WorldWideScience

Sample records for bond raman spectra

  1. Molecular structure, natural bond analysis, vibrational and electronic spectra, surface enhanced Raman scattering and Mulliken atomic charges of the normal modes of [Mn(DDTC)2] complex.

    Science.gov (United States)

    Téllez S, Claudio A; Costa, Anilton C; Mondragón, M A; Ferreira, Glaucio B; Versiane, O; Rangel, J L; Lima, G Müller; Martin, A A

    2016-12-01

    Theoretical and experimental bands have been assigned for the Fourier Transform Infrared and Raman spectra of the bis(diethyldithiocarbamate)Mn(II) complex, [Mn(DDTC)2]. The calculations have been based on the DFT/B3LYP method, second derivative spectra and band deconvolution analysis. The UV-vis experimental spectra were measured in acetonitrile solution, and the calculated electronic spectrum was obtained using the TD/B3LYP method with 6-311G(d, p) basis set for all atoms. Charge transfer bands and those d-d spin forbidden were assigned in the UV-vis spectrum. The natural bond orbital analysis was carried out using the DFT/B3LYP method and the Mn(II) hybridization leading to the planar geometry of the framework was discussed. Surface enhanced Raman scattering (SERS) was also performed. Mulliken charges of the normal modes were obtained and related to the SERS enhanced bands. PMID:27344520

  2. Raman spectra of carotenoids in natural products

    Science.gov (United States)

    Withnall, Robert; Chowdhry, Babur Z.; Silver, Jack; Edwards, Howell G. M.; de Oliveira, Luiz F. C.

    2003-08-01

    Resonance Raman spectra of naturally occurring carotenoids have been obtained from nautilus, periwinkle ( Littorina littorea) and clam shells under 514.5 nm excitation and these spectra are compared with the resonance Raman spectra obtained in situ from tomatoes, carrots, red peppers and saffron. The tomatoes, carrots and red peppers gave rise to resonance Raman spectra exhibiting a ν1 band at ca. 1520 cm -1, in keeping with its assignment to carotenoids with ca. nine conjugated carboncarbon double bonds in their main chains, whereas the resonance Raman spectrum of saffron showed a ν1 band at 1537 cm -1 which can be assigned to crocetin, having seven conjugated carboncarbon double bonds. A correlation between ν1 wavenumber location and effective conjugated chain length has been used to interpret the data obtained from the shells, and the wavenumber position (1522 cm -1) of the ν1 band of the carotenoid in the orange clam shell suggests that it contains nine conjugated double bonds in the main chain. However, the black periwinkle and nautilus shells exhibit ν1 bands at 1504 and 1496 cm -1, respectively. On the basis of the correlation between ν1 wavenumber location and effective conjugated chain length, this indicates that they contain carotenoids with longer conjugated chains, the former having ca. 11 double bonds and the latter ca. 13 or even more. Raman spectra of the nautilus, periwinkle and clam shells also exhibited a strong band at 1085 cm -1 and a doublet with components at 701 and 705 cm -1, which can be assigned to biogenic calcium carbonate in the aragonite crystallographic form.

  3. Polarized and depolarized Raman spectra of liquid carbon disulfide in the pressure range 0-10 kbar. I. Vibration frequencies, C-S bond length, and Fermi resonance

    Science.gov (United States)

    Ikawa, S.; Whalley, Edward

    1986-09-01

    The effect of pressure on the polarized and depolarized Raman spectra of liquid carbon disulphide, i.e., the peak frequencies, bandwidths, and relative intensities of both the allowed ν1 and 2ν2 bands and the interaction-induced ν2 and ν3 bands, have been measured at 22 °C up to 10 kbar. This paper discusses the effect of pressure on the frequencies and on the relative isotropic intensity of the ν1 and 2ν2 bands. The frequency of the ν1 band increases linearly with pressure, within the experimental uncertainty, at the rate 0.16±0.01 cm-1 kbar-1, and the frequencies of the ν2, ν3, and 2ν2 bands decrease nonlinearly. The frequency shifts are described by second-order perturbation theory with the molecular anharmonicity and the intermolecular interaction as perturbations. The leading terms of the shifts consist of the same derivative of the interaction potential, multiplied by different anharmonicity constants, and the shifts of the ν1 and 2ν2 bands suggests that the C-S bond length decreases at the rate 2×10-4 Å kbar-1. The relative isotropic intensity of the 2ν2 and ν1 bands increases with pressure at the rate 0.050 kbar-1, whereas the anisotropic 2ν2 intensity relative to the isotropic ν1 intensity is independent of pressure to the experimental precision of ˜0.005. The effect of pressure on the second derivative of the isotropic and anisotropic parts of the polarizability with respect to the bend coordinate was estimated as 1.1×10-43 C m2 V-1 kbar-1 and ˜0, respectively, from these values.

  4. Raman spectra of single cell from gastrointestinal cancer patients

    Institute of Scientific and Technical Information of China (English)

    Xun-Ling Yan; Rui-Xin Dong; Lei Zhang; Xue-Jun Zhang; Zong-Wang Zhang

    2005-01-01

    AIM: To explore the difference between cancer cells and normal cells, we investigated the Raman spectra of singlecells from gastrointestinal cancer patients. METHODS: All samples were obtained from 30 diagnosed as gastrointestinal cancer patients. The flesh tumor specimen is located in the center of tumor tissue, while the normal ones were 5 cm away from the outside tumor section. The imprint was put under the microscope and a single cell was chosen for Raman measurement. All spectra were collected at confocal Raman micro-spectroscopy (British Renishaw) with NIR 780 nm laser.RESULTS: We measured the Raman spectra of several cells from gastrointestinal cancer patients. The result shows that there exists the strong line at 1 002/cm with less half-width assigned to the phenylalanine in several cells. The Raman lines of white cell were lower and less, while those of red cell were not only higher in intensity and more abundant, but also had a parti cular C-N breathing stretching band of pyrrole ring at 1 620-1 540/cm. The line at 1 084/cm assigned to phosphate backbone of DNA became obviously weaker in cancer cell. The Raman spectra of stomach cancer cells were similar to those of normal cells, but the Raman intensity of cancer cells was much lower than that of normal cells, and even some lines disappear. The lines of enteric cancer cells became weaker than spectra above and many lines disappeared, and the cancer cells in different position had different fluorescence intensity.CONCLUSION: The Raman spectra of several cells from cancer patients show that the structural changes of cancer cells happen and many bonds rupture so that the biological function of cells are lost. The results indicate that Raman spectra can offer the experiment basis for the cancer diagnosis and treatment.

  5. Low-temperature Raman spectra of L-histidine crystal

    CERN Document Server

    De Sousa, G P; Filho, J Mendes; Melo, F E A; Lima, C L

    2013-01-01

    We present a Raman spectroscopy investigation of the vibrational properties of L-histidine crystals at low temperatures. The temperature dependence of the spectra show discontinuities at 165 K, which we identify with modifications in the bonds associated to both the NH3+ and CO2- motifs indicative of a conformational phase transition that changes the intermolecular bonds. Additional evidence of such a phase transition was provided by differential scanning calorimetry measurements, which identified an enthalpic anomaly at ~165 K.

  6. RAMAN-SPECTRA OF HUMAN DENTAL CALCULUS

    NARCIS (Netherlands)

    TSUDA, H; ARENDS, J

    1993-01-01

    Raman spectra of human dental calculus have been observed for the first time by use of micro-Raman spectroscopy. The spectral features of calculus were influenced easily by heating caused by laser irradiation. Therefore, the measurements were carried out at relatively low power (5 mW, 1-mu m spot si

  7. Raman spectra of nitrogen-doped tetrahedral amorphous carbon from first principles

    Institute of Scientific and Technical Information of China (English)

    NIU Li; ZHU JiaQi; GAO Wei; HAN Xiao; DU ShanYi

    2009-01-01

    The non-resonant vibrational Raman spectra of nitrogen-doped tetrahedral amorphous carbon have been calculated from first principles, including the generation of s structural model, and the calculation of vibrational frequencies, vibrational eigenmodes and Raman coupling tensors. The calculated Raman spectra are in good agreement with the experimental results. The broad band at around 500 cm~(-1) arises from mixed bonds. The T peak originates from the vibrations of sp~3 carbon and the G peak comes from the stretching vibrations of sp~2-type bonding of C=C and C=N. The simulation results indicate the direct contribution of N vibrations to Raman spectra.

  8. Raman spectra of amino acids and their aqueous solutions

    Science.gov (United States)

    Zhu, Guangyong; Zhu, Xian; Fan, Qi; Wan, Xueliang

    2011-03-01

    Amino acids are the basic "building blocks" that combine to form proteins and play an important physiological role in all life-forms. Amino acids can be used as models for the examination of the importance of intermolecular bonding in life processes. Raman spectra serve to obtain information regarding molecular conformation, giving valuable insights into the topology of more complex molecules (peptides and proteins). In this paper, amino acids and their aqueous solution have been studied by Raman spectroscopy. Comparisons of certain values for these frequencies in amino acids and their aqueous solutions are given. Spectra of solids when compared to those of the solute in solution are invariably much more complex and almost always sharper. We present a collection of Raman spectra of 18 kinds of amino acids ( L-alanine, L-arginine, L-aspartic acid, cystine, L-glutamic acid, L-glycine, L-histidine, L-isoluecine, L-leucine, L-lysine, L-phenylalanine, L-methionone, L-proline, L-serine, L-threonine, L-tryptophan, L-tyrosine, L-valine) and their aqueous solutions that can serve as references for the interpretation of Raman spectra of proteins and biological materials.

  9. Raman Spectra Of Double-Walled Carbon Nanotubes

    Science.gov (United States)

    Vuković, T.; Dmitrović, S.; Dobardžić, E.

    2007-04-01

    Using nonresonant bond-polarization theory, Raman spectra of periodic double-walled carbon nanotubes (DWCNTs) are calculated. Due to the lower symmetry of DWCNT, the number of Raman active modes is much larger compared to those of its layers. Complete frequency range of the tubes spectra has been analyzed for large number of tubes. We found that only modes whose frequencies are below 800 cm-1 have noticeable up shifts compared to those of isolated layers. Special attention is given to radial breathing modes (RBMs) and G-band region since these modes are used for the identification of singe-walled carbon nanotubes. In case of breathing like modes (BLMs), frequency of the out of phase mode is found to be chirality dependent, while the in phase one remains only diameter dependent as in the case of individual layers.

  10. Raman Optical Activity and Raman Spectra of Amphetamine Species

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Shim, Irene; White, Peter Cyril;

    2012-01-01

    Theoretical calculations and preliminary measurements of vibrational Raman optical activity (ROA) spectra of different species of amphetamine (amphetamine and amphetamine-H+) are reported for the first time. The quantum chemical calculations were carried out as hybrid ab initio DFT......-molecular orbital calculations by use of the Gaussian 03W pro- gram, based on complete geometry minimizations of the conformational energy of the S-(+)-amphetamine molecule, the S-(+)-amphetamine-H+ ion, and the R-(–)-amphetamine molecule. Following this, harmonic frequency calculations have been made, providing...... are employed for identification purposes. The DFT calculations show that the most stable conformations are those allowing for close contact between the aromatic ring and the amine hydrogen atoms. The internal rotational barrier within the same amphetamine enanti- omer has a considerable influence on the Raman...

  11. Oxide-supported metals with molecular structures: Evidence of the metal-oxygen bond from Raman and inelastic electron tunneling spectra of [Re(CO){ in3}{OMG}{HOMg} 2] and [Re(CO) 3{OAl}{HOAl} 2

    Science.gov (United States)

    Kirlin, P. S.; Dethomas, F. A.; Bailey, J. W.; Moller, K.; Gold, H. S.; Dybowski, C.; Gates, B. C.

    1986-09-01

    Raman and inelastic electron tunneling spectra of the anchored rhenium complexes [Re(CO){ in3}{OMG}{HOMg} 2] and [Re(CO) 3{OAl}{HOAl} 2] are reported, providing the first vibrational spectroscopic evidence of the metal-oxygen bond in mononuclear oxide-bound organometallic complexes.

  12. Oxide-supported metals with molecular structures: Evidence of the metal-oxygen bond from Raman and inelastic electron tunneling spectra of [Re(CO) 3{O-MG}{HO-Mg} 2] and [Re(CO) 3{O-Al}{HO-Al} 2

    Science.gov (United States)

    Kirlin, P. S.; Dethomas, F. A.; Bailey, J. W.; Moller, K.; Gold, H. S.; Dybowski, C.; Gates, B. C.

    Raman and inelastic electron tunneling spectra of the anchored rhenium complexes [Re(CO) 3{O-Mg}{HO-Mg} 2] and [Re(CO) 3{O-Al}{HO-Al} 2] are reported, providing the first vibrational spectroscopic evidence of the metal-oxygen bond in mononuclear oxide-bound organometallic complexes.

  13. Vibrational infrared and raman spectra of dicyanoacetylene

    Science.gov (United States)

    Khanna, R. K.; Perera-Jarmer, M. A.; Ospina, M. J.

    The raman and infrared spectra for solid C 4N 2 are reported. New assignments are given for ˜gn 1 (2333 cm -1), ˜gn 2 (2267) and ˜gn 3 (640 cm -1). These assignments are supported by a normal coordinate Analysis using eight force constants. Extinction coefficients for the infrared active fundamentals are also reported. Our results suggest C 4N 2 to be a likely candidate to explain the 478 cm -1 band in the Titan's emission recorded by the Voyager mission.

  14. Polarized Raman spectra and intensities of aliphatic amino acids

    Science.gov (United States)

    Himmler, Hans J.; Eysel, Hans H.

    1989-01-01

    Raman spectra of aliphatic α- L-amino acids, glycine, alanine, and valine were re-investigated both in aqueous solution and deuterium oxide solution. The spectra were taken of the zwitterionic and of the completely deprotonated form of the amino acids. Spectra of leucine and isoleucine were studied in water at the isoelectric point. Spectra were recorded both with parallel and perpendicular polarization and the isotropic and anisotropic scattering components were isolated. The integrated intensities of CH stretch, CC stretch and carboxylate bend vibrations are discussed. Linear relations between the number of CC and CH bonds and the total scattered intensity in the appropriate spectral regions are observed. The sum over the carboxylate modes shows characteristic intensities for the first three members of the aliphatic amino acids. An increase of isotropic scattering of ϱ co 2 near 510 cm -1 with increasing chain length of the amino acid (or with increasing concentration) is interpreted as the result of micelle formation.

  15. Symmetry in bonding and spectra an introduction

    CERN Document Server

    Douglas, Bodie E

    1985-01-01

    Many courses dealing with the material in this text are called ""Applications of Group Theory."" Emphasizing the central role and primary importance of symmetry in the applications, Symmetry in Bonding and Spectra enables students to handle applications, particularly applications to chemical bonding and spectroscopy. It contains the essential background in vectors and matrices for the applications, along with concise reviews of simple molecular orbital theory, ligand field theory, and treatments of molecular shapes, as well as some quantum mechanics. Solved examples in the text illustra

  16. Raman spectra of human dentin mineral

    NARCIS (Netherlands)

    Tsuda, H; Ruben, J; Arends, J

    1996-01-01

    Human dentin mineral has been investigated by using micro-Raman spectroscopy. Fluorescence and thermal problems were largely avoided by preparing dentin samples by grinding and ultrasonic agitation in acetone. The Raman spectral features were consistent with those of impure hydroxyapatite containing

  17. Microwave, infrared and Raman spectra and structure of 2-nitropropane

    Science.gov (United States)

    Durig, J. R.; Smoother Smith, J. A.; Li, Y. S.; Wasacz, F. M.

    1983-05-01

    The microwave spectrum of 2-nitropropane, C 3H 7NO 2, has been investigated from 12.5 to 40.0 GHz. Only α-type transitions were observed and R-branch assignments are made for the ground vibrational state. The effective rotational constants are found to have the following values: A = 5132 ± 12, B = 2895.70 ± 0.14, and C = 2706.51 ± 0.12 MHz. It is shown that these rotational constants are only consistent for the conformer where one NO bond eclipses the CH bond. From a diagnostic least-squares adjustment to fit these three rotational constants along with reasonably assumed structural parameters for the isopropyl moiety, excluding the CC distance, the following parameters are obtained: r( C C) = 1.533 ± 0.006 Å, r( C N) = 1.508 ± 0.018 Å, r( N O) = 1.218 ± 0.015 Å, ∩ CNO = 116.8 ± 1.5°, and ∩ CCN = 108.9 ± 1.7° . From a temperature study of the microwave spectrum, it appears that the NO 2 group is nearly freely rotating. The IR (3500-80 cm -1) and Raman (3500-10 cm -1) spectra have been recorded for both the gaseous and solid phases of 2-nitropropane. The Raman spectrum of the liquid has also been recorded and qualitative depolarization values obtained. All of the normal modes are assigned based on band contours, depolarization values, and group frequencies. The vibrational data are also consistent with a nearly freely rotating NO 2 group. These results are compared to the similar quantities for several related molecules.

  18. Proton-transfer dynamics in the hydrogen bond. Inelastic neutron scattering, infrared and Raman spectra of KH(CF 3COO) 2 and CsH(CF 3COO) 2

    Science.gov (United States)

    Fillaux, F.; Tomkinson, J.

    1991-12-01

    Inelastic neutron scattering (INS), infrared and Raman spectra of potassium and cesium hydrogen bistrifluoroacetate (KH(CF 3COO) 2 and CsH(CF 3COO) 2, respectively) at 20 K are reported. In both crystals H(CF 3COO) 2- centrosymmetric dimers are linked by strong hydrogen bonds, whose lengths are 2.435 and 2.38 Å, respectively. The principal OH modes appear at the same frequencies for both compounds. The OH stretching band shapes are similar in infrared and in INS. The submaxima are attributed to interactions with other internal modes. Below 200 cm -1, the cesium salt shows three narrow bands which emerge from the density-of-states. They are assigned to localized modes involving the proton. A sharp band at 87 cm -1 corresponds to the "tunnelling" transition in a quasi-symmetric double-minimum potential with a barrier height of 1340 cm -1. The other two narrow bands, at 36 and 49 cm -1, are assigned to the internal torsions of coupled CF 3COO groups. Potential barriers are estimated. A detailed band-shape analysis of the OH bending modes provides clear indications of different dynamics for the two salts. KH(CF 3COO) 2 is rather stiff and phonon wings involving the whole lattice density-of-states are observed for the δOH mode but not for the γOH mode. For this latter, the observed combinations indicate a dynamical coupling with the internal torsion. CsH(CF 3COO) 2 is rather soft and recoil occurs. The INS intensities of the OH bending modes are decreased by Debye-Waller factors and their frequencies are shifted upwards. The estimated masses of the recoiling particles are consistent with strong dynamical coupling of the γOH with the torsional mode on the one hand, and of the δOH with translational modes on the other. The polarizability of the counter ion appears to play a leading role in proton dynamics.

  19. Cancer detection based on Raman spectra super-paramagnetic clustering

    Science.gov (United States)

    González-Solís, José Luis; Guizar-Ruiz, Juan Ignacio; Martínez-Espinosa, Juan Carlos; Martínez-Zerega, Brenda Esmeralda; Juárez-López, Héctor Alfonso; Vargas-Rodríguez, Héctor; Gallegos-Infante, Luis Armando; González-Silva, Ricardo Armando; Espinoza-Padilla, Pedro Basilio; Palomares-Anda, Pascual

    2016-08-01

    The clustering of Raman spectra of serum sample is analyzed using the super-paramagnetic clustering technique based in the Potts spin model. We investigated the clustering of biochemical networks by using Raman data that define edge lengths in the network, and where the interactions are functions of the Raman spectra's individual band intensities. For this study, we used two groups of 58 and 102 control Raman spectra and the intensities of 160, 150 and 42 Raman spectra of serum samples from breast and cervical cancer and leukemia patients, respectively. The spectra were collected from patients from different hospitals from Mexico. By using super-paramagnetic clustering technique, we identified the most natural and compact clusters allowing us to discriminate the control and cancer patients. A special interest was the leukemia case where its nearly hierarchical observed structure allowed the identification of the patients's leukemia type. The goal of this study is to apply a model of statistical physics, as the super-paramagnetic, to find these natural clusters that allow us to design a cancer detection method. To the best of our knowledge, this is the first report of preliminary results evaluating the usefulness of super-paramagnetic clustering in the discipline of spectroscopy where it is used for classification of spectra.

