiated asteroid 4 Vesta ("Vesroids"), several outer-main-belt basaltic asteroids whose orbits exclude them from originating on 4 Vesta, and the basaltic near-Earth asteroid 4055 Magellan.

FT-IR microspectroscopy characterization of supports for enzyme immobilization in biosensing applications

Science.gov (United States)

Portaccio, M.; Della Ventura, B.; Gabrovska, K.; Marinov, I.; Godjevargova, T.; Mita, D. G.; Lepore, M.

2010-04-01

The investigation of materials suitable for enzyme immobilization in biosensing applications has a widespread interest. There are many studies on physico-chemical properties of these materials at macroscopic level but few studies have been devoted to examine and correlate these properties at microscopic level. FT-IR spectroscopy with Micro-Attenuated Total Reflection (Micro-ATR) approach can be extremely useful for understanding a variety of aspects of materials which can be used for optimising immobilization procedures. Moreover, this experimental approach is particularly simple to use (no sample preparation is required) and minimally invasive. Using a Perkin Elmer Spectrum One FT-IR spectrometer equipped with a mercury-cadmium-telluride detector and a micro-ATR element we investigated different materials used for immobilization procedures with various enzymes widely used for biosensing in environmental and clinical applications. In particular, composite membranes constituted by a chemically modified poly-acrylonitrile (PAN) membrane plus layers of tethered chitosan of different molecular weight have been examined. Also silica gel matrices without and with glucose oxidase have been investigated. Spectra have been analysed and the contribution of principal functional groups has been evidenced.

Differentiation of Body Fluid Stains on Fabrics Using External Reflection Fourier Transform Infrared Spectroscopy (FT-IR) and Chemometrics.

Science.gov (United States)

Zapata, Félix; de la Ossa, Ma Ángeles Fernández; García-Ruiz, Carmen

2016-04-01

Body fluids are evidence of great forensic interest due to the DNA extracted from them, which allows genetic identification of people. This study focuses on the discrimination among semen, vaginal fluid, and urine stains (main fluids in sexual crimes) placed on different colored cotton fabrics by external reflection Fourier transform infrared spectroscopy (FT-IR) combined with chemometrics. Semen-vaginal fluid mixtures and potential false positive substances commonly found in daily life such as soaps, milk, juices, and lotions were also studied. Results demonstrated that the IR spectral signature obtained for each body fluid allowed its identification and the correct classification of unknown stains by means of principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). Interestingly, results proved that these IR spectra did not show any bands due to the color of the fabric and no substance of those present in daily life which were analyzed, provided a false positive. © The Author(s) 2016.

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.

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.

IR Observations of a Complete Unbiased Sample of Bright Seyfert Galaxies

Science.gov (United States)

Malkan, Matthew; Bendo, George; Charmandaris, Vassilis; Smith, Howard; Spinoglio, Luigi; Tommasin, Silvia

2008-03-01

IR spectra will measure the 2 main energy-generating processes by which galactic nuclei shine: black hole accretion and star formation. Both of these play roles in galaxy evolution, and they appear connected. To obtain a complete sample of AGN, covering the range of luminosities and column-densities, we will combine 2 complete all-sky samples with complementary selections, minimally biased by dust obscuration: the 116 IRAS 12um AGN and the 41 Swift/BAT hard Xray AGN. These galaxies have been extensively studied across the entire EM spectrum. Herschel observations have been requested and will be synergistic with the Spitzer database. IRAC and MIPS imaging will allow us to separate the nuclear and galactic continua. We are completing full IR observations of the local AGN population, most of which have already been done. The only remaining observations we request are 10 IRS/HIRES, 57 MIPS-24 and 30 IRAC pointings. These high-quality observations of bright AGN in the bolometric-flux-limited samples should be completed, for the high legacy value of complete uniform datasets. We will measure quantitatively the emission at each wavelength arising from stars and from accretion in each galactic center. Since our complete samples come from flux-limited all-sky surveys in the IR and HX, we will calculate the bi-variate AGN and star formation Luminosity Functions for the local population of active galaxies, for comparison with higher redshifts.Our second aim is to understand the physical differences between AGN classes. This requires statistical comparisons of full multiwavelength observations of complete representative samples. If the difference between Sy1s and Sy2s is caused by orientation, their isotropic properties, including those of the surrounding galactic centers, should be similar. In contrast, if they are different evolutionary stages following a galaxy encounter, then we may find observational evidence that the circumnuclear ISM of Sy2s is relatively younger.

High resolution spectroscopy over 8500-8750 Å for GAIA library of synthetic spectra for T_eff <= 7500 K

Science.gov (United States)

Munari, U.; Castelli, F.

2000-01-01

We present a library of synthetic spectra characterized by -2.5 7500 K will be given later on in this series. The 254 synthetic spectra presented here are based on Kurucz's codes and line data and have been computed over a more extended wavelength interval (7650-8750 Ä) than that currently baselined for implementation on GAIA, i.e. the 8500-8750 Ä. This last range is dominated by the near-IR Ca II triplet and the head of the Paschen series. The more extended wavelength range allows us to investigate the behaviour of other strong near-IR spectral features (severely contaminated by telluric absorptions in ground-based observed spectra) as the K I doublet (7664, 7699 Ä), the Na I doublet (8183, 8194 Ä) and the lines of Fe I multiplet N.60 at 8327 and 8388 Ä. The synthetic spectra support our previous conclusions about the superior performance of the Paschen/Ca II 8500-8750 Ä region in meeting the GAIA requirements when compared to other near-IR intervals of similar bigtriangleup lambda = 250 Ä. Table 2 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html Figures 5-93 are only available in electronic form at the http://www.edpsciences.org The spectra are also available in electronic form at the CDS or via the personal HomePage http://ulisse.pd.astro.it/Astro/Atlases/

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

Spectra of matrix isolated metal atoms and clusters

International Nuclear Information System (INIS)

Meyer, B.

1977-01-01

The matrix isolation spectra of all of the 40 presently known atomic metal species show strong matrix effects. The transition energies are increased, and the bands are broad and exhibit splitting of sublevels which are degenerate in the gas phase. Several models have been proposed for splitting of levels, but basic effects are not yet understood, and spectra cannot be predicted, yet it is possible to correlate gas phase and matrix in many of the systems. Selective production of diatomics and clusters via thermal and optical annealing of atomic species can be monitored by optical spectra, but yields spectroscopically complex systems which, however, especially in the case of transition metals, can be used as precursors in novel chemical reactions. A combination of absorption, emission, ir, Raman, ESR, and other methods is now quickly yielding data which will help correlate the increasing wealth of existing data. 55 references, 6 figures

The method of extraction of subspectra with appreciably different values of hyperfine interaction parameters from Moessbauer spectra

International Nuclear Information System (INIS)

Nemtsova, O.M.

2006-01-01

The task of Moessbauer spectra processing of complex locally inhomogeneous or multi-phase systems is to reveal subspectral contributions with appreciably different values of hyperfine interaction parameters (HFI) in them. A universal method of processing such spectra is suggested which allows to extract the probability density distribution (PDD) of HFI parameters corresponding to the subspectra with essentially different parameters values. The basis of the method is Tikhonov's regularization method with selection for each subspectrum its own value of the regularization parameter. The universal application of the method is demonstrated in the examples of processing real spectra with different sets of subspectral contributions

[Application of FT-IR pattern recognition method for the quality control of pharmaceutical ingredients].

Science.gov (United States)

Horgos, József; Kóger, Péter; Zelkó, Romána

2009-01-01

Nowadays infrared spectroscopy and chemometrics have proven their effectiveness for both qualitative and quantitative analyses in different fields like agriculture, food, chemical and oil industry. Furier Transformation Infrared Spectroscopy (FT-IR) combined with Attenuated Total Reflectance (ATR) plate is a fast identification instrument. It is suitable for analysis of solid and liquid phase, too. Associated with chemometrics, it would be a powerful tool for the pharmaceutical wholesalers to detect the insufficient quality of pharmaceutical ingredients. In the present study beside the review of the infra red technology, pharmaceutical ingredients were examined with the help of our spectra library.

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.

Possible superconductivity in Sr2IrO4 probed by quasiparticle interference

Science.gov (United States)

Gao, Yi; Zhou, Tao; Huang, Huaixiang; Wang, Qiang-Hua

2015-01-01

Based on the possible superconducting (SC) pairing symmetries recently proposed, the quasiparticle interference (QPI) patterns in electron- and hole-doped Sr2IrO4 are theoretically investigated. In the electron-doped case, the QPI spectra can be explained based on a model similar to the octet model of the cuprates while in the hole-doped case, both the Fermi surface topology and the sign of the SC order parameter resemble those of the iron pnictides and there exists a QPI vector resulting from the interpocket scattering between the electron and hole pockets. In both cases, the evolution of the QPI vectors with energy and their behaviors in the nonmagnetic and magnetic impurity scattering cases can well be explained based on the evolution of the constant-energy contours and the sign structure of the SC order parameter. The QPI spectra presented in this paper can be compared with future scanning tunneling microscopy experiments to test whether there are SC phases in electron- and hole-doped Sr2IrO4 and what the pairing symmetry is. PMID:25783417

Preliminary study of corrosion mechanisms of actinides alloys: calibration of FT-IR spectroscopy

International Nuclear Information System (INIS)

Magnien, Veronique; Cadignan, Marx; Faivret, Olivier; Rosa, Gaelle

2008-01-01

In situ analyzes of gaseous atmospheres could be performed by FT-IR spectroscopy in order to study the corrosion reactions of actinides. Nevertheless experimental conditions and the nature of studied species have a strong effect on IR absorption laws. Thus a prior calibration of our set-up is required to obtain an accurate estimation of gas concentration. For this purpose, the behavior of several air pure gases has been investigated according to their concentration from IR spectra. Reproducible results revealed subsequent increases of the most significant peak areas with gas pressure and small deviations from Beer Lambert's law. This preliminary work allowed to determine precise absorption laws for each studied pure gas in our in situ experimental conditions. Besides our FT-IR set-up was well suitable to quantitative analysis of gaseous atmosphere during corrosion reactions. Finally the effect of foreign gas will be investigated through more complex air mixtures to obtain a complete calibration network. (authors)

Experimental (FT-IR, FT-Raman, 1H, 13C NMR) and theoretical study of alkali metal 2-aminobenzoates

Science.gov (United States)

Samsonowicz, M.; Świsłocka, R.; Regulska, E.; Lewandowski, W.

2008-09-01

The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of the 2-aminobenzoic acid was studied by the methods of molecular spectroscopy. The vibrational (FT-IR, FT-Raman) and NMR ( 1H and 13C) spectra for 2-aminobenzoic acid and its alkali metal salts were recorded. The assignment of vibrational spectra was done on the basis of literature data, theoretical calculations and our previous experience. Characteristic shifts of bands and changes in intensities of bands along the metal series were observed. The changes of chemical shifts of protons ( 1H NMR) and carbons ( 13C NMR) in the series of studied alkali metal 2-aminobenzoates were observed too. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G ∗∗ basis set. Geometric aromaticity indices, dipole moments and energies were also calculated. The theoretical wavenumbers and intensities of IR and Raman spectra were obtained. The calculated parameters were compared to experimental characteristic of studied compounds.

Low-frequency vibrational spectra of crystals of tutton salts

Science.gov (United States)

Barashkov, M. V.; Zazhogin, A. A.; Komyak, A. I.; Shashkov, S. N.

2000-07-01

IR absorption spectra and polarized Raman spectra of crystals of Tutton salts K2M(SO4)26H2O and (NH4)2M(SO4)2·6H2O, where M=Co, Ni, Zn, have been obtained by experiment at 93 K and at room temperature. The frequencies and forms of normal modes of the [Zn(H2O)6]2+ octahedral complex have been calculated. The observed lines are assigned to the internal modes of the [M(H2O)6]2+ complex and external modes of the crystal lattice in accordance with the results of the calculations and factor-group analysis.

FT-IR Microspectroscopy of Rat Ear Cartilage.

Directory of Open Access Journals (Sweden)

Benedicto de Campos Vidal

Full Text Available Rat ear cartilage was studied using Fourier transform-infrared (FT-IR microspectroscopy to expand the current knowledge which has been established for relatively more complex cartilage types. Comparison of the FT-IR spectra of the ear cartilage extracellular matrix (ECM with published data on articular cartilage, collagen II and 4-chondroitin-sulfate standards, as well as of collagen type I-containing dermal collagen bundles (CBs with collagen type II, was performed. Ear cartilage ECM glycosaminoglycans (GAGs were revealed histochemically and as a reduction in ECM FT-IR spectral band heights (1140-820 cm-1 after testicular hyaluronidase digestion. Although ear cartilage is less complex than articular cartilage, it contains ECM components with a macromolecular orientation as revealed using polarization microscopy. Collagen type II and GAGs, which play a structural role in the stereo-arrangement of the ear cartilage, contribute to its FT-IR spectrum. Similar to articular cartilage, ear cartilage showed that proteoglycans add a contribution to the collagen amide I spectral region, a finding that does not recommend this region for collagen type II quantification purposes. In contrast to articular cartilage, the symmetric stretching vibration of -SO3- groups at 1064 cm-1 appeared under-represented in the FT-IR spectral profile of ear cartilage. Because the band corresponding to the asymmetric stretching vibration of -SO3- groups (1236-1225 cm-1 overlapped with that of amide III bands, it is not recommended for evaluation of the -SO3- contribution to the FT-IR spectrum of the ear cartilage ECM. Instead, a peak (or shoulder at 1027-1016 cm-1 could be better considered for this intent. Amide I/amide II ratios as calculated here and data from the literature suggest that protein complexes of the ear cartilage ECM are arranged with a lower helical conformation compared to pure collagen II. The present results could motivate further studies on this tissue

IR and UV spectroscopic analysis of TBP complexes

International Nuclear Information System (INIS)

Azzouz, A.; Berrak, A.; Seridi, L.; Attou, M.

1985-06-01

The complexity of TBP molecule and the limited number of references stimulated the elaboration of this report. The spectroscopic of TBP and its complexes in the IR and UV fields permitted to elucidate or to confirm certain aspects concerning the solvation phenomenum. In IR spectroscopy, the stretching band of the P→O bond only is characteristic of the complex formed. The position of this band gives sufficient information about the kind and the stability of a complex. The TBP electronic spectra are characterized by two bands (200-220 nm) 1 and (268-290 nm) 2 whose intensity ratio (2/1) is about 0,13. The solvent nature seems to influence the positions of these bands and that of the inflexion point. The band 2 disappears when the TBP is complexed and the position and the intensity of the band 1 depend upon the complex nature

Alkoholio ir tabako pasiūlos ir paklausos teisinio reguliavimo raida Lietuvos Respublikoje: problemos ir sprendimai

OpenAIRE

Mockevičius, Arminas

2014-01-01

Viešosios teisės magistro studijų programos studento Armino Mockevičiaus buvo parašytas magistro baigiamasis darbas „Alkoholio ir tabako pasiūlos ir paklausos teisinio reguliavimo raida Lietuvos Respublikoje: problemos ir sprendimai“. Šis darbas parašytas Vilniuje, 2014 metais, Mykolo Romerio universiteto Teisės fakulteto Konstitucinės ir administracinės teisės institute, vadovaujant dr. Gintautui Vilkeliui, apimtis 98 p. Darbo tikslas yra atskleisti alkoholio ir tabako pasiūlos ir paklau...

FT-IR, FT-Raman, NMR spectra, density functional computations of the vibrational assignments (for monomer and dimer) and molecular geometry of anticancer drug 7-amino-2-methylchromone

Science.gov (United States)

Mariappan, G.; Sundaraganesan, N.

2014-04-01

Vibrational assignments for the 7-amino-2-methylchromone (abbreviated as 7A2MC) molecule using a combination of experimental vibrational spectroscopic measurements and ab initio computational methods are reported. The optimized geometry, intermolecular hydrogen bonding, first order hyperpolarizability and harmonic vibrational wavenumbers of 7A2MC have been investigated with the help of B3LYP density functional theory method. The calculated molecular geometry parameters, the theoretically computed vibrational frequencies for monomer and dimer and relative peak intensities were compared with experimental data. DFT calculations using the B3LYP method and 6-31 + G(d,p) basis set were found to yield results that are very comparable to experimental IR and Raman spectra. Detailed vibrational assignments were performed with DFT calculations and the potential energy distribution (PED) obtained from the Vibrational Energy Distribution Analysis (VEDA) program. Natural Bond Orbital (NBO) study revealed the characteristics of the electronic delocalization of the molecular structure. 13C and 1H NMR spectra have been recorded and 13C and 1H nuclear magnetic resonance chemical shifts of the molecule have been calculated using the gauge independent atomic orbital (GIAO) method. Furthermore, All the possible calculated values are analyzed using correlation coefficients linear fitting equation and are shown strong correlation with the experimental data.

FT-IR spectrum of grape seed oil and quantum models of fatty acids triglycerides

Science.gov (United States)

Berezin, K. V.; Antonova, E. M.; Shagautdinova, I. T.; Chernavina, M. L.; Dvoretskiy, K. N.; Grechukhina, O. N.; Vasilyeva, L. M.; Rybakov, A. V.; Likhter, A. M.

2018-04-01

FT-IR spectra of grape seed oil and glycerol were registered in the 650-4000 cm-1 range. Molecular models of glycerol and some fatty acids that compose the oil under study - linoleic, oleic, palmitic and stearic acids - as well as their triglycerides were developed within B3LYP/6-31G(d) density functional model. A vibrating FT-IR spectrum of grape seed oil was modeled on the basis of calculated values of vibrating wave numbers and IR intensities of the fatty acids triglycerides and with regard to their percentage. Triglyceride spectral bands that were formed by glycerol linkage vibrations were revealed. It was identified that triglycerol linkage has a small impact on the structure of fatty acids and, consequently, on vibrating wave numbers. The conducted molecular modeling became a basis for theoretical interpretation on 10 experimentally observed absorption bands in FT-IR spectrum of grape seed oil.

Characterization of proton in Y-doped SrZrO3 polycrystal by IR spectroscopy

International Nuclear Information System (INIS)

Hibino, T.; Mizutani, K.; Yajima, T.; Iwahara, H.

1992-01-01

To characterize proton in Y-doped SrZrO 3 polycrystal, protonic conductivities and infrared spectra were measured. IR spectra exhibited 2 OH bands in 3500-2800 and 2650-2300 cm -1 regions, indicating that proton was bound to lattice oxide ion and that its strength of bonding was rather weak. The decrease in conductivity by replacing H + with D + suggested that the conducting ion was not hydroxide but proton and that it migrated via the dissociation of O-H bond. (author). 15 refs., 5 figs

Time-resolved photoelectron spectroscopy of IR-driven electron dynamics in a charge transfer model system.

Science.gov (United States)

Falge, Mirjam; Fröbel, Friedrich Georg; Engel, Volker; Gräfe, Stefanie

2017-08-02

If the adiabatic approximation is valid, electrons smoothly adapt to molecular geometry changes. In contrast, as a characteristic of diabatic dynamics, the electron density does not follow the nuclear motion. Recently, we have shown that the asymmetry in time-resolved photoelectron spectra serves as a tool to distinguish between these dynamics [Falge et al., J. Phys. Chem. Lett., 2012, 3, 2617]. Here, we investigate the influence of an additional, moderately intense infrared (IR) laser field, as often applied in attosecond time-resolved experiments, on such asymmetries. This is done using a simple model for coupled electronic-nuclear motion. We calculate time-resolved photoelectron spectra and their asymmetries and demonstrate that the spectra directly map the bound electron-nuclear dynamics. From the asymmetries, we can trace the IR field-induced population transfer and both the field-driven and intrinsic (non-)adiabatic dynamics. This holds true when considering superposition states accompanied by electronic coherences. The latter are observable in the asymmetries for sufficiently short XUV pulses to coherently probe the coupled states. It is thus documented that the asymmetry is a measure for phases in bound electron wave packets and non-adiabatic dynamics.

Evaluation of MidIR fibre optic reflectance: Detection limit, reproducibility and binary mixture discrimination

Science.gov (United States)

Sessa, Clarimma; Bagán, Héctor; García, José Francisco

2013-11-01

MidIR fibre optic reflectance (MidIR-FORS) is a promising analytical technique in the field of science conservation, especially because it is non-destructive. Another advantage of MidIR-FORS is that the obtained information is representative, as a large amount of spectral data can be collected. Although the technique has a high potential and is almost routinely applied, its quality parameters have not been thoroughly studied in the specific application of analysis of artistic materials. The objective of this study is to evaluate the instrumental capabilities of MidIR-FORS for the analysis of artwork materials in terms of detection limit, reproducibility, and mixture characterisation. The study has been focused on oil easel painting and several paints of known composition have been analysed. Paint layers include blue pigments not only because of their important role along art history, but also because their physical and spectroscopic characteristics allow a better evaluation of the MidIR-FORS capabilities. The results of the analysis indicate that MidIR-FORS supplies a signal affected by different factors, such as the optical, morphological and physical properties of the surface, in addition to the composition of materials analysed. Consequently, the detection limits established are relatively high for artistic objects (Prussian blue - PB 2.1-6.5%; Phthalocyanine blue - Pht 6.3-10.2%; synthetic Ultramarine blue - UM 12.1%) and may therefore lead to an incomplete description of the artwork. Reproducibility of the technique over time and across surface has been determined. The results show that the major sources of dispersion are the heterogeneity of the pigments distribution, physical features, and band shape distortions. The total dispersion is around 4% for the most intense bands (oil) and increases up to 26% when weak or overlapped bands are considered (PB, Pht, UM). The application of different pre-treatments (cutoff of fibres absorption, Savizky-Golay smoothing

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.

Optical properties of reduced graphene oxide and CuFe2O4 composites in the IR region

Science.gov (United States)

Ma, De-yue; Li, Xiao-xia; Guo, Yu-xiang; Zeng, Yu-run

2018-01-01

The complex refractive index of reduced graphene oxide and CuFe2O4 composites prepared by hydrothermal method was calculated using infrared Micro-reflective spectra and K-K relation, and the calculation errors were analyzed according to its IR transmission and spectral reflectivity calculated by Fresnel formula. And then normal emissivity of the composite in IR atmospheric window was calculated by means of Fresnel formula and modified refraction angle formula. The calculation accuracy was verified by comparing measured normal total emissivity with the calculated one. The results show that complex refractive index and normal emissivity calculated by the formulas have a high accuracy. It has been found that the composite has a good absorption and radiation characteristics in IR atmospheric window and a strong scattering ability in middle IR region by analyzing its extinction, absorption and radiation properties in IR region. Therefore, it may be used as IR absorption, extinction and radiation materials in some special fields.

Catalysis of GTP Hydrolysis by Small GTPases at Atomic Detail by Integration of X-ray Crystallography, Experimental, and Theoretical IR Spectroscopy*

Science.gov (United States)

Rudack, Till; Jenrich, Sarah; Brucker, Sven; Vetter, Ingrid R.; Gerwert, Klaus; Kötting, Carsten

2015-01-01

Small GTPases regulate key processes in cells. Malfunction of their GTPase reaction by mutations is involved in severe diseases. Here, we compare the GTPase reaction of the slower hydrolyzing GTPase Ran with Ras. By combination of time-resolved FTIR difference spectroscopy and QM/MM simulations we elucidate that the Mg2+ coordination by the phosphate groups, which varies largely among the x-ray structures, is the same for Ran and Ras. A new x-ray structure of a Ran·RanBD1 complex with improved resolution confirmed this finding and revealed a general problem with the refinement of Mg2+ in GTPases. The Mg2+ coordination is not responsible for the much slower GTPase reaction of Ran. Instead, the location of the Tyr-39 side chain of Ran between the γ-phosphate and Gln-69 prevents the optimal positioning of the attacking water molecule by the Gln-69 relative to the γ-phosphate. This is confirmed in the RanY39A·RanBD1 crystal structure. The QM/MM simulations provide IR spectra of the catalytic center, which agree very nicely with the experimental ones. The combination of both methods can correlate spectra with structure at atomic detail. For example the FTIR difference spectra of RasA18T and RanT25A mutants show that spectral differences are mainly due to the hydrogen bond of Thr-25 to the α-phosphate in Ran. By integration of x-ray structure analysis, experimental, and theoretical IR spectroscopy the catalytic center of the x-ray structural models are further refined to sub-Å resolution, allowing an improved understanding of catalysis. PMID:26272610

Vibrational spectra and crystal lattice dynamics of hexahydrates of zinc potassium and ammonium sulfates

Science.gov (United States)

Barashkov, M. V.; Komyak, A. I.; Shashkov, S. N.

2000-03-01

The IR spectra and polarized Raman spectra of crystals of hexahydrates of zinc potassium and ammonium sulfates have been obtained experimentally at 93 K and at room temperature. The frequencies and modes of normal vibrations of the octahedral complex [Zn(H2O)6]2+ have been calculated. The assignment of the observed lines of the internal and external vibrations of the crystal cell has been made by calculations and by factor-group analysis.

TPD IR studies of CO desorption from zeolites CuY and CuX

Science.gov (United States)

Datka, Jerzy; Kozyra, Paweł

2005-06-01

The desorption of CO from zeolites CuY and CuX was followed by TPD-IR method. This is a combination of temperature programmed desorption and IR spectroscopy. In this method, the status of activated zeolite (before adsorption), the process of adsorption, and the status of adsorbed molecules can be followed by IR spectroscopy, and the process of desorption (with linear temperature increase) can be followed both by IR spectroscopy and by mass spectrometry. IR spectra have shown two kinds of Cu + sites in both CuY and CuX. Low frequency (l.f.) band (2140 cm -1 in CuY and 2130 cm -1 in CuX) of adsorbed CO represents Cu + sites for which π back donation is stronger and σ donation is weaker whereas high frequency h.f. band (2160 cm -1 in CuY and 2155 cm -1 in CuX) represent Cu + sites for which π back donation is weaker and σ donation is stronger. The TPD-IR experiments evidenced that the Cu + sites represented by l.f. band bond CO more weakly than those represented by h.f. one, indicating that σ donation has more important impact to the strength of Cu +-CO bonding. On the contrary, π back donation has bigger contribution to the activation of adsorbed molecules.