  20. Raman spectra of coal-based graphite

    Institute of Scientific and Technical Information of China (English)

    郑辙; 陈宣华

    1995-01-01

    Graphite formed in response to thermal contact metamorphism of coal bodies with magmatic intrusion is referred to as coal-based graphite. The first-order Raman spectrum of all the coal-based graphite taken from the Lutang area, Hunan Province exhibits a single Raman band near 1585cm-1, which comes directly from in-plane vibration of aromatic layer assigned to the E2g mode. Their Raman band of the structural defect in-plane can be divided into 2 types: one is the defect band (D peak) caused by the primary structural delect of the graphite in graphitization process, which is called D2-peak located at 1 360 cm-1; the other is the defect bank caused by the secondary structural defect in the graphite subject to tectonic shearing stress, which is called D1 peak located at 1370cm-1. The second Raman spectrum of the coal-based graphite shows three-dimensional lattice degree in the coal-based graphite. If the three-dimensional lattice of graphite is not well developed, it exhibits only a band of 2700cm-1; if the

  1. Raman spectra of silicon carbide small particles and nanowires

    International Nuclear Information System (INIS)

    Two manufacturing protocols of silicon carbide (SiC) nanowires are discussed. The Raman spectra of produced SiC nanowires are compared with spectra of SiC powders of various grain sizes. The temperature and pressure dependence of the Raman spectra for powders is similar to that of bulk crystals, but is different for nanowires. Frequency shifts, band broadenings and the presence of shoulders are discussed in terms of crystal size, character of defects and their population. The concentration of defects in synthesized nanowires depends on the sintering method. Raman intensity enhancement of the LO phonon was observed when the wavelength of the excitation laser was changed from 780 to 514 nm

  2. Temperature effects in low-frequency Raman spectra of corticosteroid hormones

    Science.gov (United States)

    Minaeva, V. A.; Minaev, B. F.; Baryshnikov, G. V.; Surovtsev, N. V.; Cherkasova, O. P.; Tkachenko, L. I.; Karaush, N. N.; Stromylo, E. V.

    2015-02-01

    Experimental Raman spectra of the corticosteroid hormones corticosterone and desoxycorticosterone are recorded at different temperatures (in the range of 30-310 K) in the region of low-frequency (15-120 cm-1) vibrations using a solid-state laser at 532.1 nm. The intramolecular vibrations of both hormones are interpreted on the basis of Raman spectra calculated by the B3LYP/6-31G(d) density functional theory method. The intermolecular bonds in tetramers of hormones are studied with the help of the topological theory of Bader using data of X-ray structural analysis for crystalline samples of hormones. The total energy of intermolecular interactions in the tetramer of desoxycorticosterone (-49.1 kJ/mol) is higher than in the tetramer of corticosterone (-36.9 kJ/mol). A strong intramolecular hydrogen bond O21-H⋯O=C20 with an energy of -42.4 kJ/mol was revealed in the corticosterone molecule, which is absent in the desoxycorticosterone molecule. This fact makes the Raman spectra of both hormones somewhat different. It is shown that the low-frequency lines in the Raman spectra are associated with skeletal vibrations of molecules and bending vibrations of the substituent at the C17 atom. The calculated Raman spectrum of the desoxycorticosterone dimer allows one to explain the splitting and shift of some lines and to interpret new strong lines observed in the spectra at low temperatures, which are caused by the intermolecular interaction and mixing of normal vibrations in a crystal cell. On the whole the calculated frequencies are in a good agreement with the experimental results.

  3. Raman spectra and XPS studies of phase changes in Ge2Sb2Te5 films

    Institute of Scientific and Technical Information of China (English)

    Liu Bo; Song Zhi-Tang; Zhang Ting; Feng Song-Lin; Chen Bomy

    2004-01-01

    Ge2Sb2Te5 film was deposited by RF magnetron sputtering on Si (100) substrate. The structure of amorphous and crystalline Ge2Sb2Te5 thin films was investigated using XRD, Raman spectra and XPS. XRD measurements revealed the existence of two different crystalline phases, which has a FCC structure and a hexagonal structure, respectively.The broad peak in the Raman spectra of amorphous Ge2Sb2Te5 film is due to the amorphous -Te-Te- stretching. As the annealing temperature increases, the broad peak separates into two peaks, which indicates that the heteropolar bond in GeTe4 and the Sb-Sb bond are connected with four Te atoms, and other units such as (TeSb) Sb-Sb (Te2)and (Sb2) Sb-Sb (Te2), where some of the four Te atoms in the above formula are replaced by Sb atoms, remain in crystalline Ge2Sb2Te5 thin film. And from the results of Raman spectra and XPS, higher the annealing temperature,more Te atoms bond to Ge atoms and more Sb atoms substitute Te in (Te2) Sb-Sb (Te2).

  4. Raman spectra of semiconductor nanoparticles: Disorder-activated phonons

    Science.gov (United States)

    Ingale, Alka; Rustagi, K. C.

    1998-09-01

    We present Raman spectra of four semiconductor doped glasses and a single crystal of CdS0.55Se0.45 in the range 30-800 cm-1 in the backscattering geometry. This includes the first-order Raman scattering from the disorder-activated zone-edge phonons and the LO phonons. TO phonon modes are not observed, as in bulk CdS, for the excitation well above the lowest gap. We show that the asymmetric line profile of the LO phonon structure can be understood as a composite of two phonon modes: the zone center and the zone edge phonons. Disorder-activated modes in the (30-130)-cm-1 range and the higher-order Raman spectra are also observed and found to be consistent with this assignment.

  5. First-principles simulation of Raman spectra and structural properties of quartz up to 5 GPa

    Science.gov (United States)

    Liu, Lei; Lv, Chao-Jia; Zhuang, Chun-Qiang; Yi, Li; Liu, Hong; Du, Jian-Guo

    2015-12-01

    The crystal structure and Raman spectra of quartz are calculated by using first-principles method in a pressure range from 0 to 5 GPa. The results show that the lattice constants (a, c, and V) decrease with increasing pressure and the a-axis is more compressible than the c axis. The Si-O bond distance decreases with increasing pressure, which is in contrast to experimental results reported by Hazen et al. [Hazen R M, Finger L W, Hemley R J and Mao H K 1989 Solid State Communications 725 507-511], and Glinnemann et al. [Glinnemann J, King H E Jr, Schulz H, Hahn T, La Placa S J and Dacol F 1992 Z. Kristallogr. 198 177-212]. The most striking changes are of inter-tetrahedral O-O distances and Si-O-Si angles. The volume of the tetrahedron decreased by 0.9% (from 0 to 5 GPa), which suggests that it is relatively rigid. Vibrational models of the quartz modes are identified by visualizing the associated atomic motions. Raman vibrations are mainly controlled by the deformation of the tetrahedron and the changes in the Si-O-Si bonds. Vibrational directions and intensities of atoms in all Raman modes just show little deviations when pressure increases from 0 to 5 GPa. The pressure derivatives (dνi/dP) of the 12 Raman frequencies are obtained at 0 GPa-5 GPa. The calculated results show that first-principles methods can well describe the high-pressure structural properties and Raman spectra of quartz. The combination of first-principles simulations of the Raman frequencies of minerals and Raman spectroscopy experiments is a useful tool for exploring the stress conditions within the Earth. Project supported by the Key Laboratory of Earthquake Prediction, Institute of Earthquake Science, China Earthquake Administration (CEA) (Grant No. 2012IES010201) and the National Natural Science Foundation of China (Grant Nos. 41174071 and 41373060).

  6. Breit-Wigner-Fano lineshapes in Raman spectra of graphene

    OpenAIRE

    Hasdeo, Eddwi H.; Nugraha, Ahmad R. T.; Dresselhaus, Mildred S.; Saito, Riichiro

    2014-01-01

    Excitation of electron-hole pairs in the vicinity of the Dirac cone by the Coulomb interaction gives rise to an asymmetric Breit-Wigner-Fano lineshape in the phonon Raman spectra in graphene. This asymmetric lineshape appears due to the interference effect between the phonon spectra and the electron-hole pair excitation spectra. The calculated Breit-Wigner-Fano asymmetric factor 1/qBWF as a function of the Fermi energy shows a V-shaped curve with a minimum value at the charge neutrality point...

  7. Raman spectra evaluation of the carbon layers with Voigt profile

    Directory of Open Access Journals (Sweden)

    M. Gołąbczak

    2009-12-01

    Full Text Available Purpose: Recent use of Raman spectroscopy as the valuable tool for investigations of the content and state of different material samples is rapidly growing especially in the area of the DLC (Diamond-Like Carbon layers investigation. Not only qualitative analysis but also quantitative is in the scope of this method which in turn demands use of precise mathematical tools for describing spectrograms.Design/methodology/approach: So-called Voigt profile establish basis for the relatively most precise shape-functions used for describing spectrogram shape. Voigt profile is the convolution of the very well known distribution functions: Gaussian distribution and Cauchy distribution (Lorentz distribution. Gaussian distribution is traditionally recognized as a tool for modeling multi-causal phenomena due to the Central Limit Theorem results. Cauchy distribution is recognized as modeling influence of the Fabry-Pérot interferometer (etalon used for detection of the Raman spectrum.Findings: We present successful decomposition of the Raman spectra into elements: base function, peaks’ determination and etalon influence on spectral peaks’ shapes. Thorough numerical simulation of the Fabry-Pérot interferometer has been performed and identification of its accuracy parameter has been done when matching Voigt profile based function to the experimental data.Research limitations/implications: Good computational tools for generation of the Voigt profile, being not an analytical function itself and good understanding of mutual relationships between the Voigt profile and the Fabry-Pérot interferometer is of main interest for not only practical but also precise use this tool for quantitative analysis of Raman spectra.Practical implications: The main goal of our work has been the thorough preparation for future works with spectrum deconvolution allowing better resolution in determining Raman spectrum components.Originality/value: So far no proper attention has been

  8. IR, Raman and SERS spectra of propantheline bromide.

    Science.gov (United States)

    Baraldi, C; Freguglia, G; Tinti, A; Sparta, M; Alexandrova, A N; Gamberini, M C

    2013-02-15

    The two known propantheline bromide polymorphs (form I and form II) were studied and characterized by a multianalytical approach. In the present work, the identification of propantheline bromide polymorphic forms through vibrational IR spectroscopies are presented and for the first time Raman microscopy and hot stage Raman microscopy (HSRM) studies are reported. Finally, quantum mechanical calculations were performed. For assisting the assignment of the experimental picks, the two IR spectra of the most and least stable representatives of a set of 56 conformers are calculated and studied. DSC thermograms data, are also reported. The surface enhanced Raman scattering (SERS) spectrum was also recorded in a silver colloid; it could be inferred that propantheline bromide is adsorbed on silver colloid through the oxygen atom with the molecular plane perpendicular to the metal surface.

  9. Expressions of excited states by triplet dimers in heisenberg antiferromagnetic ladders. Analysis of magnetic Raman spectra

    Energy Technology Data Exchange (ETDEWEB)

    Natsume, Yuhei; Tada, Shinichiro; Suzuki, Toshihiko [Chiba Univ., Graduate School of Science and Technology, Chiba (Japan)

    2002-06-01

    Characteristic properties of excited states in antiferromagnetic ladder systems with spin-1/2 are investigated in relation with the theoretical analysis of the quite asymmetric shape of the peak for twice the spin gap {delta}{sub g} in magnetic Raman spectra. Here, the structure of exchange-scattering spectra are reproduced by the numerical calculation for the finite Heisenberg ladder, in which legs with antiferromagnetic bond J{sub c} is connected by rungs with antiferromagnetic bond J{sub r}. The singlet ground state in this system can be expressed as the ordering of singlet dimers on rungs in the ladder for J{sub c}/J{sub r} {yields} +0. In fact, the value of 0.1 is adopted to be the ratio of J{sub c}/J{sub r} in order to discuss the experimental work of the magnetic Raman spectra for the ladder of V{sup 4+} ions in the oxide compound CaV{sub 2}O{sub 5} reported in Konstantinovic et al., Phys. Rev. B61 (2000), 15185. As for this peak of 2{delta}{sub g}, quite an asymmetric observed shape is explained by the present calculation. According to the analysis of spectra, we discuss the expression of excited states by triplet dimers on rungs: The dominant contribution of the pair of triplet dimers on adjacent rungs to the corresponding state for 2{delta}{sub g} peak is pointed out. (author)

  10. Structure, IR and Raman spectra of phosphotrihydrazide studied by DFT.

    Science.gov (United States)

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

    2016-09-01

    The FTIR and FT Raman measurements of the phosphotrihydrazide (S)P[N(Me)-NH2]3 have been performed. This compound is a zero generation dendrimer G0 with terminal amine groups. Structural optimization and normal mode analysis were obtained for G0 by the density functional theory (DFT). Optimized geometric bond length and angles obtained by DFT show good agreement with experiment. The amine terminal groups are characterized by the well-defined bands at 3321, 3238, 1614cm(-1) in the experimental IR spectrum and by bands at 3327, 3241cm(-1) in the Raman spectrum of G0. The experimental frequencies of asymmetric and symmetric NH2 stretching vibrations of amine group are lower than theoretical values due to intramolecular NH⋯S hydrogen bond. This hydrogen bond is also responsible for higher experimental infrared intensity of these bands as compared with theoretical values. Relying on DFT calculations a complete vibrational assignment is proposed for the studied dendrimer. PMID:27179692

  11. Raman spectroscopy of supported chromium oxide catalysts : determination of chromium-oxygen bond distances and bond orders

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Wachs, I.E.

    1996-01-01

    An empirical correlation is described for relating Raman stretching frequencies of chromium—oxygen (Cr—O) bonds to their bond lengths in chromium oxide reference compounds. An exponential fit of crystallographically determined Cr—O bond lengths to Cr—O Raman symmetric stretching frequencies (800–130

  12. Raman spectra of ZnBr2-based glasses

    International Nuclear Information System (INIS)

    Raman spectra of ZnBr2-KBr and ZnBr2-KBr-CaBr2 glasses contain strong bands at 60 cm-1 and 155 or 174 cm-1 and some weak bands between 200-300 cm-1. From the compositional dependence of the spectra and comparison with vibrational modes of molten mixtures and crystals, the 155 and 174 cm-1 bands are assigned to symmetric stretching modes of tetrahedra consisting of four bridging and four non-bridging bromines, respectively. It is revealed that tetrahedra of bridging bromines exist in the glasses even at the composition of so large amount of bromine that the theoretical number of non-bridging bromine per zinc is beyond 4. (author) 6 refs., 4 figs

  13. [IR and Raman spectra studies of Rotundine based on DFT].

    Science.gov (United States)

    Li, Jun-Ping; Zhou, Guang-Ming; Zhang, Li-Jun; Cheng, Hong-Mei; Qin, Hong-Ying

    2014-11-01

    Infrared spectroscopy (IR), the normal Raman spectroscopy (NRS) and the surface enhanced Raman spectroscopy (SERS) in new Ag/Cu nanomaterial of Rotundine were studied in the present paper. The IR and the NRS of Rotundine were calculated by the density functional theory (DFT) using B3LYP/6-311+G(d, p), then the spectral intensity graph of Rotundine were given. The vibrational peaks were assigned comprehensively by the visualization software of Gauss view 5. 0. Rotundine has obvious infrared and Raman vibrational peak in the wave number range of 3 300-2500 and 1 800-600 cm(-1). SnCl2 and PVP was used as capping agent for the silver nanoparticles in SERS of Rotundine. Finally, by using the method of cyclic immersion well dispersed silver nanoparticles was obtained and achieved good enhancement effect. This molecule acquired strong selective enhancement vibration peak, In the wave number ranges of 1 500-1 400 and 1 000-700 cm(-1) the enhancement effect is most obvious. After analyzed, the methylene of this molecule is adsorbed on the silver nanoparticles surface and the angle between the benzene ring and the silver substrate is close to 90 degrees. The theoretically calculated spectra of Rotundine are consistent with the obtained experimental spectra. There are some differences may be due to the interaction forces between molecules and so on. The visualization software displayed the structure characteristics and molecular group vibration of this molecular visually and provided important basis for assigning the vibrational peaks. Rotundine is an important traditional Chinese medicine agent contained in many kinds of sedative drugs. The study provides a strong basis for the rapid, feature and trace identification of Rotundine and also supplies important reference for the biological role of central inhibition of analgesic drugs. PMID:25752044

  14. Evidence of Polaron Excitations in Low Temperature Raman Spectra of Oxalic Acid Dihydrate.

    Science.gov (United States)

    Mohaček-Grošev, Vlasta; Grdadolnik, Jože; Hadži, Dušan

    2016-05-12

    Low temperature Raman spectra of oxalic acid dihydrate (8-300 K) for both the polycrystalline and single crystal phase show strong variation with temperature in the interval from 1200 to 2000 cm(-1). Previous low temperature diffraction studies all confirmed the stability of the crystal P21/n phase with no indications of any phase transition, reporting the existence of a strong hydrogen bond between the oxalic acid and a water molecule. A new group of Raman bands in the 1200-1300 cm(-1) interval below 90 K is observed, caused by possible loss of the center of inversion. This in turn could originate either due to disorder in hydroxyl proton positions or due to proton transfer from carboxylic group to water molecule. The hypothesis of proton transfer is further supported by the emergence of new bands centered at 1600 and 1813 cm(-1), which can be explained with vibrations of H3O(+) ions. The broad band at 1600 cm(-1) looses intensity, while the band at 1813 cm(-1) gains intensity on cooling. The agreement between quantum calculations of vibrational spectra and experimentally observed Raman bands of hydronium ions in oxalic acid sesquihydrate crystal corroborates this hypothesis. PMID:27093217

  15. Laser Raman and infra-red spectra of biomolecule: 5-aminouracil

    Indian Academy of Sciences (India)

    J S Singh

    2008-03-01

    Laser Raman (200-4000 cm-1) and IR (200-4000 cm-1) spectra of 5-aminouracil were recorded in the region 200{4000 cm-1. Assuming a planar geometry and C point group symmetry, it has been possible to assign all the 36 (25′ + 11″) normal modes of vibration for the first time. The two NH bonds of the NH2 group appear to be equivalent as the NH2 stretching frequencies satisfy the empirical relation proposed for the two equivalent NH bonds of the NH2 group. The two NH2 stretching frequencies are distinctly separated from the CH/NH ring stretching frequencies. A strong and sharp IR band at 3360 cm-1 could be identified as the anti-symmetric NH2 mode whereas the band at 3290 cm-1 with smaller density could be identified as the symmetric NH2 stretching mode. All other bands have also been assigned different fundamentals/overtones/combinations.

  16. [Correction Multiplicative Effects in Raman Spectra through Vector Angle Transformation].