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.

Distinct signalling properties of insulin receptor substrate (IRS)-1 and IRS-2 in mediating insulin/IGF-1 action

DEFF Research Database (Denmark)

Rabiee, Atefeh; Krüger, Marcus; Ardenkjær-Larsen, Jacob

2018-01-01

Insulin/IGF-1 action is driven by a complex and highly integrated signalling network. Loss-of-function studies indicate that the major insulin/IGF-1 receptor substrate (IRS) proteins, IRS-1 and IRS-2, mediate different biological functions in vitro and in vivo, suggesting specific signalling...... properties despite their high degree of homology. To identify mechanisms contributing to the differential signalling properties of IRS-1 and IRS-2 in the mediation of insulin/IGF-1 action, we performed comprehensive mass spectrometry (MS)-based phosphoproteomic profiling of brown preadipocytes from wild type......, IRS-1-/-and IRS-2-/-mice in the basal and IGF-1-stimulated states. We applied stable isotope labeling by amino acids in cell culture (SILAC) for the accurate quantitation of changes in protein phosphorylation. We found ~10% of the 6262 unique phosphorylation sites detected to be regulated by IGF-1...

Spitzer/IRS Observations Of Multiple Main-Belt And Binary Near-Earth Asteroids

Science.gov (United States)

Enriquez, J. Emilio; Marchis, F.; Emery, J. P.; Im, S.

2010-10-01

Since the discovery of Ida's companion in 1993, 195 companions of asteroids have been discovered. To understand the formation process of these interesting bodies, their physical properties such as their bulk density, size, shape, and surface roughness need to be determined. During the Spitzer Cycle-4, we obtained IRS thermal emission spectra (5-42 um) of 23 known binary systems. The majority of asteroids are from the main-belt (16), while the rest are NEOs (7). After extracting the thermal spectra, we used a modified Standard Thermal Model (STM) to calculate their equivalent diameter (from 0.8 km to 237 km), their albedo (from 0.04 for C-type to 0.394 for a V-type) and their beaming factor related to the surface roughness and thermal inertia. We derive their emissivity spectra, which is useful to detect silicate features. Combining these measurements with 3D-models of these multiple asteroid systems obtained by lightcurve inversion, we should be able to derive an accurate estimate of their bulk-density and contrast them with their taxonomic classes. Preliminary studies by Marchis et al. (2008)1, suggested a relationship between bulk density and the taxonomic class of asteroids, which varies from 0.9 g/cc for C-complex to 2.4 g/cc for S-complex asteroids. The National Science Foundation supported this research under award number AAG-0807468. It was conducted with the Spitzer space telescope, which is operated by JPL under a contract with NASA. 1 Marchis et al. , 2008, "Mid-infrared Spectra of Binary Asteroids With Spitzer/IRS", 40th DPS Meeting, Bulletin of the American Astronomical Society, 40, 508

Spatially resolved star formation and dust attenuation in Mrk 848: Comparison of the integral field spectra and the UV-to-IR SED

Science.gov (United States)

Yuan, Fang-Ting; Argudo-Fernández, María; Shen, Shiyin; Hao, Lei; Jiang, Chunyan; Yin, Jun; Boquien, Médéric; Lin, Lihwai

2018-05-01

We investigate the star formation history and the dust attenuation in the galaxy merger Mrk 848. Thanks to the multiwavelength photometry from the ultraviolet (UV) to the infrared (IR), and MaNGA's integral field spectroscopy, we are able to study this merger in a detailed way. We divide the whole merger into the core and tail regions, and fit both the optical spectrum and the multi-band spectral energy distribution (SED) to models to obtain the star formation properties for each region respectively. We find that the color excess of stars in the galaxy E(B-V)sSED measured with the multi-band SED fitting is consistent with that estimated both from the infrared excess (the ratio of IR to UV flux) and from the slope of the UV continuum. Furthermore, the reliability of the E(B-V)sSED is examined with a set of mock SEDs, showing that the dust attenuation of the stars can be well constrained by the UV-to-IR broadband SED fitting. The dust attenuation obtained from optical continuum E(B-V)sspec is only about half of E(B-V)sSED. The ratio of the E(B-V)sspec to the E(B-V)g obtained from the Balmer decrement is consistent with the local value (around 0.5). The difference between the results from the UV-to-IR data and the optical data is consistent with the picture that younger stellar populations are attenuated by an extra dust component from the birth clouds compared to older stellar populations which are only attenuated by the diffuse dust. Both with the UV-to-IR SED fitting and the spectral fitting, we find that there is a starburst younger than 100 Myr in one of the two core regions, consistent with the scenario that the interaction-induced gas inflow can enhance the star formation in the center of galaxies.

The laser desorption/laser ionization mass spectra of some methylated xanthines and the laser desorption of caffeine and theophylline from thin layer chromatography plates

Science.gov (United States)

Rogers, Kevin; Milnes, John; Gormally, John

1993-02-01

Laser desorption/laser ionization time-of-flight mass spectra of caffeine, theophylline, theobromine and xanthine are reported. These mass spectra are compared with published spectra obtained using electron impact ionization. Mass spectra of caffeine and theophylline obtained by IR laser desorption from thin layer chromatography plates are also described. The laser desorption of materials from thin layer chromatography plates is discussed.

Comparison of calculated and experimental isotope edited FTIR difference spectra for purple bacterial photosynthetic reaction centers with different quinones incorporated into the QA binding site.

Directory of Open Access Journals (Sweden)

Nan eZhao

2013-08-01

Full Text Available Previously we have shown that ONIOM type (QM/MM calculations can be used to simulate isotope edited FTIR difference spectra for neutral ubiquinone in the QA binding site in Rhodobacter sphaeroides photosynthetic reaction centers. Here we considerably extend upon this previous work by calculating isotope edited FTIR difference spectra for reaction centers with a variety of unlabeled and 18O labeled foreign quinones incorporated into the QA binding site. Isotope edited spectra were calculated for reaction centers with 2,3-dimethoxy-5,6-dimethyl-1,4-benzoquinone (MQ0, 2,3,5,6-tetramethyl-1,4-benzoquinone (duroquinone, DQ, and 2,3-dimethyl-l,4-naphthoquinone (DMNQ incorporated, and compared to corresponding experimental spectra. The calculated and experimental spectra agree well, further demonstrating the utility and applicability of our ONIOM approach for calculating the vibrational properties of pigments in protein binding sites.The normal modes that contribute to the bands in the calculated spectra, their composition, frequency and intensity, and how these quantities are modified upon 18O labeling, are presented. This computed information leads to a new and more detailed understanding/interpretation of the experimental FTIR difference spectra. Hydrogen bonding to the carbonyl groups of the incorporated quinones is shown to be relatively weak. It is also shown that there is some asymmetry in hydrogen bonding, accounting for 10-13 cm-1 separation in the frequencies of the carbonyl vibrational modes of the incorporated quinones. The extent of asymmetry H-bonding could only be established by considering the spectra for various types of quinones incorporated into the QA binding site. The quinones listed above are tail-less. Spectra were also calculated for reaction centers with corresponding tail containing quinones incorporated, and it is found that replacement of the quinone methyl group by a phytyl or prenyl chain does not alter ONIOM calculated s

Optical Response of Cu1-xZnxIr2S4 Due to Metal--Insulator Transition

International Nuclear Information System (INIS)

Chen, L.; Matsunami, M.; Nanba, T.; Cao, G.; Suzuki, H.; Isobe, M.; Matsumoto, T.

2003-01-01

The mother material CuIr 2 S 4 of the thiospinel system Cu 1-x Zn x Ir 2 S 4 undergoes a temperature-induced metal--insulator (Mi) transition. We report the temperature dependence of the optical reflection spectra of Cu 1-x Zn x Ir 2 S 4 (x ≤ 0.5) at the temperatures of 8-300 K in the energy regions of 0.005--30 eV in order to study the change in the electronic structure due to the Zn substitution for Cu. Zn substitution induced mainly the splitting of the hybridization band between the Ir-5d(t 2g ) and S-3 p states crossing the E F . Obtained optical conductivity (σ ) spectrum is discussed in relation to the change in the electronic structure close to the E F . (author)

Influence of TiO2 Nanocrystals Fabricating Dye-Sensitized Solar Cell on the Absorption Spectra of N719 Sensitizer

Directory of Open Access Journals (Sweden)

Puhong Wen

2012-01-01

Full Text Available The absorption spectra of N719 sensitizer anchored on the films prepared by TiO2 nanocrystals with different morphology and size were investigated for improving the performance of dye-sensitized solar cell (DSC. We find that the morphology and size of TiO2 nanocrystals can affect the UV-vis and FT-IR spectra of the sensitizer anchored on their surfaces. In particular, the low-energy metal-to-ligand charge-transfer transitions (MLCT band in the visible absorption spectra of N719 is strongly affected, and locations of these MLCT bands revealed larger differences. The results indicate that there is a red shift of MLCT band in the spectra obtained by using TiO2 nanocrystals with long morphology and large size compared to that in solution. And it produced a larger red-shift on the MLCT band after TiO2 nanocrystals with small size mixed with some long nanocrystals. Accordingly, the utilization rate to visible light is increased. This is a reason why the DSC prepared by using such film as a photoelectrode has better performance than before mixing.

A novel FT-IR spectroscopic method based on lipid characteristics for qualitative and quantitative analysis of animal-derived feedstuff adulterated with ruminant ingredients.

Science.gov (United States)

Gao, Fei; Zhou, Simiao; Han, Lujia; Yang, Zengling; Liu, Xian

2017-12-15

The objective of this study was to explore the ability of Fourier transform infrared (FT-IR) spectroscopy to authenticate adulterated animal-derived feedstuff. A total of 18 raw meat and bone meals (MBMs), including 9 non-ruminant MBMs and 9 ruminant MBMs, were mixed to obtain 81 binary mixtures with specific proportions (1-35%). Lipid spectral characteristics were analyzed by FT-IR spectroscopy combined with chemometrics. Changes in FT-IR spectra were observed as adulterant concentration was varied. The results illustrate ruminant adulteration can be successfully distinguished based on lipid characteristics. PLS model was established to quantify ruminant adulteration, which was shown to be valid (R 2 P >0.90). Furthermore, the ratios of CC/CO and CC/CH(CH 2 ), as well as the number of CH(CH 2 ) in the fatty acids of adulterated lipids, were calculated, which showed that differences in the trans fatty acid content and the degree of unsaturation were the main contributors to determination of adulteration based on FT-IR spectroscopy. Copyright © 2017. Published by Elsevier Ltd.

Cold, Gas-Phase UV and IR Spectroscopy of Protonated Leucine Enkephalin and its Analogues

Science.gov (United States)

Burke, Nicole L.; Redwine, James; Dean, Jacob C.; McLuckey, Scott A.; Zwier, Timothy S.

2014-06-01

, structural analogues were investigated. Determining the [YGGFL+Na]+ structure will lend insight as to the impact of the ammonium group and methyl esterification of the C-terminus eliminates the carboxy proton. The talk will also report on high resolution, cold UV spectra, non-conformation specific IR gain spectra and conformation specific IR dip spectra for the analogues.

Interstellar dehydrogenated PAH anions: vibrational spectra

Science.gov (United States)

Buragohain, Mridusmita; Pathak, Amit; Sarre, Peter; Gour, Nand Kishor

2018-03-01

Interstellar polycyclic aromatic hydrocarbon (PAH) molecules exist in diverse forms depending on the local physical environment. Formation of ionized PAHs (anions and cations) is favourable in the extreme conditions of the interstellar medium (ISM). Besides in their pure form, PAHs are also likely to exist in substituted forms; for example, PAHs with functional groups, dehydrogenated PAHs etc. A dehydrogenated PAH molecule might subsequently form fullerenes in the ISM as a result of ongoing chemical processes. This work presents a density functional theory (DFT) calculation on dehydrogenated PAH anions to explore the infrared emission spectra of these molecules and discuss any possible contribution towards observed IR features in the ISM. The results suggest that dehydrogenated PAH anions might be significantly contributing to the 3.3 μm region. Spectroscopic features unique to dehydrogenated PAH anions are highlighted that may be used for their possible identification in the ISM. A comparison has also been made to see the size effect on spectra of these PAHs.

Preliminary observations on differences in the Raman spectra of cancerous and noncancerous cells and connective tissue of human skin

Science.gov (United States)

Short, Michael A.; Lui, Harvey; McLean, David I.; Zeng, Haishan; Alajlan, Abdulmajeed; Chen, Michael X.

2005-04-01

A less invasive method of reliably detecting skin cancers is required. Raman spectroscopy is just one of several spectroscopic methods that look promising, but are not yet sufficiently reliable. More information is needed on how and why the Raman spectra of cancerous skin tissue is different from its normal counterpart. We have used confocal micro-Raman spectroscopy with a spatial resolution of about a micron to obtain spectra of unstained thin sections of human skin. We found that there were clear differences in the Raman spectra between cancerous and non-cancerous tissue both in cells and in the connective tissue. The DNA contribution to the spectra was generally stronger in malignant cells than normal ones. In regions of the dermis far away from the tumor one obtains the usual collagen spectra of normal skin, but adjacent to the tumor the spectra no longer appeared to be those of native collagen.

THE STUDY OF CLINOPTILOLITE MODIFIED WITH3d METALS HALIDES BY IR AND DIFFUSE REFLECTANCE SPECTROSCOPY

Directory of Open Access Journals (Sweden)

T. L. Rakitskaya

2015-11-01

Full Text Available The results of investigation of natural clinoptilolite (N-CLI and that modified with 3d metal halides (MeCl2/N-CLI, where Me are Cu, Co, and Mn by IR and diffuse reflectance spectroscopy are summarized. A band at 3437 cm-1 assigned to stretching vibrations of hydroxyl groups (nOH is found in the IR spectrum of the N-CLI sample. A location of the band was practically the same as for all above MeCl2/N-CLI samples. A band of middle intensity at 1638 cm-1 in the range of deformation vibrations of zeolite water observed in the IR spectrum of N-CLI slightly displays to lower frequencies in the case of the modified samples. An intensive wide band of a complex shape in the range from 1250 to 980 cm-1 assigned to Si–O–Si and Si–O–Al vibrations appears in IR spectra of all samples. A doublet band of middle intensity at 797 and 778 cm-1 is assigned to external symmetric stretching T-O vibrations and a band at 606 cm-1-to vibrations of a double ring. A location of the above bands is the same for all listed samples but their intensity is higher for MnCl2/N-CLI and CoCl2/N-CLI samples. After the reaction with ozone, significant changes in the IR spectra are observed only for MnCl2/N-CLI. They are due to MnO2 formation on the clinoptilolite surface resulting in a high frequency displacement of some bands. Based on UV-vi spectroscopy results, it is reasonable to make conclusions about the coordination and valence state of a central atom in the MeCl2/N-CLI samples under study. A location of charge transfer bands for these samples only slightly differs from that for N-CLI however the intensity of such bands increases for the MeCl2/N-CLI samples. The UV-vis spectrum of MnCl2/N-CLI changes after the reaction with ozone: the appearance of new bands of  charge transfer at 363 and 354 nm and also the two-fold increase in intensity of a charge transfer band at 272 nm in comparison with those of N-CLI and MnCl2/N-CLI are the evidence of change in both the

Magnetic structure and excitation spectrum of the hyperhoneycomb Kitaev magnet β -Li2IrO3

Science.gov (United States)

Ducatman, Samuel; Rousochatzakis, Ioannis; Perkins, Natalia B.

2018-03-01

We present a theoretical study of the static and dynamical properties of the three-dimensional, hyperhoneycomb Kitaev magnet β -Li2IrO3 . We argue that the observed incommensurate order can be understood in terms of a long-wavelength twisting of a nearby commensurate period-3 state, with the same key qualitatively features. The period-3 state shows very different structure when either the Kitaev interaction K or the off-diagonal exchange anisotropy Γ is dominant. A comparison of the associated static spin structure factors with reported scattering experiments in zero and finite fields gives strong evidence that β -Li2IrO3 lies in the regime of dominant Kitaev coupling, and that the Heisenberg exchange J is much weaker than both K and Γ . Our predictions for the magnon excitation spectra, the dynamical spin structure factors, and their polarization dependence provide additional distinctive fingerprints that can be checked experimentally.

Application of FT-IR Classification Method in Silica-Plant Extracts Composites Quality Testing

Science.gov (United States)

Bicu, A.; Drumea, V.; Mihaiescu, D. E.; Purcareanu, B.; Florea, M. A.; Trică, B.; Vasilievici, G.; Draga, S.; Buse, E.; Olariu, L.

2018-06-01

Our present work is concerned with the validation and quality testing efforts of mesoporous silica - plant extracts composites, in order to sustain the standardization process of plant-based pharmaceutical products. The synthesis of the silica support were performed by using a TEOS based synthetic route and CTAB as a template, at room temperature and normal pressure. The silica support was analyzed by advanced characterization methods (SEM, TEM, BET, DLS and FT-IR), and loaded with Calendula officinalis and Salvia officinalis standardized extracts. Further desorption studies were performed in order to prove the sustained release properties of the final materials. Intermediate and final product identification was performed by a FT-IR classification method, using the MID-range of the IR spectra, and statistical representative samples from repetitive synthetic stages. The obtained results recommend this analytical method as a fast and cost effective alternative to the classic identification methods.

FT-IR imaging for quantitative determination of liver fat content in non-alcoholic fatty liver.

Science.gov (United States)

Kochan, K; Maslak, E; Chlopicki, S; Baranska, M

2015-08-07

In this work we apply FT-IR imaging of large areas of liver tissue cross-section samples (∼5 cm × 5 cm) for quantitative assessment of steatosis in murine model of Non-Alcoholic Fatty Liver (NAFLD). We quantified the area of liver tissue occupied by lipid droplets (LDs) by FT-IR imaging and Oil Red O (ORO) staining for comparison. Two alternative FT-IR based approaches are presented. The first, straightforward method, was based on average spectra from tissues and provided values of the fat content by using a PLS regression model and the reference method. The second one – the chemometric-based method – enabled us to determine the values of the fat content, independently of the reference method by means of k-means cluster (KMC) analysis. In summary, FT-IR images of large size liver sections may prove to be useful for quantifying liver steatosis without the need of tissue staining.

Catalysis of GTP hydrolysis by small GTPases at atomic detail by integration of X-ray crystallography, experimental, and theoretical IR spectroscopy.

Science.gov (United States)

Rudack, Till; Jenrich, Sarah; Brucker, Sven; Vetter, Ingrid R; Gerwert, Klaus; Kötting, Carsten

2015-10-02

Small GTPases regulate key processes in cells. Malfunction of their GTPase reaction by mutations is involved in severe diseases. Here, we compare the GTPase reaction of the slower hydrolyzing GTPase Ran with Ras. By combination of time-resolved FTIR difference spectroscopy and QM/MM simulations we elucidate that the Mg(2+) coordination by the phosphate groups, which varies largely among the x-ray structures, is the same for Ran and Ras. A new x-ray structure of a Ran·RanBD1 complex with improved resolution confirmed this finding and revealed a general problem with the refinement of Mg(2+) in GTPases. The Mg(2+) coordination is not responsible for the much slower GTPase reaction of Ran. Instead, the location of the Tyr-39 side chain of Ran between the γ-phosphate and Gln-69 prevents the optimal positioning of the attacking water molecule by the Gln-69 relative to the γ-phosphate. This is confirmed in the RanY39A·RanBD1 crystal structure. The QM/MM simulations provide IR spectra of the catalytic center, which agree very nicely with the experimental ones. The combination of both methods can correlate spectra with structure at atomic detail. For example the FTIR difference spectra of RasA18T and RanT25A mutants show that spectral differences are mainly due to the hydrogen bond of Thr-25 to the α-phosphate in Ran. By integration of x-ray structure analysis, experimental, and theoretical IR spectroscopy the catalytic center of the x-ray structural models are further refined to sub-Å resolution, allowing an improved understanding of catalysis. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Intramolecular hydrogen bonding in N-salicylideneaniline: FT-IR spectrum and quantum chemical calculations

Science.gov (United States)

Moosavi-Tekyeh, Zainab; Dastani, Najmeh

2015-12-01

FT-IR and FT-Raman spectra of N-salicylideneaniline (SAn) and its deuterated analogue (D-SAn) are recorded, and the theoretical calculations are performed on their molecular structures and vibrational frequencies. The same calculations are performed for SAn in different solutions using the polarizable conductor continuum model (CPCM) method. Comparisons between the spectra obtained and the corresponding theoretical calculations are used to assign the vibrational frequencies for these compounds. The spectral behavior of SAn upon deuteration is also used to distinguish the positions of OH vibrational frequencies. The hydrogen bond strength of SAn is investigated by applying the atoms-in-molecules (AIM) theory, natural bond orbital (NBO) analysis, and geometry calculations. The harmonic vibrational frequencies of SAn are calculated at B3LYP and X3LYP levels of theory using 6-31G*, 6-311G**, and 6-311++G** basis sets. The AIM results support a medium hydrogen bonding in SAn. The observed νOH/νOD and γOH/γOD for SAn appear at 2940/2122 and 830/589 cm-1, respectively.

Mid-IR and far-IR investigation of AgI-doped silver diborate glasses

International Nuclear Information System (INIS)

Hudgens, J.J.; Martin, S.W.

1996-01-01

The structures of xAgI+(1-x)Ag 2 O·2B 2 O 3 glasses, where 0.2≤x≤0.6, have been investigated using mid- and far-infrared spectroscopy. The mid-IR spectra revealed that in those glasses prepared using AgNO 3 as the starting material for Ag 2 O, the BO 4 - /BO 3 ratio is constant with increasing amounts of AgI as would be expected form the proposed behavior of AgI in these glasses. However, a survey of the literature revealed those glasses prepared from pure Ag 2 O show a strong linear dependence of the BO 4 - /BO 3 ratio on AgI content. Most probably, in those glasses prepared with Ag 2 O the Ag 2 O/B 2 O 3 ratio changes with AgI content due to the decomposition of Ag 2 O during melting. This different behavior is associated with AgNO 3 decomposing to Ag 2 O with heating followed by incorporation into the glassy network. For Ag 2 O used directly, it is proposed that it decomposes to Ag metal and O 2 (gas) with heating before it can be incorporated into the borate network. This latter behavior decreases with increasing AgI in the batch composition because AgI lowers the liquidus temperature of the melt considerably. The far-IR analysis of the AgI-doped silver diborate glasses suggests that there are three coordination environments for the Ag + ions; one with iodide anions and the other two with oxygen ions. It is proposed that the separate oxygen coordination environments for the Ag + ions arise from one with bridging oxygens of BO 4 - units, and the other with nonbridging oxygens on BO 3 - units. Furthermore, it is proposed that the Ag + ions in the iodide-ion environments progressively agglomerate into disordered regions of AgI, but do not form structures similar to α-AgI. (Abstract Truncated)

Effect of different light spectra on the pigmentation of stored elephant garlic.

Science.gov (United States)

Comparini, Diego; Nguyen, Hieu Th; Ueda, Kota; Moritaka, Kyoshi; Kihara, Toshihiko; Kawano, Tomonori

2018-05-01

In the present study high-brightness light-emitting diodes were used to investigate the influence of different light spectra on garlic discoloration at different humidity levels and temperature. Many processes involved in the discoloration process of garlic/leek during storage under different conditions remain unanswered. For this reason in this study the ability of specific light spectra to enhance the production of desirable pigments has been evaluated in elephant garlic. It is well known that the pigments involved in the discoloration reaction are of great interest because of their potential ability to increase the nutritional value and health benefits of the food. In the present study, we show how the chlorophyll content of the sprout increases directly proportionally to the wavelength of the light tested; green/blue light delays the greening process of garlic young shoots whilst red/infra-red light irradiance conditions increase the greening process at different storage temperatures and humidity. Moreover different lights in the visible spectrum have been observed to stimulate and enhance the outer layer purple coloration. The use of different lights to modulate garlic pigmentation has been demonstrated and, in particular, the utilisation of red/green/blue lights and lower temperature resulted in higher red/pink pigments production supporting the hypothesis that this process involves more than one light to be fully performed and the low temperature is a condition that influences the formation of these products. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

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.

Characterization of Paracoccidioides brasiliensis by FT-IR spectroscopy and nanotechnology

Science.gov (United States)

Ferreira, Isabelle; Ferreira-Strixino, Juliana; Castilho, Maiara L.; Campos, Claudia B. L.; Tellez, Claudio; Raniero, Leandro

2016-01-01

Paracoccidioides brasiliensis, the etiological agent of paracoccidioidomycosis, is a dimorphic fungus existing as mycelia in the environment (or at 25 °C in vitro) and as yeast cells in the human host (or at 37 °C in vitro). Because mycological examination of lesions in patients frequently is unable to show the presence of the fungus and serological tests can misdiagnose the disease with other mycosis, the development of new approach's for molecular identification of P. brasiliensis spurges is needed. This study describes the use of a gold nanoprobe of a known gene sequence of P. brasiliensis as a molecular tool to identify P. brasiliensis by regular polymerase chain reaction (PCR) associated with a colorimetric methods. This approach is suitable for testing in remote areas because it does not require any further step than gene amplification, being safer and cheaper than electrophoresis methods. The proposed test showed a color change of the PCR reaction mixture from red to blue in negative samples, whereas the solution remains red in positive samples. We also performed a Fourier Transform Infrared (FT-IR) Spectroscopy analysis to characterize and compare the chemical composition between yeast and mycelia forms, which revealed biochemical differences between these two forms. The analysis of the spectra showed that differences were distributed in chemical bonds of proteins, lipids and carbohydrates. The most prominent difference between both forms was vibration modes related to 1,3-β-glucan usually found in mycelia and 1,3-α-glucan found in yeasts and also chitin forms. In this work, we introduce FT-IR as a new method suitable to reveal overall differences that biochemically distinguish each form of P. brasiliensis that could be additionally used to discriminate biochemical differences among a single form under distinct environmental conditions.