    Science.gov (United States)

    Yao, Zhi-xiang; Sun, Zeng-qiang; Su, Hui; Yuan, Hong-fu

    2016-02-01

    The linear relationship between the Raman spectral intensity and the analyte amount is frequently disrupted for a variety of complex reasons, which include these variations in laser source, focusing effect, sample scattering and refracting, so that causes poor quantitative results. As a whole, these disturbing effects can be divided to be additive and multiplicative, and the multiplicative effects are generally more difficult to be eliminated. A spectrum is a series data, also can be treated as a vector. In principle, unstable motions in spectrum intensity/amplitude corresponding to the module shifts for a vector, doesn't impact the vector direction which is the essence of the vector, so it is reasonable to rewrite the data form on module to on space angle for the same measurement. This thesis employed a data transformation to eliminate the multiplicative effects within spectra, i. e. , the spectrum signal on its amplitude has been transformed to be on the vector angles. The first step of the transformation is the selection of a stand vector which is near to the analyte and almost orthogonal to the background within the sample space; and the next step is to define a moving window, then to find out the angle between the sample vector (i. e. the transformed spectrum) and the stand vector within the window; while the window is moved along the spectrum data series, the transformation for vector angle (VA) series has been finished. The thesis has proved that an approximate linear quantitative relationship has been remained in the VA series. Multivariate calibration need full rank matrix which is combined by spectrum from variety samples, and variety VA series also can combine a full rank VA matrix, so the approximate linear VA matrix still perfectly meeting the demand for multivariate calibration. A mixed system consisted by methanol-ethanol-isopropanol has been employed to verify the eliminations to the multiplicative effects. These measuring values of the system are

  17. Using Raman Spectroscopy and ab initio Calculations to Investigate lntermolecular Hydrogen Bonds in Binary Mixture (Tetrahydrofuran+Water)

    Institute of Scientific and Technical Information of China (English)

    WU Nan-nan; OUYANG Shun-li; LI Zuo-wei; LIU Jing-yao; GAO Shu-qin

    2011-01-01

    We analyzed the properties and structures of the hydrogen-bonded complexes of tetrahydrofuran(THF)and water by means of experimental Raman spectra and ab initio calculations.The optimized geometries and vibrational frequencies of the neat THF molecule and its hydrogen-bonded complexes with water(THF/H2O) were calculated at the MP2/6-31 l+G(d,p) level of theory.We found that the intermolecular hydrogen bonds which are formed from the binary mixtures of the neat THF and water with different molar ratios could explain the changes in wavenumber position and linewidth very well.The combination of ab initio calculations and experimental Raman spectral data provides an insight into the hydrogen bonds leading to the concentration dependent changes in the spectral features.

  18. Resonance Raman spectra of black soap film containing dye molecule

    Institute of Scientific and Technical Information of China (English)

    梁映秋; 张韫宏

    1995-01-01

    Dye molecule brilliant yellow (BY) has been used as an acid-base probe in the study of the resonance Raman spectra of three kinds of microenvironments of the black soap film (BSF) containing BY, the BY-CTAB micellar solution, and the aqueous BY solution under various pH conditions. It has been revealed that BY bound to the sandwich interface of the BSF and that to the micellar interface show similar spectral changes, but the former owns the character of coexistence of acidic and basic structures in a relatively large range of pH values (neutral to basic). Further investigations have demonstrated that BSF exhibits the buffer effect that the pH value of the aqueous core is insensitive to the pH change of the bulk solution.

  19. Simulations and analysis of the Raman scattering and differential Raman scattering/Raman optical activity (ROA) spectra of amino acids, peptides and proteins in aqueous solution

    DEFF Research Database (Denmark)

    Jalkanen, Karl J.; Nieminen, R. M.; Bohr, Jakob

    2000-01-01

    The Raman and Raman optical activity (ROA) spectra of amino acids and small peptides in aqueous solution have been simulated by density functional theory and restricted Hartree/Fock methods. The treatment of the aqueous environment in treated in two ways. The water molecules in the first hydration...... shell which strongly interact with the molecule are treated explicitly while the waters in the bulk are treated by a continuum model. The structures are optimized and the harmonic force elds are calculated. The derivatives needed to simulate the Raman and ROA intensities are calculated from first...... principles. The simulated Raman and ROA spectra have been compared to recently meassured spectra on amino acids and peptides. The simulations and understanding from them are used to interpret the Raman and ROA spectra of proteins. A comparison to vibrational absorption (VA) and vibrational circular dichroism...

  20. Raman Spectra of High-κ Dielectric Layers Investigated with Micro-Raman Spectroscopy Comparison with Silicon Dioxide

    OpenAIRE

    Borowicz, P.; A. Taube; Rzodkiewicz, W.; Latek, M.; S. Gierałtowska

    2013-01-01

    Three samples with dielectric layers from high- κ dielectrics, hafnium oxide, gadolinium-silicon oxide, and lanthanum-lutetium oxide on silicon substrate were studied by Raman spectroscopy. The results obtained for high- κ dielectrics were compared with spectra recorded for silicon dioxide. Raman spectra suggest the similarity of gadolinium-silicon oxide and lanthanum-lutetium oxide to the bulk nondensified silicon dioxide. The temperature treatment of hafnium oxide shows the evolution of the...

  1. The discovery of the hydrogen bond from p-Nitrothiophenol by Raman spectroscopy: Guideline for the thioalcohol molecule recognition tool

    Science.gov (United States)

    Ling, Yun; Xie, Wen Chang; Liu, Guo Kun; Yan, Run Wen; Wu, De Yin; Tang, Jing

    2016-01-01

    Inter- and intra- molecular hydrogen bonding plays important role in determining molecular structure, physical and chemical properties, which may be easily ignored for molecules with a non-typical hydrogen bonding structure. We demonstrated in this paper that the hydrogen bonding is responsible for the different Raman spectra in solid and solution states of p-Nitrothiophenol (PNTP). The consistence of the theoretical calculation and experiment reveals that the intermolecular hydrogen bonding yields an octatomic ring structure (8) of PNTP in the solid state, confirmed by the characteristic S-H---O stretching vibration mode at 2550 cm−1; when it comes to the solution state, the breakage of hydrogen bond of S-H---O induced the S-H stretching vibration at 2590 cm−1. Our findings may provide a simple and fast method for identifying the intermolecular hydrogen bonding. PMID:27659311

  2. 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.

  3. A study of aliphatic amino acids using simulated vibrational circular dichroism and Raman optical activity spectra

    CERN Document Server

    Ganesan, Aravindhan; Wang, Feng

    2013-01-01

    Vibrational optical activity (VOA) spectra, such as vibrational circular dichroism (VCD) and Raman optical activity (ROA) spectra, of aliphatic amino acids are simulated using density functional theory (DFT) methods in both gas phase (neutral form) and solution (zwitterionic form), together with their respective infrared (IR) and Raman spectra of the amino acids. The DFT models, which are validated by excellent agreements with the available experimental Raman and ROA spectra of alanine in solution, are employed to study other aliphatic amino acids. The inferred (IR) intensive region (below 2000 cm-1) reveals the signature of alkyl side chains, whereas the Raman intensive region (above 3000 cm-1) contains the information of the functional groups in the amino acids. Furthermore, the chiral carbons of the amino acids (except for glycine) dominate the VCD and ROA spectra in the gas phase, but the methyl group vibrations produce stronger VCD and ROA signals in solution. The C-H related asymmetric vibrations domina...

  4. Infrared Spectra and Hydrogen Bonds of Biologically Active Benzaldehydes

    Science.gov (United States)

    Tolstorozhev, G. B.; Skornyakov, I. V.; Belkov, M. V.; Shimko, A. N.; Shadyro, O. I.; Brinkevich, S. D.; Samovich, S. N.

    2013-09-01

    IR-Fourier spectra of solutions and crystals of biologically active benzaldehyde derivatives were studied. Specific features of the formation of intra- and intermolecular hydrogen bonds were analyzed. Spectral signatures that characterized participation of the hydroxyl OH group and also the OCH3 and C=O groups in the formation of intramolecular hydrogen bonds of the three different types O-H···O-H, O-H···O-CH3, and O-H···O=C were revealed. Intramolecular hydrogen bonds of the types O-H···O-H and O-H···O-CH3 were absent for benzaldehyde derivatives in the crystal phase. Only hydroxyl and carbonyl groups participated in intermolecular interactions. This resulted in the formation of linear intermolecular dimers. Seven various configurations of the linear dimers were identified in solutions and crystals.

  5. Raman spectra of electrochemically hydrogenated diamond like carbon surface

    OpenAIRE

    Biswas, Hari Shankar; Datta, Jagannath; Sen, Pintu; Ghosh, Uday Chand; Ray, Nihar Ranjan

    2013-01-01

    Raman spectroscopy has been employed to distinguish between the Raman spectrum of pristine hydrogenated diamond like carbon (PHDLC) and that of electrochemically hydrogenated diamond like carbon (ECHDLC). The enhancement of the background photoluminescence (PL) in the Raman spectrum and broadening of PL spectrum of ECHDLC are identified to be due to increase of sp3 C-H density onto the PHDLC surface, during novel electrochemical process of hydrogenation of sp2 C=C into sp3 C-H.

  6. Raman Spectra of High-κ Dielectric Layers Investigated with Micro-Raman Spectroscopy Comparison with Silicon Dioxide

    Directory of Open Access Journals (Sweden)

    P. Borowicz

    2013-01-01

    Full Text Available Three samples with dielectric layers from high-κ dielectrics, hafnium oxide, gadolinium-silicon oxide, and lanthanum-lutetium oxide on silicon substrate were studied by Raman spectroscopy. The results obtained for high-κ dielectrics were compared with spectra recorded for silicon dioxide. Raman spectra suggest the similarity of gadolinium-silicon oxide and lanthanum-lutetium oxide to the bulk nondensified silicon dioxide. The temperature treatment of hafnium oxide shows the evolution of the structure of this material. Raman spectra recorded for as-deposited hafnium oxide are similar to the results obtained for silicon dioxide layer. After thermal treatment especially at higher temperatures (600°C and above, the structure of hafnium oxide becomes similar to the bulk non-densified silicon dioxide.

  7. Raman Spectra of Methane, Ethylene, Ethane, Dimethyl ether, Formaldehyde and Propane for Combustion Applications

    KAUST Repository

    Magnotti, G.

    2015-05-09

    Spontaneous Raman scattering measurements of temperature and major species concentration in hydrocarbon-air flames require detailed knowledge of the Raman spectra of the hydrocarbons present when fuels more complex than methane are used. Although hydrocarbon spectra have been extensively studied at room temperature, there are no data available at higher temperatures. Quantum mechanical calculations, when available are not sufficiently accurate for combustion applications. This work presents experimental measurements of spontaneous Stokes-Raman scattering spectra of methane, ethylene, ethane, dimethyl ether, formaldehyde and propane in the temperature range 300-860 K. Raman spectra from heated hydrocarbons jets have been collected with a higher resolution than is generally employed for Raman measurements in combustion applications. A set of synthetic spectra have been generated for each hydrocarbon, providing the basis for extrapolation to higher temperatures. The spectra provided here will enable simultaneous measurements of multiple hydrocarbons in flames. This capability will greatly extend the range of applicability of Raman measurements in combustion applications. In addition, the experimental spectra provide a validation dataset for quantum mechanical models.

  8. Estimating and suppressing background in Raman spectra with an artificial neural network

    DEFF Research Database (Denmark)

    Sigurdsson, Sigurdur; Larsen, Jan; Philipsen, Peter Alshede;

    2003-01-01

    In this report we address the problem of skin fluorescence in feature extraction from Raman spectra of skin lesions. We apply a highly automated neural network method for suppressing skin fluorescence from Raman spectrum of skin lesions before dimension reduction with principal components analysis...

  9. [Effect on Fermi Resonance by Some External Fields: Investigation of Fermi Resonance According to Raman Spectra].

    Science.gov (United States)

    Jiang, Xiu-lan; Sun, Cheng-lin; Zhou, Mi; Li, Dong-fei; Men, Zhi-wei; Li, Zuo-wei; Gao, Shu-qin

    2015-03-01

    Fermi resonance is a phenomenon of molecular vibrational coupling and energy transfer occurred between different groups of a single molecule or neighboring molecules. Many properties of Fermi resonance under different external fields, the investigation method of Raman spectroscopy as well as the application of Fermi resonance, etc need to be developed and extended further. In this article the research results and development about Fermi resonance obtained by Raman spectral technique were introduced systematically according to our work and the results by other researchers. Especially, the results of the behaviors of intramolecular and intermolecular Fermi resonance of some molecules under some external fields such as molecular field, pressure field and temperature field, etc were investigated and demonstrated in detail according to the Raman spectra obtained by high pressure DAC technique, temperature variation technique as well as the methods we planed originally in our group such as solution concentration variation method and LCOF resonance Raman spectroscopic technique, and some novel properties of Fermi resonance were found firstly. Concretely, (1) Under molecular field. a. The Raman spectra of C5H5 N in CH3 OH and H2O indicates that solvent effect can influence Fermi resonance distinctly; b. The phenomena of the asymmetric movement of the Fermi resonance doublets as well as the fundamental involved is tuned by the Fermi resonance which had not been found by other methods were found firstly by our variation solution concentration method; c. The Fermi resonance properties can be influenced distinctly by the molecular group reorganization induced by the hydrogen bond and anti-hydrogen bond in solution; d. Fermi resonance can occurred between C7 H8 and m-C8H10, and the Fermi resonance properties behave quite differently with the solution concentration; (2) Under pressure field. a. The spectral lines shift towards high wavenumber with increasing pressure, and

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-15

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

  11. Evaluation of Raman spectra of human brain tumor tissue using the learning vector quantization neural network

    Science.gov (United States)

    Liu, Tuo; Chen, Changshui; Shi, Xingzhe; Liu, Chengyong

    2016-05-01

    The Raman spectra of tissue of 20 brain tumor patients was recorded using a confocal microlaser Raman spectroscope with 785 nm excitation in vitro. A total of 133 spectra were investigated. Spectra peaks from normal white matter tissue and tumor tissue were analyzed. Algorithms, such as principal component analysis, linear discriminant analysis, and the support vector machine, are commonly used to analyze spectral data. However, in this study, we employed the learning vector quantization (LVQ) neural network, which is typically used for pattern recognition. By applying the proposed method, a normal diagnosis accuracy of 85.7% and a glioma diagnosis accuracy of 89.5% were achieved. The LVQ neural network is a recent approach to excavating Raman spectra information. Moreover, it is fast and convenient, does not require the spectra peak counterpart, and achieves a relatively high accuracy. It can be used in brain tumor prognostics and in helping to optimize the cutting margins of gliomas.

  12. Combined quantum mechanics (TDDFT) and classical electrodynamics (Mie theory) methods for calculating surface enhanced Raman and hyper-Raman spectra.

    Science.gov (United States)

    Mullin, Jonathan; Valley, Nicholas; Blaber, Martin G; Schatz, George C

    2012-09-27

    Multiscale models that combine quantum mechanics and classical electrodynamics are presented, which allow for the evaluation of surface-enhanced Raman (SERS) and hyper-Raman scattering spectra (SEHRS) for both chemical (CHEM) and electrodynamic (EM) enhancement mechanisms. In these models, time-dependent density functional theory (TDDFT) for a system consisting of the adsorbed molecule and a metal cluster fragment of the metal particle is coupled to Mie theory for the metal particle, with the surface of the cluster being overlaid with the surface of the metal particle. In model A, the electromagnetic enhancement from plasmon-excitation of the metal particle is combined with the chemical enhancement associated with a static treatment of the molecule-metal structure to determine overall spectra. In model B, the frequency dependence of the Raman spectrum of the isolated molecule is combined with the enhancements determined in model A to refine the enhancement estimate. An equivalent theory at the level of model A is developed for hyper-Raman spectra calculations. Application to pyridine interacting with a 20 nm diameter silver sphere is presented, including comparisons with an earlier model (denoted G), which combines plasmon enhanced fields with gas-phase Raman (or hyper-Raman) spectra. The EM enhancement factor for spherical particles at 357 nm is found to be 10(4) and 10(6) for SERS and SEHRS, respectively. Including both chemical and electromagnetic mechanisms at the level of model A leads to enhancements on the order of 10(4) and 10(9) for SERS and SEHRS.

  13. Effect of axial ligands on the spectroelectrochemical properties of zinc phthalocyanine films. In situ Raman and electroreflection spectra

    NARCIS (Netherlands)

    Palys, B.J.; Ham, van den D.M.W.; Otto, C.

    1994-01-01

    Electroreflection and Raman spectra (in situ and ex situ) of zinc phthalocyanine (ZnPc) films (80 nm thick) have been studied. Raman spectra were resonantly and preresonantly enhanced. Both electroreflection and Raman experiments reveal the homogeneous inclusion of electrolyte anions upon oxidation

  14. [Laser Raman spectra study on Co-Mo/Al2O3 hydrodesulphurization catalysts].

    Science.gov (United States)

    Yuan, Hui; Xu, Guang-Tong; Qiherima; Li, Hui-Feng; Lu, Li-Jun; Yang, Xing-Yuan; Tana

    2014-02-01

    Due to the implementation of more stringent specifications in sulfur content for gasoline , a deep understanding of the active phase of Co-Mo/Al2O3 catalysts is necessary to the development of hydrodesulphurization (HDS) catalysts. A series of Co-Mo/Al2O3 HDS catalysts with different metal loading were studied by laser Raman spectra. The existence form and the content of the active component of the catalyst were obtained by Raman spectra. The result shows that the percentage of characteristic Raman bands 940 cm(-1) correlates linearly with the HDS selectivity, which can be used as an experimental evidence for developing industrial selective HDS catalysts. Raman spectra of sulfided catalysts show that the bands of oxidic catalysts at 839 and 940 cm(-1) disappeared, and simultaneously, the bands of Mo-S at 372 and 408 cm(-1) emerged, which indicate that the oxidic sample is sulfided completely. PMID:24822416

  15. Interpretation of the resonance Raman spectra of linear tetrapyrroles based on DFT calculations

    Science.gov (United States)

    Kneip, Christa; Hildebrandt, Peter; Németh, Károly; Mark, Franz; Schaffner, Kurt

    1999-10-01

    Raman spectra of linear methine-bridged tetrapyrroles in different conformational and protonation states were calculated on the basis of scaled force fields obtained by density functional theory. Results are reported for protonated phycocyanobilin in the extended ZZZasa configuration, as it is found in C-phycocyanin of cyanobacteria. The calculated spectra are in good agreement with experimental spectra of the protein-bound chromophore in the α-subunit of C-phycocyanin and allow a plausible and consistent assignment of most of the observed resonance Raman bands in the region between 1000 and 1700 cm -1.

  16. Raman spectra of normal and cancerous mouse mammary gland tissue using near infrared excitation energy

    Science.gov (United States)

    Naik, Vaman; Serhatkulu, G. K.; Dai, H.; Shukla, N.; Weber, R.; Thakur, J. S.; Freeman, D. C.; Pandya, A. K.; Auner, G. W.; Naik, R.; Miller, R. F.; Cao, A.; Klein, M. D.; Rabah, R.

    2006-03-01

    Raman spectra of normal mammary gland tissues, malignant mammary gland tumors, and lymph nodes have been recorded using fresh tissue from mice. Tumors were induced in mice by subcutaneously injecting 4T1 BALB/c mammary tumor (a highly malignant) cell line. The Raman spectra were collected using the same tissues that were examined by histopathology for determining the cancerous/normal state of the tissue. Differences in various peak intensities, peak shifts and peak ratios were analyzed to determine the Raman spectral features that differentiate mammary gland tumors from non-tumorous tissue. Tissues that were confirmed by pathology as cancerous (tumors) show several distinctive features in the Raman spectra compared to the spectra of the normal tissues. For example, the cancerous tissues show Raman peaks at 621, 642, 1004, 1032, 1175 and 1208 cm-1 that are assignable to amino acids containing aromatic side-chains such as phenylalanine, tryptophan and tyrosine. Further, the cancerous tissues show a greatly reduced level of phospholipids compared to the normal tissues. The Raman spectral regions that are sensitive to pathologic alteration in the tissue will be discussed.