Spectra processing at tooth enamel dosimetry: Analytical description of EPR spectrum at different microwave power

International Nuclear Information System (INIS)

Tieliewuhan, E.; Ivannikov, A.; Zhumadilov, K.; Nalapko, M.; Tikunov, D.; Skvortsov, V.; Stepanenko, V.; Toyoda, S.; Tanaka, K.; Endo, S.; Hoshi, M.

2006-01-01

Variation of the electron paramagnetic resonance (EPR) spectrum of the human tooth enamel recorded at different microwave power is investigated. The analytical models describing the native and the radiation-induced signals in the enamel are proposed, which fit the experimental spectra in wide range of microwave power. These models are designed to use for processing the spectra of irradiated enamel at determination of the absorbed dose from the intensity of the radiation-induced signal

Power-Law Template for IR Point Source Clustering

Science.gov (United States)

Addison, Graeme E.; Dunkley, Joanna; Hajian, Amir; Viero, Marco; Bond, J. Richard; Das, Sudeep; Devlin, Mark; Halpern, Mark; Hincks, Adam; Hlozek, Renee;

Advantages of TOF-SIMS analysis of hydroxyapatite and fluorapatite in comparison with XRD, HR-TEM and FT-IR.

Science.gov (United States)

Okazaki, Masayuki; Hirata, Isao; Matsumoto, Takuya; Takahashi, Junzo

2005-12-01

The chemical analysis of hydroxyapatite and fluorapatite was carried out using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Hydroxyapatite and fluorapatite were synthesized at 80 +/- 1 degrees C and pH 7.4 +/- 0.2. Fluorapatite was better crystallized, with its (300) reflection shifted to a slightly higher angle. High-resolution transmission electron microscopy clearly revealed a typical, regular hexagonal cross section perpendicular to the c-axis for fluorapatite and a flattened hexagonal cross section for hydroxyapatite. FT-IR spectra of fluorapatite confirmed the absence of OH absorption peak--which was seen in hydroxyapatite at about 3570 cm(-1). TOF-SIMS mass spectra showed a peak at 40 amu due to calcium. In addition, a peak at 19 amu due to fluorine could be clearly seen, although the intensities of PO, PO2, and PO3 were very low. It was confirmed that TOF-SIMS clearly showed the differences between positive and negative mass spectra of hydroxyapatite and fluorapatite, especially for F-. We concluded that TOF-SIMS exhibited distinct advantages compared with other methods of analysis.

Assessment of Azithromycin in Pharmaceutical Formulation by Fourier-transform Infrared (FT-IR Transmission Spectroscopy

Directory of Open Access Journals (Sweden)

Muhammad Ali Mallah

2011-12-01

Full Text Available A simple, rapid and economical method for azithromycin quantification in solid tablet and capsule formulations has been developed by applying Fourier-transform Infrared (FT-IR transmission spectroscopy for regular quality monitoring. The newly developed method avoids the sample preparation, except grinding for pellet formation and does not involve consumption of any solvent as it absolutely eliminates the need of extraction. KBr pellets were employed for the appraisal of azithromycin while acquiring spectra of standards as well as samples on FT-IR. By selecting the FT-IR carbonyl band (C=O in the region 1,744–1,709 cm−1 the calibration model was developed based on simple Beer’s law. The excellent regression coefficient (R2 0.999 was accomplished for calibration set having standard error of calibration equal to 0.01 mg. The current work exposes that transmission FT-IR spectroscopy can definitely be applied to determine the exact amount of azithromycin to control the processing and quality of solid formulations with reduced cost and short analysis time.

Structural, phase stability, electronic, elastic properties and hardness of IrN{sub 2} and zinc blende IrN: First-principles calculations

Energy Technology Data Exchange (ETDEWEB)

Zhou, Zhaobo [Key Laboratory of Advanced Materials of Yunnan Province & Key Laboratory of Advanced Materials of Non-Ferrous and Precious Rare Metals Ministry of Education, Kunming University of Science and Technology, Kunming 650093 (China); Zhou, Xiaolong, E-mail: kmzxlong@163.com [Key Laboratory of Advanced Materials of Yunnan Province & Key Laboratory of Advanced Materials of Non-Ferrous and Precious Rare Metals Ministry of Education, Kunming University of Science and Technology, Kunming 650093 (China); Zhang, Kunhua [State Key Laboratory of Rare Precious Metals Comprehensive Utilization of New Technologies, Kunming Institute of Precious Metals, Kunming 650106 (China)

2016-12-15

First-principle calculations were performed to investigate the structural, phase stability, electronic, elastic properties and hardness of monoclinic structure IrN{sub 2} (m-IrN{sub 2}), orthorhombic structure IrN{sub 2} (o-IrN{sub 2}) and zinc blende structure IrN (ZB IrN). The results show us that only m-IrN{sub 2} is both thermodynamic and dynamic stability. The calculated band structure and density of states (DOS) curves indicate that o-IrN{sub 2} and ZB Ir-N compounds we calculated have metallic behavior while m-IrN{sub 2} has a small band gap of ~0.3 eV, and exist a common hybridization between Ir-5d and N-2p states, which forming covalent bonding between Ir and N atoms. The difference charge density reveals the electron transfer from Ir atom to N atom for three Ir-N compounds, which forming strong directional covalent bonds. Notable, a strong N-N bond appeared in m-IrN{sub 2} and o-IrN{sub 2}. The ratio of bulk to shear modulus (B/G) indicate that three Ir-N compounds we calculated are ductile, and ZB IrN possesses a better ductility than two types IrN{sub 2}. m-IrN{sub 2} has highest Debye temperature (736 K), illustrating it possesses strongest covalent bonding. The hardness of three Ir-N compounds were also calculated, and the results reveal that m-IrN{sub 2} (18.23 GPa) and o-IrN{sub 2} (18.02 GPa) are ultraincompressible while ZB IrN has a negative value, which may be attributed to phase transition at ca. 1.98 GPa.

Vibrational spectra of monouranates and uranium hydroxides as reaction products of alkali with uranyl nitrate

International Nuclear Information System (INIS)

Komyak, A.I.; Umrejko, D.S.; Posledovich, M.R.

2013-01-01

Vibrational (IR absorption and Raman scattering) spectra for the reaction products of uranyl nitrate hexahydrate with NaOH and KOH have been studied. As a result of exchange reactions, the uranyl-ion coordinated nitrate groups are completely replaced by hydroxyl ions and various uranium and uranyl oxides or hydrates are formed. An analysis of the vibrations has been performed in terms of the frequencies of a free or coordinated nitrate group; comparison with the vibrations of the well-known uranium oxides and of the uranyl group UO 2 2+ has been carried out. Vibrational spectra of a free nitrate group are characterized by four vibrational frequencies 1050, 724, 850, and 1380 cm -1 , among which the frequencies at 724 and 1380 cm -1 are doubly degenerate and attributed to E’ symmetry of the point group D 3h . When this group is uranium coordinated, its symmetry level is lowered to C 2v , all vibrations of this group being active both in Raman and IR spectra. The doubly degenerate vibrations are exhibited as two bands and a frequency of the out-of-plane vibration is lowered to 815 cm -1 . (authors)

A comparative study of different aspects of manipulating ratio spectra applied for ternary mixtures: derivative spectrophotometry versus wavelet transform.

Science.gov (United States)

Salem, Hesham; Lotfy, Hayam M; Hassan, Nagiba Y; El-Zeiny, Mohamed B; Saleh, Sarah S

2015-01-25

This work represents a comparative study of different aspects of manipulating ratio spectra, which are: double divisor ratio spectra derivative (DR-DD), area under curve of derivative ratio (DR-AUC) and its novel approach, namely area under the curve correction method (AUCCM) applied for overlapped spectra; successive derivative of ratio spectra (SDR) and continuous wavelet transform (CWT) methods. The proposed methods represent different aspects of manipulating ratio spectra of the ternary mixture of Ofloxacin (OFX), Prednisolone acetate (PA) and Tetryzoline HCl (TZH) combined in eye drops in the presence of benzalkonium chloride as a preservative. The proposed methods were checked using laboratory-prepared mixtures and were successfully applied for the analysis of pharmaceutical formulation containing the cited drugs. The proposed methods were validated according to the ICH guidelines. A comparative study was conducted between those methods regarding simplicity, limitation and sensitivity. The obtained results were statistically compared with those obtained from the reported HPLC method, showing no significant difference with respect to accuracy and precision. Copyright © 2014 Elsevier B.V. All rights reserved.

Three-dimensional thermoluminescence spectra of different origin quartz from Altay Orogenic belt, Xinjiang, China

International Nuclear Information System (INIS)

Tan Kaixuan; Liu Zehua; Zeng Sheng; Liu Yan; Xie Yanshi; Rieser, Uwe

2009-01-01

Three-dimensional thermoluminescence spectra are measured for different types of geological origin quartz from the Altay orogenic belt, northern Xinjiang, China. The results show striking differences which appear to be characteristic of their geological origin. Granitic quartz is dominated by emission bands at 420-430 nm, 550-560 nm, at a temperature of 170 deg. C. Pegmatite quartz is characterized by an intense 480 nm emission band at 170 deg. C. Volcanic quartz has exclusive UV (340-360 nm) and violet (410-430 nm) emission bands. Hydrothermal quartz exhibits very different TL spectral characteristics because of different hydrothermal activity and mineralization. Only one TL peaks at 485 nm/170 deg. C was observed in sedimentary quartz. An intense 730 nm emission band observed at 170 deg. C considered generally to be characteristics of feldspar was observed in quartz from granite and hydrothermal Au-bearing quartz. This TL peak is probably related to the centre of [FeO 4 ] 0 on an Si site. All samples show an intense 990-1000 nm emission band at 330 deg. C. Identical types of quartz formed in different regions or different geological and tectonic settings can also exhibit striking differences in TL spectra.

High-Energy, Multi-Octave-Spanning Mid-IR Sources via Adiabatic Difference Frequency Generation

Science.gov (United States)

2016-10-17

MASSACHUSETTS AVE CAMBRIDGE , MA 02139-4301 US 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) AF Office...ADFG) stage, illustrated in Fig. 2. This system represents a very simple extension of a near-IR OPCPA system to octave-spanning mid-IR, requiring...retrieved, as shown in Fig. 10. For illustration , 3 pulse shapes were selected. First, a simple linear chirp was applied to show that the pulse can be

Raman and IR-ATR spectroscopy studies of heteroepitaxial structures with a GaN:C top layer

Science.gov (United States)

Cerqueira, M. F.; Vieira, L. G.; Alves, A.; Correia, R.; Huber, M.; Andreev, A.; Bonanni, A.; Vasilevskiy, M. I.

2017-09-01

This work, motivated by the technologically important task of determination of carbon dopant location in the GaN crystal lattice, employed Raman spectroscopy, with both resonant and non-resonant excitation, and infrared (IR) spectroscopy, in the attenuated total reflection (ATR) configuration, to study lattice vibration modes in a set of carbon-doped GaN (GaN:C) epilayers grown by metalorganic vapour phase epitaxy. We analyse Raman and IR-ATR spectra from the point of view of possible effects of the carbon doping, namely: (i) local vibration mode of C atoms in the nitrogen sublattice (whose frequency we theoretically estimate as 768 cm-1 using an isotope defect model), and (ii) shift in the positions of longitudinal modes owing to the phonon-plasmon coupling. We find only indirect hints of the doping effect on the resonant Raman spectra. However, we show theoretically and confirm experimentally that the IR-ATR spectroscopy can be a much more sensitive tool for this purpose, at least for the considered structures. A weak perturbation of the dielectric function of GaN:C, caused by the substitutional carbon impurity, is shown to produce a measurable dip in the ATR reflectivity spectra at  ≈770 cm-1 for both p- and s-polarizations. Moreover, it influences a specific (guided-wave type) mode observed at  ≈737 cm-1, originating from the GaN layer, which appears in the narrow frequency window where the real parts of the two components of the dielectric tensor of the hexagonal crystal have opposite signs. This interpretation is supported by our modelling of the whole multilayer structure, using a transfer matrix formalism.

Closed N-shell alkali spectra

International Nuclear Information System (INIS)

Ellis, D.G.; Curtis, L.J.

1982-01-01

Term values and ionization potentials have been calculated for several ions in the promethium (N = 61) isoelectronic sequence. As the nuclear charge is increased, the ground configuration changes from 4f 13 5s 2 to 4f 14 5s giving the upper portion of the sequence an alkali-like character. According to our most recent Hartree-Fock calculations with first-order relativistic corrections, the ground term is 5s 2 S for Z > 77 (Ir XVII) and the first excited term is 5p 2 P 0 for Z > 84 (P 0 XXIV). Comparisons are made with calculations of Cowan in W XIV. The prospects for observation of these spectra in fast ion beams are discussed. (orig.)

IR and SFG vibrational spectroscopy of the water bend in the bulk liquid and at the liquid-vapor interface, respectively

Energy Technology Data Exchange (ETDEWEB)

Ni, Yicun; Skinner, J. L. [Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)

2015-07-07

Vibrational spectroscopy of the water bending mode has been investigated experimentally to study the structure of water in condensed phases. In the present work, we calculate the theoretical infrared (IR) and sum-frequency generation (SFG) spectra of the HOH bend in liquid water and at the water liquid/vapor interface using a mixed quantum/classical approach. Classical molecular dynamics simulation is performed by using a recently developed water model that explicitly includes three-body interactions and yields a better description of the water surface. Ab-initio-based transition frequency, dipole, polarizability, and intermolecular coupling maps are developed for the spectral calculations. The calculated IR and SFG spectra show good agreement with the experimental measurements. In the theoretical imaginary part of the SFG susceptibility for the water liquid/vapor interface, we find two features: a negative band centered at 1615 cm{sup −1} and a positive band centered at 1670 cm{sup −1}. We analyze this spectrum in terms of the contributions from molecules in different hydrogen-bond classes to the SFG spectral density and also compare to SFG results for the OH stretch. SFG of the water bending mode provides a complementary picture of the heterogeneous hydrogen-bond configurations at the water surface.

IR and SFG vibrational spectroscopy of the water bend in the bulk liquid and at the liquid-vapor interface, respectively

Science.gov (United States)

Ni, Yicun; Skinner, J. L.

2015-07-01

Vibrational spectroscopy of the water bending mode has been investigated experimentally to study the structure of water in condensed phases. In the present work, we calculate the theoretical infrared (IR) and sum-frequency generation (SFG) spectra of the HOH bend in liquid water and at the water liquid/vapor interface using a mixed quantum/classical approach. Classical molecular dynamics simulation is performed by using a recently developed water model that explicitly includes three-body interactions and yields a better description of the water surface. Ab-initio-based transition frequency, dipole, polarizability, and intermolecular coupling maps are developed for the spectral calculations. The calculated IR and SFG spectra show good agreement with the experimental measurements. In the theoretical imaginary part of the SFG susceptibility for the water liquid/vapor interface, we find two features: a negative band centered at 1615 cm-1 and a positive band centered at 1670 cm-1. We analyze this spectrum in terms of the contributions from molecules in different hydrogen-bond classes to the SFG spectral density and also compare to SFG results for the OH stretch. SFG of the water bending mode provides a complementary picture of the heterogeneous hydrogen-bond configurations at the water surface.

The investigation of hydrogens bonds between sulphur-bearing heterocyclic and proton-donor compounds by IR absorption spectra

International Nuclear Information System (INIS)

Narziev, B.N.; Nurulloev, M.; Makhkambaev, D.

1982-01-01

In this article the results of intermolecular interaction study of sulfur-containing heterocyclic (thiophene, thiophane) and proton-donar (water, alcohol, carbonic acids, chlorophon) molecules for measuring of IR spectrum absorption of protondonar compounds in soluted shape are presented

Proposals of electronic-vibrational energy relaxation studies by using laser pulses synchronized with IR-SR pulses

International Nuclear Information System (INIS)

Nakagawa, Hideyuki

2000-01-01

Synchrotron radiation is expected to be the sharp infrared light source for the advanced experiments on IR and FIR spectroscopy in wide research fields. Especially, synchronized use of SR with VIS and/or UV laser light is to be a promising technique for the research on the dynamical properties of the photo-excited states in condensed materials. Some proposals are attempted for high resolution IR spectroscopy to elucidate fine interaction of molecular ions in crystalline solids with their environmental field and for time-resolved IR spectroscopic studies on the electronic and vibrational energy relaxation by using laser pulses synchronized with IR-SR pulses. Several experimental results are presented in relevance to the subjects; on high-resolution FTIR spectra of cyanide ions and metal cyanide complexes in cadmium halide crystals, on the energy up-conversion process among the vibrational levels of cyanide ions in alkali halide crystals, and on the electronic-to-vibrational energy conversion process in metal cyanide complexes. (author)

35Cl, sup(79,81)Br NQR spectra of chalcogenide molybdenum (5) complexes

International Nuclear Information System (INIS)

Fokina, Z.A.; Kuznetsov, S.I.; Timoshchenko, N.I.; Kolesnichenko, V.L.; Bryukhova, E.V.; Semin, G.K.

1984-01-01

The NQR spectra of molybdenum thioselenohalogenides MoS 2 SeX 5 (X=Cl, Br) are studied. A high-frequency doublet and a low-frequency triplet are observed in both spectra, one of the lines in the latter being noticeably higher by frequency than two others. The NKR spectra structure, with accoUnt of data on thermography and IR-spectroscopy, points to the MoS 2 X 3 xSeX 2 strrcture where two halide atoms are bound with a chalcogen atom and three others with Mo, one of the three chalcogen atoms being in trans-position to SeX 2 . Essential splittings in low-frequency triplet take place at the expense of intrasphere effect of coordinated S 2 -2 and SeX 2 groups

Surface enhanced imaging and IR spectroscopy of the biological cells on the nanostructured gold film

Directory of Open Access Journals (Sweden)

G.I. Dovbeshko

2017-07-01

Full Text Available New approach for optical imaging, structural study and cell cultivation based on the effect of the enhancement of optical signals from biomolecules and biological cells near nanostructured rough gold surface is proposed. The surface enhanced IR absorption (SEIRA spectroscopy and confocal microscopy experiments were made using the culture of SPEV (porcine embryonic kidney epithelium transplantable line and fibroblast cells, cultivated and/or adsorbed on the gold substrate. The SEIRA spectra registered from monolayer of the SPEV cells cultivated on the rough gold showed a low frequency shift of about 2 to 7 cm 1 for the most characteristic IR vibrations, compared with those adsorbed from suspension on the same substrate. An enhancement factor of 15…30 was obtained for different molecular vibrations. The confocal microscopy contrast images of the SPEV cells on rough gold substrate were obtained in laser fluorescence mode. This approach opens new possibilities for visualization of the living cells in vivo without staining. The fluorescence of the rough gold surfaces and effects responsible for our findings have been discussed.

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.

Intra-operative on-line discrimination of kidney cancer from normal tissue by IR ATR spectroscopy of extracellular fluid

Science.gov (United States)

Urboniene, V.; Velicka, M.; Ceponkus, J.; Pucetaite, M.; Jankevicius, F.; Sablinskas, V.; Steiner, G.

2016-03-01

Determination of cancerous and normal kidney tissues during partial, simple or radical nephrectomy surgery was performed by using differences in the IR absorption spectra of extracellular fluid taken from the corresponding tissue areas. The samples were prepared by stamping of the kidney tissue on ATR diamond crystal. The spectral measurements were performed directly in the OR during surgery for 58 patients. It was found that intensities of characteristic spectral bands of glycogen (880-1200 cm-1) in extracellular fluid are sensitive to the type of the tissue and can be used as spectral markers of tumours. Characteristic spectral band of lactic acid (1730 cm-1) - product of the anaerobic glycolysis, taking place in the cancer cells is not suitable for use as a spectral marker of cancerous tissue, since it overlaps with the band of carbonyl stretch in phospholipids and fatty acids. Results of hierarchical cluster analysis of the spectra show that the spectra of healthy and tumour tissue films can be reliably separated into two groups. On the other hand, possibility to differentiate between tumours of different types and grades remains in question. While the fluid from highly malignant G3 tumour tissue contains highly pronounced glycogen spectral bands and can be well separated from benign and G1 tumours by principal component analysis, the variations between spectra from sample to sample prevent from obtaining conclusive results about the grouping between different tumour types and grades. The proposed method is instant and can be used in situ and even in vivo.

Tarptautinio turizmo raida ir vystymo prognozės Lietuvoje ir Lenkijoje

OpenAIRE

Veličkaitė, Dalia

2009-01-01

Išanalizuota ir įvertinta Lietuvos ir Lenkijos atvykstamojo turizmo raida 2000- 2007m., užsienio turistų srautai, apgyvendinimo paslaugų paklausa, turistų tikslai ir kelionių transporto pasirinkimas, turistų išlaidos ir šalių turizmo pajamos, iškeltos atvykstamojo turizmo problemos bei pateikti jų sprendimo siūlymai.paskutinėje darbo dalyje buvo atliktos 2008- 2015metų Lietuvos ir Lenkijos turizmo raidos prognozės. In the final master work Lithuanian and Poland arriving tourism development...

Distinct signalling properties of insulin receptor substrate (IRS)-1 and IRS-2 in mediating insulin/IGF-1 action.

Science.gov (United States)

Rabiee, Atefeh; Krüger, Marcus; Ardenkjær-Larsen, Jacob; Kahn, C Ronald; Emanuelli, Brice

2018-07-01

Insulin/IGF-1 action is driven by a complex and highly integrated signalling network. Loss-of-function studies indicate that the major insulin/IGF-1 receptor substrate (IRS) proteins, IRS-1 and IRS-2, mediate different biological functions in vitro and in vivo, suggesting specific signalling properties despite their high degree of homology. To identify mechanisms contributing to the differential signalling properties of IRS-1 and IRS-2 in the mediation of insulin/IGF-1 action, we performed comprehensive mass spectrometry (MS)-based phosphoproteomic profiling of brown preadipocytes from wild type, IRS-1 -/- and IRS-2 -/- mice in the basal and IGF-1-stimulated states. We applied stable isotope labeling by amino acids in cell culture (SILAC) for the accurate quantitation of changes in protein phosphorylation. We found ~10% of the 6262 unique phosphorylation sites detected to be regulated by IGF-1. These regulated sites included previously reported substrates of the insulin/IGF-1 signalling pathway, as well as novel substrates including Nuclear Factor I X and Semaphorin-4B. In silico prediction suggests the protein kinase B (PKB), protein kinase C (PKC), and cyclin-dependent kinase (CDK) as the main mediators of these phosphorylation events. Importantly, we found preferential phosphorylation patterns depending on the presence of either IRS-1 or IRS-2, which was associated with specific sets of kinases involved in signal transduction downstream of these substrates such as PDHK1, MAPK3, and PKD1 for IRS-1, and PIN1 and PKC beta for IRS-2. Overall, by generating a comprehensive phosphoproteomic profile from brown preadipocyte cells in response to IGF-1 stimulation, we reveal both common and distinct insulin/IGF-1 signalling events mediated by specific IRS proteins. Copyright © 2018 Elsevier Inc. All rights reserved.

Using mid-Infrared External Reflectance Spectroscopy to Distinguish Between Different Commercially Produced Poly[Methyl MethAcrylate] (PMMA) Samples - A Null Result

Science.gov (United States)

Fajardo, Mario; Neel, Christopher; Lacina, David

2017-06-01

We report (null) results of experiments testing the hypothesis that mid-infrared (mid-IR) spectroscopy can be used to distinguish samples of poly[methyl methacrylate] (PMMA) obtained from different commercial suppliers. This work was motivated by the desire for a simple non-destructive and non-invasive test for pre-sorting PMMA samples prior to use in shock and high-strain-rate experiments, where PMMA is commonly used as a standard material. We discuss: our choice of mid-IR external reflectance spectroscopy, our approach to recording reflectance spectra at near-normal (θ = 0 + / - 5 degree) incidence and for extracting the wavelength-weighted absorption spectrum from the raw reflectance data via a Kramers-Krönig analysis. We employ extensive signal, which necessitates adopting a special experimental protocol to mitigate the effects of instrumental drift. Finally, we report spectra of three PMMA samples with different commercial pedigrees, and show that they are virtually identical (+ / - 1 % error, 95% confidence); obviating the use of mid-IR reflectance spectroscopy to tell the samples apart.

PKCδ-mediated IRS-1 Ser24 phosphorylation negatively regulates IRS-1 function

International Nuclear Information System (INIS)

Greene, Michael W.; Ruhoff, Mary S.; Roth, Richard A.; Kim, Jeong-a; Quon, Michael J.; Krause, Jean A.

2006-01-01

The IRS-1 PH and PTB domains are essential for insulin-stimulated IRS-1 Tyr phosphorylation and insulin signaling, while Ser/Thr phosphorylation of IRS-1 disrupts these signaling events. To investigate consensus PKC phosphorylation sites in the PH-PTB domains of human IRS-1, we changed Ser24, Ser58, and Thr191 to Ala (3A) or Glu (3E), to block or mimic phosphorylation, respectively. The 3A mutant abrogated the inhibitory effect of PKCδ on insulin-stimulated IRS-1 Tyr phosphorylation, while reductions in insulin-stimulated IRS-1 Tyr phosphorylation, cellular proliferation, and Akt activation were observed with the 3E mutant. When single Glu mutants were tested, the Ser24 to Glu mutant had the greatest inhibitory effect on insulin-stimulated IRS-1 Tyr phosphorylation. PKCδ-mediated IRS-1 Ser24 phosphorylation was confirmed in cells with PKCδ catalytic domain mutants and by an RNAi method. Mechanistic studies revealed that IRS-1 with Ala and Glu point mutations at Ser24 impaired phosphatidylinositol-4,5-bisphosphate binding. In summary, our data are consistent with the hypothesis that Ser24 is a negative regulatory phosphorylation site in IRS-1

Spitzer mid-IR spectroscopy of powerful 2Jy and 3CRR radio galaxies. II. AGN power indicators and unification

Energy Technology Data Exchange (ETDEWEB)

Dicken, D. [CEA-Saclay, F-91191 Gif-sur-Yvette (France); Tadhunter, C. [University of Sheffield, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Morganti, R. [ASTRON, P.O. Box 2, 7990 AA Dwingeloo (Netherlands); Axon, D.; Robinson, A.; Magagnoli, M. [Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623 (United States); Kharb, P. [Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560034 (India); Ramos Almeida, C. [Instituto de Astrofisica de Canarias (IAC), C/V ia Lactea, s/n, E-38205 La Laguna, Tenerife (Spain); Mingo, B. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Hardcastle, M. [School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield AL10 9AB (United Kingdom); Nesvadba, N. P. H.; Singh, V. [Institut d' Astrophysique Spatiale, CNRS, Université Paris Sud, F-91405 Orsay (France); Kouwenhoven, M. B. N. [Kavli Institute for Astronomy and Astrophysics, Peking University, Yi He Yuan Lu 5, Haidian Qu, Beijing 100871 (China); Rose, M.; Spoon, H. [224 Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Inskip, K. J. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Holt, J., E-mail: daniel.dicken@cea.fr [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands)

2014-06-20

It remains uncertain which continuum and emission line diagnostics best indicate the bolometric powers of active galactic nuclei (AGNs), especially given the attenuation caused by the circumnuclear material and the possible contamination by components related to star formation. Here we use mid-IR spectra along with multiwavelength data to investigate the merit of various diagnostics of AGN radiative power, including the mid-IR [Ne III] λ25.89 μm and [O IV] λ25.89 μm fine-structure lines, the optical [O III] λ5007 forbidden line, and mid-IR 24 μm, 5 GHz radio, and X-ray continuum emission, for complete samples of 46 2Jy radio galaxies (0.05 < z < 0.7) and 17 3CRR FRII radio galaxies (z < 0.1). We find that the mid-IR [O IV] line is the most reliable indicator of AGN power for powerful radio-loud AGNs. By assuming that the [O IV] is emitted isotropically, and comparing the [O III] and 24 μm luminosities of the broad- and narrow-line AGNs in our samples at fixed [O IV] luminosity, we show that the [O III] and 24 μm emission are both mildly attenuated in the narrow-line compared to the broad-line objects by a factor of ≈2. However, despite this attenuation, the [O III] and 24 μm luminosities are better AGN power indicators for our sample than either the 5 GHz radio or the X-ray continuum luminosities. We also detect the mid-IR 9.7 μm silicate feature in the spectra of many objects but not ubiquitously: at least 40% of the sample shows no clear evidence for these features. We conclude that, for the majority of powerful radio galaxies, the mid-IR lines are powered by AGN photoionization.

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.

Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, and trimethylgermyl derivatives of 3,3-dimethylcyclopropene II. 3,3-Dimethyl-1,2-bis(trimethylsilyl)cyclopropene

Science.gov (United States)

Panchenko, Yu. N.; De Maré, G. R.; Abramenkov, A. V.; Baird, M. S.; Tverezovsky, V. V.; Nizovtsev, A. V.; Bolesov, I. G.

2003-07-01

The IR and Raman spectra of 3,3-dimethyl-1,2-bis(trimethylsilyl)cyclopropene (I) (synthesised using standard procedures) were measured in the liquid phase. Total geometry optimisation was performed at the HF/6-31G* level. The HF/6-31G*//HF/6-31G* quantum mechanical force field (QMFF) was calculated and used to determine the theoretical fundamental vibrational frequencies, their predicted IR intensities, Raman activities, and Raman depolarisation ratios. Using Pulay's scaling method and the theoretical molecular geometry, the QMFF of I was scaled by a set of scaling factors used previously for 3,3-dimethyl-1,2-bis(tert-butyl)cyclopropene (17 scale factors for a 105-dimensional problem). The scaled QMFF obtained was used to solve the vibrational problem. The quantum mechanical values of the Raman activities were converted to differential Raman cross sections. The figures for the experimental and theoretical Raman and IR spectra are presented. Assignments of the experimental vibrational spectra of I are given. They take into account the calculated potential energy distribution and the correlation between the estimations of the experimental IR and Raman intensities and Raman depolarisation ratios and the corresponding theoretical values (including Raman cross sections) calculated using the unscaled QMFF.

Studies on molecular structure, vibrational spectra and molecular docking analysis of 3-Methyl-1,4-dioxo-1,4-dihydronaphthalen-2-yl 4-aminobenzoate

Science.gov (United States)

Suresh, D. M.; Amalanathan, M.; Hubert Joe, I.; Bena Jothy, V.; Diao, Yun-Peng

2014-09-01

The molecular structure, vibrational analysis and molecular docking analysis of the 3-Methyl-1,4-dioxo-1,4-dihydronaphthalen-2-yl 4-aminobenzoate (MDDNAB) molecule have been carried out using FT-IR and FT-Raman spectroscopic techniques and DFT method. The equilibrium geometry, harmonic vibrational wave numbers, various bonding features have been computed using density functional method. The calculated molecular geometry has been compared with experimental data. The detailed interpretation of the vibrational spectra has been carried out by using VEDA program. The hyper-conjugative interactions and charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The simulated FT-IR and FT-Raman spectra satisfactorily coincide with the experimental spectra. The PES and charge analysis have been made. The molecular docking was done to identify the binding energy and the Hydrogen bonding with the cancer protein molecule.

FT-IR spectroscopic analyses of 2-(2-furanylmethylene) propanedinitrile

Science.gov (United States)

Soliman, H. S.; Eid, Kh. M.; Ali, H. A. M.; El-Mansy, M. A. M.; Atef, S. M.

2013-03-01

In the present work, a computational study for the optimized molecular structural parameters, thermo-chemical parameters, total dipole moment, HOMO-LUMO energy gap and a combined experimental and computational study for FT-IR spectra for 2-(2-furanylmethylene) propanedinitrile have been investigated using B3LYP utilizing 6-31G and 6-311G basis set. Our calculated results showed that the investigated compound possesses a dipole moment of 7.5 D and HOMO-LUMO energy gap of 3.92 eV using B3LYP/6-311G which indicates that our investigated compound is highly applicable for photovoltaic solar cell applications.

Multi-pollutants sensors based on near-IR telecom lasers and mid-IR difference frequency generation: development and applications; Instruments de mesure multi-polluants par spectroscopie infrarouge bases sur des lasers fibres et par generation de difference de frequences: developpement et applications

Energy Technology Data Exchange (ETDEWEB)

Cousin, J

2006-12-15

At present the detection of VOC and other anthropic trace pollutants is an important challenge in the measurement of air quality. Infrared spectroscopy, allowing spectral regions rich in molecular absorption to be probed, is a suitable technique for in-situ monitoring of the air pollution. Thus the aim of this work was to develop instruments capable of detecting multiple pollutants for in-situ monitoring by IR spectroscopy. A first project benefited from the availability of the telecommunications lasers emitting in near-IR. This instrument was based on an external cavity diode laser (1500 - 1640 nm) in conjunction with a multipass cell (100 m). The detection sensitivity was optimised by employing a balanced detection and a sweep integration procedure. The instrument developed is deployable for in-situ measurements with a sensitivity of < 10{sup -8} cm{sup -1} Hz{sup -1/2} and allowed the quantification of chemical species such as CO{sub 2}, CO, C{sub 2}H{sub 2}, CH{sub 4} and the determination of the isotopic ratio {sup 13}CO{sub 2}/{sup 12}CO{sub 2} in combustion environment The second project consisted in mixing two near-IR fiber lasers in a non-linear crystal (PPLN) in order to produce a laser radiation by difference frequency generation in the middle-IR (3.15 - 3.43 {mu}m), where the absorption bands of the molecules are the most intense. The first studies with this source were carried out on detection of ethylene (C{sub 2}H{sub 4}) and benzene (C{sub 6}H{sub 6}). Developments, characterizations and applications of these instruments in the near and middle IR are detailed and the advantages of the 2 spectral ranges is highlighted. (author)

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

Ultraviolet spectra of planetary nebulae

International Nuclear Information System (INIS)

Harrington, J.P.; Seaton, M.J.; Adams, S.; Lutz, J.H.

1982-01-01

A detailed study of NGC 7662 is based on UV results obtained from 15 IUE spectra and on observations of other workers at optical, IR and radio wavelengths. Improved techniques are used to extract IUE data for an extended source. Relative fluxes in the different apertures which have been used are obtained using the brightness contours of Coleman, Reay and Worswick. There is close agreement between the reddening deduced from the ratios He II (lambda 1640)/(lambda 4686) and (radio)/(Hβ) and the nebular continuum emission observed with the IUE large slots agrees closely with that predicted using absolute radio and Hβ fluxes. The fluxes in nebular emission lines observed with the small slots are smaller than expected from brightness distributions; it is concluded that, for an extended source, the small slots have aperture transmission factors of 0.85 for SWP and 0.46 for LWR. The central star is fainter than has been previously supposed (by more than two magnitudes). The blackbody He II Zanstra temperature of 113 000 K is consistent with the UV colour temperature. Previous work on colour temperatures of central stars is discussed critically. Two models are discussed. (author)

Multichannel Dynamic Fourier-Transform IR Spectrometer

Science.gov (United States)

Balashov, A. A.; Vaguine, V. A.; Golyak, Il. S.; Morozov, A. N.; Khorokhorin, A. I.

2017-09-01

A design of a multichannel continuous scan Fourier-transform IR spectrometer for simultaneous recording and analysis of the spectral characteristics of several objects is proposed. For implementing the design, a multi-probe fiber is used, constructed from several optical fibers connected into a single optical connector and attached at the output of the interferometer. The Fourier-transform spectrometer is used as a signal modulator. Each fiber is individually mated with an investigated sample and a dedicated radiation detector. For the developed system, the radiation intensity of the spectrometer is calculated from the condition of the minimum spectral resolution and parameters of the optical fibers. Using the proposed design, emission spectra of a gas-discharge neon lamp have been recorded using a single fiber 1 mm in diameter with a numerical aperture NA = 0.22.

Hydrogen Bonding in Proteins and Water Studied by Far-IR and Low-Wavenumber Raman Spectroscopy

International Nuclear Information System (INIS)

Greve, Tanja Maria; Birklund Andersen, Kristine; Engdahl, Anders; Nelander, Bengt; Faurskov Nielsen, Ole

2008-01-01

Far-IR spectra with a synchrotron radiation source were for the first time recorded through a microscope coupled to an FTIR-spectrometer. A comparison with spectra recorded with an ordinary globar source revealed that no artifacts occurred with synchrotron radiation. A comparison of ATR (Si-prism) and transmission spectra of a tetrapeptide showed that the ATR-microscope technique could be applied. ATR- and transmission spectra were recorded of polyglycine and compared to the low wavenumber Raman spectrum in the R(v)-representation. A protein band at 115-125 cm -1 was assigned to hydrogen bond modes. Collectively these modes might drive conformational changes in proteins. Based mainly on previously published results the determination of water with a structure like that in bulk liquid water was performed for human and animal skin samples. Changes in water content were reported for freezing and thawing of human skin biopsies and for human skin with benign or malignant skin diseases.

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

Effect of heparin calcium different concentrations on some physical properties and structure in polyacrylamide matrix

International Nuclear Information System (INIS)

Abdelrazek, E.M.; Ibrahim, Hosam S.

2010-01-01

Films of polyacrylamide (PAAm) doped with different concentrations of heparin calcium, from 0.0 to 8 wt%, have been prepared by casting method. Studies were carried out utilizing X-ray, FT-IR, UV/VIS, DSC and DC electrical conduction to characterize the structural, optical and thermal properties of the films. Results revealed that the structural and chemical characterizations of PAAm films are affected by the addition of heparin calcium content. XRD spectra revealed that the amorphous phases increase with increase in filling levels of heparin (FLs). FT-IR analysis revealed that incorporation of heparin calcium leads to a small modification in the spectra of films. The optical absorption spectra in the UV/VIS region revealed structural variation increases with increase in concentration, which is reflected in the form of decrease in the energy band gap E g . Significant changes of DSC curves of the films suggest that strong interaction established between heparin calcium and PAAm molecules. The DC electric conduction data were interpreted on the basis of an intrachain one-dimensional interpolaron hopping model of Kuivalainen.

FT-IR study of gamma-radiation induced degradation of polyvinyl alcohol (PVA) and PVA/humic acids blends

International Nuclear Information System (INIS)

Ilcin, M.; Hola, O.; Bakajova, B.; Kucerik, J.

2010-01-01

Samples of pure polyvinyl alcohol (PVA) and PVA doped with humic acids were exposed to gamma radiation. Gamma rays induced the degradation of the pure polymer. Degradation changes were observed using ATR FT-IR equipment. Dehydration, double bond creation, and their subsequent oxidation (surrounding atmosphere was air) were found out. Also, other degradation reactions (e.g. chain scission, cyclization) occur simultaneously. Formation of C=C and C=O bonds is apparent from FT-IR spectra. In contrast the presence of humic acids in the PVA sample showed stabilizing effect on PVA structure within the concentration range 0.5-10%. (author)

[Infrared spectroscopic analysis of Guilin watermelon frost products].

Science.gov (United States)

Huang, Dong-lan; Chen, Xiao-kang; Xu, Yong-qun; Sun, Su-qin; Zhou, Qun; Lu, Wen-guan

2012-08-01

The objective of the present study is to analyze different products of Guilin watermelon frost by Fourier transform infrared spectroscopy (FTIR), second derivative infrared spectroscopy and two-dimensional correlation spectroscopy (2D-IR) under thermal perturbation. The structural information of the samples indicates that samples from the same factory but of different brands had some dissimilarities in the IR spectra, and the type and content of accessories of them were different compared with conventional IR spectra of samples, peaks at 638 and 616 cm(-1) all arise from anhydrous sodium sulfate in watermelon frost spray and watermelon frost capsule; the characteristic absorption peaks of the sucrose, dextrin or other accessories can be seen clearly in the spectra of watermelon frost throat-clearing buccal tablets, watermelon frost throat tablets and watermelon frost lozenge. And the IR spectra of watermelon frost lozenge is very similar to the IR spectra of sucrose, so it can be easily proved that the content of sucrose in watermelon frost lozenge is high. In the 2D-IR correlation spectra, the samples presented the differences in the position, number and relative intensity of autopeaks and correlation peak clusters. Consequently, the macroscopical fingerprint characters of FTIR, second derivative infrared spectra and 2D-IR spectra can not only provide the information about main chemical constituents in medical materials, but also analyze and identify the type and content of accessories in Guilin watermelon frost. In conclusion, the multi-steps IR macro-fingerprint method is rapid, effective, visual and accurate for pharmaceutical research.

Ligand binding affinity at the insulin receptor isoform A (IR-A and subsequent IR-A tyrosine phosphorylation kinetics are important determinants of mitogenic biological outcomes.

Directory of Open Access Journals (Sweden)

Harinda eRajapaksha

2015-07-01

Full Text Available The insulin receptor (IR is a tyrosine kinase receptor that can mediate both metabolic and mitogenic biological actions. The IR isoform-A (IR-A arises from alternative splicing of exon 11 and has different ligand binding and signalling properties compared to the IR isoform-B. The IR-A not only binds insulin but also insulin-like growth factor-II (IGF-II with high affinity. IGF-II acting through the IR-A promotes cancer cell proliferation, survival and migration by activating some unique signalling molecules compared to those activated by insulin. This observation led us to investigate whether the different IR-A signalling outcomes in response to IGF-II and insulin could be attributed to phosphorylation of a different subset of IR-A tyrosine residues or to the phosphorylation kinetics. We correlated IR-A phosphorylation to activation of molecules involved in mitogenic and metabolic signalling (MAPK and Akt and receptor internalisation rates (related to mitogenic signalling. We also extended this study to incorporate two ligands that are known to promote predominantly mitogenic ([His4, Tyr15, Thr49, Ile51] IGF-I, qIGF-I or metabolic (S597 peptide biological actions, to see if common mechanisms can be used to define mitogenic or metabolic signalling through the IR-A. The 3-fold lower mitogenic action of IGF-II compared to insulin was associated with a decreased potency in activation of Y960, Y1146, Y1150, Y1151, Y1316 and Y1322, in MAPK phosphorylation and in IR-A internalization. With the poorly mitogenic S597 peptide it was a decreased rate of tyrosine phosphorylation rather than potency that was associated with a low mitogenic potential. We conclude that both decreased affinity of IR-A binding and the kinetics of IR-A phosphorylation can independently lead to a lower mitogenic activity. None of the studied parameters could account for the lower metabolic activity of qIGF-I.

Synthesis of iridacarborane halide complexes [(η-9-SMe2-7,8-C2B9H10)IrX2]2 (X=Cl, Br, I)

International Nuclear Information System (INIS)

Kudinov, A.R.; Perekalin, D.S.; Petrovskij, P.V.

2001-01-01

By interaction between Na[9-SMe 2 -7,8-C 2 B 9 H 10 ] and [(Cod)IrCl] 2 (Cod - cycloocta-1,5-diene) iridium complex (η-9-SMe 2 -7,8-C 2 B 9 H 10 )Ir(Cod), which under the action of anhydrous hydrohalogenic acids HX (X=Cl, Br, I) yields iridacarborane halide complexes [(η-9-SMe 2 -7,8-C 2 B 9 H 10 )IrX 2 ] 2 , being analogs of cyclopentadienyl complexes [(C 5 Me 5 )IrX 2 ] 2 . The complexes prepared were characterized on the basis of data of elementary analysis and 1 H, 11 B NMR spectra [ru

Comet Grains: Their IR Emission and Their Relation to ISM Grains

Science.gov (United States)

Wooden, Diane H.; DeVincenzi, Donald (Technical Monitor)

2002-01-01

Comets and the chodritic, porous interplanetary dust particles (CP IDPs) that they shed in their comae are reservoirs of primitive solar nebula materials. The high porosity and fragility of cometary grains and CP IDPs, and anomalously high deuterium contents of highly fragile, pyroxene-rich Cluster IDPs imply these aggregate particles contain significant abundances of grains from the interstellar medium (ISM). IR spectra of comets (3 - 40 micron) reveal the presence of a warm (nearIR) featureless emission modeled by amorphous carbon grains. Broad and narrow resonances near 10 and 20 microns are modeled by warm chondritic (50% Fe and 50% Mg) amorphous silicates and cooler Mg-rich crystalline silicate minerals, respectively. Cometary amorphous silicates resonances are well matched by IR spectra of CP IDPs dominated by GEMS (0.1 micron silicate spherules) that are thought to be the interstellar Fe-bearing amorphous silicates produced in AGB stars. Acid-etched ultramicrotomed CP IDP samples, however, show that both the carbon phase (amorphous and aliphatic) and the Mg-rich amorphous silicate phase in GEMS are not optically absorbing. Rather, it is Fe and FeS nanoparticles embedded in the GEMS that makes the CP IDPs dark. Therefore, CP IDPs suggest significant processing has occurred in the ISM. ISM processing probably includes in He' ion bombardment in supernovae shocks. Laboratory experiments show He+ ion bombardment amorphizes crystalline silicates, increases porosity, and reduces Fe into nanoparticles. Cometary crystalline silicate resonances are well matched by IR spectra of laboratory submicron Mg-rich olivine crystals and pyroxene crystals. Discovery of a Mg-pure olivine crystal in a Cluster IDP with isotopically anomalous oxygen indicates that a small fraction of crystalline silicates may have survived their journey from AGB stars through the ISM to the early solar nebula. The ISM does not have enough crystalline silicates (ISM Mg-rich crystals leads to the

One- and two-photon spectra of Nd3+ clusters in CaF2 and SrF2 crystals

International Nuclear Information System (INIS)

Basiev, Tasoltan T; Voronov, Valerii V; Glotova, M Yu; Papashvili, A G; Karasik, Aleksandr Ya

2003-01-01

The polarised two-photon (IR) and one-photon (visible) luminescence excitation spectra of Nd 3+ nanoclusters in CaF 2 and SrF 2 crystals are measured at 10 K using a F - 2 :LiF colour centre laser tunable in spectral ranges 1090 - 1230 nm and 545 - 615 nm with an emission linewidth of ∼0.02 - 0.03 cm -1 , an average output power of ∼55 mW, and a pulse repetition rate of 10 Hz. The two-photon excitation spectra at the 4 I 9/2 → 4 G 5/2 transition reveal the structure, which is absent upon one-photon excitation, which can be explained by different selection rules for some Stark - Stark transitions upon one- and two-photon absorption. (special issue devoted to the memory of academician a m prokhorov)

FT-IR, FT-Raman, and DFT computational studies of melaminium nitrate molecular-ionic crystal

Science.gov (United States)

Tanak, Hasan; Marchewka, Mariusz K.

2013-02-01

The experimental and theoretical vibrational spectra of melaminium nitrate were studied. The Raman and infrared (FT-IR) spectra of the melaminium nitrate and its deuterated analogue were recorded in the solid phase. Molecular geometry and vibrational frequency values of melaminium nitrate in the electronic ground state were calculated using the density functional method (B3LYP) with the 6-31++G(d,p) basis set. The calculated results show that the optimized geometry can well reproduce the crystal structure, and the theoretical vibrational frequency values show good agreement with experimental values. The NBO analysis reveals that the N-H···O and N-H···N intermolecular interactions significantly influence crystal packing in this molecule.

Mid-IR Properties of an Unbiased AGN Sample of the Local Universe. 1; Emission-Line Diagnostics

Science.gov (United States)

Weaver, K. A.; Melendez, M.; Muhotzky, R. F.; Kraemer, S.; Engle, K.; Malumuth. E.; Tueller, J.; Markwardt, C.; Berghea, C. T.; Dudik, R. P.;

Combined microcalorimetric and IR spectroscopic study on carbon dioxide adsorption in H-MCM-22

Energy Technology Data Exchange (ETDEWEB)

Arean, C.O., E-mail: co.arean@uib.es [Department of Chemistry, University of the Balearic Islands, 07122 Palma de Mallorca (Spain); Delgado, M.R. [Department of Chemistry, University of the Balearic Islands, 07122 Palma de Mallorca (Spain); Bulánek, R.; Frolich, K. [Department of Physical Chemistry, Faculty of Chemical Technology, University of Pardubice, 532 10 Pardubice (Czech Republic)

2014-10-15

Highlights: • Adsorption calorimetry and variable temperature IR spectroscopy is used to study adsorption of CO{sub 2} in the protonic zeolite H-MCM-22. • By simultaneously recording IR absorbance over a temperature range, temperature and equilibrium pressure, standard adsorption enthalpy and entropy of CO{sub 2} was determined. • The results are discussed in the broader context of carbon dioxide capture from the flue gas of fossil fuel fired power stations. - Abstract: The thermodynamics of carbon dioxide adsorption in the protonic zeolite H-MCM-22 (Si:Al = 16:1) was investigated by means of adsorption calorimetry and variable-temperature IR spectroscopy, a technique that affords determination of standard adsorption enthalpy (ΔH{sup 0}) and entropy (ΔS{sup 0}) from analysis of a series of IR spectra recorded over a temperature range while simultaneously measuring equilibrium pressure inside a closed IR cell. ΔH{sup 0} resulted to be −24.5 (±2) kJ mol{sup −1}, while for the entropy change the value of ΔS{sup 0} = −115 (±10) J mol{sup −1} K{sup −1} was obtained. The obtained ΔH{sup 0} value is compared with those reported in the literature for the adsorption of CO{sub 2} on other zeolites, and discussed in the context of carbon dioxide capture and sequestration.

Airborne pipeline leak detection: UV or IR?

Science.gov (United States)

Babin, François; Gravel, Jean-François; Allard, Martin

2016-05-01

This paper presents a study of different approaches to the measurement of the above ground vapor plume created by the spill caused by a small 0.1 l/min (or less) leak in an underground liquid petroleum pipeline. The scenarios are those for the measurement from an airborne platform. The usual approach is that of IR absorption, but in the case of liquid petroleum products, there are drawbacks that will be discussed, especially when using alkanes to detect a leak. The optical measurements studied include UV enhanced Raman lidar, UV fluorescence lidar and IR absorption path integrated lidars. The breadboards used for testing the different approaches will be described along with the set-ups for leak simulation. Although IR absorption would intuitively be the most sensitive, it is shown that UV-Raman could be an alternative. When using the very broad alkane signature in the IR, the varying ground spectral reflectance are a problem. It is also determined that integrated path measurements are preferred, the UV enhanced Raman measurements showing that the vapor plume stays very close to the ground.

Microsolvation of the acetanilide cation (AA(+)) in a nonpolar solvent: IR spectra of AA(+)-L(n) clusters (L = He, Ar, N2; n ≤ 10).

Science.gov (United States)

Schmies, Matthias; Patzer, Alexander; Schütz, Markus; Miyazaki, Mitsuhiko; Fujii, Masaaki; Dopfer, Otto

2014-05-07

Infrared photodissociation (IRPD) spectra of mass-selected cluster ions of acetanilide (N-phenylacetamide), AA(+)-Ln, with the ligands L = He (n = 1-2), Ar (n = 1-7), and N2 (n = 1-10) are recorded in the hydride stretch (amide A, νNH, νCH) and fingerprint (amide I-III) ranges of AA(+) in its (2)A'' ground electronic state. Cold AA(+)-Ln clusters are generated in an electron impact ion source, which predominantly produces the most stable isomer of a given cluster ion. Systematic vibrational frequency shifts of the N-H stretch fundamentals (νNH) provide detailed information about the sequential microsolvation process of AA(+) in a nonpolar (L = He and Ar) and quadrupolar (L = N2) solvent. In the most stable AA(+)-Ln clusters, the first ligand forms a hydrogen bond (H-bond) with the N-H proton of trans-AA(+) (t-AA(+)), whereas further ligands bind weakly to the aromatic ring (π-stacking). There is no experimental evidence for complexes with the less stable cis-AA(+) isomer. Quantum chemical calculations at the M06-2X/aug-cc-pVTZ level confirm the cluster growth sequence derived from the IR spectra. The calculated binding energies of De(H) = 720 and 1227 cm(-1) for H-bonded and De(π) = 585 and 715 cm(-1) for π-bonded Ar and N2 ligands in t-AA(+)-L are consistent with the observed photofragmentation branching ratios of AA(+)-Ln. Comparison between charged and neutral AA((+))-L dimers indicates that ionization switches the preferred ion-ligand binding motif from π-stacking to H-bonding. Electron removal from the HOMO of AA(+) delocalized over both the aromatic ring and the amide group significantly strengthens the C[double bond, length as m-dash]O bond and weakens the N-H bond of the amide group.