  17. Effect of TiO2 particles on normal and resonance Raman spectra of coumarin 343: a theoretical investigation.

    Science.gov (United States)

    Yang, Linzhi; Wu, Wenpeng; Zhao, Yi

    2015-04-28

    It is well known that interfacial structures and charge transfer in dye-sensitized solar cells are extremely important for the enhancement of cell efficiency. Here, the normal Raman spectra (NRS) and resonance Raman spectra (RRS) of a C343-sensitized TiO2 cluster (Ti9O18) are theoretically predicted from combined electronic structure calculations and a vibrationally-resolved spectral method to reveal the relationship between interfacial geometries and excited-state dynamics. The results show that although the NRS of free C343 and the C343-TiO2 cluster correspond to the vibrational motions of C343 in a high frequency domain, their mode frequencies show obvious differences due to the interaction of the TiO2 cluster on C343, and several new Raman active fingerprint modes, such as bidentate chelating bonding modes, can be used to determine interfacial geometries. However, the resonance Raman activities of low-frequency modes are significantly enhanced and several modes from the TiO2 cluster can be observed, consistent with experimental measurements. Furthermore, the RRS from a locally excited state and a charge transfer state of C343-TiO2 are dramatically different, for instance, new Raman active modes with 1212 cm(-1), 1560 cm(-1) and 1602 cm(-1), corresponding to the motions of CH2 rocking, C=C/C-N/C=O stretching and C=O/C=C stretching, appear from the charge transfer state. The obtained information on mode-specific reorganization energies from these excited states is greatly helpful to understand and control interfacial electron transfer.

  18. Contrastive Analysis of the Raman Spectra of Polychlorinated Benzene: Hexachlorobenzene and Benzene

    Directory of Open Access Journals (Sweden)

    Zhengjun Zhang

    2011-12-01

    Full Text Available Detection of persistent pollutants such as polychlorinated benzene in environment in trace amounts is challenging, but important. It is more difficult to distinguish homologues and isomers of organic pollutantd when present in trace amounts because of their similar physical and chemical properties. In this work we simulate the Raman spectra of hexachlorobenzene and benzene, and figure out the vibration mode of each main peak. The effect on the Raman spectrum of changing substituents from H to Cl is analyzed to reveal the relations between the Raman spectra of homologues and isomers of polychlorinated benzene, which should be helpful for distinguishing one kind of polychlorinated benzene from its homologues and isomers by surface enhanced Raman scattering.

  19. Investigation of Surface-Enhanced Raman Spectra of Human Gallstones on Colloidal Silver

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The surface-enhanced Raman scatterihg (SERS) spectra of human gallstones is investigated. Complicated Raman bands were due to multiple components that include bilirubin, bilirubinate salts, cholesterol, fatty salts and proteins. The results suggest that besides bilirubin and cholesterol, fatty salts and proteins may play an important role in the formation of gallstone. The experimental data supply an useful information for the research of the formation mechanism of gallstones.

  20. SURFACE ENHANCED RAMAN SPECTRA FROM OXYGEN ON SILVER

    OpenAIRE

    Pettenkofer, C.; Pockrand, I.; Otto, A.

    1983-01-01

    Silver is an important catalyst for the epoxidation of ethylene and the production of formaldehyd from methanol. It is not yet known with certainty which form of adsorbed oxygen on silver is the catalytically active one. Therefore we have started to study the adsorption of oxygen on silver films by Raman spectroscopy. From previous investigations, especially from UPS work /1/, we know that at low exposures of ground state molecular oxygen, oxygen sticks on evaporated silver films only at defe...

  1. Structural characterization of a bonded silicon-on-insulator layer with voids by micro-Raman spectroscopy

    OpenAIRE

    Usami, Akira; Ichimura, Masaya; Wada, Takao; Ishigami, Shun-ichiro; イチムラ, マサヤ; 市村, 正也

    1994-01-01

    Crystalline quality in a void region of a bonded silicon‐on‐insulator (SOI) wafer is evaluated by micro‐Raman spectroscopy. Downshifting and broadening of the Si optical‐phonon peak are observed at the edge of the void, while spectra within the void are little different from those outside the void. Comparison with calculated results based on the theory of the phonon localization shows that both the shift and the broadening are mainly due to structural disorder and not strain. Electrical prope...

  2. 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.

  3. A Probabilistic Framework for Detection of Skin Cancer by Raman Spectra

    DEFF Research Database (Denmark)

    Sigurdsson, Sigurdur

    2003-01-01

    This Ph.D. thesis focuses on objective methods for diagnosing skin cancer from Raman spectra. A method for suppressing background noise and dimension reduction in Raman spectra is suggested. A robust Bayesian framework for training a neural network is proposed, including an overfit control...... and outlier framework. Finally a visualization scheme for extracting important features from the trained neural network classifier based on sensitivity analysis is defined. The performance on two types of skin cancer showed that 97.9% of basal cell carcinoma were identified correctly and 85.5% of malignant....... These identified important features are shown to originate from molecular structure changes in lipids and proteins. While the theme of this dissertation is skin cancer diagnosis from Raman spectra, the dimension reduction and the neural network classifier can be applied in general to other types of pattern...

  4. Infrared and Raman spectra of inorganic and coordination compounds theory and applications in inorganic chemistry

    CERN Document Server

    Nakamoto, Kazuo

    2008-01-01

    The Sixth Edition of this classic work comprises the most comprehensive and current guide to infrared and Raman spectra of inorganic, organometallic, bioinorganic, and coordination compounds. From fundamental theories of vibrational spectroscopy to applications in a variety of compound types, this has been extensively updated. New topics include the theoretical calculations of vibrational frequencies (DFT method), chemical synthesis by matrix co-condensation reactions, time-resolved Raman spectroscopy, and more. This volume is a core reference for chemists and medical professionals working with infrared or Raman spectroscopies and an excellent textbook for graduate courses.

  5. Temperature Dependence of the Raman Spectra and Phase Transition of Zirconia

    Institute of Scientific and Technical Information of China (English)

    尤静林; 蒋国昌; 杨松华; 马金昌; 徐匡迪

    2001-01-01

    A newly constructed high-temperature Raman spectrometer was used to study the temperature-dependence Raman spectra (up to 2023 K) and transformation of zirconia crystal. High-temperature Raman scattering is a useful tool in characterizing the different structures of zirconia and offers the possibility of identifying the phase transformation. It shows that monoclinic zirconia transforms to tetragonal phase at about 1440 K during the process of increasing temperature, but shows a lower transformation temperature from tetragonal to monoclinic phase at about 1323 K while the temperature decreases.

  6. Re-examination of the SiGe Raman spectra: Percolation/one-dimensional-cluster scheme and ab initio calculations

    Science.gov (United States)

    Pagès, O.; Souhabi, J.; Torres, V. J. B.; Postnikov, A. V.; Rustagi, K. C.

    2012-07-01

    We report on the detailed assignment of various features observed in the Raman spectra of SiGe alloys along the linear chain approximation (LCA), as achieved based on remarkable intensity interplays with composition between such neighboring features known from the literature but which so far have not been fully exploited. Such an assignment is independently supported by ab initio calculation of the frequencies of bond-stretching modes taking place in different local environments, which we define at one dimension (1D) for consistency with the LCA. Fair contour modeling of the SiGe Raman spectra is eventually obtained via a so-called 1D-cluster version of the phenomenological (LCA-based) percolation scheme, as originally developed for zincblende alloys, after ab initio calibration of the intrinsic Si-Si, Si-Ge, and Ge-Ge Raman efficiencies. The 1D-cluster scheme introduces a seven-oscillator [1 × (Ge-Ge), 4 × (Si-Ge), 2 × (Si-Si)] Raman behavior for SiGe, which considerably deviates from the currently accepted six-oscillator [1 × (Ge-Ge), 1 × (Si-Ge), 4 × (Si-Si)] behavior. Different numbers of Raman modes per bond are interpreted as different sensitivities to the local environment of Ge-Ge (insensitive), Si-Si (sensitive to first neighbors), and Si-Ge (sensitive to second neighbors) bond stretching. The as-obtained SiGe 1D-cluster/percolation scheme is also compared with the current version for zincblende alloys, using GaAsP as a natural reference. A marked deviation is concerned with an inversion of the like phonon branches in each multiplet. This is attributed either to the considerable Si and Ge phonon dispersions (Si-Si doublet) or to a basic difference in the lattice relaxations of diamond and zincblende alloys (Si-Ge multiplet). The SiGe vs GaAsP comparison is supported by ab initio calculation of the local lattice relaxation/dynamics related to prototype impurity motifs that are directly transposable to the two crystal structures.

  7. Temperature-Dependent Raman Spectra and Microstructure of Barium Metaborate Crystals and Its Melts

    Institute of Scientific and Technical Information of China (English)

    尤静林; 蒋国昌; 侯怀宇; 吴永全; 陈辉; 徐匡迪

    2002-01-01

    We have measured the Raman spectra of β- and α-barium metaborate in crystal and liquid states from room temperature to 1873K, with a semiconductor laser as the laser source, coupled with a time-resolved detection system to eliminate the dense thermal emission background when temperature was considerably high.Temperature-dependent Raman spectra can clearly indicate that the phase transformation from β- to α-barium metaborate has been completed during 1273 - 1300 K. Variations of different kinds of microstructure units with temperature are identified and discussed.

  8. Hydrogen Bonding in Ion-pair Molecules in Vapors over ionic liquids, studied by Raman Spectroscopy and ab initio Calculations

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    The hydrogen bonding interactions in selected archetypal vapor molecules formed in the gas phase over protic ionic liquids are discussed, based on Raman spectroscopy assisted with ab initio molecular orbital DFT-type quantum mechanical calculations (B3LYP with 6-311+G(d,p) basis sets) on assumed......-O distances in the N-H…O bond were found as 1.730 and 1.005 Å. The comparable H-O distance in solid ethanoic acid is ~1.011 Å (neutron diffraction). [1] R. W. Berg, A. Riisager & R. Fehrmann, Formation of an ion pair molecule with a single NH+…Cl- hydrogen bond: Raman spectra of 1,1,3,3-Tetramethylguanidin...... of 1,1,3,3-tetramethylguanidinium chloride. The optimized N-H distance in the N-H…Cl bond was 1.099 Å. The H-Cl distance was 1.832 Å to compare with the ~1.27 Å in HCl gas. The bromide behaved similarly [ref 2]. Fig. 2. Not so likely 1-methylimidazolium ethanoate gas molecule. The optimized N-H and H...

  9. Quantum-mechanical analysis of the intensity distribution in spectra of resonant Raman scattering spectra of aqueous solutions of tyrosine

    Science.gov (United States)

    Burova, T. G.; Shcherbakov, R. S.

    2016-05-01

    Quantum-mechanical calculations of the intensity distribution in the resonant Raman scattering spectra of aqueous solutions of tyrosine excited by laser radiation with wavelengths of 244, 229, 218, 200, and 193 nm, as well as in the nonresonant Raman scattering spectrum excited at a wavelength of 488 nm, are performed. Satisfactory agreement is achieved between the calculation results and the experimental data. It is shown that the changes in the intensity distribution observed in the spectra with a change in the excitation wavelength from 244 to 193 nm correlate with the determined changes in the contribution made by excited electronic states into the scattering tensor components. It is noted that it is necessary to take into account the Herzberg-Teller effect and that the number of excited electronic states taken into account considerably affects the calculated relative intensities of lines. The possibility of existence of several tyrosine conformers in aqueous solution at room temperature is shown.

  10. Effect of Two-Photon Stark Shift on the Multi-Frequency Raman Spectra

    Directory of Open Access Journals (Sweden)

    Hao Yan

    2014-09-01

    Full Text Available High order Raman generation has received considerable attention as a possible method for generating ultrashort pulses. A large number of Raman orders can be generated when the Raman-active medium is pumped by two laser pulses that have a frequency separation equal to the Raman transition frequency. High order Raman generation has been studied in the different temporal regimes, namely: adiabatic, where the pump pulses are much longer than the coherence time of the transition; transient, where the pulse duration is comparable to the coherence time; and impulsive, where the bandwidth of the ultrashort pulse is wider than the transition frequency. To date, almost all of the work has been concerned with generating as broad a spectrum as possible, but we are interested in studying the spectra of the individual orders when pumped in the transient regime. We concentrate on looking at extra peaks that are generated when the Raman medium is pumped with linearly chirped pulses. The extra peaks are generated on the low frequency side of the Raman orders. We discuss how linear Raman scattering from two-photon dressed states can lead to the generation of these extra peaks.

  11. Raman spectra of Martian glass analogues: A tool to approximate their chemical composition

    Science.gov (United States)

    Di Genova, Danilo; Kolzenburg, Stephan; Vona, Alessandro; Chevrel, Magdalena Oryaëlle; Hess, Kai-Uwe; Neuville, Daniel R.; Ertel-Ingrisch, Werner; Romano, Claudia; Dingwell, Donald B.

    2016-05-01

    Raman spectrometers will form a key component of the analytical suite of future planetary rovers intended to investigate geological processes on Mars. In order to expand the applicability of these spectrometers and use them as analytical tools for the investigation of silicate glasses, a database correlating Raman spectra to glass composition is crucial. Here we investigate the effect of the chemical composition of reduced silicate glasses on their Raman spectra. A range of compositions was generated in a diffusion experiment between two distinct, iron-rich end-members (a basalt and a peralkaline rhyolite), which are representative of the anticipated compositions of Martian rocks. Our results show that for silica-poor (depolymerized) compositions the band intensity increases dramatically in the regions between 550-780 cm-1 and 820-980 cm-1. On the other hand, Raman spectra regions between 250-550 cm-1 and 1000-1250 cm-1 are well developed in silica-rich (highly polymerized) systems. Further, spectral intensity increases at ~965 cm-1 related to the high iron content of these glasses (~7-17 wt % of FeOtot). Based on the acquired Raman spectra and an ideal mixing equation between the two end-members we present an empirical parameterization that enables the estimation of the chemical compositions of silicate glasses within this range. The model is validated using external samples for which chemical composition and Raman spectra were characterized independently. Applications of this model range from microanalysis of dry and hydrous silicate glasses (e.g., melt inclusions) to in situ field investigations and studies under extreme conditions such as extraterrestrial (i.e., Mars) and submarine volcanic environments.

  12. Pressure dependence of Hexanitrostilbene Raman/ electronic absorption spectra to validate DFT EOS

    Science.gov (United States)

    Farrow, Darcie; Alam, Kathleen; Martin, Laura; Fan, Hongyou; Kay, Jeffrey; Wixom, Ryan

    2015-06-01

    Due to its thermal stability and low vapor pressure, Hexanitrostilbene (HNS) is often used in high-temperature or vacuum applications as a detonator explosive or in mild detonating fuse. Toward improving the accuracy of the equation of state used in hydrodynamic simulations of the performance of HNS, we have measured the Raman and electronic absorption spectra of this material under static pressure in a diamond anvil cell. Density functional theory calculations were used to simulate the pressure dependence of the Raman/Electronic spectra along the Hugoniot and 300K isotherm for comparison and to aid in interpreting the data. We will discuss changes in the electronic structure of HNS under pressure, validation of a DFT predicted equation of state (EOS), and using this data as a basis for understanding future pulsed Raman measurements on dynamically compressed HNS samples.

  13. Temperature Dependence of the Raman Spectra of Na2Si2O5

    Institute of Scientific and Technical Information of China (English)

    YOU Jing-Lin; JIANG Guo-Chang; XU Kuang-Di

    2001-01-01

    The microstructures of Na2Si2O5 from room temperature up to 1773 K are studied by high-temperature Paman spectroscopy. Deconvolutions of complex Raman spectra of crystal and amorphous states (glass and melt) are described. The results show that the temperature-dependent Raman spectra clearly indicate phase transition.The relative abundance of various kinds of SiO4 tetrahedrons (each Si binding to different numbers of bridging oxygens) can be qualitatively and quantitatively resolved as to be varied obviously with different temperatures.This shows that high-temperature Raman spectroscopy provides a useful tool for microstructure research under high temperature and helps to explain the properties of silicate glasses and melts.

  14. Microstructure and Raman spectra of Ag-MgF2 cermet films

    Institute of Scientific and Technical Information of China (English)

    Shouhua Shi(史守华); Zhuoliang Cao(曹卓良); Zhaoqi Sun(孙兆奇)

    2003-01-01

    Ag-MgF2 cermet films with different Ag fractions were prepared by vacuum evaporation. The microstruc-ture of the films was examined by Raman scattering technique. The surface-enhanced Raman spectrumfor MgF2 molecules in the cermet film strongly suggests the existence of Ag nanoparticles dispersed inMgF2 matrix. The intensities of the Raman spectra of Ag-MgF2 cermet films increase with Ag fraction.The enhancement of Raman scattering disappears when Ag content reaches wt.20%. The analyses withthe transmission electron microscopy showed that Ag-MgF2 cermet films are mainly composed of amor-phous MgF2 matrix with embedded faced-center-cubic Ag nanoparticles. It suggests that the percolationthreshold should be around wt.20% of Ag content.

  15. Resonance raman and absorption spectra of isomeric retinals in their lowest excited triplet states

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter; Jensen, N.-H.; Houee-Levin, C.

    1985-01-01

    implications about the size of the energy barriers separating the various triplet species are discussed. The resonance Raman spectra obtained by using either anthracene (ET = 177.7 kJ mol-1) or naphthalene (ET = 254.8 kJ mol-1) as sensitizers were virtually identical for the corresponding triplet states from...

  16. Raman spectroscopic characterization of the core-rim structure in reaction bonded boron carbide ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Jannotti, Phillip; Subhash, Ghatu, E-mail: subhash@ufl.edu [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611 (United States); Zheng, James Q.; Halls, Virginia [Program Executive Office—Soldier Protection and Individual Equipment, US Army, Fort Belvoir, Virginia 22060 (United States); Karandikar, Prashant G.; Salamone, S.; Aghajanian, Michael K. [M-Cubed Technologies, Inc., Newark, Delaware 19711 (United States)

    2015-01-26

    Raman spectroscopy was used to characterize the microstructure of reaction bonded boron carbide ceramics. Compositional and structural gradation in the silicon-doped boron carbide phase (rim), which develops around the parent boron carbide region (core) due to the reaction between silicon and boron carbide, was evaluated using changes in Raman peak position and intensity. Peak shifting and intensity variation from the core to the rim region was attributed to changes in the boron carbide crystal structure based on experimental Raman observations and ab initio calculations reported in literature. The results were consistent with compositional analysis determined by energy dispersive spectroscopy. The Raman analysis revealed the substitution of silicon atoms first into the linear 3-atom chain, and then into icosahedral units of the boron carbide structure. Thus, micro-Raman spectroscopy provided a non-destructive means of identifying the preferential positions of Si atoms in the boron carbide lattice.

  17. Lattice vibration frequencies in Raman spectra of manganese and rhenium decacarbonyls

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, V.E.; Danilov, I.Yu.; Zhidkov, L.L.; Kovalev, Yu.G.; Ioganson, A.A. (AN SSSR, Krasnoyarsk. Inst. Khimii i Khimicheskoj Tekhnologii)

    1983-06-01

    Raman spectra (RS) in the 170-10 cm/sup -1/ region of Mn/sub 2/(CO)/sub 10/, Re/sub 2/(CO)/sub 10/ polycrystal samples and their mixed crystals with different component percentage were obtained in the 296-123 K range. Investigations at low temperatures enabled to obtain most complete spectra in the given region. The spectra were separated to intramolecular and lattice ones on the basis of both comparing the spectra of pure components with those of mixed crystals, and studying the temperature behaviour of frequencies in the spectra. It was established that frequencies, placed below 60 cm/sup -1/ as well as in the region of 130-150 cm/sup -1/ in the spectra of manganese- and rhenium decacarbonyls are determined by the lattice vibrations of molecules in crystals.

  18. Calculation of Raman optical activity spectra for vibrational analysis.

    Science.gov (United States)

    Mutter, Shaun T; Zielinski, François; Popelier, Paul L A; Blanch, Ewan W

    2015-05-01

    By looking back on the history of Raman Optical Activity (ROA), the present article shows that the success of this analytical technique was for a long time hindered, paradoxically, by the deep level of detail and wealth of structural information it can provide. Basic principles of the underlying theory are discussed, to illustrate the technique's sensitivity due to its physical origins in the delicate response of molecular vibrations to electromagnetic properties. Following a short review of significant advances in the application of ROA by UK researchers, we dedicate two extensive sections to the technical and theoretical difficulties that were overcome to eventually provide predictive power to computational simulations in terms of ROA spectral calculation. In the last sections, we focus on a new modelling strategy that has been successful in coping with the dramatic impact of solvent effects on ROA analyses. This work emphasises the role of complementarity between experiment and theory for analysing the conformations and dynamics of biomolecules, so providing new perspectives for methodological improvements and molecular modelling development. For the latter, an example of a next-generation force-field for more accurate simulations and analysis of molecular behaviour is presented. By improving the accuracy of computational modelling, the analytical capabilities of ROA spectroscopy will be further developed so generating new insights into the complex behaviour of molecules.

  19. Vibrational analysis of various irotopes of L-alanyl-L-alanine in aqueous solution: Vibrational Absorption (VA), Vibrational Circular Dichroism (VCD), Raman and Raman Optical Activity (ROA) Spectra

    DEFF Research Database (Denmark)

    Jalkanen, Karl J.; Nieminen, R.M.; Knapp-Mohammady, M.;

    2003-01-01

    been reported. Subsequently, the vibrational absorption (VA) and vibrational circular dichroism (VCD) and the Raman and Raman Optical Activity (ROA) spectra have been reported. In this work an analysis of the aqueous solution VA, VCD, Raman, and ROA spectra for various isotopomers of LALA are reported....... DFT Becke3LYP/6-31G* theory has been used to determine the geometry, Hessian, atomic polar tensors (APT), and atomic axial tensors (AAT), and the electric dipole-electric dipole polarizability derivatives (EDEDPD), which are required for us to simulate the VA, VCD, and Raman spectra. The electric...... dipole-magnetic dipole polarizability derivatives (EDMDPD) and the electric dipole-electric cluadrapole polarizability derivatives (EDEQPD) have been calculated at the RHF/6-31G* level of theory, The VA, VCD, Raman, and ROA spectral simulations for the various isotoporners are compared...

  20. Quantum-based Molecular Dynamics Simulations of Shock-induced Reactions with Time-resolved Raman Spectra

    Science.gov (United States)

    Cawkwell, Marc; Sanville, Edward; Coe, Joshua; Niklasson, Anders

    2012-02-01

    Shock-induced reactions in liquid hydrocarbons have been studied using quantum-based, self-consistent tight-binding (SC-TB) molecular dynamics simulations with an accurate and transferable model for interatomic bonding. Our SC-TB code LATTE enables explicit simulations of shock compression using the universal liquid Hugoniot. Furthermore, the effects of adiabatic shock heating are captured precisely using Niklasson's energy conserving extended Lagrangian Born-Oppenheimer Molecular Dynamics formalism. We have been able to perform relatively large-scale SC-TB simulations by either taking advantage of the sparsity of the density matrix to achieve O(N) performance or by using graphics processing units to accelerate O(N^3) algorithms. We have developed the capability for the on-the-fly computation of Raman spectra from the Fourier transform of the polarizability autocorrelation function via the density matrix perturbation theory of Niklasson and Challacombe. These time-resolved Raman spectra enable us compare the results of our simulations with identical diagnostics collected experimentally. We will illustrate these capabilities with a series of simulations of shock-induced reaction paths in a number of simple molecules.

  1. In Situ Raman Spectra from the SeaCliff Hydrothermal Field (Gorda Ridge)

    Science.gov (United States)

    White, S. N.; Dunk, R. M.; Brewer, P. G.; Peltzer, E. T.; Sherman, A. D.; Freeman, J. J.

    2004-12-01

    MBARI's in situ laser Raman spectrometer (DORISS - Deep Ocean Raman In Situ Spectrometer) was deployed at the SeaCliff Hydrothermal Field on the Gorda Ridge in July 2004. The first in situ Raman spectra of hydrothermal minerals and high-temperature fluid venting from the seafloor were obtained. These spectra are analyzed and compared to laboratory measurements of samples collected from the site. Laser Raman spectroscopy is a proven, powerful geochemical technique for analyzing the chemical composition and molecular structure of solids, liquids, and gases. During an expedition to Gorda Ridge on the R/V Western Flyer in July 2004, DORISS was deployed successfully by the ROV Tiburon at hydrothermal vents on the seafloor ( ˜2700 m depth). Data were collected from hydrothermal fluids, chimney minerals (e.g., anhydrite and barite), and bacterial mats using two types of sampling optics: an immersion optic, and a non-contact optic. To collect spectra from opaque mineral samples, a precision underwater positioner (PUP) was used to position the DORISS probe head. PUP is a stand-alone, three degree-of-freedom positioner capable of moving the DORISS probe head with a precision of 0.1 mm (required by the small focal volume of the sampling optic). Raman spectra were collected of ˜300° C vent fluids with both sampling optics. The Raman spectrum of seawater contains bands from the bending ( ˜1640 cm-1) and stretching (3000-3700 cm-1) vibrational modes of the water molecule and a small peak from the S-O stretch of the sulfate ion ( ˜981 cm-1). Compared to ˜2° C ambient seawater, vent fluid spectra show changes in the intensity ratios of the water bands due to the elevated temperature, and the sulfate peak is reduced. Additional components of hydrothermal fluid are present in such low concentrations that it is difficult to detect them with the current Raman system. The chimneys in the SeaCliff field are primarily anhydrite, and debris in the area also contains barite. We were

  2. Resonance Raman scattering and excitonic spectra in TlInS{sub 2} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Zalamai, V.V. [Institute of Applied Physics, Academy of Sciences of Moldova, 5 Academy Street, 2028 Chisinau, Republic of Moldova (Moldova, Republic of); Stamov, I.G. [T.G. Shevchenko State University of Pridnestrovie, 25 Oktyabrya Street 107, 3300 Tiraspol, Republic of Moldova (Moldova, Republic of); Syrbu, N.N., E-mail: sirbunn@yahoo.com [Technical University of Moldova, 168 Stefan cel Mare Avenue, 2004 Chisinau, Republic of Moldova (Moldova, Republic of); Ursaki, V.V. [Institute of Applied Physics, Academy of Sciences of Moldova, 5 Academy Street, 2028 Chisinau, Republic of Moldova (Moldova, Republic of); Dorogan, V. [Technical University of Moldova, 168 Stefan cel Mare Avenue, 2004 Chisinau, Republic of Moldova (Moldova, Republic of)

    2015-04-15

    The excitons ground and excited states for E∥a and E∥b polarizations in absorption and reflection spectra of TlInS{sub 2} crystals were detected. The fundamental parameters of excitons and bands were determined at k=0. The resonance Raman spectra were investigated in the region of excitons transitions. The resonance Raman scattering spectra with participation of optical phonons that are active at the center of Brillouin zone were identified. The Raman scattering in Y(YX)Z and Y(ZX)Z geometries at 10 K with excitation by He–Ne laser was researched. Energies of phonons with A{sub g} and B{sub g} symmetries were determined. It was shown that the number of modes at 10 K was two times lower than expected according to theoretical calculations. - Highlights: • The resonance Raman scattering in geometry Y(YX)Z and Y(ZX)Z at 10 K was investigated. • Energies of phonons with A{sub g} and B{sub g} symmetries were determined. • The experimental and theoretical calculations completely conform if crystals are described by symmetry group D{sub 4h}{sup 15}. • The main parameters of excitons and bands were determined. • The model of electron transitions in k=0 was suggested.

  3. Biophotonics of skin: method for correction of deep Raman spectra distorted by elastic scattering

    Science.gov (United States)

    Roig, Blandine; Koenig, Anne; Perraut, François; Piot, Olivier; Gobinet, Cyril; Manfait, Michel; Dinten, Jean-Marc

    2015-03-01

    Confocal Raman microspectroscopy allows in-depth molecular and conformational characterization of biological tissues non-invasively. Unfortunately, spectral distortions occur due to elastic scattering. Our objective is to correct the attenuation of in-depth Raman peaks intensity by considering this phenomenon, enabling thus quantitative diagnosis. In this purpose, we developed PDMS phantoms mimicking skin optical properties used as tools for instrument calibration and data processing method validation. An optical system based on a fibers bundle has been previously developed for in vivo skin characterization with Diffuse Reflectance Spectroscopy (DRS). Used on our phantoms, this technique allows checking their optical properties: the targeted ones were retrieved. Raman microspectroscopy was performed using a commercial confocal microscope. Depth profiles were constructed from integrated intensity of some specific PDMS Raman vibrations. Acquired on monolayer phantoms, they display a decline which is increasing with the scattering coefficient. Furthermore, when acquiring Raman spectra on multilayered phantoms, the signal attenuation through each single layer is directly dependent on its own scattering property. Therefore, determining the optical properties of any biological sample, obtained with DRS for example, is crucial to correct properly Raman depth profiles. A model, inspired from S.L. Jacques's expression for Confocal Reflectance Microscopy and modified at some points, is proposed and tested to fit the depth profiles obtained on the phantoms as function of the reduced scattering coefficient. Consequently, once the optical properties of a biological sample are known, the intensity of deep Raman spectra distorted by elastic scattering can be corrected with our reliable model, permitting thus to consider quantitative studies for purposes of characterization or diagnosis.

  4. Infrared and Raman spectra, r0 structural parameters, conformational stability, and vibrational assignment of 2-cyanoethylamine

    Science.gov (United States)

    Durig, James R.; Darkhalil, Ikhlas D.; Klaassen, Joshua J.

    2012-09-01

    The infrared spectra (4000-200 cm-1) of the gas and solid and the Raman spectrum (4000-40 cm-1) of the liquid have been recorded. Vibrational fundamentals have been identified for four of the possible five stable conformers and complete vibrational assignments have been made for the Gg and Gt forms where the Capital G is for Gauche for the orientation around the Csbnd C bond and the lower cases g and t for gauche and trans orientation for the amine. These forms are the two lowest energy conformers. Vibrational assignments have been supported by MP2(full)/6-31G(d) ab initio calculations to predict harmonic force constants, fundamental frequencies, infrared intensities, Raman activities, and depolarization ratios. The conformational stabilities have been predicted from ab initio calculations utilizing several different basis sets up to aug-cc-pVTZ for both MP2(full) and density functional theory calculations by the B3LYP method. The enthalpy differences between the Gg and Gt conformers was determined to be 75 cm-1 and for the Gg to Tg form 333 cm-1. The r0 structural parameters have been obtained for the two most stable conformers from predicted parameters from ab initio MP2(full)/6-311+G(d,p) calculations adjusted to fit the previously reported microwave rotational constants. The determined heavy atom structural values for the Gg [Gt] conformer are: the distances (Å) N1sbnd C2 = 1.461(3) [1.453(3)], C2sbnd C3 = 1.535(3) [1.545(3)], C3sbnd C4 = 1.466(3) [1.463(3)], C4tbnd N5 = 1.161(3) [1.161(3)] and angles (°) ∠N1C2C3 = 109.5(5) [116.0(5)], ∠C2C3C4 = 111.1(5) [111.1(5)], ∠C3C4N5 = 177.4(5) [177.0(5)]. These parameters are compared to those estimated from the microwave study. The results are discussed and compared to the corresponding properties of some similar molecules.

  5. Resonance Raman spectra of phthalocyanine monolayers on different supports. A normal mode analysis of zinc phthalocyanine by means of the MNDO method

    NARCIS (Netherlands)

    Palys, Barbara J.; Ham, van den Dirk M.W.; Briels, Wim; Feil, Dirk

    1995-01-01

    Resonance Raman spectra of monolayers of transition metal phthalocyanines reveal specific interaction with the support. To elucidate its mechanism, Raman spectra of zinc phthalocyanine monolayers were studied. The analysis was based largely on the results of MNDO calculations. Calculated wavenumbers

  6. IR absorption and surface-enhanced Raman spectra of the isoquinoline alkaloid berberine

    Science.gov (United States)

    Strekal', N. D.; Motevich, I. G.; Nowicky, J. W.; Maskevich, S. A.

    2007-01-01

    We present the IR absorption and surface-enhanced Raman scattering (SERS) spectra of the isoquinoline alkaloid berberine adsorbed on a silver hydrosol and on the surface of a silver electrode for different potentials. Based on quantum chemical calculations, for the first time we have assigned the vibrations in the berberine molecule according to vibrational mode. The effect of the potential of the silver electrode on the geometry of sorption of the molecule on the surface is considered, assuming a short-range mechanism for enhancement of Raman scattering.

  7. Nonlinearity in Intensity versus Concentration Dependence for the Deep UV Resonance Raman Spectra of Toluene and Heptane

    DEFF Research Database (Denmark)

    Liu, Chuan; Berg, Rolf W.

    2013-01-01

    by absorption and Resonance Raman effects. Raman spectra of toluene and heptane mixtures - with progressively increasing concentrations of heptane - were measured by use of 229 nm excitation. The results show that the characteristic band intensities are not directly proportional to the relative concentrations...... of the compounds and deviate due to absorption resonance effects. An approximated mathematical model is developed to demonstrate that the intensities of the normal Raman scattering bands are suppressed. An inhibition coefficient Ki is introduced to describe the situation and determine the penetration depth. Most......The relation between Raman scattering, resonance Raman scattering and absorption is reviewed to see to what extent quantitative analysis can be applied in Resonance Raman spectroscopy. In addition to this it is demonstrated experimentally that normal Raman spectra can be dramatically inhibited...

  8. A study of hydrogen bonded vibrational spectra of (R)-(+)-Methylsuccinic acid, as aided by DFT dimer analysis

    Science.gov (United States)

    Tonannavar, J.; Chavan, Yashaswita B.; Yenagi, Jayashree

    2016-05-01

    Infrared and Raman spectral measurements in the region 4000-400 cm- 1 have been carried out for (R)-(+)-Methylsuccinic acid. The vibrational band structures near 3100-3040 cm- 1 in the IR and near 1650 cm- 1 in the Raman spectra have indicated the presence of an inter-molecular hydrogen bonding. A DFT dimer model has been proposed that involves O-H ⋯ OC type of hydrogen bonding. The proposed dimer model has been derived from the three stable monomers computed at RHF/3-21G and B3LYP/6-311 + G(d,p) levels of theory. A total of six dimer structures have been considered with a Boltzmann population of 38% for the most stable dimer and 62% for the remaining five dimer populations. A Boltzmann population weighted vibration spectrum has predicted bands, among others, for O-H ⋯ OC group that are in very good agreement with experiment. All the dimers have the same structure in that the two pairs of -O-H and -OC form a closed cyclic structure with a local center of inversion. This dimer geometry has given rise to one asymmetric mode at 1683 and one symmetric -CO mode at 1637 cm- 1 corresponding to mutually exclusive an experimental IR band at 1700 and a Raman band at 1651 cm- 1. Further, the bond length, H ⋯ O, for the most stable dimer is 1.686 Å, being shorter than the sums of van der Waals radii, 2.72 Å and the angle between O-H and H ⋯ O is almost linear (179°) suggesting that the hydrogen bonding is fairly strong.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    There are some discrepancies in both the vibrational assignments and in the metal-ligand (M-L) bond strengths predicted in the previous studies on the copper (II) chelated complex of dibenzoylmethane, Cu(dbm)2. Also, there is a lack of theoretical structure, Raman spectrum and full vibrational...... assignment for Cu(dbm)2 in the literatures. Density functional theory (DFT) at the B3LYP level and also MP2 calculations using different basis sets, besides Natural Bond Orbital (NBO) and Atoms-in-Molecules (AIM) analyses, have been employed to investigate the effect of methyl substitution with the phenyl...... group on the stabilities of bis(acetylacetonate) copper (II), Cu(acac)2, and Cu(dbm)2 complexes and the electron delocalization in their chelated rings. Measured solid phase infrared and Raman bands for Cu(dbm)2 complex have been interpreted in terms of the calculated vibrational modes and detailed...

  10. [Comparison and analysis of laser Raman spectra of common drinking water].

    Science.gov (United States)

    Yang, Chang-hu; Yuan, Jian-hui; Zeng, Xiao-ying

    2007-10-01

    In order to detect the drinking water quality in our country at the present time effectively, several brand brands of drinking water on the market and the distilled water that laboratory offered were measured and calculad were measured and calculated. The laser Raman spectra of samples were measured, while the sample's degree of degeneracy polarization at the symmetric stretching peak was calculated from the measurements. Results indicate that the relative intensity of the Raman spectrum and the degree of degeneracy polarization follow the same rule. Through comparison and analysis of the results of measurement and calculation, it is concluded that we can judge the relative content of mineral substance of drinking water by comparing the strengths of laser Raman spectrum characteristic peak and the magnitudes of the sample's degree of degeneracy polarization at the same characteristic peak. This conclusion will provide us a new and effective path to assaying the quality of drinking water. PMID:18306794

  11. [Raman spectra and its application of graphite enclaves in nephrite-jades in Xiuyan, Liaoning].

    Science.gov (United States)

    Qiu, Zhi-li; Jiang, Qi-yun; Luo, Han; Qin, She-cai; Li, Liu-fen

    2010-11-01

    Xiuyan, Liaoning was an important locality of jade material of the Red Mountain Culture in the Neolithic Age in Chinese history where there are two types of raw material of nephrite jades, namely gravel nephrite jade (Hemo Yu in Chinese) and old nephrite jade (Lao Yu in Chinese). In the present paper, Laser Raman spectrum technique was applied to analyze the graphite enclaves in the nephrite jades of the two types of materials. The results show that the graphite enclaves in the two types of jades have different characteristics of Raman spectra, indicating that they probably were formed under different geological conditions, or originated from different ore-forming periods or were exploited from different section of ore body. Hence, laser Raman spectrum technique could be used as a supplementary measure for nondestructive detection to determine the occurrence of jades.

  12. An Ab-Initio Calculation of Raman Spectra of Binary Sodium Silicates

    Institute of Scientific and Technical Information of China (English)

    尤静林; 蒋国昌; 侯怀宇; 陈辉; 吴永全; 徐匡迪

    2004-01-01

    Raman spectra of binary sodium silicates are calculated by self-consistent field (SCF) molecular orbital ab initio calculation of the quantum chemical method with several poly silicon-oxygen tetrahedral model clusters when both the basis sets of 6-31 G and 6-31 G(d) are applied. The symmetric stretching vibrational frequency of non-bridging oxygen in a high frequency range and its Raman optical activity and scattering cross section are deduced and analysed. The correlation between this vibrational Raman shift and its microscopic environment of the silicon-oxygen tetrahedron is found based on interior stress of configuration, which depends on the connecting topology of adjacent silicon-oxygen tetrahedra (SiOT). A newly established empirical stress index of tetrahedron is introduced to elucidate the above relationship.

  13. 食用植物油的激光喇曼光谱研究%Study on laser Raman spectra of edible vegetable oil

    Institute of Scientific and Technical Information of China (English)

    陈慰宗; 宋应谦; 忽满利; 高平安

    2001-01-01

    The vibration Raman spectra of molecular groups in edible vegetable oils were investigated by laser.The C=C double bond vibration Raman spectra in unsaturative fatty acids were observed and found it declined after the edible vegetable oils have been heated.%用激光喇曼光谱方法测量和研究了食用植物油中某些分子基团的振动谱线,观察到了不饱合脂肪酸中的C=C双键的振动喇曼谱线在油被长时间加热后减弱的现象。

  14. Experimental study of corrosion behavior for burnished aluminum alloy by EWF, EBSD, EIS and Raman spectra

    Energy Technology Data Exchange (ETDEWEB)

    Jinlong, Lv, E-mail: ljlhit@126.com [School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Xueyuan Road 37, Beijing, 100191 (China); Hongyun, Luo, E-mail: luo7128@163.com [School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Xueyuan Road 37, Beijing, 100191 (China); Jinpeng, Xie [School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Xueyuan Road 37, Beijing, 100191 (China)

    2013-05-15

    The effect of burnish process on 2024 aluminum alloy was studied by electron work function and electron backscattered diffraction (EBSD). Moreover, the corrosion resistance of thin passive films formed on 2024 aluminum alloy in borate buffer solutions was studied by the electrochemical impedance spectroscopy (EIS), the Mott–Schottky plots and the galvanostatic techniques. The composition of passive films was analyzed by Raman spectra. The results obtained indicated that the impedance increased due to burnish and this was attributed to decreased electron work function and higher current efficiency in the burnished aluminum alloy which led to thicker passive films. It was further supported by Raman spectra experiment. Moreover, the donor and acceptor concentration of passive films and their the semiconductor type have changed due to burnish.