Electronic [UV-Visible] and vibrational [FT-IR, FT-Raman] investigation and NMR-mass spectroscopic analysis of terephthalic acid using quantum Gaussian calculations

Science.gov (United States)

Karthikeyan, N.; Joseph Prince, J.; Ramalingam, S.; Periandy, S.

2015-03-01

In this research work, the vibrational IR, polarization Raman, NMR and mass spectra of terephthalic acid (TA) were recorded. The observed fundamental peaks (IR, Raman) were assigned according to their distinctiveness region. The hybrid computational calculations were carried out for calculating geometrical and vibrational parameters by DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results were tabulated. The molecular mass spectral data related to base molecule and substitutional group of the compound was analyzed. The modification of the chemical property by the reaction mechanism of the injection of dicarboxylic group in the base molecule was investigated. The 13C and 1H NMR spectra were simulated by using the gauge independent atomic orbital (GIAO) method and the absolute chemical shifts related to TMS were compared with experimental spectra. The study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, were performed by hybrid Gaussian calculation methods. The orbital energies of different levels of HOMO and LUMO were calculated and the molecular orbital lobe overlapping showed the inter charge transformation between the base molecule and ligand group. From the frontier molecular orbitals (FMO), the possibility of electrophilic and nucleophilic hit also analyzed. The NLO activity of the title compound related to Polarizability and hyperpolarizability were also discussed. The present molecule was fragmented with respect to atomic mass and the mass variation depends on the substitutions have also been studied.

Analysis of the structure and the FT-IR and Raman spectra of 2-(4-nitrophenyl)-4H-3,1-benzoxazin-4-one. Comparisons with the chlorinated and methylated derivatives

Science.gov (United States)

Castillo, María V.; Rudyk, Roxana A.; Davies, Lilian; Brandán, Silvia Antonia

2017-07-01

In this work, the structural, topological and vibrational properties of the monomer and three dimers of the 2-(4-nitrophenyl)-4H-3,1-benzoxazin-4-one (NPB) derivative were studied combining the experimental FTIR and FT-Raman spectra in the solid phase with DFT calculations. Here, Natural Bond Orbital (NBO), Atoms in Molecules (AIM) and HOMO and LUMO calculations were performed by using the hybrid B3LYP/6-31G*and B3LYP/6-311++G** methods in order to compute those properties and to predict their reactivities. The comparisons with the properties reported for the chlorinated (Cl-PB) and methylated (CH3-PB) derivatives at the same levels of theory can be clearly justified by the activating (CH3) and deactivating (NO2 and Cl) characteristics of the different groups linked to oxaxin rings. The NBO and AIM studies evidence the following stability orders: Cl-PB > NO2-PB > CH3-PB in very good concordance with the f(νC23-X26) force constants values. The frontier orbitals analyses reveal that the Cl-PB and NO2-PB derivatives have good stabilities and high chemical hardness while CH3-PB has a higher chemical reactivity. On the other hand, the complete vibrational assignments for monomer and dimers species of NPB were presented. The presence of the IR bands at 1574 and 1037 cm-1 and, of the Raman bands at 1571 and 1038 cm-1 support clearly the presence of the different dimeric species proposed for NPB.

Investigation of the chemical origin and evidential value of differences in the SERS spectra of blue gel inks.

Science.gov (United States)

Ho, Yen Cheng; Lee, Wendy W Y; Bell, Steven E J

2016-08-15

Highly swellable polymer films doped with Ag nanoparticle aggregates (poly-SERS films) have been used to record very high signal : noise ratio, reproducible surface-enhanced (resonance) Raman (SER(R)S) spectra of in situ dried ink lines and their constituent dyes using both 633 and 785 nm excitation. These allowed the chemical origins of differences in the SERRS spectra of different inks to be determined. Initial investigation of pure samples of the 10 most common blue dyes showed that the dyes which had very similar chemical structures such as Patent Blue V and Patent Blue VF (which differ only by a single OH group) gave SERRS spectra in which the only indications that the dye structure had been changed were small differences in peak positions or relative intensities of the bands. SERRS studies of 13 gel pen inks were consistent with this observation. In some cases inks from different types of pens could be distinguished even though they were dominated by a single dye such as Victoria Blue B (Zebra Surari) or Victoria Blue BO (Pilot Acroball) because their predominant dye did not appear in other inks. Conversely, identical spectra were also recorded from different types of pens (Pilot G7, Zebra Z-grip) because they all had the same dominant Brilliant Blue G dye. Finally, some of the inks contained mixtures of dyes which could be separated by TLC and removed from the plate before being analysed with the same poly-SERS films. For example, the Pentel EnerGel ink pen was found to give TLC spots corresponding to Erioglaucine and Brilliant Blue G. Overall, this study has shown that the spectral differences between different inks which are based on chemically similar, but nonetheless distinct dyes, are extremely small, so very close matches between SERRS spectra are required for confident identification. Poly-SERS substrates can routinely provide the very stringent reproducibility and sensitivity levels required. This, coupled with the awareness of the reasons

Defense Strategy of Aircraft Confronted with IR Guided Missile

Directory of Open Access Journals (Sweden)

Hesong Huang

2017-01-01

Full Text Available Surface-type infrared (IR decoy can simulate the IR characteristics of the target aircraft, which is one of the most effective equipment to confront IR guided missile. In the air combat, the IR guided missile poses a serious threat to the aircraft when it comes from the front of target aircraft. In this paper, firstly, the model of aircraft and surface-type IR decoy is established. To ensure their authenticity, the aircraft maneuver and radiation models based on real data of flight and exhaust system radiation in the state of different heights and different speeds are established. Secondly, the most effective avoidance maneuver is simulated when the missile comes from the front of the target aircraft. Lastly, combining maneuver with decoys, the best defense strategy is analysed when the missile comes from the front of aircraft. The result of simulation, which is authentic, is propitious to avoid the missile and improve the survivability of aircraft.

Intensity dependence of nonsequential double ionization of helium in IR+XUV two-color laser fields

International Nuclear Information System (INIS)

Jin, Facheng; Wang, Bingbing; Chen, Jing; Yang, Yujun; Yan, Zong-Chao

2016-01-01

By applying the frequency-domain theory, we investigate the dependence of momentum spectra on laser intensity in a nonsequential double ionization (NSDI) process of helium in infrared (IR) and extreme ultraviolet (XUV) two-color laser fields. We find that the two-color laser fields play distinct roles in an NSDI process, where the IR laser field mainly determines the width of each band, and the XUV laser field mainly plays a role on the NSDI probability. Furthermore, an NSDI process can be decoupled into a two-step process: an above-threshold ionization (ATI), followed by a laser-assisted collision (LAC). It is found that, the IR laser field is responsible for broadening the peak in the ATI process and providing additional momenta to the two ionized electrons in the LAC process; while the XUV laser field plays a crucial role on the strength of the spectrum in the ATI process, and influences the radii of orbits in momentum space in the LAC process. (paper)

NLTE ANALYSIS OF HIGH-RESOLUTION H -BAND SPECTRA. I. NEUTRAL SILICON

Energy Technology Data Exchange (ETDEWEB)

Zhang, Junbo; Shi, Jianrong; Liu, Chao [Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Road, Chaoyang District, Beijing 100012 (China); Pan, Kaike [Apache Point Observatory and New Mexico State University, P.O. Box 59, Sunspot, NM, 88349-0059 (United States); Prieto, Carlos Allende, E-mail: sjr@bao.ac.cn [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)

2016-12-20

We investigated the reliability of our silicon atomic model and the influence of non-local thermodynamical equilibrium (NLTE) on the formation of neutral silicon (Si i) lines in the near-infrared (near-IR) H -band. We derived the differential Si abundances for 13 sample stars with high-resolution H -band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE), as well as from optical spectra, both under local thermodynamical equilibrium (LTE) and NLTE conditions. We found that the differences between the Si abundances derived from the H -band and from optical lines for the same stars are less than 0.1 dex when the NLTE effects are included, and that NLTE reduces the line-to-line scatter in the H -band spectra for most sample stars. These results suggest that our Si atomic model is appropriate for studying the formation of H -band Si lines. Our calculations show that the NLTE corrections of the Si i H -band lines are negative, i.e., the final Si abundances will be overestimated in LTE. The corrections for strong lines depend on surface gravity, and tend to be larger for giants, reaching ∼−0.2 dex in our sample, and up to ∼−0.4 dex in extreme cases of APOGEE targets. Thus, the NLTE effects should be included in deriving silicon abundances from H -band Si i lines, especially for the cases where only strong lines are available.

Study of (n,2n reaction on 191,193Ir isotopes and isomeric cross section ratios

Directory of Open Access Journals (Sweden)

Vlastou R.

2017-01-01

Full Text Available The cross section of 191Ir(n,2n190Irg+m1 and 191Ir(n,2n190Irm2 reactions has been measured at 17.1 and 20.9 MeV neutron energies at the 5.5 MV tandem T11/25 Accelerator Laboratory of NCSR “Demokritos”, using the activation method. The neutron beams were produced by means of the 3H(d,n4He reaction at a flux of the order of 2 × 105 n/cm2s. The neutron flux has been deduced implementing the 27Al(n,α reaction, while the flux variation of the neutron beam was monitored by using a BF3 detector. The 193Ir(n,2n192Ir reaction cross section has also been determined, taking into account the contribution from the contaminant 191Ir(n,γ192Ir reaction. The correction method is based on the existing data in ENDF for the contaminant reaction, convoluted with the neutron spectra which have been extensively studied by means of simulations using the NeusDesc and MCNP codes. Statistical model calculations using the code EMPIRE 3.2.2 and taking into account pre-equilibrium emission, have been performed on the data measured in this work as well as on data reported in literature.

Compilation of neutron flux density spectra and reaction rates in different neutron fields

International Nuclear Information System (INIS)

Ertek, C.

1979-07-01

Upon the recommendation of International Working Group of Reactor Radiation Measurements (IWGRRM), the compilation of neutron flux density spectra and the reaction rates obtained by activation and fission foils in different neutron fields is presented. The neutron fields considered are as follows: 1/E; iron block; LWR core and pressure vessel; LMFBR core and blanket; CTR first wall and blanket; fission spectrum

HIGH-RESOLUTION IR ABSORPTION SPECTROSCOPY OF POLYCYCLIC AROMATIC HYDROCARBONS: THE REALM OF ANHARMONICITY

Energy Technology Data Exchange (ETDEWEB)

Maltseva, Elena; Buma, Wybren Jan [University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands); Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Tielens, Alexander G. G. M. [Leiden Observatory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands); Huang, Xinchuan; Lee, Timothy J. [SETI Institute, 189 Bernardo Avenue, Suite 100, Mountain View, CA 94043 (United States); Oomens, Jos, E-mail: w.j.buma@uva.nl, E-mail: petrignani@strw.leidenuniv.nl [Radboud University, Toernooiveld 7, 6525 ED Nijmegen (Netherlands)

2015-11-20

We report on an experimental and theoretical investigation of the importance of anharmonicity in the 3-μm CH stretching region of polycyclic aromatic hydrocarbon (PAH) molecules. We present mass-resolved, high-resolution spectra of the gas-phase cold (∼4 K) linear PAH molecules naphthalene, anthracene, and tetracene. The measured IR spectra show a surprisingly high number of strong vibrational bands. For naphthalene, the observed bands are well separated and limited by the rotational contour, revealing the band symmetries. Comparisons are made to the harmonic and anharmonic approaches of the widely used Gaussian software. We also present calculated spectra of these acenes using the computational program SPECTRO, providing anharmonic predictions with a Fermi-resonance treatment that utilizes intensity redistribution. We demonstrate that the anharmonicity of the investigated acenes is strong, dominated by Fermi resonances between the fundamental and double combination modes, with triple combination bands as possible candidates to resolve remaining discrepancies. The anharmonic spectra as calculated with SPECTRO lead to predictions of the main bands that fall within 0.5% of the experimental frequencies. The implications for the aromatic infrared bands, specifically the 3-μm band, are discussed.

High-Resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons: The Realm of Anharmonicity

Science.gov (United States)

Maltseva, Elena; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

2016-01-01

We report on an experimental and theoretical investigation of the importance of anharmonicity in the 3 micrometers CH stretching region of Polycyclic Aromatic Hydrocarbon (PAH) molecules. We present mass-resolved, high-resolution spectra of the gas-phase cold ((is) approximately 4K) linear PAH molecules naphthalene, anthracene, and tetracene. The measured IR spectra show a surprisingly high number of strong vibrational bands. For naphthalene, the observed bands are well separated and limited by the rotational contour, revealing the band symmetries. Comparisons are made to the harmonic and anharmonic approaches of the widely used Gaussian software. We also present calculated spectra of these acenes using the computational program SPECTRO, providing anharmonic predictions enhanced with a Fermi-resonance treatment that utilizes intensity redistribution. We demonstrate that the anharmonicity of the investigated acenes is strong, dominated by Fermi resonances between the fundamental and double combination modes, with triple combination bands as possible candidates to resolve remaining discrepancies. The anharmonic spectra as calculated with SPECTRO lead to predictions of the main modes that fall within 0.5% of the experimental frequencies. The implications for the Aromatic Infrared Bands, specifically the 3-m band are discussed.

Vibrational spectra of solid solution series with ordered perovskite structure

NARCIS (Netherlands)

Blasse, G.

I.R. and Raman spectra are reported for the following three systems: Ba2CaMo1−xTexO6, Ba2−xSrxMgWO6 and Ba2Ca1−xMgxWO6. In the first series the internal vibrations of the M6+O6 octahedra do not influence each other. The intensity of ν1 (MoO6) is five times that of ν1 (TeO6). In the second system

Validation of Correction Algorithms for Near-IR Analysis of Human Milk in an Independent Sample Set-Effect of Pasteurization.

Science.gov (United States)

Kotrri, Gynter; Fusch, Gerhard; Kwan, Celia; Choi, Dasol; Choi, Arum; Al Kafi, Nisreen; Rochow, Niels; Fusch, Christoph

2016-02-26

Commercial infrared (IR) milk analyzers are being increasingly used in research settings for the macronutrient measurement of breast milk (BM) prior to its target fortification. These devices, however, may not provide reliable measurement if not properly calibrated. In the current study, we tested a correction algorithm for a Near-IR milk analyzer (Unity SpectraStar, Brookfield, CT, USA) for fat and protein measurements, and examined the effect of pasteurization on the IR matrix and the stability of fat, protein, and lactose. Measurement values generated through Near-IR analysis were compared against those obtained through chemical reference methods to test the correction algorithm for the Near-IR milk analyzer. Macronutrient levels were compared between unpasteurized and pasteurized milk samples to determine the effect of pasteurization on macronutrient stability. The correction algorithm generated for our device was found to be valid for unpasteurized and pasteurized BM. Pasteurization had no effect on the macronutrient levels and the IR matrix of BM. These results show that fat and protein content can be accurately measured and monitored for unpasteurized and pasteurized BM. Of additional importance is the implication that donated human milk, generally low in protein content, has the potential to be target fortified.

Compilation of neutron flux density spectra and reaction rates in different neutron fields. V.3

International Nuclear Information System (INIS)

Ertek, C.

1980-04-01

Upon the recommendation of the International Working Group of Reactor Radiation Measurements (IWGRRM) a compilation of documents containing neutron flux density spectra and the reaction rates obtained by activiation and fission foils in different neutron fields is presented

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

New High-Resolution Absorption Cross-Section Measurements of HCFC-142B in the Mid-Ir

Science.gov (United States)

Le Bris, Karine; Strong, Kimberly; Melo, Stella

2009-06-01

HCFC-142b (1-chloro-1,1-difluoroethane) is a temporary substitute for ozone-depleting chlorofluorocarbons (CFCs). However, due to its high absorption cross-sections in the mid-IR, HCFC-142b is also a highly potent greenhouse gas, now detectable from space by satellite missions. So far, the accuracy of the retrieval has been limited by the lack of reference data in a range of temperatures compatible with atmospheric observations. We present new absorption cross section measurements of HCFC-142b at high-resolution (0.02 cm^{-1}) from 223 K to 283 K in the 600 cm^{-1}- 4000 cm^{-1} spectral window. The composite spectra are calculated for each temperature from a set of acquisitions at different pressures by Fourier transform spectroscopy.

Integrating Field Spectra and Worldview-2 Data for Grapevine Productivity in Different Irrigation Treatments

Science.gov (United States)

Maimaitiyiming, M.; Bozzolo, A.; Wulamu, A.; Wilkins, J. L.

2015-12-01

Precision farming requires high spectral, spatial and temporal resolution remote sensing data to detect plant physiological changes. The higher spatial resolution is particularly as important as the spectral resolution for crop monitoring. It is important to develop data integration techniques between field or airborne hyperspectral data with spaceborne broad band multispectral images for plant productivity monitoring. To investigate varying rootstock and irrigation interactions, different irrigation treatments are implemented in a vineyard experimental site either i) unirrigated ii) full replacement of evapotranspiration (ET) iii) irrigated at 50 % of the potential ET. In summer 2014, we collected leaf and canopy spectra of the vineyard using field spectroscopy along with other plant physiological and nutritional variables. In this contribution, we integrate the field spectra and the spectral wavelengths of WorldView-2 to develop a predictive model for plant productivity,i.e., fruit quality and yield. First, we upscale field and canopy spectra to WorldView-2 spectral bands using radiative transfer simulations (e.g., MODTRAN). Then we develop remote sensing techniques to quantify plant productivity in different scenarios water stress by identifying the most effective and sensitive wavelengths, and indices that are capable of early detection of plant health and estimation of crop nutrient status. Finally we present predictive models developed from partial least square regression (PLSR) for plant productivity using spectral wavelengths and indices derived from integrated field and satellite remote sensing data.

The Photoluminescent Properties of New Cationic Iridium(III Complexes Using Different Anions and Their Applications in White Light-Emitting Diodes

Directory of Open Access Journals (Sweden)

Hui Yang

2015-09-01

Full Text Available Three cationic iridium(III complexes [Ir(ppy2(phen][PF6] (C1, [Ir(ppy2(phen]2SiF6 (C2 and [Ir(ppy2(phen]2TiF6 (C3 (ppy: 2-phenylpyridine, phen: 1, 10-phenanthroline using different anions were synthesized and characterized by 1H Nuclear magnetic resonance (1HNMR, mass spectra (MS, Fourier transform infrared (FTIR spectra and element analysis (EA. After the ultraviolet visible (UV-vis absorption spectra, photoluminescent (PL properties and thermal properties of the complexes were investigated, complex C1 and C3 with good optical properties and high thermal stability were used in white light-emitting diodes (WLEDs as luminescence conversion materials by incorporation with 460 nm-emitting blue GaN chips. The integrative performances of the WLEDs fabricated with complex C1 and C3 are better than those fabricated with the widely used yellow phosphor Y3Al5O12:Ce3+ (YAG. The color rendering indexes of the WLEDs with C1 and C3 are 82.0 and 82.6, the color temperatures of them are 5912 K and 3717 K, and the maximum power efficiencies of them are 10.61 Lm·W−1 and 11.41 Lm·W−1, respectively.

The Photoluminescent Properties of New Cationic Iridium(III) Complexes Using Different Anions and Their Applications in White Light-Emitting Diodes.

Science.gov (United States)

Yang, Hui; Meng, Guoyun; Zhou, Yayun; Tang, Huaijun; Zhao, Jishou; Wang, Zhengliang

2015-09-14

Three cationic iridium(III) complexes [Ir(ppy)₂(phen)][PF₆] (C1), [Ir(ppy)₂(phen)]₂SiF₆ (C2) and [Ir(ppy)₂(phen)]₂TiF₆ (C3) (ppy: 2-phenylpyridine, phen: 1, 10-phenanthroline) using different anions were synthesized and characterized by ¹H Nuclear magnetic resonance (¹HNMR), mass spectra (MS), Fourier transform infrared (FTIR) spectra and element analysis (EA). After the ultraviolet visible (UV-vis) absorption spectra, photoluminescent (PL) properties and thermal properties of the complexes were investigated, complex C1 and C3 with good optical properties and high thermal stability were used in white light-emitting diodes (WLEDs) as luminescence conversion materials by incorporation with 460 nm-emitting blue GaN chips. The integrative performances of the WLEDs fabricated with complex C1 and C3 are better than those fabricated with the widely used yellow phosphor Y₃Al₅O 12 :Ce 3+ (YAG). The color rendering indexes of the WLEDs with C1 and C3 are 82.0 and 82.6, the color temperatures of them are 5912 K and 3717 K, and the maximum power efficiencies of them are 10.61 Lm·W -1 and 11.41 Lm·W -1 , respectively.

The extreme, possible symbiotic Mira V407 Cyg and its relevance to the OH/IR sources

International Nuclear Information System (INIS)

Munari, U.; Margoni, R.; Stagni, R.

1990-01-01

New optical and IR magnitudes are presented and we review all the available photometric data on the very interesting variable V407 Cyg. A preliminary discussion of new high- and low-resolution optical spectra is given. The nature of V407 Cyg is discussed in the light of available data and a classification as a symbiotic star is suggested. (author)

Atomic Data for Stellar Astrophysics: from the UV to the IR

Science.gov (United States)

Wahlgren, Glenn M.

2011-01-01

The study of stars and stellar evolution relies heavily on the analysis of stellar spectra. The need for atomic line data from the ultraviolet (UV) to the infrared (lR) regions is greater now than ever. In the past twenty years, the time since the launch of the Hubble Space Telescope, great progress has been made in acquiring atomic data for UV transitions. The optical wavelength region, now expanded by progress in detector technology, continues to provide motivation for new atomic data. In addition, investments in new instrumentation for ground-based and space observatories has lead to the availability of high-quality spectra at IR wavelengths, where the need for atomic data is most critical. In this review, examples are provided of the progress made in generating atomic data for stellar studies, with a look to the future for addressing the accuracy and completeness of atomic data for anticipated needs.

Surface studies on graphite furnace platforms covered with Pd, Rh and Ir as modifiers in graphite furnace atomic absorption spectrometry of tellurium

Energy Technology Data Exchange (ETDEWEB)

Pedro, Juana [Area de Química Analítica, Departamento de Química, Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829 (S3000GL.N), Santa Fe (Argentina); Stripekis, Jorge [Laboratorio de Análisis de Trazas, Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria (1428), Buenos Aires (Argentina); Departamento de Ingeniería Química, Instituto Tecnológico de Buenos Aires, Av. Eduardo Madero 399 (1106), Buenos Aires (Argentina); Bonivardi, Adrian [Area de Química Analítica, Departamento de Química, Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829 (S3000GL.N), Santa Fe (Argentina); Tudino, Mabel, E-mail: tudino@qi.fcen.uba.ar [Laboratorio de Análisis de Trazas, Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria (1428), Buenos Aires (Argentina)

2015-05-01

The main objective of this work is the study of correlations between the efficiency of the distribution of the permanent platinum group modifiers Pd, Rh and Ir over the graphite surface with the aim of improving analytical signal of tellurium. Modifier solution was deposited onto the platform and pyrolysed after drying. In the case of Pd, the physical vaporization/deposition technique was also tested. In order to analyze the differences amongst coverings (morphology, topology and distribution), the graphite surfaces were studied with scanning electron microscopy and energy dispersive X-ray microscopy. Micrographs for physical vaporization and pyrolytic deposition of Pd were also analyzed in order to explain the lack of signal obtained for tellurium with the first alternative. Similar micrographs were obtained for pyrolytic deposition of Ir and Rh and then, compared to those of Pd. Ir showed the most homogeneous distribution on the graphite surface and the tallest and sharpest transient. With the aim of improving the analytical signal of tellurium, the correlation between the surface studies and the tellurium transient signal (height, area and shape) is discussed. - Highlights: • Distribution of Rh, Pd and Ir onto graphite furnaces is evaluated by SEM and EDX • Micrographs and spectra showed that surface distribution could influence Te signal. • Ir showed the best signal together with the most homogeneous surface distribution. • Pd-PVD micrographs revealed the absence of graphite and no signal for Te.

Weak carbonyl-methyl intermolecular interactions in acetone clusters explored by IR plus VUV spectroscopy

International Nuclear Information System (INIS)

Guan, Jiwen; Hu, Yongjun; Xie, Min; Bernstein, Elliot R.

2012-01-01

Highlights: ► The carbonyl overtone of acetone clusters is observed by IR-VUV spectroscopy. ► Acetone molecules in the dimer are stacked with an antiparallel way. ► The structure of the acetone trimer and the tetramer are the cyclic structures. ► The carbonyl groups would interact with the methyl groups in acetone clusters. ► These weak interactions are further confirmed by H/D substitution experiment. -- Abstract: Size-selected IR–VUV spectroscopy is employed to detect vibrational characteristics in the region 2850 ∼ 3550 cm −1 of neutral acetone and its clusters (CH 3 COCH 3 ) n (n = 1–4). Features around 3440 cm −1 in the spectra of acetone monomer and its clusters are assigned to the carbonyl stretch (CO) overtone. These features red-shift from 3455 to 3433 cm −1 as the size of the clusters increases from the monomer to the tetramer. Based on calculations, the experimental IR spectra in the C=O overtone region suggest that the dominant structures for the acetone trimer and tetramer should be cyclic in the supersonic expansion sample. This study also suggests that the carbonyl groups interact with the methyl groups in the acetone clusters. These weak interactions are further confirmed by the use of deuterium substitution.

Cascaded nano-porous silicon for high sensitive biosensing and functional group distinguishing by Mid-IR spectra.