  15. The use of near infrared Fourier Transform techniques in the study of surface enhanced Raman spectra

    Science.gov (United States)

    Fleischmann, M.; Sockalingum, D.; Musiani, M. M.

    Near infrared Fourier Transform Raman spectroscopy has been used to study the SERS of a number of electrode-solution interfaces. These measurements are illustrated by the following examples: the adsorption of pyridine on Ag, Cu and An surfaces; the adsorption of ferri- and ferrocyanide ions on An electrodes in two different support electrolytes; the behaviour of the corrosion inhibitors benzotriazole and 2-aminopyrimidine at Cu surfaces. Measurements of the DSERS spectra of pyridine at Ag electrodes and of normal Raman spectra of pyridine at Pt electrodes are also reported. The results are also compared with data taken by conventional methods in the visible region and the advantages of this newly developed technique are assessed.

  16. Raman spectra of bilayer graphene covered with Poly(methyl methacrylate) thin film

    OpenAIRE

    Minggang Xia; Zhidan Su; Shengli Zhang

    2012-01-01

    The Raman spectra of bilayer graphene covered with poly(methyl methacrylate) (PMMA) were investigated. Both the G and 2D peaks of PMMA-coated graphene were stiff and broad compared with those of uncovered graphene. This could be attributed to the residual strain induced by high-temperature baking during fabrication of the nanodevice. Furthermore, the two 2D peaks stiffened and broadened with increasing laser power, which is just the reverse to uncovered graphene. The stiffness is likely cause...

  17. Raman spectra of probably shock-metamorphosed zircon in structures of the Kola Peninsula

    Science.gov (United States)

    Kaulina, Tatiana; Nerovich, Luidmila; Lialina, Luidmila; Il'chenko, Vadim; Bocharov, Vladimir; Kunakkuzin, Evgeny

    2016-04-01

    Zircon crystals were studied by means of Raman spectroscopy from certain structures of the Kola Peninsula, for which impact events are expected according to geological and geochemical data: circular structure in Javrozersky area of the Tanaelv belt and granophyres of Jarva-Varaka layered massif of the Monchegorsky ore district. Zircons from anorthosites of the Javrozersky area showed some features of impact zircons: wavy extinction, blurred "aurora-like" CL image and a presence of additional bands in the Raman spectrum, which may indicate the presence of ZrSiO4 with the scheelite-type structure (reidite) surrounded by zircon material. Zircon crystals of Yavra-Varaka granophyres showed variation of Raman spectra from the core part of crystals with typical zircon Raman pattern to complete absence of spectral bands in the marginal parts and rims. There was also a transition zone between cores and marginal parts of crystals, where the Raman spectrum is "blurred". Such pattern may be associated with the transformation of crystalline zircon to diaplectic glass under the influence of shock metamorphism, since the Jarva-Varaka massif according to geological and geochemical data is compared with the Sudbury structure, for which impact origin is assumed. The work is supported by RSF grant N 16-17-10051.

  18. [Study on the infrared spectra and raman spectra of steel rusty layer with atmospheric corrosion].

    Science.gov (United States)

    Yang, Xiao-mei

    2006-12-01

    In the present study two methods, infrared and Raman spectral analyses, were used to measure the rusty layer of samples with atmospheric corrosion from Qingdao. The main component rust phase of the rusty layer was observed, showing that the relative content of the rust phase varies with the change in corrosion time. The main component rust phases of the rusty layer were found to be alpha-Fe2O3 , gamma-FeOOH, alpha-FeOOH, delta-FeOOH and Fe3O4, with the relative content of each rust phase of A3 (1) rusty layer sample exhibiting the following relation: gamma-FeOOH> alpha-FeOOH>delta-FeOOH, and the relative contents of other rusty layer samples were found to follow the relation: gamma-FeOOH> delta-FeOOH>alpha-FeOOH. PMID:17361722

  19. Raman and IR studies and DFT calculations of the vibrational spectra of 2,4-Dithiouracil and its cation and anion

    Science.gov (United States)

    Singh, R.; Yadav, R. A.

    2014-09-01

    Raman and FTIR spectra of solid 2,4-Dithiouracil (DTU) at room temperature have been recorded. DFT calculations were carried out to compute the optimized molecular geometries, GAPT charges and fundamental vibrational frequencies along with their corresponding IR intensities, Raman activities and depolarization ratios of the Raman bands for the neutral DTU molecule and its cation (DTU+) and anion (DTU-) using the Gaussian-03 software. Addition of one electron leads to increase in the atomic charges on the sites N1 and N3 and decrease in the atomic charges on the sites S8 and S10. Due to ionization of DTU molecule, the charge at the site C6 decreases in the cationic and anionic radicals of DTU as compared to its neutral species. As a result of anionic radicalization, the C5sbnd C6 bond length increases and loses its double bond character while the C4sbnd C5 bond length decreases. In the case of the DTU+ ion the IR and Raman band corresponding to the out-of-phase coupled Nsbnd H stretching mode is strongest amongst the three species. The anionic DTU radical is found to be the most stable. The two NH out-of-plane bending modes are found to originate due to out-of-phase and in-phase coupling of the two NH bonds in the anion and cation contrary to the case of the neutral DTU molecule in which the out-of-plane bending motions of the two NH bonds are not coupled.

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

    Science.gov (United States)

    Sahu, Nityananda; Gadre, Shridhar R.

    2016-03-01

    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, 310- and α-helix of acetyl(alanine)nNH2 (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-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)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.

  1. Manifestation of Structure of Electron Bands in Double-Resonant Raman Spectra of Single-Walled Carbon Nanotubes.

    Science.gov (United States)

    Stubrov, Yurii; Nikolenko, Andrii; Gubanov, Viktor; Strelchuk, Viktor

    2016-12-01

    Micro-Raman spectra of single-walled carbon nanotubes in the range of two-phonon 2D bands are investigated in detail. The fine structure of two-phonon 2D bands in the low-temperature Raman spectra of the mixture and individual single-walled carbon nanotubes is considered as the reflection of structure of their π-electron zones. The dispersion behavior of 2D band fine structure components in the resonant Raman spectra of single-walled carbon nanotube mixture is studied depending on the energy of excitating photons. The role of incoming and outgoing electron-phonon resonances in the formation of 2D band fine structure in Raman spectra of single-walled carbon nanotubes is analyzed. The similarity of dispersion behavior of 2D phonon bands in single-walled carbon nanotubes, one-layer graphene, and bulk graphite is discussed. PMID:26729220

  2. Fermi energy dependence of first- and second-order Raman spectra in graphene: Kohn anomaly and quantum interference effect

    Science.gov (United States)

    Hasdeo, Eddwi H.; Nugraha, Ahmad R. T.; Dresselhaus, Mildred S.; Saito, Riichiro

    2016-08-01

    Intensities of the first- and the second-order Raman spectra are calculated as a function of the Fermi energy. We show that the Kohn anomaly effect, i.e., phonon frequency renormalization, in the first-order Raman spectra originates from the phonon renormalization by the interband electron-hole excitation, whereas in the second-order Raman spectra, a competition between the interband and intraband electron-hole excitations takes place. By this calculation, we confirm the presence of different dispersive behaviors of the Raman peak frequency as a function of the Fermi energy for the first- and the second-order Raman spectra, as observed in some previous experiments. Moreover, the calculated results of the Raman intensity sensitively depend on the Fermi energy for both the first- and the second-order Raman spectra, indicating the presence of the quantum interference effect. The electron-phonon matrix element plays an important role in the intensity increase (decrease) of the combination (overtone) phonon modes as a function of the Fermi energy.

  3. FT-IR and FT-Raman spectra, normal coordinate analysis and ab initio computations of Trimesic acid.

    Science.gov (United States)

    Mahalakshmi, G; Balachandran, V

    2014-04-24

    The FT-IR and FT-Raman spectra have been recorded of Trimesic acid (1,3,5-benzenetricarboxylic acid, H3BTC). The molecular structure, conformational stability, geometry optimization, vibrational frequencies have been investigated. The total energy calculations of H3BTC were tried for various possible conformers. The spectra were interpreted with the aid of normal coordinate analysis based on ab initio Hartree-Fock (HF) and density functional theory (DFT/B3LYP) methods and 6-31+G(d,p) basis set level and was scaled using scale factors yielding good agreement between observed and calculated frequencies. Vibrational assignments and Natural bonding orbital (NBO) calculations are performed on the stable monomer of H3BTC using the same level of theory. Intramolecular hydrogen bond exists via COOH group gives the evidence for the formation of dimer entities in the title molecule. UV-VIS spectral analyses of H3BTC have been researched by theoretical calculations. In order to understand electronic transitions of the compound, TD-DFT calculations on electronic absorption spectra in gas phase and solvent (DMSO and Chloroform) were performed. The calculated frontier orbital energies, absorption wavelengths (λ), oscillator strengths (ƒ) and excitation energies (E) for gas phase and solvent (DMSO and Chloroform) are also illustrated. The statistical thermodynamic functions were obtained for the range of temperature 100-1000 K. Reliable vibrational modes associated with H3BTC are made on the basis of total energy distribution (TED) results obtained from scaled quantum mechanical (SQM) method. PMID:24508892

  4. Discriminating model for diagnosis of basal cell carcinoma and melanoma in vitro based on the Raman spectra of selected biochemicals

    Science.gov (United States)

    Silveira, Landulfo; Silveira, Fabrício Luiz; Bodanese, Benito; Zângaro, Renato Amaro; Pacheco, Marcos Tadeu T.

    2012-07-01

    Raman spectroscopy has been employed to identify differences in the biochemical constitution of malignant [basal cell carcinoma (BCC) and melanoma (MEL)] cells compared to normal skin tissues, with the goal of skin cancer diagnosis. We collected Raman spectra from compounds such as proteins, lipids, and nucleic acids, which are expected to be represented in human skin spectra, and developed a linear least-squares fitting model to estimate the contributions of these compounds to the tissue spectra. We used a set of 145 spectra from biopsy fragments of normal (30 spectra), BCC (96 spectra), and MEL (19 spectra) skin tissues, collected using a near-infrared Raman spectrometer (830 nm, 50 to 200 mW, and 20 s exposure time) coupled to a Raman probe. We applied the best-fitting model to the spectra of biochemicals and tissues, hypothesizing that the relative spectral contribution of each compound to the tissue Raman spectrum changes according to the disease. We verified that actin, collagen, elastin, and triolein were the most important biochemicals representing the spectral features of skin tissues. A classification model applied to the relative contribution of collagen III, elastin, and melanin using Euclidean distance as a discriminator could differentiate normal from BCC and MEL.

  5. Infrared and Raman spectroscopy and quantum chemistry calculation studies of C H⋯O hydrogen bondings and thermal behavior of biodegradable polyhydroxyalkanoate

    Science.gov (United States)

    Sato, Harumi; Dybal, Jiří; Murakami, Rumi; Noda, Isao; Ozaki, Yukihiro

    2005-06-01

    This review paper reports infrared (IR) and Raman spectroscopy and quantum chemistry calculation studies of C-H⋯O hydrogen bondings and thermal behavior of biodegradable polyhydroxyalkanoates. IR and Raman spectra were measured for poly(3-hydroxybutyrate) (PHB) and a new type of bacterial copolyester, poly(3-hydroxybutyrate- co-3-hydroxyhexanoate), P(HB- co-HHx) (HHx=12 mol%) over a temperature range of 20 °C to higher temperatures (PHB, 200 °C; HHx=12 mol%, 140 °C) to explore their structure and thermal behavior. One of bands due to the CH 3 asymmetric stretching modes appears near 3010 cm -1 in the IR and Raman spectra of PHB and P(HB- co-HHx) at 20 °C. These frequencies of IR and Raman CH 3 asymmetric stretching bands are much higher than usual. These anomalous frequencies of the CH 3 asymmetric stretching bands together with the X-ray crystallographic structure of PHB have suggested that there is an inter- or intra-molecular C-H⋯O hydrogen bond between the C dbnd6 O group in one helical structure and the CH 3 group in the other helical structure in PHB and P(HB- co-HHx). The quantum chemical calculation of model compounds of PHB also has suggested the existence of C-H⋯O hydrogen bonds in PHB and P(HB- co-HHx). It is very likely that a chain of C-H⋯O hydrogen bond pairs link two parallel helical structures in the crystalline parts. The temperature-dependent IR and Raman spectral variations have revealed that the crystallinity of P(HB- co-HHx) (HHx=12 mol%) decreases gradually from a fairly low temperature (about 60 °C), while the crystallinity of PHB remains almost unchanged until just below its melting temperature. It has also been found from the IR and Raman studies that for both PHB and P(HB- co-HHx) the weakening of the C-H⋯O hydrogen bonds starts from just above room temperature, but the deformation of helical structures occurs after the weakening of the C-H⋯O hydrogen bonds advances to some extent.

  6. Structural and spectroscopic study of a pectin isolated from citrus peel by using FTIR and FT-Raman spectra and DFT calculations

    Science.gov (United States)

    Bichara, Laura C.; Alvarez, Patricia E.; Fiori Bimbi, María V.; Vaca, Hugo; Gervasi, Claudio; Brandán, Silvia Antonia

    2016-05-01

    In this work, pectin isolated from citrus peel with a degree of esterification of 76% was characterized by Fourier Transform Infrared (FTIR) and Fourier Transform Raman (FT-Raman) spectroscopies. Structural studies were carried out taking into account their partial degree of esterification and considering the polygalacturonic acid chain as formed by two different subunits, one with both COOH and COOsbnd CH3 groups (Ac) and the other one as constituted by two subunits with two COOsbnd CH3 groups (Es). Their structural properties, harmonic frequencies, force fields and force constants in gas and aqueous solution phases were calculated by using the hybrid B3LYP/6-31G∗ method. Then, their complete vibrational analyses were performed by using the IR and Raman spectra accomplished with the scaled quantum mechanical (SQM) methodology. Reactivities and behaviors in both media were predicted for Ac and Es by using natural bond orbital (NBO), atoms in molecules (AIM), and frontier orbitals calculations. We report for first time the complete assignments of those two different units of polygalacturonic acid chain which are the 132 normal vibration modes of Ac and the 141 normal vibration modes of Es, combining the normal internal coordinates with the SQM methodology. In addition, three subunits were also studied. Reasonable correlations between the experimental and theoretical spectra were obtained. Thus, this work would allow the quick identification of pectin by using infrared and Raman spectroscopies and also provides new insight into the interactions that exist between subunits of a large pectin chain.

  7. Raman spectra and structure study of silicate glasses and their liquids

    Institute of Scientific and Technical Information of China (English)

    YOU Jinglin; JIANG Guochang; CHEN Hui; XU Kuangdi

    2006-01-01

    Stress index of tetrahedron (SIT) was defined to describe the topological connectivities among various silicon-oxygen tetrahedra (SiOT) in anionic clusters of binary silicate crystals, glasses, and melts. It was found that the value of SIT was well correlated with the wavenumber of Raman active symmetric stretching vibration of non-bridging oxygen of SiOT. The spatial fractional dimension of hyperfine structure was introduced while comparative analysis was made with the value of SIT. It can be concluded that the concepts of SIT, vibrational wavenumber, and spatial fractional dimension were inherently and holographically correlated and exhibit isomorphic representations of complex structure of binary silicates.Experimental Raman spectra of binary silicates with different alkali cations were investigated. It was demonstrated that alkali cations have little effect on the vibrational wavenumber of symmetric stretching of non-bridging oxygen (NBO) of SiOT, but remarkably affect its Raman active optical cross section, as was consensus resulted from ab initio calculation. It can also be concluded that the spatial fractional dimension of binary silicate is predominantly determined by the hyperfine structure of the anionic clusters and little affected by alkali cations, although the species of anionic clusters and their distributions were originally assigned by the content of alkali oxides. And Raman optical activity extinct effect of isolated SiOT at high basicity should be considered while being applied to quantitatively analysis.

  8. Density functional theory study, FT-IR and FT-Raman spectra and SQM force field calculation for vibrational analysis of 1, 3-Bis (hydroxymethyl) benzimidazolin-2-one

    Science.gov (United States)

    Joseph, Lynnette; Sajan, D.; Chaitanya, K.; Devarajegowda, H. C.; Isac, Jayakumary

    2013-10-01

    FT-IR and FT-Raman spectra of 1, 3-Bis (hydroxymethyl) benzimidazolin-2-one were recorded and analyzed in the solid phase. The optimized molecular geometry and vibrational wavenumbers have also been calculated in optimized structure by using DFT method. Scaled quantum mechanical force fields have also been used to calculate potential energy distributions in order to make conspicuous vibrational assignments. The red shifting of the Osbnd H stretching wavenumber is due to the formation of Osbnd H⋯O intermolecular hydrogen bonding. The lowering and splitting of the carbonyl stretching vibrational modes is assigned to the intermolecular association based on Cdbnd O⋯H type hydrogen bonding in the molecule. Chemical interpretation of hyperconjugative interactions was done by natural bond orbital analysis.

  9. In Situ Resonance Raman Spectra of Organic Pigments in Momo Coral

    Institute of Scientific and Technical Information of China (English)

    Fan Luwei; Yang Mingxing

    2008-01-01

    In this study, Raman scattering measurements were obtained for momo corals covering their typical range of colors. Three different excitation wavelengths (785, 633, 514 nm) are used for the same samples at the same points. All the samples show the two major Raman features of polyenic compounds assigned to double carbon-carbon (C=C) stretching vibration at approximately 1 500 cm-1 and single carbon-carbon (C--C) stretching vibration at approximately 1 130 cm-1 bond stretching mode. These peaks are not detected in the corresponding white parts of momo corals. However, somechanges in intensities, shape, and position of C=C stretching vibrations of the same point are observed by using different excitation wavelengths. The exact position of C-C stretching vibration of polyenic molecules depends strongly on the number of double bonds contained in their polyenic chain. In addition, the number of double bonds contained in the polyenic chains shows that different colors of the red momo coral are caused by different mixtures of polyenic compounds.

  10. Evaluation of Silver and Gold Nanoparticles on Polyester Fibers by Fluorescent Polarization Raman Spectra

    Directory of Open Access Journals (Sweden)

    V.M. Emelyanov

    2014-07-01

    Full Text Available The results of the validation of identification nanoparticle colloidal silver and gold on the polyester fibers on the background component of the Raman spectra in the control based on the polarization characteristics. The accuracy of identification of nanoparticles was evaluated by the joint probability of crossing normal scatter intensity distributions Raman spectrograms as silver nanoparticles and gold nanoparticles on polyester fibers, depending on the longitudinal and transverse polarization of the laser radiation on the entire range of wave numbers. Defined generalized parameter values common to distributions over the entire range for each wave numbers with the polarization of the laser and across the grain, and generalized reliability of the control and identification of nanoparticles of silver, gold for assessing the likelihood of the complete group of events. Set the sensitivity of detection reliability.

  11. The VA, VCD, Raman and ROA spectra of tri-L-serine in aqueous solution

    DEFF Research Database (Denmark)

    Jürgensen, Vibeke Würtz; Jalkanen, Karl J.

    2006-01-01

    investigated for one conformer, with the goal to determine which level of theory is appropriate to use in the systematic search of the conformational space. In addition, the effects of the counterion, here Cl- anion, are also investigated. Here we present the current state of the art in nanobiology, where......The structures of one conformer of the nonionic neutral and zwitterionic species of L-serinyl L-serinyl L-serine (SSS or tri-L-serine), together with its cationic and anionic species and the capped N-acetyl tri-L-serine N'-methylamide analog were optimized with density functional theory...... with the Becke 3LYP hybrid exchange correlation (XC) functional and the PW91 GGA XC functional and the 6-31G* and aug-cc-pVDZ basis sets. Subsequently, the vibrational absorption, vibrational circular dichroism, Raman and Raman optical activity spectra were simulated in order to compare them to experimentally...

  12. IR, Raman and SERS spectra of 2-(methoxycarbonylmethylsulfanyl)-3,5-dinitrobenzene carboxylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Raj, Asha [Government Polytechnic Coll., Attingal, Kerala (India). Dept. of Physics; Raju, K. [University College, Trivandrum, Kerala (India). Dept. of Physics; Varghese, Hema Tresa [Fatima Mata National Coll., Kollam, Kerala (India). Dept. of Physics; Granadeiro, Carlos M.; Nogueira, Helena I. S. [University of Aveiro (Portugal). Centro de Investigacao em Materiais Ceramicos e Compositos (CICECO). Dept. of Chemistry; Panicker, C. Yohannan [TKM College of Arts and Science, Kollam, Kerala (India). Dept. of Physics]. E-mail: cyphyp@rediffmail.com

    2009-07-01

    2-(Methoxycarbonylmethylsulfanyl)-3,5-dinitrobenzenecarboxylic acid was prepared by nucleophilic substitution. FT-IR and FT-Raman spectra of 2-(methoxycarbonylmethylsulfanyl)-3,5-dinitrobenzenecarboxylic acid were recorded and analyzed. Surface enhanced Raman scattering (SERS) spectrum was recorded on a silver colloid. The vibrational wavenumbers were computed by density functional theoretical (DFT) computations at the B3LYP/6-31G{sup *} level and they were found to be in good agreement with the experimental values. Significant metal-molecule interaction has been substantiated by the appearance of intense Ag-O mode in the SERS spectrum and this is indicative of the nearness of nitro and carbonyl group to the silver surface. SERS studies suggest a tilted orientation of the molecule at the metal surface. (author)

  13. Evaluation of human dentine demineralization of yellow race by Raman spectra

    Science.gov (United States)

    Zhan, Zhenlin; Guo, Wenqing; Liu, Haishan; Zhang, Xianzeng; Xie, Shusen

    2012-12-01

    The aim of this study is to evaluate the demineralization process in human dentine using Raman spectroscopy (RS). Nine human molars from Chinese subjects were cut into twelve tooth sections. The sections were painted with an acidresistant varnish leaving one dentine surface exposed and then immersed into 0.3% citric acid to simulate the oral natural demineralization. According to the acid-etch time, specimens were randomly divided into four groups: Ⅰ5 min, Ⅱ 10 min, Ⅲ 20 min and Ⅳ 40 min. Raman spectra were measured before and after each treatment. The result showed that no new bands, bands shifts, or disappearance of bands occurred in the whole process. However, the peak intensities of inorganic constituents decreased with the increase of acid-etch time, while the trends of organic constituents were opposite. In conclusion, RS could be able to efficiently monitor the demineralization status of human dentine.

  14. Calculation of the lattice dynamics and Raman spectra of copper zinc tin chalcogenides and comparison to experiments

    Science.gov (United States)

    Khare, Ankur; Himmetoglu, Burak; Johnson, Melissa; Norris, David J.; Cococcioni, Matteo; Aydil, Eray S.

    2012-04-01

    The electronic structure, lattice dynamics, and Raman spectra of the kesterite, stannite, and pre-mixed Cu-Au (PMCA) structures of Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) were calculated using density functional theory (DFT). Differences in longitudinal and transverse optical (LO-TO) splitting in kesterite, stannite, and PMCA structures can be used to differentiate them. The Γ-point phonon frequencies, which give rise to Raman scattering, exhibit small but measurable shifts, for these three structures. Experimentally measured Raman scattering from CZTS and CZTSe thin films were examined in light of DFT calculations and deconvoluted to explain subtle shifts and asymmetric line shapes often observed in CZTS and CZTSe Raman spectra. Raman spectroscopy in conjunction with ab initio calculations can be used to differentiate between kesterite, stannite, and PMCA structures of CZTS and CZTSe.

  15. Surface bonding on silicon surfaces as probed by tip-enhanced Raman spectroscopy

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Tip-enhanced Raman spectroscopy (TERS) has been used to obtain the Raman signal of surface species on silicon single crystal surfaces without the necessity for surface enhancement by addition of Ag nanoparticles. By illuminating the hydrogen terminated silicon surface covered with a droplet of 4-vinylpyridine with UV light, a 4-ethylpyridine modified silicon surface can be easily obtained. By bringing a scanning tunneling microscope (STM) Au tip with a nanoscale tip apex to a distance of ca. 1 nm from the modified silicon surface, enhanced Raman signals of the silicon phonon vibrations and the surface-bonded 4-ethylpyridine were obtained. The Raman enhancement factor was estimated to be close to 107. By comparing the surface enhanced Raman scattering (SERS) signal obtained after surface enhancement with Ag nanoparticles and the TERS signal of the surface, the advantage of TERS over SERS for characterizing the surface species on substrates becomes apparent: TERS readily affords vibrational information about the system without disturbing it by surface enhancement. In this sense, TERS can be considered a truly non-invasive tool which is ideal for characterizing the actual surface species on substrates.

  16. Influence of Co Content on Raman and Photoluminescence Spectra of Co Doped ZnO Nanowires

    Institute of Scientific and Technical Information of China (English)

    Y.Q. Chang; P.W. Wang; S.L. Ni; Y. Long; X.D. Li

    2012-01-01

    Co doped ZnO nanowires with different Co contents have been fabricated by a chemical vapor deposition method. X-ray diffraction results show that all the samples are of single phase and crystallize in wurtzite ZnO structure. The lattice parameter a increases with increasing Co content, while the parameter c has no obvious change with increasing Co. Raman spectra show that the nonpolar E2(High) mode becomes broad and weak with the doping of Co, which indicates that the incorporation of Co causes structural disorder in the crystalline columnar ZnO lattice. The photolurninescence spectra exhibit that the position of the ultraviolet emission shifts to short wavelength and the intensity decreases with increasing Co. The green emission is affected by two contrary factors. It is increased by the introduced defects, but suppressed by the interaction between Co doping and native defects and the later affects it more significantly.

  17. Comparison of Surface-enhanced Raman Scattering Spectra of Two Kinds of Silver Nanoplate Films

    Institute of Scientific and Technical Information of China (English)

    TAO Jin-long; TANG Bin; XU Shu-ping; PAN Ling-yun; XU Wei-qing

    2012-01-01

    Surface-enhanced Raman scattering(SERS) spectra of different silver nanoplate self-assembled films at different excitation wavelengths were fairly compared.Shape conversion from silver nanoprisms to nanodisks on slides was in situ carried out.The SERS spectra of 4-mercaptopyridine(4-MPY) on these anisotropic silver nanoparticle self-assembled films present that strong enhancement appeared when the excitation line and the surface plasmon resonance(SPR) band of silver substrate overlapped.In this model,the influence of the crystal planes of silver nanoplates on SERS enhancement could be ignored because the basal planes were nearly unchanged in two kinds of silver nanoplate self-assembled films.

  18. Raman spectra of bixbyite, Mn2O3, up to 40 GPa

    Science.gov (United States)

    Shim, S.-H.; Labounty, D.; Duffy, T. S.

    2011-10-01

    The Raman spectra of bixbyite, Mn2O3, were measured up to 40 GPa at room temperature. Mn2O3 undergoes a phase transition from the C-type rare earth structure to the CaIrO3-type (post-perovskite) structure at 16-25 GPa. The transition pressure measured in Raman spectroscopy is significantly lower than the pressure reported previously by an X-ray diffraction study. This could be due to the greater polarizability in the CaIrO3-type structure, consistent with high-pressure observation on the CaIrO3 type in MgGeO3, although it is still possible that experimental differences may cause the discrepancy. Unlike the change at the perovskite to CaIrO3-type transition, the spectroscopic Grüneisen parameter does not decrease at the C-type to CaIrO3-type transition. The spectroscopic Grüneisen parameter of the low-pressure phase (C type) is significantly lower than thermodynamic Grüneisen parameter, suggesting significant magnetic contributions to the thermodynamic property of this material. Our Raman measurements on CaIrO3-type Mn2O3 contribute to building systematic knowledge about this structure, which has emerged as one of the common structures found in geophysically important materials.

  19. Time-dependent wave packet averaged vibrational frequencies from femtosecond stimulated Raman spectra

    Science.gov (United States)

    Wu, Yue-Chao; Zhao, Bin; Lee, Soo-Y.

    2016-02-01

    Femtosecond stimulated Raman spectroscopy (FSRS) on the Stokes side arises from a third order polarization, P(3)(t), which is given by an overlap of a first order wave packet, |" separators=" Ψ2 ( 1 ) ( p u , t ) > , prepared by a narrow band (ps) Raman pump pulse, Epu(t), on the upper electronic e2 potential energy surface (PES), with a second order wave packet, resembles the zeroth order wave packet |" separators=" Ψ1 ( 0 ) ( t ) > on the lower PES spatially, but with a force on |" separators=" Ψ2 ( 1 ) ( p u , t ) > along the coordinates of the reporter modes due to displacements in the equilibrium position, so that . The observable FSRS Raman gain is related to the imaginary part of P(3)(ω). The imaginary and real parts of P(3)(ω) are related by the Kramers-Kronig relation. Hence, from the FSRS Raman gain, we can obtain the complex P(3)(ω), whose Fourier transform then gives us the complex P(3)(t) to analyze for ω ¯ j ( t ) . We apply the theory, first, to a two-dimensional model system with one conformational mode of low frequency and one reporter vibrational mode of higher frequency with good results, and then we apply it to the time-resolved FSRS spectra of the cis-trans isomerization of retinal in rhodopsin [P. Kukura et al., Science 310, 1006 (2005)]. We obtain the vibrational frequency up-shift time constants for the C12-H wagging mode at 216 fs and for the C10-H wagging mode at 161 fs which are larger than for the C11-H wagging mode at 127 fs, i.e., the C11-H wagging mode arrives at its final frequency while the C12-H and C10-H wagging modes are still up-shifting to their final values, agreeing with the findings of Yan et al. [Biochemistry 43, 10867 (2004)].

  20. Study on UV, IR and NMR Spectra of Double Hydrogen-bonded Complexes

    Institute of Scientific and Technical Information of China (English)

    ZHU Liang-Liang; TENG Qi-Wen; WU Shi

    2006-01-01

    AM1, PM3 and DFT methods were used to study on the hydrogen-bonded dimer of melamine and [1,3] dioxane-2,4,6-trione. The electronic spectra, IR and NMR spectra of some complexes were calculated with INDO/SCI, AM1 and B3LYP/6-31G(d) methods, respectively. It is demonstrated that the negative stability energy is responsible for the formation of the complexes. Stabilization energies of these complexes were altered among the variations of electric property and steric effects of the monomers. HOMO-LUMO energy gaps were shrunk and the blue-shift of absorptions in the electronic spectra occurred. The vibrations of N-H bonds and chemical shifts of the protons changed with the formation of hydrogen bonds.

  1. Efficient "on-the-fly" calculation of Raman spectra from \\textit{ab-initio} molecular dynamics: Application to hydrophobic/hydrophilic solutes in bulk water

    CERN Document Server

    Partovi-Azar, Pouya

    2015-01-01

    We present a computational method to accurately calculate Raman spectra from first principles with an at least one order of magnitude higher efficiency. This scheme thus allows to routinely calculate finite-temperature Raman spectra "on-the-fly" by means of \\textit{ab-initio} molecular dynamics simulations. To demonstrate the predictive power of this approach we investigate the effect of hydrophobic and hydrophilic solutes in water solution on the infrared and Raman spectra.

  2. Observation and analysis of Fano-like lineshapes in the Raman spectra of molecules adsorbed at metal interfaces

    Science.gov (United States)

    Dey, S.; Banik, M.; Hulkko, E.; Rodriguez, K.; Apkarian, V. A.; Galperin, M.; Nitzan, A.

    2016-01-01

    Surface-enhanced Raman scattering (SERS) from bipyridyl ethylene adsorbed on gold dumbbells shows Fano-like spectra at high incident light intensity. This is accompanied by an increased electronic temperature, while no vibrational anti-Stokes scattering is observed. Theory indicates that interference between vibrational and electronic Raman scattering can yield such asymmetric scattering lineshapes. The best fit to observations is however obtained by disregarding this coupling and accounting for the detailed lineshape of the continuous electronic component of the SERS.

  3. Observation and analysis of Fano-like lineshapes in the Raman spectra of molecules adsorbed at metal interfaces

    OpenAIRE

    Dey, S; Banik, M; Hulkko, E.; Rodriguez, K.; Apkarian, V. A.; Galperin, M.; Nitzan, A.

    2015-01-01

    Surface enhanced Raman spectra from molecules (bipyridyl ethylene) adsorbed on gold dumbells are observed to become increasingly asymmetric (Fano-like) at higher incident light intensity. The electronic temperature (inferred from the anti-Stokes (AS) electronic Raman signal increases at the same time while no vibrational AS scattering is seen. These observations are analyzed by assuming that the molecule-metal coupling contains an intensity dependent contribution (resulting from light-induced...

  4. Characterizing variability in in vivo Raman spectra of different anatomical locations in the upper gastrointestinal tract toward cancer detection

    Science.gov (United States)

    Bergholt, Mads Sylvest; Zheng, Wei; Lin, Kan; Ho, Khek Yu; Teh, Ming; Yeoh, Khay Guan; So, Jimmy Bok Yan; Huang, Zhiwei

    2011-03-01

    Raman spectroscopy is an optical vibrational technology capable of probing biomolecular changes of tissue associated with cancer transformation. This study aimed to characterize in vivo Raman spectroscopic properties of tissues belonging to different anatomical regions in the upper gastrointestinal (GI) tract and explore the implications for early detection of neoplastic lesions during clinical gastroscopy. A novel fiber-optic Raman endoscopy technique was utilized for real-time in vivo tissue Raman measurements of normal esophageal (distal, middle, and proximal), gastric (antrum, body, and cardia) as well as cancerous esophagous and gastric tissues from 107 patients who underwent endoscopic examinations. The non-negativity-constrained least squares minimization coupled with a reference database of Raman active biochemicals (i.e., actin, histones, collagen, DNA, and triolein) was employed for semiquantitative biomolecular modeling of tissue constituents in the upper GI. A total of 1189 in vivo Raman spectra were acquired from different locations in the upper GI. The Raman spectra among the distal, middle, and proximal sites of the esophagus showed no significant interanatomical variability. The interanatomical variability of Raman spectra among normal gastric tissue (antrum, body, and cardia) was subtle compared to cancerous tissue transformation, whereas biomolecular modeling revealed significant differences between the two organs, particularly in the gastroesophageal junction associated with proteins, DNA, and lipids. Cancerous tissues can be identified across interanatomical regions with accuracies of 89.3% [sensitivity of 92.6% (162/175) specificity of 88.6% (665/751)], and of 94.7% [sensitivity of 90.9% (30/33) specificity of 93.9% (216/230)] in the gastric and esophagus, respectively, using partial least squares-discriminant analysis together with the leave-one tissue site-out, cross validation. This work demonstrates that Raman endoscopy technique has

  5. The Utilization of Low Frequency Raman Spectra of Gases for the Study of Molecules with Large Amplitude Vibration

    Institute of Scientific and Technical Information of China (English)

    James R. Durig; Sarah Xiao-hua Zhou; Joshua Klaassen; Arindam Ganguly

    2009-01-01

    The utilization of the Raman spectra of the low frequency bending mode for three quasi-linear molecules, disiloxane, (SiH3)2 O; methylisocyanate, CH3NCO; and dimethy lisocyanate, (CH3)2SiHNCO for observing the low frequency anharmonic bending vibration is demonstrated which is superior to the corresponding far infrared spectra. From the observed frequencies from the Raman spectra the potential function governing the heavy atom motion to linearity has been obtained from which the barrier has been determined. These experimental values are compared to the ab ini-tio predicted values. Also low frequency Raman spectra of the ring puckering vibration of chlorocy-clobutane, c-C4H7Cl, bromocyclobutane, c-C4H7Br, and aminocyclobutane, c-C4H7NH2, have been utilized to obtain the potential function governing the ring inversion for these molecules. The deter-mined barriers to planarity are compared to those obtained from MP2 (full) ab initio and density functional theory B3LYP calculations by utilizing a variety of basis sets. For all of these studies it is shown that the Raman spectra are superior to the infrared spectra for determining the frequencies of the excited state transitions.

  6. Optimum Metallic-Bond Scheme: A Quantitative Analysis of Mass Spectra of Sodium Clusters

    Institute of Scientific and Technical Information of China (English)

    苏长荣; 李家明

    2001-01-01

    Based on the results of the optimum metallic-bond scheme for sodium clusters, we present a quantitative analysis of the detailed features of the mass spectra of sodium clusters. We find that, in the generation of sodium clusters with various abundances, the quasi-steady processes through adding or losing a sodium atom dominate. The quasi-steady processes through adding or losing a sodium dimer are also important to understand the detailed features of mass spectra for small clusters.

  7. DFT study of structure, IR and Raman spectra of the first generation dendron built from cyclotriphosphazene core with terminal carbamate and ester groups

    Science.gov (United States)

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

    2012-06-01

    The FTIR and FT-Raman spectra of the first generation dendron built from the cyclotriphosphazene core, five arms sbnd Osbnd C6H4sbnd CHdbnd Nsbnd N(CH3)sbnd P(S)rbond2 with ten carbamate terminal groups and one ester function Gv1 have been recorded. The IR and Raman spectra of the zero generation dendron Gv0 and first generation dendrimer G1 with the same core and terminal groups were also examined. The structural optimization and normal mode analysis were performed for dendron Gv1 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 Gv1 has a concave lens structure with planar sbnd Osbnd C6H4sbnd CHdbnd Nsbnd N(CH3)sbnd P(S)rbond2 fragments and slightly non-planar cyclotriphosphazene core. The carbamate groups attached to different arms show significant deviations from a symmetrical arrangement relative to the local planes of repeating units. The experimental IR spectrum of Gv1 dendron was interpreted by means of potential energy distributions. The strong band 1604 cm-1 shows marked changes of the optical density in dependence of the carbamate, ester or azomethyne substituents in the aromatic ring. The frequencies of ν(Nsbnd H) and ν(Cdbnd O) bands in the IR spectra reveal the presence of the different types of H-bonds in the studied dendrimers.

  8. Raman Spectra of Luminescent Graphene Oxide (GO-Phosphor Hybrid Nanoscrolls

    Directory of Open Access Journals (Sweden)

    Janardhanan. R. Rani

    2015-12-01

    Full Text Available Graphene oxide (GO-phosphor hybrid nanoscrolls were synthesized using a simple chemical method. The GO-phosphor ratio was varied to find the optimum ratio for enhanced optical characteristics of the hybrid. A scanning electron microscope analysis revealed that synthesized GO scrolls achieved a length of over 20 μm with interior cavities. The GO-phosphor hybrid is extensively analyzed using Raman spectroscopy, suggesting that various Raman combination modes are activated with the appearance of a low-frequency radial breathing-like mode (RBLM of the type observed in carbon nanotubes. All of the synthesized GO-phosphor hybrids exhibit an intense luminescent emission around 540 nm along with a broad emission at approximately 400 nm, with the intensity ratio varying with the GO-phosphor ratio. The photoluminescence emissions were gauged using Commission Internationale d'Eclairage (CIE coordinates and at an optimum ratio. The coordinates shift to the white region of the color spectra. Our study suggests that the GO-phosphor hybrid nanoscrolls are suitable candidates for light-emitting applications.