Science.gov (United States)

Nguyen, Minh-Hang; Tsai, Hau-Jie; Wu, Jen-Kuei; Wu, Yi-Shiuan; Lee, Ming-Chang; Tseng, Fan-Gang

2013-09-15

We present a chemical-biosensor in the Mid-IR range and based on cascaded porous silicon made on p- and n-type (100) silicon substrates of resistivities between 0.001Ωcm and 0.005Ωcm. The stacked porous layers of various porosities (20-80%) and thicknesses (5-9μm) are formed by successive electrochemical etchings with different current densities. Working with FTIR technique that possesses fast response, high sensitivity, and capability of detecting and identifying functional groups, the cascaded porous structures provided enhanced refractive index sensitivities and reduced detection limits in chemical and biodetection. The largest wavenumber shifts were 50cm(-1)/mM obtained for d-(+)-glucose and 96cm(-1)/μg/mL for Cy5-conjungated Rabbit Anti-Mouse IgG. The lowest detectable concentration of glucose was 80μM (1.4mg/mL) with PS porosity of 40% and thickness of about 9μm while it was 40ng/mL for Cy5-conjugated Rabbit Anti-Mouse IgG which is 2.5×10(5) folds better than those in literature. Copyright © 2013 Elsevier B.V. All rights reserved.

Giant-Planet Chemistry: Ammonium Hydrosulfide (NH4SH), Its IR Spectra and Thermal and Radiolytic Stabilities

Science.gov (United States)

Loeffler, Mark J.; Hudson, Reggie L.; Chanover, Nancy J.; Simon, Amy A.

2015-01-01

Here we present our recent studies of proton-irradiated and unirradiated ammonium hydrosulfide, NH4SH, a compound predicted to be an important tropospheric cloud component of Jupiter and other giant planets. We irradiated both crystalline and amorphous NH4SH at 10-160 K and used IR spectroscopy to observe and identify reaction products in the ice, specifically NH3 and long-chained sulfur-containing ions. Crystalline NH4SH was amorphized during irradiation at all temperatures studied with the rate being the fastest at the lowest temperatures. Irradiation of amorphous NH4SH at approximately 10-75 K showed that 60-80% of the NH4 + remained when equilibrium was reached, and that NH4SH destruction rates were relatively constant within this temperature range. Irradiations at higher temperatures produced different dose dependence and were accompanied by pressure outbursts that, in some cases, fractured the ice. The thermal stability of irradiated NH4SH was found to be greater than that of unirradiated NH4SH, suggesting that an irradiated giant-planet cloud precipitate can exist at temperatures and altitudes not previously considered.

A Simple Approach to Distinguish Classic and Formaldehyde-Free Tannin Based Rigid Foams by ATR FT-IR

Directory of Open Access Journals (Sweden)

Gianluca Tondi

2015-01-01

Full Text Available Tannin based rigid foams (TBRFs have been produced with formaldehyde since 1994. Only recently several methods have been developed in order to produce these foams without using formaldehyde. TBRFs with and without formaldehyde are visually indistinguishable; therefore a method for determining the differences between these foams had to be found. The attenuated total reflectance infrared spectroscopy (ATR FT-IR investigation of the TBRFs presented in this paper allowed discrimination between the formaldehyde-containing (classic and formaldehyde-free TBRFs. The spectra of the formaldehyde-free TBRFs, indeed, present decreased band intensity related to the C–O stretching vibration of (i the methylol groups and (ii the furanic rings. This evidence served to prove the chemical difference between the two TBRFs and explained the slightly higher mechanical properties measured for the classic TBRFs.

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

Detecting infrared luminescence and non-chemical signaling of living cells: single cell mid-IR spectroscopy in cryogenic environments

Science.gov (United States)

Pereverzev, Sergey

2017-02-01

Many life-relevant interaction energies are in IR range, and it is reasonable to believe that some biochemical reactions inside cells can results in emission of IR photons. Cells can use this emission for non-chemical and non-electrical signaling. Detecting weak infrared radiation from live cells is complicated because of strong thermal radiation background and absorption of radiation by tissues. A microfluidic device with live cells inside a vacuum cryogenic environment should suppress this background, and thereby permit observation of live cell auto-luminescence or signaling in the IR regime. One can make IR-transparent windows not emitting in this range, so only the cell and a small amount of liquid around it will emit infrared radiation. Currently mid-IR spectroscopy of single cells requires the use of a synchrotron source to measure absorption or reflection spectra. Decreasing of thermal radiation background will allow absorption and reflection spectroscopy of cells without using synchrotron light. Moreover, cell auto-luminescence can be directly measured. The complete absence of thermal background radiation for cryogenically cooled samples allows the use IR photon-sensitive detectors and obtaining single molecule sensitivity in IR photo-luminescence measurements. Due to low photon energies, photo-luminescence measurements will be non-distractive for pressures samples. The technique described here is based upon US patent 9366574.

Identification of forged Bank of England £20 banknotes using IR spectroscopy.

Science.gov (United States)

Sonnex, Emily; Almond, Matthew J; Baum, John V; Bond, John W

2014-01-24

Bank of England notes of £20 denomination have been studied using infrared spectroscopy in order to generate a method to identify forged notes. An aim of this work was to develop a non-destructive method so that a small, compact Fourier transform infrared spectrometer (FT-IR) instrument could be used by bank workers, police departments or others such as shop assistants to identify forged notes in a non-lab setting. The ease of use of the instrument is the key to this method, as well as the relatively low cost. The presence of a peak at 1400 cm(-1) arising from νasym (CO3(2-)) from the blank paper section of a forged note proved to be a successful indicator of the note's illegality for the notes that we studied. Moreover, differences between the spectra of forged and genuine £20 notes were observed in the ν(OH) (ca. 3500 cm(-1)), ν(C-H) (ca. 2900 cm(-1)) and ν(C=O) (ca. 1750 cm(-1)) regions of the IR spectrum recorded for the polymer film covering the holographic strip. In cases where these simple tests fail, we have shown how an infrared microscope can be used to further differentiate genuine and forged banknotes by producing infrared maps of selected areas of the note contrasting inks with background paper. Copyright © 2013 Elsevier B.V. All rights reserved.

Identification of forged Bank of England £20 banknotes using IR spectroscopy

Science.gov (United States)

Sonnex, Emily; Almond, Matthew J.; Baum, John V.; Bond, John W.

2014-01-01

Bank of England notes of £20 denomination have been studied using infrared spectroscopy in order to generate a method to identify forged notes. An aim of this work was to develop a non-destructive method so that a small, compact Fourier transform infrared spectrometer (FT-IR) instrument could be used by bank workers, police departments or others such as shop assistants to identify forged notes in a non-lab setting. The ease of use of the instrument is the key to this method, as well as the relatively low cost. The presence of a peak at 1400 cm-1 arising from νasym (CO32-) from the blank paper section of a forged note proved to be a successful indicator of the note's illegality for the notes that we studied. Moreover, differences between the spectra of forged and genuine £20 notes were observed in the ν(OH) (ca. 3500 cm-1), ν(Csbnd H) (ca. 2900 cm-1) and ν(Cdbnd O) (ca. 1750 cm-1) regions of the IR spectrum recorded for the polymer film covering the holographic strip. In cases where these simple tests fail, we have shown how an infrared microscope can be used to further differentiate genuine and forged banknotes by producing infrared maps of selected areas of the note contrasting inks with background paper.

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.

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.

Essential spectra of difference operators on Zn-periodic graphs

International Nuclear Information System (INIS)

Rabinovich, Vladimir S; Roch, Steffen

2007-01-01

Let (X, ρ) be a discrete metric space. We suppose that the group Z n acts freely on X and that the number of orbits of X with respect to this action is finite. Then we call X a Z n -periodic discrete metric space. We examine the Fredholm property and essential spectra of band-dominated operators on l p (X) when 1 n and their limit operators. In the case where X is the set of vertices of a combinatorial graph, the graph structure defines a Schroedinger operator on l p (X) in a natural way. We illustrate our approach by determining the essential spectra of Schroedinger operators with slowly oscillating potential both on zig-zag and on hexagonal graphs, the latter being related to nano-structures

Strong ligand field effects of blue phosphorescent Ir(III) complexes with phenylpyrazole and phosphines.

Science.gov (United States)

Park, Se Won; Ham, Ho Wan; Kim, Young Sik

2012-04-01

In the paper, we describe new Ir complexes for achieving efficient blue phosphorescence. New blue-emitting mixed-ligand Ir complexes comprising one cyclometalating, two phosphines trans to each other such as Ir(dppz)(PPh3)2(H)(L) (Ll= Cl, NCMe+, CN), [dppz = 3,5-Diphenylpyrazole] were synthesized and studied to tune the phosphorescence wavelength to the deep blue region and to enhance the luminescence efficiencies. To gain insight into the factors responsible for the emission color change and the variation of luminescence efficiency, we investigate the electron-withdrawing capabilities of ancillary ligands using DFT and TD-DFT calculations on the ground and excited states of the complexes. To achieve deep blue emission and increase the emission efficiency, (1) we substitute the phenyl group on the 3-position of the pyrazole ring that lowers the triplet energy enough that the quenching channel is not thermally accessible and (2) change the ancillary ligands coordinated to iridium atom to phosphine and cyano groups known as very strong field ligands. Their inclusion in the coordination sphere can increase the HOMO-LUMO gap to achieve the hypsochromic shift in emission color and lower the HOMO and LUMO energy level, which causes a large d-orbital energy splitting and avoids the quenching effect to improve the luminescence efficiency. The maximum emission spectra of Ir(dppz)(PPh3)2(H)(CI) and Ir(dppz)(PPh3)2(H)(CN) were in the ranges of 439, 432 nm, respectively.

Visible-IR and Raman micro-spectroscopic investigation of three Itokawa particles collected by Hayabusa

Science.gov (United States)

Brunetto, R.; Bonal, L.; Beck, P.; Dartois, E.; Dionnet, Z.; Djouadi, Z.; Füri, E.; Kakazu, Y.; Oudayer, P.; Quirico, E.; Engrand, C.

2014-07-01

HAYABUSA grains offer a unique perspective to better understand the link between asteroids and cosmomaterials available in the laboratory and to get an insight on the early stages of surface space weathering. The scientific objectives of our consortium are threefold: (i) the characterization of asteroidal surface processes (e.g., space weathering alteration); (ii) the assessment of parent-body alteration processes; (iii) the search for a possible association between S-type asteroids and micrometeorites. To this aim, our strategy is based on a combination of analytical techniques. Here we report a first series of results obtained through Visible-Infrared and Raman spectroscopy of three Itokawa particles (RA-QD02-0163, -0174, and -0213) collected by the Hayabusa spacecraft and provided by JAXA for our consortium. In a first step, our main objective was to collect maximum information without altering the particles. Reported results were thus obtained on the raw particles, both (i) in their original containers, and (ii) deposited on diamond windows. Raman and IR confocal spectra were acquired at the SMIS beamline of the French national synchrotron facility SOLEIL and at the Lyon Raman national facility using spots of 2 μ m for the Raman, and 10--20 μ m for the IR analyses. Point analyses and automatic mapping were performed. Analytical parameters (e.g., laser power on the sample) were optimized to prevent any damage. Diffuse reflectance spectra (i=45°, e=0°) in the visible and near-IR wavelengths were obtained with an IAS-CSNSM in-home system coupling a fiber spectrometer to an optical microscope, providing a 20-μ m spot on sample. In the case of particle -0163, Raman and IR results reveal a heterogeneous mixing of minerals, mostly olivine (Fo76), and Ca-rich (En50, Wo50) and Ca-poor (En85) pyroxenes. The modal distribution of these minerals is determined based on the spectral maps. The mineral compositions of -0163 are consistent with those previously reported on

Comparison of Off-Line IR Bump and Action-Angle Kick Minimization

CERN Document Server

Luo, Yun; Ptitsyn, Vadim; Trbojevic, Dejan; Wei, Jie

2005-01-01

The interaction region bump (IR bump) nonlinear correction method has been used for the sextupole and octupole field error on-line corrections in the Relativistic Heavy Ion Collider (RHIC). Some differences were found for the sextupole and octupole corrector strengths between the on-line IR bump correction and the predictions from the action-angle kick minimization. In this report we compare the corrector strengths from these two methods based on the RHIC Blue ring lattice with the IR nonlinear modeling. The comparison confirms the differences between resulting corrector strengths. And the reason for the differences is found and discussed. It is followed by a further discussion of the operational IR bump applications to the octupole, and skew sextupole and skew quadrupole field error corrections.

Spin orientations of the spin-half Ir(4+) ions in Sr3NiIrO6, Sr2IrO4, and Na2IrO3: Density functional, perturbation theory, and Madelung potential analyses.

Science.gov (United States)

Gordon, Elijah E; Xiang, Hongjun; Köhler, Jürgen; Whangbo, Myung-Hwan

2016-03-21

The spins of the low-spin Ir(4+) (S = 1/2, d(5)) ions at the octahedral sites of the oxides Sr3NiIrO6, Sr2IrO4, and Na2IrO3 exhibit preferred orientations with respect to their IrO6 octahedra. We evaluated the magnetic anisotropies of these S = 1/2 ions on the basis of density functional theory (DFT) calculations including spin-orbit coupling (SOC), and probed their origin by performing perturbation theory analyses with SOC as perturbation within the LS coupling scheme. The observed spin orientations of Sr3NiIrO6 and Sr2IrO4 are correctly predicted by DFT calculations, and are accounted for by the perturbation theory analysis. As for the spin orientation of Na2IrO3, both experimental studies and DFT calculations have not been unequivocal. Our analysis reveals that the Ir(4+) spin orientation of Na2IrO3 should have nonzero components along the c- and a-axis directions. The spin orientations determined by DFT calculations are sensitive to the accuracy of the crystal structures employed, which is explained by perturbation theory analyses when interactions between adjacent Ir(4+) ions are taken into consideration. There are indications implying that the 5d electrons of Na2IrO3 are less strongly localized compared with those of Sr3NiIrO6 and Sr2IrO4. This implication was confirmed by showing that the Madelung potentials of the Ir(4+) ions are less negative in Na2IrO3 than in Sr3NiIrO6 and Sr2IrO4. Most transition-metal S = 1/2 ions do have magnetic anisotropies because the SOC induces interactions among their crystal-field split d-states, and the associated mixing of the states modifies only the orbital parts of the states. This finding cannot be mimicked by a spin Hamiltonian because this model Hamiltonian lacks the orbital degree of freedom, thereby leading to the spin-half syndrome. The spin-orbital entanglement for the 5d spin-half ions Ir(4+) is not as strong as has been assumed.

How do users of different academic areas perceive user friendliness of IR

Directory of Open Access Journals (Sweden)

Polona Vilar

2008-01-01

Full Text Available The paper presents one part of a wider study,performed at the Department of LIS&BS at the Faculty of Arts in Ljubljana. The study investigated the perceptions of user friendliness of information retrieval systems’ (IRSinterfaces and the role of individual characteristics of users in these perceptions. A user study with 61 postgraduate students of the University of Ljubljana was performed.Three interfaces were studied: Science Direct,Proquest Direct and Ebsco Host.Questionnaires and observation were used for data collection. The users’ perceptions of importance of auxiliary functions, interface preference and perceptions of user friendliness of certain interface elements were investigated.Also,the connections between these perceptions and the users’individual characteristics were identified. Three sets of individual characteristics were included:approaches to studying,thinking styles and hemisphere leanings. In connection with the dimensions of individual characteristics very different user perceptions were expressed. Some dimensions of individual characteristics were also found to be connected to the users’academic areas. It is shown that the participants from different academic areas have different requirements and perceptions of user friendliness. The results of the study are relevant for the design of the user interfaces of disciplinary IRS.They also have implications for other areas,e.g.user education and training,acquisition and marketing.

The use of difference spectra with a filtered rolling average background in mobile gamma spectrometry measurements

International Nuclear Information System (INIS)

Cresswell, A.J.; Sanderson, D.C.W.

2009-01-01

The use of difference spectra, with a filtering of a rolling average background, as a variation of the more common rainbow plots to aid in the visual identification of radiation anomalies in mobile gamma spectrometry systems is presented. This method requires minimal assumptions about the radiation environment, and is not computationally intensive. Some case studies are presented to illustrate the method. It is shown that difference spectra produced in this manner can improve signal to background, estimate shielding or mass depth using scattered spectral components, and locate point sources. This approach could be a useful addition to the methods available for locating point sources and mapping dispersed activity in real time. Further possible developments of the procedure utilising more intelligent filters and spatial averaging of the background are identified.

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

Low-energy levels calculation for 193Ir

International Nuclear Information System (INIS)

Zahn, Guilherme Soares; Zamboni, Cibele Bugno; Genezini, Frederico Antonio; Mesa-Hormaza, Joel; Cruz, Manoel Tiago Freitas da

2006-01-01

In this work, a model based on single particle plus pairing residual interaction was used to study the low-lying excited states of the 193 Ir nucleus. In this model, the deformation parameters in equilibrium were obtained by minimizing the total energy calculated by the Strutinsky prescription; the macroscopic contribution to the potential was taken from the Liquid Droplet Model, with the shell and paring corrections used as as microscopic contributions. The nuclear shape was described using the Cassinian ovoids as base figures; the single particle energy spectra and wave functions for protons and neutrons were calculated in a deformed Woods-Saxon potential, where the parameters for neutrons were obtained from the literature and the parameters for protons were adjusted in order to describe the main sequence of angular momentum and parity of the band heads, as well as the proton binding energy of 193 Ir. The residual pairing interaction was calculated using the BCS prescription with Lipkin-Nogami approximation. The results obtained for the first three band heads (the 3/2 + ground state, the 1/2 + excited state at E ∼ 73 keV and the the 11/2 - isomeric state at E ∼ 80 keV) showed a very good agreement, but the model so far greatly overestimated the energy of the next band head, a 7/2 - at E ∼ 299 keV. (author)

Fabrication and characterization of implantable and flexible nerve cuff electrodes with Pt, Ir and IrOx films deposited by RF sputtering

International Nuclear Information System (INIS)

Lee, Soo Hyun; Jung, Jung Hwan; Chae, Youn Mee; Kang, Ji Yoon; Suh, Jun-Kyo Francis

2010-01-01

This paper presents the fabrication and characterization of implantable and flexible nerve cuff electrodes for neural interfaces using the conventional BioMEMS technique. In order to fabricate a flexible nerve electrode, polyimide (PI) was chosen as the substrate material. Then, nerve electrodes were thermally re-formed in a cuff shape so as to increase the area in which the charges were transferred to the nerve. Platinum (Pt), iridium (Ir) and iridium oxide (IrO x ) films, which were to serve as conducting materials for the nerve electrodes, were deposited at different working pressures by RF magnetron sputtering. The electrochemical properties of the deposited films were characterized by electrochemical impedance spectroscopy (EIS). The charge delivery capacities of the films were recorded and calculated by cyclic voltammetry (CV). The deposited films of Pt, Ir and IrO x have strong differences in electrochemical properties, which depend on the working pressure of sputter. Each film deposited at 30 mTorr of working pressure shows the highest value of charge delivery capacity (CDC). For the IrO x films, the electrochemical properties were strongly affected by the working pressure as well as the Ar:O 2 gas ratio. The IrO x film deposited with an Ar:O 2 gas ratio of 8:1 showed the highest CDC of 59.5 mC cm −2 , which was about five times higher than that of films deposited with a 1:1 gas ratio.

Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, and trimethylgermyl derivatives of 3,3-dimethylcyclopropene IV. 3,3-Dimethyl-1,2-bis(trimethylgermyl)cyclopropene

Science.gov (United States)

Panchenko, Yu. N.; De Maré, G. R.; Abramenkov, A. V.; Baird, M. S.; Tverezovsky, V. V.; Nizovtsev, A. V.; Bolesov, I. G.

2003-06-01

The infrared (IR) and Raman spectra of 3,3-dimethyl-1,2-bis(trimethylgermyl)cyclopropene (I) were measured in the liquid phase. Total geometry optimisation was performed at the HF/6-31G* level. The HF/6-31G*//HF6-31G* quantum mechanical force field (QMFF) was calculated and used to determine the theoretical fundamental vibrational frequencies, their predicted IR intensities, Raman activities, and Raman depolarisation ratios. Using Pulay's scaling method and the theoretical molecular geometry, the QMFF of I was scaled by a set of scaling factors comprised of elements transferred from the sets used to correct the QMFF's of 3,3-dimethylbutene-1, and 1-methyl-, 1,2-dimethyl-, and 3,3-dimethylcyclopropene (17 scale factors for a 105-dimensional problem). This set of scale factors was used previously to correct the QMFF of 3,3-dimethyl-1,2-bis(tert-butyl)cyclopropene and 3,3-dimethyl-1,2-bis(trimethylsilyl)cyclopropene. The scaled QMFF obtained was used to solve the vibrational problem. Differential Raman cross-sections were calculated using the quantum mechanical values of the Raman activities. The appropriate theoretical spectrograms for the Raman and IR spectra of I were constructed. Assignments of the experimental vibrational spectra of I are given. They take into account the calculated potential energy distributions and the correlation between the estimations of the experimental IR and Raman intensities and Raman depolarisation ratios and the corresponding theoretical values calculated using the unscaled QMFF.

Electronic [UV-Visible] and vibrational [FT-IR, FT-Raman] investigation and NMR-mass spectroscopic analysis of terephthalic acid using quantum Gaussian calculations.

Science.gov (United States)

Karthikeyan, N; Prince, J Joseph; Ramalingam, S; Periandy, S

2015-03-15

In this research work, the vibrational IR, polarization Raman, NMR and mass spectra of terephthalic acid (TA) were recorded. The observed fundamental peaks (IR, Raman) were assigned according to their distinctiveness region. The hybrid computational calculations were carried out for calculating geometrical and vibrational parameters by DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results were tabulated. The molecular mass spectral data related to base molecule and substitutional group of the compound was analyzed. The modification of the chemical property by the reaction mechanism of the injection of dicarboxylic group in the base molecule was investigated. The (13)C and (1)H NMR spectra were simulated by using the gauge independent atomic orbital (GIAO) method and the absolute chemical shifts related to TMS were compared with experimental spectra. The study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, were performed by hybrid Gaussian calculation methods. The orbital energies of different levels of HOMO and LUMO were calculated and the molecular orbital lobe overlapping showed the inter charge transformation between the base molecule and ligand group. From the frontier molecular orbitals (FMO), the possibility of electrophilic and nucleophilic hit also analyzed. The NLO activity of the title compound related to Polarizability and hyperpolarizability were also discussed. The present molecule was fragmented with respect to atomic mass and the mass variation depends on the substitutions have also been studied. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

Theoretical studies on photoelectron and IR spectral properties of Br2.-(H2O)n clusters.

Science.gov (United States)

Pathak, A K; Mukherjee, T; Maity, D K

2007-07-28

We report vertical detachment energy (VDE) and IR spectra of Br2.-.(H2O)n clusters (n=1-8) based on first principles electronic structure calculations. Cluster structures and IR spectra are calculated at Becke's half-and-half hybrid exchange-correlation functional (BHHLYP) with a triple split valence basis function, 6-311++G(d,p). VDE for the hydrated clusters is calculated based on second order Moller-Plesset perturbation (MP2) theory with the same set of basis function. On full geometry optimization, it is observed that conformers having interwater hydrogen bonding among solvent water molecules are more stable than the structures having double or single hydrogen bonded structures between the anionic solute, Br2.-, and solvent water molecules. Moreover, a conformer having cyclic interwater hydrogen bonded network is predicted to be more stable for each size hydrated cluster. It is also noticed that up to four solvent H2O units can reside around the solute in a cyclic interwater hydrogen bonded network. The excess electron in these hydrated clusters is localized over the solute atoms. Weighted average VDE is calculated for each size (n) cluster based on statistical population of the conformers at 150 K. A linear relationship is obtained for VDE versus (n+3)(-1/3) and bulk VDE of Br2.- aqueous solution is calculated as 10.01 eV at MP2 level of theory. BHHLYP density functional is seen to make a systematic overestimation in VDE values by approximately 0.5 eV compared to MP2 data in all the hydrated clusters. It is observed that hydration increases VDE of bromine dimer anion system by approximately 6.4 eV. Calculated IR spectra show that the formation of Br2.--water clusters induces large shifts from the normal O-H stretching bands of isolated water keeping bending modes rather insensitive. Hydrated clusters, Br2.-.(H2O)n, show characteristic sharp features of O-H stretching bands of water in the small size clusters.

Theoretical studies on photoelectron and IR spectral properties of Br2.-(H2O)n clusters

Science.gov (United States)

Pathak, A. K.; Mukherjee, T.; Maity, D. K.

2007-07-01

We report vertical detachment energy (VDE) and IR spectra of Br2•-•(H2O)n clusters (n=1-8) based on first principles electronic structure calculations. Cluster structures and IR spectra are calculated at Becke's half-and-half hybrid exchange-correlation functional (BHHLYP) with a triple split valence basis function, 6-311++G(d,p). VDE for the hydrated clusters is calculated based on second order Moller-Plesset perturbation (MP2) theory with the same set of basis function. On full geometry optimization, it is observed that conformers having interwater hydrogen bonding among solvent water molecules are more stable than the structures having double or single hydrogen bonded structures between the anionic solute, Br2•-, and solvent water molecules. Moreover, a conformer having cyclic interwater hydrogen bonded network is predicted to be more stable for each size hydrated cluster. It is also noticed that up to four solvent H2O units can reside around the solute in a cyclic interwater hydrogen bonded network. The excess electron in these hydrated clusters is localized over the solute atoms. Weighted average VDE is calculated for each size (n) cluster based on statistical population of the conformers at 150K. A linear relationship is obtained for VDE versus (n+3)-1/3 and bulk VDE of Br2•- aqueous solution is calculated as 10.01eV at MP2 level of theory. BHHLYP density functional is seen to make a systematic overestimation in VDE values by ˜0.5eV compared to MP2 data in all the hydrated clusters. It is observed that hydration increases VDE of bromine dimer anion system by ˜6.4eV. Calculated IR spectra show that the formation of Br2•--water clusters induces large shifts from the normal O-H stretching bands of isolated water keeping bending modes rather insensitive. Hydrated clusters, Br2•-•(H2O)n, show characteristic sharp features of O-H stretching bands of water in the small size clusters.

Validation of Correction Algorithms for Near-IR Analysis of Human Milk in an Independent Sample Set—Effect of Pasteurization

Science.gov (United States)

Kotrri, Gynter; Fusch, Gerhard; Kwan, Celia; Choi, Dasol; Choi, Arum; Al Kafi, Nisreen; Rochow, Niels; Fusch, Christoph

2016-01-01

Commercial infrared (IR) milk analyzers are being increasingly used in research settings for the macronutrient measurement of breast milk (BM) prior to its target fortification. These devices, however, may not provide reliable measurement if not properly calibrated. In the current study, we tested a correction algorithm for a Near-IR milk analyzer (Unity SpectraStar, Brookfield, CT, USA) for fat and protein measurements, and examined the effect of pasteurization on the IR matrix and the stability of fat, protein, and lactose. Measurement values generated through Near-IR analysis were compared against those obtained through chemical reference methods to test the correction algorithm for the Near-IR milk analyzer. Macronutrient levels were compared between unpasteurized and pasteurized milk samples to determine the effect of pasteurization on macronutrient stability. The correction algorithm generated for our device was found to be valid for unpasteurized and pasteurized BM. Pasteurization had no effect on the macronutrient levels and the IR matrix of BM. These results show that fat and protein content can be accurately measured and monitored for unpasteurized and pasteurized BM. Of additional importance is the implication that donated human milk, generally low in protein content, has the potential to be target fortified. PMID:26927169

FT-IR and X-ray spectroscopic investigations of Na-diclofenac-cyclodextrins interactions

Science.gov (United States)

Bratu, I.; Astilean, S.; Ionesc, Corina; Indrea, E.; Huvenne, J. P.; Legrand, P.

1998-01-01

The association of DCF-Na (the salt of the 2-[(2,6-dichlorophenyl)amino]-phenyl-acetic acid) with β-CD (cyclodextrin) in some therapeutic formulas can contribute to the optimisation of the physico-chemical and pharmaceutical properties of the parent drug. The understanding of the interaction between DCF with β-CD represents the objective of this study. FT-IR spectroscopy is one of the methods which clarify the nature of these interactions in complexes of such type. Therefore the changes in FT-IR spectra of binary dispersed systems DCF/ β-CD in physical mixture and coprecipitate from methanol (molar ratios: 1/1, 1/2, 2/3, 3/4, 7/4) were analysed. The analysis of the broadening of the X-ray powder diffraction line has been applied to investigate the average effective crystallite size, the mean square of the microstrain caused by distortions within β-CD crystallite and the fault probability in the binary dispersed DCF/ β-CD coprecipitate system.

Emission from water vapor and absorption from other gases at 5-7.5 μm in Spitzer-IRS Spectra Of Protoplanetary Disks

Energy Technology Data Exchange (ETDEWEB)

Sargent, B. A. [Center for Imaging Science and Laboratory for Multiwavelength Astrophysics, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623 (United States); Forrest, W.; Watson, Dan M.; Kim, K. H.; Richter, I.; Tayrien, C. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 (United States); D' Alessio, P.; Calvet, N. [Department of Astronomy, The University of Michigan, 500 Church Street, 830 Dennison Building, Ann Arbor, MI 48109 (United States); Furlan, E. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Green, J. [Department of Astronomy, University of Texas, 1 University Station, Austin, TX 78712 (United States); Pontoppidan, K., E-mail: baspci@rit.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2014-09-10

We present spectra of 13 T Tauri stars in the Taurus-Auriga star-forming region showing emission in Spitzer Space Telescope Infrared Spectrograph 5-7.5 μm spectra from water vapor and absorption from other gases in these stars' protoplanetary disks. Seven stars' spectra show an emission feature at 6.6 μm due to the ν{sub 2} = 1-0 bending mode of water vapor, with the shape of the spectrum suggesting water vapor temperatures >500 K, though some of these spectra also show indications of an absorption band, likely from another molecule. This water vapor emission contrasts with the absorption from warm water vapor seen in the spectrum of the FU Orionis star V1057 Cyg. The other 6 of the 13 stars have spectra showing a strong absorption band, peaking in strength at 5.6-5.7 μm, which for some is consistent with gaseous formaldehyde (H{sub 2}CO) and for others is consistent with gaseous formic acid (HCOOH). There are indications that some of these six stars may also have weak water vapor emission. Modeling of these stars' spectra suggests these gases are present in the inner few AU of their host disks, consistent with recent studies of infrared spectra showing gas in protoplanetary disks.

{sup 7}Li and {sup 23}Na NMR measurements on (Na{sub 0.75}Li{sub 0.25}){sub 2}IrO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Dey, Tusharkanti; Freund, Friedrich; Manni, Soham; Gegenwart, Philipp [EP-VI, Electronic Correlations and Magnetism, University of Augsburg (Germany); Prinz-Zwick, Markus; Schaedler, Martina; Buettgen, Norbert [EP-V, Electronic Correlations and Magnetism, University of Augsburg (Germany); Mahajan, Avinash [EP-V, Electronic Correlations and Magnetism, University of Augsburg (Germany); IIT Bombay (India)

2016-07-01

An experimental realization of the proposed Kitaev spin-liquid phase in Na{sub 2}IrO{sub 3} and Li{sub 2}IrO{sub 3} is still a big challenge. Efforts to suppress the magnetic ordering in Na{sub 2}IrO{sub 3} by substituting isoelectronic Li in the Na site was partially successful. An earlier report suggests the optimum doping to be 25% where the magnetic ordering is suppressed to 6 K while the structure remains undisturbed. Interestingly, for the (Na{sub 0.75}Li{sub 0.25}){sub 2}IrO{sub 3} sample Na and Li are crystallographically ordered where the Li ions reside at the centre of the Ir honeycombs. We have studied the material using both {sup 7}Li and {sup 23}Na NMR. Results of our spectra, spin-lattice and spin-spin relaxation measurements will be discussed in the poster.

Multi-component EPR spectra of coals with different carbon content

Energy Technology Data Exchange (ETDEWEB)

Pilawa, B.; Wieckowski, A.B.; Pietrzak, R.; Wachowska, H. [Polish Academy of Science, Gliwice (Poland). Inst. for Coal Chemistry

2005-08-01

EPR spectra of lignite 'Mequinenza' (Spain) (62.3 wt% C) and Polish orthocoking coal (87.8 wt% C) were compared. The spectra were superpositions of broad Gaussian, broad Lorentzian 1, and narrow Lorentzian 3 lines. Concentration of paramagnetic centers - mainly delocalized pi electrons responsible for narrow Lorentzian 3 lines increases with increase in carbon content in coal. Coal units with slow and fast spin-lattice relaxation processes exist in the two studied samples. Slow spin-lattice interactions occur in simple aromatic coal units with broad Gaussian and Lorentzian 1 lines. Fast spin-lattice relaxation processes are characteristic of large aromatic units with narrow Lorentzian 3 lines.

Evaluation of Turmeric Powder Adulterated with Metanil Yellow Using FT-Raman and FT-IR Spectroscopy

Directory of Open Access Journals (Sweden)

Sagar Dhakal

2016-05-01

Full Text Available Turmeric powder (Curcuma longa L. is valued both for its medicinal properties and for its popular culinary use, such as being a component in curry powder. Due to its high demand in international trade, turmeric powder has been subject to economically driven, hazardous chemical adulteration. This study utilized Fourier Transform-Raman (FT-Raman and Fourier Transform-Infra Red (FT-IR spectroscopy as separate but complementary methods for detecting metanil yellow adulteration of turmeric powder. Sample mixtures of turmeric powder and metanil yellow were prepared at concentrations of 30%, 25%, 20%, 15%, 10%, 5%, 1%, and 0.01% (w/w. FT-Raman and FT-IR spectra were acquired for these mixture samples as well as for pure samples of turmeric powder and metanil yellow. Spectral analysis showed that the FT-IR method in this study could detect the metanil yellow at the 5% concentration, while the FT-Raman method appeared to be more sensitive and could detect the metanil yellow at the 1% concentration. Relationships between metanil yellow spectral peak intensities and metanil yellow concentration were established using representative peaks at FT-Raman 1406 cm−1 and FT-IR 1140 cm−1 with correlation coefficients of 0.93 and 0.95, respectively.

Matrix isolation FT-IR spectroscopy and molecular orbital study of sarcosine methyl ester

Science.gov (United States)

Gómez-Zavaglia, A.; Fausto, R.

2004-02-01

N-methylglycine methyl ester (sarcosine-Me) has been studied by matrix isolation FT-IR spectroscopy and molecular orbital calculations undertaken at the DFT/B3LYP and MP2 levels of theory with the 6-311++G(d,p) and 6-31++G(d,p) basis set, respectively. Twelve different conformers were located in the potential energy surface of the studied compound, with the ASC conformer being the ground conformational state. This form is analogous to the dimethylglycine methyl ester most stable conformer and is characterized by a NH⋯O intramolecular hydrogen bond; in this form, the ester group assumes the cis configuration and the OC-C-N and Lp-N-C-C (where Lp is the nitrogen lone electron pair) dihedral angles are ca. -17.8 and 171.3°, respectively. The second most stable conformer ( GSC) differs from the ASC conformer essentially in the conformation assumed by the methylamino group, which in this case is gauche ( Lp-N-C-C dihedral angle equal to 79.4°). On the other hand, the third most stable conformer ( AAC) differs from the most stable form in the conformation of the OC-C-N axis (151.4°). These three forms were predicted to differ in energy by less than ca. 5 kJ mol -1 and represent ≈95% of the total conformational population at room temperature. FT-IR spectra were obtained for sarcosine-Me isolated in argon matrices (T=9 K) revealing the presence in the matrices of the three lowest energy conformers predicted by the calculations. The matrices were prepared by deposition of the vapour of the compound using two different nozzle temperatures, 25 and 60 °C. The relative populations of the three conformers trapped in the matrices were found to be consistent with occurrence of conformational cooling during matrix deposition and with a stabilization of the most polar GSC and AAC conformers in the matrices compared to the gas phase. Indeed, like it was previously observed for the methyl ester of dimethylglycine [Phys. Chem. Chem. Phys. 5 (2003) 52] the different

IR emission and UV extinction in two open clusters

International Nuclear Information System (INIS)

Hackwell, J.A.; Hecht, J.H.

1989-01-01

Recent models of interstellar extinction have shown the importance of understanding both the UV and IR properties of interstellar dust grains. IRAS data have shown variations in 60 and 100 micron emissions presumably due to the presence of IR cirrus, while recent observations in the UV by Fitzpatrick and Massa have identified components in the UV extinction curve which vary in different star regions. A Draine and Anderson model connects these results by proposing that different size variations in interstellar grains would cause distinct changes in both the IR emission and the UV extinction. In order to test this model it is necessary to make observations in well defined locations away from peculiar extinction regions. In the infrared this means looking away from the galactic plane so as to limit non-local sources of IR radiation. Two open clusters that are out of the galactic plane and which contain a number of late B and early A stars suitable for UV extinction studies, and whose IRAS data show variations in the 60/100 micron ratio were studied. Based on the Drain and Anderson model, variations were expected in their UV extinction curves that correlate with the IR cirrus emission

Temperature dependence of the vibrational spectra of acetanilide: Davydov solitons or Fermi coupling

Energy Technology Data Exchange (ETDEWEB)

Johnston, C.T.; Swanson, B.I.

1985-03-15

The unusual temperature dependence of the amide-I region in the IR spectrum of acetanilide (C/sub 6/H/sub 5/NHCOCH/sub 3/) has recently been attributed to a self-trapped Davydov-like soliton. The temperature dependence of the single-crystal Raman scattering from acetanilide and its N-D and /sup 13/C-O substituted analogs in the phonon and internal mode regions has now been studied. The behavior of the amide-I region in the Raman spectra of the normal isotopic species is similar to that observed earlier in infrared studies. However, on the basis of results obtained from the N-D and /sup 13/C-O substituted species the unusual temperature dependence in the 1650 cm/sup -1/ region has been attributed to Fermi coupling of the amide-I fundamental and a combination band involving the in-plane N-H deformation and a low-frequency torsional mode. As temperature is lowered, the strong blue-shift of the torsional mode results in a commensurate blue-shift in the combination level thereby increasing the Fermi coupling. Temperature tuning of the Fermi coupling results in the anomalous intensity changes observed in the IR and Raman spectra of the amide-I region for the normal isotopic species. 20 references, 3 figures.

Temperature dependence of the vibrational spectra of acetanilide: Davydov solitons or Fermi coupling?

Science.gov (United States)

Johnston, Clifford T.; Swanson, Basil I.

1985-03-01

The unusual temperature dependence of the amide-I region in the IR spectrum of acetanilide (C 6H 5NHCOCH 3) has recently been attributed to a self-trapped Davydov-like soliton. The temperature dependence of the single-crystal Raman scattering, from acetanilide and its ND and 13CO substituted analogs in the phonon and internal mode regions has now been studied. The behavior of the amide-I region in the Raman spectra of the normal isotopic species is similar to that observed earlier in infrared studies. However, on the basis of results obtained from the ND and 13CO substituted species the unusual temperature dependence in the 1650 cm -1 region has been attributed to Fermi coupling of the amide-I fundamental and a combination band involving the in-plane NH deformation and a low-frequency torsional mode. As temperature is lowered, the strong blue-shift of the torsional mode results in a commensurate blue-shift in the combination level thereby increasing the Fermi coupling. Temperature tuning of the Fermi coupling results in the anomalous intensity changes observed in the IR and Raman spectra of the amide-I region for the normal isotopic species.

UV, visible, and near-IR reflectivity data for magnetic soils/rocks from Brazil

Science.gov (United States)

Vempati, R. K.; Morris, R. V.; Lauer, H. V., Jr.; Coey, J. M. D.

1991-01-01

The objective is to obtain UV, visible, and near-IR reflectivity spectra for several magnetic Brazilian soils/rocks and compare them to corresponding data for Mars to see if these materials satisfy both magnetic and spectral constraints for Mars. Selected physical properties of the magnetic Brazilian soils/rocks are presented. In general, the spectral features resulting from ferric crystal-field transitions are much better defined in the spectra of the magnetic Brazilian soils/rocks than in Martian spectral data. Presumably, this results from a relatively higher proportion of crystalline ferric oxides for the former. The apparent masking of the spectral signature of maghemite by hematite or goethite for the Brazilian samples implies the magnetic and spectral constraints for Mars can be decoupled. That is, maghemite may be present in magnetically-significant but optically-insignificant amounts compared to crystalline hematite.

The study of the radiation chemical transformation of the hexane on the surface of aluminium by IR-spectroscopy method

International Nuclear Information System (INIS)

Rimikhanova, A.N.

2006-01-01

Full text: In this work the experimental results of the radiation-chemical transformation of hexane on the aluminum surface obtained by IR spectroscopy method at room temperature have been presented. The metallic aluminum plates which was obtained by stage pressing granules by mark of AD-00 with the reflection coefficient R=0,85 in the middle infrared range of waves length λ=15 ± 2,2 mkm were used. As an adsorbate unsaturated vapors of hexane were used, the absorption of which was being carried out at the room temperature by the method. The radiation of system was carried out with γ-quanta of Co 60 with doze rate of 1,03 Gy/s - 1, and the absorbed doze in the system was (0,5-2)10 4 Gy. IR reflection spectra when beams fall on the sample under angle near the slipping were measured in diapason of 3600-650 cm - 1 by the spectrophotometer S pecord 71IR . The radiation chemical decomposition of hexane in heterosystem was being traced in stretching (3000-2700 cm - 1) and deformation (1500-1300 cm - 1) vibration diapasons of C-H bonds. The analysis of IR reflection spectra of Al-ads.hexane heterosystem showed that the main products of radiation chemical transformation are hydrocarbons C1-C5, olefins: propylene, butene-1, hexene-1, transhexene-3 and hydrocarbons more heavy than hexane. In frequency range of 1700-2000 cm - 1 the absorption bands of Al-H vibration which concern to aluminum hydrides are founded. By increasing of radiation dose the tendency of increasing of hydrogen accumulation as aluminum hydrides has been established

Characterization of Meldrum's acid derivative 5-(5-Ethyl-1,3,4-thiadiazol-2-ylamino)methylene-2,2-dimethyl-1,3-dioxane-4,6-dione by Raman and FT-IR spectroscopy and DFT calculations

Science.gov (United States)

de Toledo, T. A.; da Silva, L. E.; Teixeira, A. M. R.; Freire, P. T. C.; Pizani, P. S.

2015-07-01

In this study, the structural and vibrational properties of Meldrum's acid derivative 5-(5-Ethyl-1,3,4-thiadiazol-2-ylamino)methylene-2,2-dimethyl-1,3-dioxane-4,6-dione, C11H13N3O4S were studied combining experimental techniques such as Raman and FT-IR spectroscopy and density functional theory (DFT) calculations. The Raman and FT-IR spectra were recorded at room conditions in the regions from 80 to 3400 cm-1 and 400 to 4000 cm-1, respectively. Vibrational wavenumbers were predicted using DFT calculations with the hybrid functional B3LYP and basis set 6-31G(d,p). A comparison between experimental and theoretical data is provided for the Raman and FT-IR spectra. The descriptions of the normal modes were carried by means of potential energy distribution (PED).

Hydration effects on the molecular structure of silica-supported vanadium oxide catalysts: A combined IR, Raman, UV–vis and EXAFS study

NARCIS (Netherlands)

Keller, D.E.; Visser, T.; Soulimani, F.; Koningsberger, D.C.; Weckhuysen, B.M.

2007-01-01

The effect of hydration on the molecular structure of silica-supported vanadium oxide catalysts with loadings of 1–16 wt.% V has been systematically investigated by infrared, Raman, UV–vis and EXAFS spectroscopy. IR and Raman spectra recorded during hydration revealed the formation of V–OH groups,

Suppression of superconductivity in Nb by IrMn in IrMn/Nb bilayers

KAUST Repository

Wu, B. L.

2013-10-10

Effect of antiferromagnet on superconductivity has been investigated in IrMn/Nb bilayers. Significant suppression of both transition temperature (Tc) and lower critical field (Hc1) of Nb is found in IrMn/Nb bilayers as compared to a single layer Nb of same thickness; the suppression effect is even stronger than that of a ferromagnet in NiFe/Nb bilayers. The addition of an insulating MgO layer at the IrMn-Nb interface nearly restores Tc to that of the single layer Nb, but Hc1 still remains suppressed. These results suggest that, in addition to proximity effect and magnetic impurity scattering, magnetostatic interaction also plays a role in suppressing superconductivity of Nb in IrMn/Nb bilayers. In addition to reduced Tc and Hc1, the IrMn layer also induces broadening in the transition temperature of Nb, which can be accounted for by a finite distribution of stray field from IrMn.

Novel absorptivity centering method utilizing normalized and factorized spectra for analysis of mixtures with overlapping spectra in different matrices using built-in spectrophotometer software.

Science.gov (United States)

Lotfy, Hayam Mahmoud; Omran, Yasmin Rostom

2018-07-05

A novel, simple, rapid, accurate, and economical spectrophotometric method, namely absorptivity centering (a-Centering) has been developed and validated for the simultaneous determination of mixtures with partially and completely overlapping spectra in different matrices using either normalized or factorized spectrum using built-in spectrophotometer software without a need of special purchased program. Mixture I (Mix I) composed of Simvastatin (SM) and Ezetimibe (EZ) is the one with partial overlapping spectra formulated as tablets, while mixture II (Mix II) formed by Chloramphenicol (CPL) and Prednisolone acetate (PA) is that with complete overlapping spectra formulated as eye drops. These procedures do not require any separation steps. Resolution of spectrally overlapping binary mixtures has been achieved getting recovered zero-order (D 0 ) spectrum of each drug, then absorbance was recorded at their maxima 238, 233.5, 273 and 242.5 nm for SM, EZ, CPL and PA, respectively. Calibration graphs were established with good correlation coefficients. The method shows significant advantages as simplicity, minimal data manipulation besides maximum reproducibility and robustness. Moreover, it was validated according to ICH guidelines. Selectivity was tested using laboratory-prepared mixtures. Accuracy, precision and repeatability were found to be within the acceptable limits. The proposed method is good enough to be applied to an assay of drugs in their combined formulations without any interference from excipients. The obtained results were statistically compared with those of the reported and official methods by applying t-test and F-test at 95% confidence level concluding that there is no significant difference with regard to accuracy and precision. Generally, this method could be used successfully for the routine quality control testing. Copyright © 2018 Elsevier B.V. All rights reserved.

Correlated electronic properties of different SrIrO{sub 3}/SrTiO{sub 3} heterostructures

Energy Technology Data Exchange (ETDEWEB)

Kraberger, Gernot J.; Aichhorn, Markus [Institute of Theoretical and Computational Physics, NAWI Graz, Graz University of Technology, Petersgasse 16, 8010 Graz (Austria)

2016-07-01

Strontium iridates are materials that combine strong electronic correlations with pronounced spin-orbit coupling, giving rise to fascinating physical properties. Strategies to purposefully influence and design these materials are a crucial step to further advance this field. A highly promising candidate for achieving this goal is the formation of heterostructures with other materials. Motivated by this quest, we perform calculations within the DFT+DMFT framework to investigate how the geometry of heterostructures of perovskite SrIrO{sub 3} with SrTiO{sub 3} influences their correlated electronic structure. We explore the differences between (001)- and (111)-stacked heterostructures, where the latter are particularly interesting because they form buckled honeycomb lattices that have non-trivial topological properties. For the (001)-heterostructures the effect of varying the thickness of the SrIrO{sub 3} layers, and thus their effective dimensionality, are studied. As an important ingredient we have to consider the effect of lattice distortions - in the form of a rotation of the oxygen cages - on the electronic correlations. We argue how the interplay of all these factors together allows a targeted modification of the electronic properties of the material.

Response of exciton polariton spectra and electric fields to different additional boundary conditions

International Nuclear Information System (INIS)

Nkoma, J.S.

1982-08-01

The effects of three additional boundary conditions (ABC's) on the reflection and transmission spectra for exciton polaritons propagating in a spatially dispersive media are studied for both p and s configurations. An investigation of the ratios of the electric field amplitudes associated with the normal modes in these media is carried out. There is qualitative agreement among the predictions of the different ABC's, but there are significant quantitative differences, especially in the longitudinal polariton spike excited only in the p-geometry. Contact with formulations not using the ABC approach is made. The results are illustrated by parameters modelling the 1s exciton of PbI 2 . (author)

Computational NMR, IR/RAMAN calculations in sodium pravastatin: Investigation of the Self-Assembled Nanostructure of Pravastatin-LDH (Layered Double Hydroxides) Systems

Science.gov (United States)

Petersen, Philippe; Cunha, Vanessa; Gonçalves, Marcos; Petrilli, Helena; Constantino, Vera; Instituto de Física, Departamento de Física de Materiais e Mecânica Team; Instituto de Química, Departamento de Química Fundamental Team

2013-03-01

Layered double hydroxides (LDH) can be used as nanocontainers for immobilization of Pravastatin, in order to obtain suitable drug carriers. The material's structure and spectroscopic properties were analyzed by NMR, IR/RAMAN and supported by theoretical calculations. Density Functional Theory (DFT) calculations were performed using the Gaussian03 package. The geometry optimizations were performed considering the single crystal X-ray diffraction data of tert-octylamonium salt of Pravastatin. Tetramethylsilane (TMS), obtained with the same basis set, was used as reference for calculating the chemical shift of 13C. A scaling factor was used to compare theoretical and experimental harmonic vibrational frequencies. Through the NMR and IR/RAMAN spectra, we were able to make precise assignments of the NMR and IR/RAMAN of Sodium Pravastatin. We acknowledge support from CAPES, INEO and CNPQ.

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.

Statistical properties of Fermi GBM GRBs' spectra

Science.gov (United States)

Rácz, István I.; Balázs, Lajos G.; Horvath, Istvan; Tóth, L. Viktor; Bagoly, Zsolt

2018-03-01

Statistical studies of gamma-ray burst (GRB) spectra may result in important information on the physics of GRBs. The Fermi GBM catalogue contains GRB parameters (peak energy, spectral indices, and intensity) estimated fitting the gamma-ray spectral energy distribution of the total emission (fluence, flnc), and during the time of the peak flux (pflx). Using contingency tables, we studied the relationship of the models best-fitting pflx and flnc time intervals. Our analysis revealed an ordering of the spectra into a power law - Comptonized - smoothly broken power law - Band series. This result was further supported by a correspondence analysis of the pflx and flnc spectra categorical variables. We performed a linear discriminant analysis (LDA) to find a relationship between categorical (spectral) and model independent physical data. LDA resulted in highly significant physical differences among the spectral types, that is more pronounced in the case of the pflx spectra, than for the flnc spectra. We interpreted this difference as caused by the temporal variation of the spectrum during the outburst. This spectral variability is confirmed by the differences in the low-energy spectral index and peak energy, between the pflx and flnc spectra. We found that the synchrotron radiation is significant in GBM spectra. The mean low-energy spectral index is close to the canonical value of α = -2/3 during the peak flux. However, α is ˜ -0.9 for the spectra of the fluences. We interpret this difference as showing that the effect of cooling is important only for the fluence spectra.

Solution Structures of Highly Active Molecular Ir Water-Oxidation Catalysts from Density Functional Theory Combined with High-Energy X-ray Scattering and EXAFS Spectroscopy.

Science.gov (United States)

Yang, Ke R; Matula, Adam J; Kwon, Gihan; Hong, Jiyun; Sheehan, Stafford W; Thomsen, Julianne M; Brudvig, Gary W; Crabtree, Robert H; Tiede, David M; Chen, Lin X; Batista, Victor S

2016-05-04

The solution structures of highly active Ir water-oxidation catalysts are elucidated by combining density functional theory, high-energy X-ray scattering (HEXS), and extended X-ray absorption fine structure (EXAFS) spectroscopy. We find that the catalysts are Ir dimers with mono-μ-O cores and terminal anionic ligands, generated in situ through partial oxidation of a common catalyst precursor. The proposed structures are supported by (1)H and (17)O NMR, EPR, resonance Raman and UV-vis spectra, electrophoresis, etc. Our findings are particularly valuable to understand the mechanism of water oxidation by highly reactive Ir catalysts. Importantly, our DFT-EXAFS-HEXS methodology provides a new in situ technique for characterization of active species in catalytic systems.

FT-IR spectroscopic and thermodynamic study on the adsorption of carbon dioxide and dinitrogen in the alkaline zeolite K-L

International Nuclear Information System (INIS)

Arean, C.O.; Bibiloni, G.F.; Delgado, M.R.

2012-01-01

Highlights: ► Variable temperature IR spectroscopy is used to study adsorption of CO 2 and N 2 in the alkaline zeolite K-L. ► By simultaneously recording IR absorbance, temperature and equilibrium pressure, standard adsorption enthalpy and entropy for each gas was determined. ► The results are discussed in the broader context of gas separation using zeolites; focusing on carbon dioxide capture. - Abstract: The thermodynamics of carbon dioxide and dinitrogen adsorption on the zeolite K-L was investigated by means of variable temperature IR spectroscopy, a technique that affords determination of standard adsorption enthalpy (ΔH°) and entropy (ΔS°) from analysis of IR spectra recorded over a temperature range while simultaneously measuring equilibrium pressure inside a closed IR cell. ΔH° resulted to be −42.5 and −20.6 kJ mol −1 for CO 2 and N 2 , respectively. Corresponding values of ΔS° were found to be −182 and −151 J mol −1 K −1 . The obtained adsorption enthalpy values are discussed in the context of carbon dioxide capture and sequestration.

Spectra from 2.5-15 μm of tissue phantom materials, optical clearing agents and ex vivo human skin: implications for depth profiling of human skin

International Nuclear Information System (INIS)

Viator, John A; Choi, Bernard; Peavy, George M; Kimel, Sol; Nelson, J Stuart

2003-01-01

Infrared measurements have been used to profile or image biological tissue, including human skin. Usually, analysis of such measurements has assumed that infrared absorption is due to water and collagen. Such an assumption may be reasonable for soft tissue, but introduction of exogenous agents into skin or the measurement of tissue phantoms has raised the question of their infrared absorption spectrum. We used Fourier transform infrared spectroscopy in attenuated total reflection mode to measure the infrared absorption spectra, in the range of 2-15 μm, of water, polyacrylamide, Intralipid, collagen gels, four hyperosmotic clearing agents (glycerol, 1,3-butylene glycol, trimethylolpropane, Topicare TM ), and ex vivo human stratum corneum and dermis. The absorption spectra of the phantom materials were similar to that of water, although additional structure was noted in the range of 6-10 μm. The absorption spectra of the clearing agents were more complex, with molecular absorption bands dominating between 6 and 12 μm. Dermis was similar to water, with collagen structure evident in the 6-10 μm range. Stratum corneum had a significantly lower absorption than dermis due to a lower content of water. These results suggest that the assumption of water-dominated absorption in the 2.5-6 μm range is valid. At longer wavelengths, clearing agent absorption spectra differ significantly from the water spectrum. This spectral information can be used in pulsed photothermal radiometry or utilized in the interpretation of reconstructions in which a constant μ ir is used. In such cases, overestimating μ ir will underestimate chromophore depth and vice versa, although the effect is dependent on actual chromophore depth. (note)

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.

Difference optimization: Automatic correction of relative frequency and phase for mean non-edited and edited GABA 1H MEGA-PRESS spectra

Science.gov (United States)

Cleve, Marianne; Krämer, Martin; Gussew, Alexander; Reichenbach, Jürgen R.

2017-06-01

Phase and frequency corrections of magnetic resonance spectroscopic data are of major importance to obtain reliable and unambiguous metabolite estimates as validated in recent research for single-shot scans with the same spectral fingerprint. However, when using the J-difference editing technique 1H MEGA-PRESS, misalignment between mean edited (ON ‾) and non-edited (OFF ‾) spectra that may remain even after correction of the corresponding individual single-shot scans results in subtraction artefacts compromising reliable GABA quantitation. We present a fully automatic routine that iteratively optimizes simultaneously relative frequencies and phases between the mean ON ‾ and OFF ‾ 1H MEGA-PRESS spectra while minimizing the sum of the magnitude of the difference spectrum (L1 norm). The proposed method was applied to simulated spectra at different SNR levels with deliberately preset frequency and phase errors. Difference optimization proved to be more sensitive to small signal fluctuations, as e.g. arising from subtraction artefacts, and outperformed the alternative spectral registration approach, that, in contrast to our proposed linear approach, uses a nonlinear least squares minimization (L2 norm), at all investigated levels of SNR. Moreover, the proposed method was applied to 47 MEGA-PRESS datasets acquired in vivo at 3 T. The results of the alignment between the mean OFF ‾ and ON ‾ spectra were compared by applying (a) no correction, (b) difference optimization or (c) spectral registration. Since the true frequency and phase errors are not known for in vivo data, manually corrected spectra were used as the gold standard reference (d). Automatically corrected data applying both, method (b) or method (c), showed distinct improvements of spectra quality as revealed by the mean Pearson correlation coefficient between corresponding real part mean DIFF ‾ spectra of Rbd = 0.997 ± 0.003 (method (b) vs. (d)), compared to Rad = 0.764 ± 0.220 (method (a) vs

Complex magnetism of the Fe monolayer on Ir(111)

International Nuclear Information System (INIS)

Bergmann, Kirsten von; Heinze, Stefan; Bode, Matthias; Bihlmayer, Gustav; Bluegel, Stefan; Wiesendanger, Roland

2007-01-01

The electronic and magnetic properties of Fe on Ir(111) have been investigated experimentally by spin-polarized scanning tunneling microscopy (SP-STM) and theoretically by first-principles calculations based on density functional theory. While the growth of an Fe monolayer is in-plane commensurate, deposition of a double-layer shows a rearrangement of atoms due to strain relief accompanied by local variations of the electronic structure. Both stackings of the monolayer, i.e. face centered cubic (fcc) and hexagonal closed packed (hcp), are observed experimentally. The magnetic structure of both types is imaged with SP-STM. From these experiments, we propose a nanoscale magnetic mosaic structure for the fcc-stacking with 15 atoms in the unit cell. For hcp-stacking, the tunneling spectra are similar to the fcc case, however, the magnetic contrast in the SP-STM images is not as obvious. In our first-principles calculations, a collinear antiferromagnetic (AFM) state with a 15 atom in-plane unit cell (AFM 7 : 8 state) is found to be more favorable than the ferromagnetic state for both fcc- and hcp-stacking. Calculated SP-STM images and spectra are also in good agreement with the experimental data for the fcc case. We performed spin spiral calculations which are mapped to a classical Heisenberg model to obtain the exchange-interaction constants. From these calculations, it is found that the AFM 7 : 8 state is energetically more favorable than all solutions of the classical Heisenberg model. While the obtained magnetic exchange constants are rather similar for the fcc and hcp stacking, a comparison with the experiments indicates that competing interactions could be responsible for the differences observed in the magnetically sensitive measurements

Matrix-isolation FT-IR and DFT theoretical studies of the intramolecular hydrogen bonding in Mannich bases

International Nuclear Information System (INIS)

Pajak, J.; Rospenk, M.; Maes, G.; Sobczyk, L.

2006-01-01

FT-IR Ar-matrix isolated spectra were studied for dichloro- (Cl 2 -MB) and tetrachloroderivatives (Cl 4 -MB) of the ortho Mannich base. The spectra were analyzed based on the DFT calculated frequencies and intensities and compared with those recorded in CCl 4 solution in the region of the ν(OH) and ν(OD) vibrations. The matrix-isolated spectra are characterized by narrower ν(OH) and ν(OD) bands with much better resolved fine structure than in solution. The fine structure originates from the anharmonic coupling with the low frequency modes as well as from Fermi resonance. The ν(OD) band shapes can be reproduced exclusively by assuming the Fermi resonance with overtones and summation of the frequencies of modes into which the bridge atoms are involved. The frequency isotopic ratio (ISR) is for both compounds 1.33 while the half-width ratios are equal to 1.82 and 1.94, for Cl 2 -MB and Cl 4 -MB, respectively

High-Resolution IR Absorption Spectroscopy of Polycyclic Aromatic Hydrocarbons in the 3-micrometers Region: Role of Periphery

Science.gov (United States)

Maltseva, Elena; Petrignani, Annemieke; Candian, Alessandra; Mackie, Cameron J.; Huang, Xinchuan; Lee, Timothy J.; Tielens, Alexander G. G. M.; Oomens, Jos; Buma, Wybren Jan

2017-01-01

In this work we report on high-resolution IR absorption studies that provide a detailed view on how the peripheral structure of irregular polycyclic aromatic hydrocarbons (PAHs) affects the shape and position of their 3-micrometers absorption band. To this purpose we present mass-selected, high-resolution absorption spectra of cold and isolated phenanthrene, pyrene, benz[a]antracene, chrysene, triphenylene, and perylene molecules in the 2950-3150 per cm range. The experimental spectra are compared with standard harmonic calculations, and anharmonic calculations using a modified version of the SPECTRO program that incorporates a Fermi resonance treatment utilizing intensity redistribution. We show that the 3-micrometers region is dominated by the effects of anharmonicity, resulting in many more bands than would have been expected in a purely harmonic approximation. Importantly, we find that anharmonic spectra as calculated by SPECTRO are in good agreement with the experimental spectra. Together with previously reported high-resolution spectra of linear acenes, the present spectra provide us with an extensive dataset of spectra of PAHs with a varying number of aromatic rings, with geometries that range from open to highly-condensed structures, and featuring CH groups in all possible edge configurations. We discuss the astrophysical implications of the comparison of these spectra on the interpretation of the appearance of the aromatic infrared 3-micrometers band, and on features such as the two-component emission character of this band and the 3-micrometers emission plateau.

Cooperativity of hydrogen-bonded networks in 7-azaindole(CH3OH)n (n=2,3) clusters evidenced by IR-UV ion-dip spectroscopy and natural bond orbital analysis.

Science.gov (United States)

Sakota, Kenji; Kageura, Yutaka; Sekiya, Hiroshi

2008-08-07

IR-UV ion-dip spectra of the 7-azaindole (7AI)(CH(3)OH)(n) (n=1-3) clusters have been measured in the hydrogen-bonded NH and OH stretching regions to investigate the stable structures of 7AI(CH(3)OH)(n) (n=1-3) in the S(0) state and the cooperativity of the H-bonding interactions in the H-bonded networks. The comparison of the IR-UV ion-dip spectra with IR spectra obtained by quantum chemistry calculations shows that 7AI(CH(3)OH)(n) (n=1-3) have cyclic H-bonded structures, where the NH group and the heteroaromatic N atom of 7AI act as the proton donor and proton acceptor, respectively. The H-bonded OH stretch fundamental of 7AI(CH(3)OH)(2) is remarkably redshifted from the corresponding fundamental of (CH(3)OH)(2) by 286 cm(-1), which is an experimental manifestation of the cooperativity in H-bonding interaction. Similarly, two localized OH fundamentals of 7AI(CH(3)OH)(3) also exhibit large redshifts. The cooperativity of 7AI(CH(3)OH)(n) (n=2,3) is successfully explained by the donor-acceptor electron delocalization interactions between the lone-pair orbital in the proton acceptor and the antibonding orbital in the proton donor in natural bond orbital (NBO) analyses.

Modeling Microalgal Biosediment Formation Based on Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Monitoring.

Science.gov (United States)

Ogburn, Zachary L; Vogt, Frank

2018-03-01

With increasing amounts of anthropogenic pollutants being released into ecosystems, it becomes ever more important to understand their fate and interactions with living organisms. Microalgae play an important ecological role as they are ubiquitous in marine environments and sequester inorganic pollutants which they transform into organic biomass. Of particular interest in this study is their role as a sink for atmospheric CO 2 , a greenhouse gas, and nitrate, one cause of harmful algal blooms. Novel chemometric hard-modeling methodologies have been developed for interpreting phytoplankton's chemical and physiological adaptations to changes in their growing environment. These methodologies will facilitate investigations of environmental impacts of anthropogenic pollutants on chemical and physiological properties of marine microalgae (here: Nannochloropsis oculata). It has been demonstrated that attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy can gain insights into both and this study only focuses on the latter. From time-series of spectra, the rate of microalgal biomass settling on top of a horizontal ATR element is derived which reflects several of phytoplankton's physiological parameters such as growth rate, cell concentrations, cell size, and buoyancy. In order to assess environmental impacts on such parameters, microalgae cultures were grown under 25 different chemical scenarios covering 200-600 ppm atmospheric CO 2 and 0.35-0.75 mM dissolved NO 3 - . After recording time-series of ATR FT-IR spectra, a multivariate curve resolution-alternating least squares (MCR-ALS) algorithm extracted spectroscopic and time profiles from each data set. From the time profiles, it was found that in the considered concentration ranges only NO 3 - has an impact on the cells' physiological properties. In particular, the cultures' growth rate has been influenced by the ambient chemical conditions. Thus, the presented spectroscopic�

Simultaneous formation and detection of the reaction product of solid-state aspartame sweetener by FT-IR/DSC microscopic system.

Science.gov (United States)

Lin, S Y; Cheng, Y D

2000-10-01

The solid-state stability of aspartame hemihydrate (APM) sweetener during thermal treatment is important information for the food industry. The present study uses the novel technique of Fourier transform infrared microspectroscopy equipped with differential scanning calorimetry (FT-IR/DSC microscopic system) to accelerate and determine simultaneously the thermal-dependent impurity formation of solid-state APM. The results indicate a dramatic change in IR spectra from 50, 110 or 153 degrees C, which was respectively attributed to the onset temperature of water evaporation, dehydration and cyclization processes. It is suggested that the processes of dehydration and intramolecular cyclization occurred in the solid-state APM during the heating process. As an impurity, 3-carboxymethyl-6-benzyl-2,5-diketopiperazine (DKP) degraded from solid state APM via intramolecular cyclization and liberation of methanol. This was evidenced by this novel FT-IR/DSC microscopic system in a one-step procedure.

Time-domain SFG spectroscopy using mid-IR pulse shaping: practical and intrinsic advantages.

Science.gov (United States)

Laaser, Jennifer E; Xiong, Wei; Zanni, Martin T

2011-03-24

Sum-frequency generation (SFG) spectroscopy is a ubiquitous tool in the surface sciences. It provides infrared transition frequencies and line shapes that probe the structure and environment of molecules at interfaces. In this article, we apply techniques learned from the multidimensional spectroscopy community to SFG spectroscopy. We implement balanced heterodyne detection to remove scatter and the local oscillator background. Heterodyning also separates the resonant and nonresonant signals by acquiring both the real and imaginary parts of the spectrum. We utilize mid-IR pulse shaping to control the phase and delay of the mid-IR pump pulse. Pulse shaping allows phase cycling for data collection in the rotating frame and additional background subtraction. We also demonstrate time-domain data collection, which is a Fourier transform technique, and has many advantages in signal throughput, frequency resolution, and line shape accuracy over existing frequency domain methods. To demonstrate time-domain SFG spectroscopy, we study an aryl isocyanide on gold, and find that the system has an inhomogeneous structural distribution, in agreement with computational results, but which was not resolved by previous frequency-domain SFG studies. The ability to rapidly and actively manipulate the mid-IR pulse in an SFG pules sequence makes possible new experiments and more accurate spectra. © 2011 American Chemical Society

Optical absorption spectra of Ag-11 isomers

DEFF Research Database (Denmark)

Martinez, Jose Ignacio; Fernandez, E. M.

2009-01-01

The optical absorption spectra of the three most; stable structural isomers of the Ag-11 cluster were calculated using the time-dependent, density functional theory within the Casida formalism. The slightly different, spectra, of the isomers may permit the identification of the ground-stale confi......The optical absorption spectra of the three most; stable structural isomers of the Ag-11 cluster were calculated using the time-dependent, density functional theory within the Casida formalism. The slightly different, spectra, of the isomers may permit the identification of the ground...

Raman Spectra from Pesticides on the Surface of Fruits

International Nuclear Information System (INIS)

Zhang, P X; Zhou Xiaofang; Cheng, Andrew Y S; Fang Yan

2006-01-01

Raman spectra of several vegetables and fruits were studied by micro-Raman spectrometer (514.5 nm) and Near-infrared Fourier Transform Raman spectrometer (FTRaman). It is shown that at 514.5 nm excitation, most of the spectra are from that of carotene with some very strong fluorescence in some cases. While at 1064 nm wavelength excitation, the spectra from the different samples demonstrate different characteristic Raman spectra without fluorescence. We discuss the spectroscopic difference by the two excitation wavelengths, and the application of Raman spectra for detection of pesticides left on the surface of vegetables and fruits. Raman spectra of fruits and pesticides were successfully recorded, and using the FT-Raman spectra the pesticides left on the surface of the fruits can be detected conveniently

Mesoporous silica nanoparticle supported PdIr bimetal catalyst for selective hydrogenation, and the significant promotional effect of Ir

Energy Technology Data Exchange (ETDEWEB)

Yang, Hui; Huang, Chao; Yang, Fan [The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Yang, Xu [Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China); Du, Li [The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China); Liao, Shijun, E-mail: chsjliao@scut.edu.cn [The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China)

2015-12-01

Graphical abstract: A mesoporous silica nanoparticle (MSN) supported bimetal catalyst, PdIr/MSN, was prepared by a facile impregnation and hydrogen reduction method. The strong promotional effect of Ir was observed and thoroughly investigated. At the optimal molar ratio of Ir to Pd (N{sub Ir}/N{sub Pd} = 0.1), the activity of PdIr{sub 0.1}/MSN was up to eight times and 28 times higher than that of monometallic Pd/MSN and Ir/MSN, respectively. The catalysts were characterized comprehensively by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature programmed reduction, which revealed that the promotional effect of Ir may be due to the enhanced dispersion of active components on the MSN, and to the intensified Pd–Ir electronic interaction caused by the addition of Ir. - Highlights: • Mesoporous nanoparticles were synthesized and used as support for metal catalyst. • PdIr bimetallic catalyst exhibited significantly improved hydrogenation activity. • The strong promotion of Ir was recognized firstly and investigated intensively. • PdIr exhibits 18 times higher activity than Pd to the hydrogenation of nitrobenzene. - Abstract: A mesoporous silica nanoparticle (MSN) supported bimetal catalyst, PdIr/MSN, was prepared by a facile impregnation and hydrogen reduction method. The strong promotional effect of Ir was observed and thoroughly investigated. At the optimal molar ratio of Ir to Pd (N{sub Ir}/N{sub Pd} = 0.1), the activity of PdIr{sub 0.1}/MSN was up to eight times and 28 times higher than that of monometallic Pd/MSN and Ir/MSN, respectively. The catalysts were characterized comprehensively by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature programmed reduction, which revealed that the promotional effect of Ir may be due to the enhanced dispersion of active components on the MSN, and to the intensified Pd–Ir electronic interaction

A conformation-selective IR-UV study of the dipeptides Ac-Phe-Ser-NH2 and Ac-Phe-Cys-NH2: probing the SH···O and OH···O hydrogen bond interactions.

Science.gov (United States)

Yan, Bin; Jaeqx, Sander; van der Zande, Wim J; Rijs, Anouk M

2014-06-14

The conformational preferences of peptides are mainly controlled by the stabilizing effect of intramolecular interactions. In peptides with polar side chains, not only the backbone but also the side chain interactions determine the resulting conformations. In this paper, the conformational preferences of the capped dipeptides Ac-Phe-Ser-NH2 (FS) and Ac-Phe-Cys-NH2 (FC) are resolved under laser-desorbed jet cooling conditions using IR-UV ion dip spectroscopy and density functional theory (DFT) quantum chemistry calculations. As serine (Ser) and cysteine (Cys) only differ in an OH (Ser) or SH (Cys) moiety; this subtle alteration allows us to study the effect of the difference in hydrogen bonding for an OH and SH group in detail, and its effect on the secondary structure. IR absorption spectra are recorded in the NH stretching region (3200-3600 cm(-1)). In combination with quantum chemical calculations the spectra provide a direct view of intramolecular interactions. Here, we show that both FS as FC share a singly γ-folded backbone conformation as the most stable conformer. The hydrogen bond strength of OH···O (FS) is stronger than that of SH···O (FC), resulting in a more compact gamma turn structure. A second conformer is found for FC, showing a β turn interaction.

Biological Action Spectra (invited paper)

Energy Technology Data Exchange (ETDEWEB)

Gruijl, F.R. de

2000-07-01

Ultraviolet (UV) radiation induces a wide variety of biological responses: ranging in humans from well-known short-term effects like sunburn to long-term effects like skin cancer. The wavelength dependencies ('action spectra') of the responses can differ significantly, depending on the UV-targeted molecules (their absorption spectra), their localisation (transmission to the target depth) and the photochemical reactions involved (e.g. quantum yields, competing reaction). An action spectrum (e.g. of sunburn) is usually determined in a wavelength by wavelength analysis of the response. This is not always possible (e.g. in case of skin cancer), and an action spectrum may then be extracted mathematically from differences in responses to broadband UV sources of various spectral compositions (yielding 'biological spectral weights'). However, relative spectral weights may shift with exposure levels and contributions from different wavelengths may not always add up. Under these circumstances conventional analyses will yield different action spectra for different experimental conditions. (author)

Biological Action Spectra (invited paper)

International Nuclear Information System (INIS)

Gruijl, F.R. de

2000-01-01

Ultraviolet (UV) radiation induces a wide variety of biological responses: ranging in humans from well-known short-term effects like sunburn to long-term effects like skin cancer. The wavelength dependencies ('action spectra') of the responses can differ significantly, depending on the UV-targeted molecules (their absorption spectra), their localisation (transmission to the target depth) and the photochemical reactions involved (e.g. quantum yields, competing reaction). An action spectrum (e.g. of sunburn) is usually determined in a wavelength by wavelength analysis of the response. This is not always possible (e.g. in case of skin cancer), and an action spectrum may then be extracted mathematically from differences in responses to broadband UV sources of various spectral compositions (yielding 'biological spectral weights'). However, relative spectral weights may shift with exposure levels and contributions from different wavelengths may not always add up. Under these circumstances conventional analyses will yield different action spectra for different experimental conditions. (author)

Modeling and measurements of XRD spectra of extended solids under high pressure

Science.gov (United States)

Batyrev, I. G.; Coleman, S. P.; Stavrou, E.; Zaug, J. M.; Ciezak-Jenkins, J. A.

2017-06-01

We present results of evolutionary simulations based on density functional calculations of various extended solids: N-Si and N-H using variable and fixed concentration methods of USPEX. Predicted from the evolutionary simulations structures were analyzed in terms of thermo-dynamical stability and agreement with experimental X-ray diffraction spectra. Stability of the predicted system was estimated from convex-hull plots. X-ray diffraction spectra were calculated using a virtual diffraction algorithm which computes kinematic diffraction intensity in three-dimensional reciprocal space before being reduced to a two-theta line profile. Calculations of thousands of XRD spectra were used to search for a structure of extended solids at certain pressures with best fits to experimental data according to experimental XRD peak position, peak intensity and theoretically calculated enthalpy. Comparison of Raman and IR spectra calculated for best fitted structures with available experimental data shows reasonable agreement for certain vibration modes. Part of this work was performed by LLNL, Contract DE-AC52-07NA27344. We thank the Joint DoD / DOE Munitions Technology Development Program, the HE C-II research program at LLNL and Advanced Light Source, supported by BES DOE, Contract No. DE-AC02-05CH112.

IGF-IR internalizes with Caveolin-1 and PTRF/Cavin in HaCat cells.

Directory of Open Access Journals (Sweden)

Barbara Salani

Full Text Available BACKGROUND: Insulin-like growth factor-I receptor (IGF-IR is a tyrosine kinase receptor (RTK associated with caveolae, invaginations of the plasma membrane that regulate vesicular transport, endocytosis and intracellular signaling. IGF-IR internalization represents a key mechanism of down-modulation of receptors number on plasma membrane. IGF-IR interacts directly with Caveolin-1 (Cav-1, the most relevant protein of caveolae. Recently it has been demonstrated that the Polymerase I and Transcript Release Factor I (PTRF/Cavin is required for caveolae biogenesis and function. The role of Cav-1 and PTRF/Cavin in IGF-IR internalization is still to be clarified. METHODOLOGY/PRINCIPAL FINDINGS: We have investigated the interaction of IGF-IR with Cav-1 and PTRF/Cavin in the presence of IGF1in human Hacat cells. We show that IGF-IR internalization triggers Cav-1 and PTRF/Cavin translocation from plasma membrane to cytosol and increases IGF-IR interaction with these proteins. In fact, Cav-1 and PTRF/Cavin co-immunoprecipitate with IGF-IR during receptor internalization. We found a different time course of co-immunoprecipitation between IGF-IR and Cav-1 compared to IGF-IR and PTRF/Cavin. Cav-1 and PTRF/Cavin silencing by siRNA differently affect surface IGF-IR levels following IGF1 treatment: Cav-1 and PTRF/Cavin silencing significantly affect IGF-IR rate of internalization, while PTRF/Cavin silencing also decreases IGF-IR plasma membrane recovery. Since Cav-1 phosphorylation could have a role in IGF-IR internalization, the mutant Cav-1Y14F lacking Tyr14 was transfected. Cav-1Y14F transfected cells showed a reduced internalization of IGF-IR compared with cells expressing wild type Cav-1. Receptor internalization was not impaired by Clathrin silencing. These findings support a critical role of caveolae in IGF-IR intracellular traveling. CONCLUSIONS/SIGNIFICANCE: These data indicate that Caveolae play a role in IGF-IR internalization. Based on these findings

Development of Cytoplasmic Male Sterile IR24 and IR64 Using CW-CMS/Rf17 System.

Science.gov (United States)

Toriyama, Kinya; Kazama, Tomohiko

2016-12-01