  9. Raman spectra of bilayer graphene covered with Poly(methyl methacrylate thin film

    Directory of Open Access Journals (Sweden)

    Minggang Xia

    2012-09-01

    Full Text Available The Raman spectra of bilayer graphene covered with poly(methyl methacrylate (PMMA were investigated. Both the G and 2D peaks of PMMA-coated graphene were stiff and broad compared with those of uncovered graphene. This could be attributed to the residual strain induced by high-temperature baking during fabrication of the nanodevice. Furthermore, the two 2D peaks stiffened and broadened with increasing laser power, which is just the reverse to uncovered graphene. The stiffness is likely caused by graphene compression induced by the circular bubble of the thin PMMA film generated by laser irradiation. Our findings may contribute to the application of PMMA in the strain engineering of graphene nanodevices.

  10. Comparative Analysis of Temperature-dependent .Raman Spectra of GaN and GaN/Mg Films

    Institute of Scientific and Technical Information of China (English)

    WANG Rui-min; CHEN Guang-de; LIN J.-Y.,; JIANG H.-X.

    2006-01-01

    The Raman spectra of unintentionally doped gallium nitride (GaN) and Mg-doped GaN films were investigated and compared at room temperature and low temperature.The differences of E2 and AI(LO) mode in two samples are discussed.Stress relaxation is observed in Mg-doped GaN,and it is suggested that Mg-induced misfit dislocation and electron-phonon interaction are the possible origins.A peak at 247 cm-1 is observed in both the Raman spectra of GaN and Mg-doped GaN.Temperature-dependent Raman scattering experiment of Mgdoped GaN shows the frequency and intensity changes of this peak with temperature.This peak is attributed to the defect-induced vibrational mode.

  11. A study of the experimental and theoretical infrared, Raman, 1H and 13C NMR spectra of the biochemicals valeric and valproic acids

    Science.gov (United States)

    Badawi, Hassan M.; Förner, Wolfgang; Ali, Shaikh A.

    2014-10-01

    The structural stability, vibrational, 1H and 13C NMR spectra of valeric and valproic acids were investigated by the B3LYP calculations with the 6-311G** basis set. Valeric acid is predicted to exist predominantly in the planar cis form (80% abundance). Valproic acid is predicted to have an equilibrium mixture of 68% gauche-1 and 32% gauche-2 structures at 298.15 K. The spectral feature of the Osbnd H stretching mode in the infrared spectra of both acids suggests the presence of strong H-bonding in the condensed phase of valeric acid and weak H-bonding in the case of valproic acid. The harmonic and anharmonic vibrational wavenumbers were computed at the B3LYP level of theory and tentative vibrational assignments were provided on the basis of combined theoretical and experimental infrared and Raman data of the molecules. Not all of the calculated anharmonic wavenumbers showed a consistent trend with the observed wavenumbers. The 1H and 13C NMR spectra of both acids were interpreted by experimental and DFT calculated chemical shifts of the two acids. The RMSD between experimental and theoretical 1H and 13C chemical shifts for valeric acid is 1.8 and 3.8 ppm, whereas for valproic acid, it is 1.4 and 4.5 ppm, respectively.

  12. Assessing Polarizability Models for the Simulation of Low-Frequency Raman Spectra of Benzene.

    Science.gov (United States)

    Bender, John S; Coasne, Benoit; Fourkas, John T

    2015-07-23

    Optical Kerr effect (OKE) spectroscopy is a widely used technique for probing the low-frequency, Raman-active dynamics of liquids. Although molecular simulations are an attractive tool for assigning liquid degrees of freedom to OKE spectra, the accurate modeling of the OKE and the motions that contribute to it relies on the use of a realistic and computationally tractable molecular polarizability model. Here we explore how the OKE spectrum of liquid benzene, and the underlying dynamics that determines its shape, are affected by the polarizability model employed. We test a molecular polarizability model that uses a point anisotropic molecular polarizability and three other models that distribute the polarizability over the molecule. The simplest and most computationally efficient distributed polarizability model tested is found to be sufficient for the accurate simulation of the many-body polarizability dynamics of this liquid. We further find that the atomic-to-molecular polarizability transformation approximation [Hu et al. J. Phys. Chem. B 2008, 112, 7837-7849], used in conjunction with this distributed polarizability model, yields OKE spectra whose shapes differ negligibly from those calculated without this approximation, providing a substantial increase in computational efficiency.

  13. Accurate Simulation of Resonance-Raman Spectra of Flexible Molecules: An Internal Coordinates Approach.

    Science.gov (United States)

    Baiardi, Alberto; Bloino, Julien; Barone, Vincenzo

    2015-07-14

    The interpretation and analysis of experimental resonance-Raman (RR) spectra can be significantly facilitated by vibronic computations based on reliable quantum-mechanical (QM) methods. With the aim of improving the description of large and flexible molecules, our recent time-dependent formulation to compute vibrationally resolved electronic spectra, based on Cartesian coordinates, has been extended to support internal coordinates. A set of nonredundant delocalized coordinates is automatically generated from the molecular connectivity thanks to a new general and robust procedure. In order to validate our implementation, a series of molecules has been used as test cases. Among them, rigid systems show that normal modes based on Cartesian and delocalized internal coordinates provide equivalent results, but the latter set is much more convenient and reliable for systems characterized by strong geometric deformations associated with the electronic transition. The so-called Z-matrix internal coordinates, which perform well for chain molecules, are also shown to be poorly suited in the presence of cycles or nonstandard structures.

  14. Discriminating adenocarcinoma from normal colonic mucosa through deconvolution of Raman spectra

    Science.gov (United States)

    Cambraia Lopes, Patricia; Moreira, Joaquim Agostinho; Almeida, Abilio; Esteves, Artur; Gregora, Ivan; Ledinsky, Martin; Lopes, Jose Machado; Henrique, Rui; Oliveira, Albino

    2011-12-01

    In this work, we considered the feasibility of Raman spectroscopy for discriminating between adenocarcinomatous and normal mucosal formalin-fixed colonic tissues. Unlike earlier studies in colorectal cancer, a spectral deconvolution model was implemented to derive spectral information. Eleven samples of human colon were used, and 55 spectra were analyzed. Each spectrum was resolved into 25 bands from 975 to 1720 cm-1, where modes of proteins, lipids, and nucleic acids are observed. From a comparative study of band intensities, those presenting higher differences between tissue types were correlated to biochemical assignments. Results from fitting procedure were further used as inputs for linear discriminant analysis, where combinations of band intensities and intensity ratios were tested, yielding accuracies up to 81%. This analysis yields objective discriminating parameters after fitting optimization. The bands with higher diagnosis relevance detected by spectra deconvolution enable to confine the study to some spectral regions instead of broader ranges. A critical view upon limitations of this approach is presented, along with a comparison of our results to earlier ones obtained in fresh colonic tissues. This enabled to assess the effect of formalin fixation in colonic tissues, and determine its relevance in the present analysis.

  15. Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques.

    Science.gov (United States)

    Singh, Gurpreet; Mohanty, B P; Saini, G S S

    2016-02-15

    Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide.

  16. Polysulfide anions II: structure and vibrational spectra of the S4(2-) and S5(2-) anions. Influence of the cations on bond length, valence, and torsion angle.

    Science.gov (United States)

    el Jaroudi, O; Picquenard, E; Demortier, A; Lelieur, J P; Corset, J

    2000-06-12

    The influence of the cations on bond length, valence, and torsion angle of S4(2-) and S5(2-) anions was examined in a series of solid alkali tetra- and pentasulfides by relating their Raman spectra to their known X-ray structures through a force-field analysis. The IR and Raman spectra of BaS4.H2O and the Raman spectra of (NH4)2S4.nNH3, gamma-Na2S4, and delta-Na2S5 are presented. The similarity of spectra of gamma-Na2S4 with those of BaS4.H2O suggests similar structures of the S4(2-) anions in these two compounds with a torsion angle smaller than 90 degrees. The variations of SS bond length, SSS valence angle, and dihedral angle of Sn2- anions are related to the polarization of the lone pair and electronic charge of the anion by the electric field of the cations. A correlation between the torsion angle and the SSS valence angle is shown as that previously reported between the length of the bond around which the torsion takes place and the dihedral angle value. These geometry changes are explained by the hyperconjugation concept and the electron long-pair repulsion.

  17. Effects of high pressure on the Raman and fluorescence emission spectra of two novel 1,3,4-oxadiazole derivatives

    Institute of Scientific and Technical Information of China (English)

    Luo Ji-Feng; Tang Ben-Chen; Gao Chun-Xiao; Li Min; Han Yong-Hao; Zou Guang-Tian

    2005-01-01

    The effects of pressure on the fluorescence emission and Raman spectra of 1,4-bis[(4-methyloxyphenyl)-1,3,4-oxadiazolyl]- 2,5-bisheptyloxyphenylene (OXD-2) and on the fluorescence emission spectra of 1,4-bis[(4-methylphenyl)-1,3,4-oxadiazolyl]phenylene (OXD-1) are investigated using a diamond anvil cell. With the increase of pressure, the intensity of the fluorescence emission increases and reaches maxima at 13GPa for OXD-1 and at 9.6GPa for OXD-2.The effect of pressure on the peak position of the emission shows a similar trend, red shift with the increase of pressure.But at higher pressures, the intensity of emission drops down dramatically. The Raman spectra of OXD-2 indicate that there appears a structural change at ca 3GPa.

  18. Chiral asymmetry of anti-symmetric coordinates studied by the Raman differential bond polarizability of S-phenylethylamine

    Institute of Scientific and Technical Information of China (English)

    Shen Hong-Xia; Wu Guo-Zhen; Wang Pei-Jie

    2012-01-01

    The Raman optical activity (ROA) study on S-phenylethylamine is presented by the intensity analyses via bond polarizability and differential bond polarizability.Ample information concerning the physical picture of this chiral system is obtained,and its ROA mechanism is constructed.Especially,we propose that the asymmetric modes and/or the off-diagonal elements of the electronic polarizability tensor are the potential keys to the exploration of ROA.

  19. Dependence of Raman and absorption spectra of stacked bilayer MoS2 on the stacking orientation.

    Science.gov (United States)

    Park, Seki; Kim, Hyun; Kim, Min Su; Han, Gang Hee; Kim, Jeongyong

    2016-09-19

    Stacked bilayer molybdenum disulfide (MoS2) exhibits interesting physical properties depending on the stacking orientation and interlayer coupling strength. Although optical properties, such as photoluminescence, Raman, and absorption properties, are largely dependent on the interlayer coupling of stacked bilayer MoS2, the origin of variations in these properties is not clearly understood. We performed comprehensive confocal Raman and absorption mapping measurements to determine the dependence of these spectra on the stacking orientation of bilayer MoS2. The results indicated that with 532-nm laser excitation, the Raman scattering intensity gradually increased upon increasing the stacking angle from 0° to 60°, whereas 458-nm laser excitation resulted in the opposite trend of decreasing Raman intensity with increasing stacking angle. This opposite behavior of the Raman intensity dependence was explained by the varying resonance condition between the Raman excitation wavelength and C exciton absorption energy of bilayer MoS2. Our work sheds light on the intriguing effect of the subtle interlayer interaction in stacked MoS2 bilayers on the resulting optical properties.

  20. 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.

  1. Depth profile study on Raman spectra of high-energy-electron-irradiated hydrogenated amorphous silicon films

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    According to the different penetration depths for the incident lights of 472 nm and 532 nm in hydrogenated amorphous silicon (a-Si:H) thin films, the depth profile study on Raman spectra of a-Si:H films was carried out. The network ordering evolution in the near surface and interior region of the unirradiated and irradiated a-Si:H films was investigated. The results show that there is a structural improvement in the shortand intermediate-range order towards the surface of the unirradiated a-Si:H films. The amorphous silicon network in the near and interior region becomes more disordered on the shortand intermediate-range scales after being irradiated with high energy electrons. However, the surface of the irradiated films becomes more disordered in comparison with their interior region, indicating that the created defects caused by electron irradiation are concentrated in the near surface of the irradiated films. Annealing eliminates the irradiation effects on a-Si:H thin films and the structural order of the irradiated films is similar to that of the unirradiated ones after being annealed. There exists a structural improvement in the shortand intermediate-range order towards the surface of the irradiated a-Si:H films after being annealed.

  2. Revised vibrational band assignments for the experimental IR and Raman spectra of 2,3,4-trifluorobenzonitrile based on ab initio, DFT and normal coordinate calculations

    Science.gov (United States)

    Hiremath, C. S.; Kalkoti, G. B.; Aralakkanavar, M. K.

    2009-09-01

    In the present study, a systematic vibrational spectroscopic investigation for the experimental IR and Raman spectra of 2,3,4-trifluorobenzonitrile (TFB), aided by electronic structure calculations has been carried out. The electronic structure calculations - ab initio (RHF) and hybrid density functional methods (B3LYP) - have been performed with 6-31G* basis set. Molecular equilibrium geometries, electronic energies, IR intensities, harmonic vibrational frequencies, depolarization ratios and Raman activities have been computed. The results of the calculations have been used to simulate IR and Raman spectra for TFB that showed excellent agreement with the observed spectra. Potential energy distribution (PED) and normal mode analysis have also been performed. The assignments proposed based on the experimental IR and Raman spectra have been reviewed. A complete assignment of the observed spectra has been proposed.

  3. Raman and FTIR spectra of CeO2 and Gd2O3 in iron phosphate glasses

    International Nuclear Information System (INIS)

    Highlights: • The structure of the studied samples has been investigated by Raman and FTIR spectroscopy. • The structure for the all samples has similar features. • The structure consists of predominantly Q1 with a fraction of Q0 and Q2 units. • The Ce and Gd enters in the structure of studied glasses as a network modifier. - Abstract: In the present work, multicomponent oxide samples of composition x(CeO2 + Gd2O3)–(40 − x)Fe2O3–60P2O5 (0 ⩽ x ⩽ 8 mol%) were produced by conventional melting method. The samples were investigated to examine the effect of the CeO2 and Gd2O3 composition on the structure of the iron phosphate glasses system. The X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) for the x ⩽ 6 mol% samples show all the samples formed homogeneous glass, but for the x = 8 mol% samples show the presence of randomly distributed crystalline phase embedded in an amorphous matrix. The x(CeO2 + Gd2O3)–(40 − x)Fe2O3–60P2O5 glass containing 8 mol% CeO2 and Gd2O3 partially crystallized during annealing and Ce/Gd-rich were identified by EDS in the crystalline phase. The structure of the studied samples has been investigated using Raman and Fourier transform infrared spectroscopy (FTIR). The Raman and FTIR spectra for the samples have analogous spectral features. The Raman and FTIR spectra suggest that the structure is mainly constituted by the pyrophosphate glass based structure, with a part proportion of metaphosphate and orthophosphate structure. Raman and FTIR spectra allowed us to identify the structural units which appear in the structural network of these phosphate glasses and also the network modifier role of cerium and gadolinium ions

  4. Molecular structure (monomeric and dimeric) and hydrogen bonds in 5-benzyl 2-thiohydantoin studied by FT-IR and FT-Raman spectroscopy and DFT calculations

    Science.gov (United States)

    Deval, Vipin; Kumar, Amit; Gupta, Vineet; Sharma, Anamika; Gupta, Archana; Tandon, Poonam; Kunimoto, Ko-Ki

    2014-11-01

    In the present work the structural and spectral characteristics of 5-benzyl-2-thiohydantoin (5-BTH) have been studied by methods of infrared, Raman spectroscopy and quantum chemistry. Electrostatic potential surface, optimized geometry, harmonic vibrational frequencies, infrared intensities and activities of Raman scattering were calculated by density functional theory (DFT) employing B3LYP with complete relaxation in the potential energy surface using 6-311G++(d,p) basis set. Our results support the hydrogen bonding pattern proposed by reported crystalline structure. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule are calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. UV-vis spectrum of the compound was recorded in methanol solvent. The TD-DFT calculations have been performed to explore the influence of electronic absorption spectra in the gas phase, as well as in solution environment using PCM and 6-311++G(d,p) basis set. In addition, the thermodynamic properties of the compound were calculated at different temperatures and corresponding relations between the properties and temperature were also studied.

  5. Computation of Raman Spectra from Density Matrix Linear Response Theory in Extended Lagrangian Born-Oppenheimer Molecular Dynamics

    Science.gov (United States)

    Niklasson, Anders; Coe, Joshua; Cawkwell, Marc

    2011-06-01

    Linear response calculations based on density matrix perturbation theory [A. M. N. Niklasson and M. Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] have been developed within a self-consistent tight-binding method for extended Lagrangian Born-Oppenheimer molecular dynamics [A. M. N. Niklasson, Phys. Rev. Lett., 100, 123004 (2008)]. Besides the nuclear coordinates, extended auxiliary electronic degrees of freedom are added to the regular Born-Oppenheimer Lagrangian, both for the electronic ground state and response densities. This formalism enables highly efficient, on-the-fly, analytic computations of the polarizability autocorrelation functions and the Raman spectra during energy conserving Born-Oppenheimer molecular dynamics trajectories. We will illustrate these capabilities via time-resolved Raman spectra computed during explicit, reactive molecular dynamics simulations of the shock compression of methane, benzene, tert-butylacetylene. Comparisons will be made with experimental results where possible.

  6. An analysis of stable forms of CL-20: A DFT study of conformational transitions, infrared and Raman spectra

    Science.gov (United States)

    Kholod, Yana; Okovytyy, Sergiy; Kuramshina, Gulnara; Qasim, Mohammad; Gorb, Leonid; Leszczynski, Jerzy

    2007-10-01

    The most stable forms of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) were analyzed at the B3LYP/6-31G+(d,p) level of theory. The mechanism of conformational transformations was clarified. The activation energies of those transitions were found to be quite low and lie in the range 1.2-4.0 kcal mol -1. IR and Raman spectra of the studied CL-20 forms were simulated. The predicted vibrational modes were used for comparison with the experimental values. The unique peaks for each of the conformers in IR and Raman spectra were found. These peaks can be used as the "signatures" of the studied conformers and for identification of different polymorphs of CL-20 in mixtures.

  7. Photoluminescence and Raman spectra of the ordered vacancy compound CuGa{sub 5}Se{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Grossberg, M. [Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia)], E-mail: mgross@staff.ttu.ee; Krustok, J. [Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn (Estonia); Bodnar, I. [Department of Chemistry, Belarussian State University of Informatics and Radioelectronics, P. Brovka str. 6, 220027 Minsk (Belarus); Siebentritt, S. [Universite du Luxembourg, 162a avenue de la Faiencerie, L-1511 (Luxembourg); Albert, J. [Hahn-Meitner Institut, Glienicker Strasse 100, 14109 Berlin (Germany)

    2008-01-01

    We studied the photoluminescence (PL) and Raman properties of the ordered defect compound CuGa{sub 5}Se{sub 8}. Twelve peaks were detected from the room-temperature Raman spectra with the A{sub 1} mode around 160 cm{sup -1}. Due to the stress in the polycrystalline thin film the corresponding frequencies of the Raman modes of a CuGa{sub 5}Se{sub 8} single crystal were slightly shifted. One broad asymmetric PL band at 1.788 and 1.765 eV was observed at 10 K in the PL spectra of CuGa{sub 5}Se{sub 8} single crystal and polycrystalline layer, respectively. The temperature and laser power dependencies of the PL spectra were also studied. The shape and properties of the PL band assure the presence of potential fluctuations and the analyses of the PL data suggest that the emission is due to band-to-tail (BT) or band-to-impurity (BI) recombination.

  8. Hydrogen Bonding and Dielectric Spectra of Ethylene Glycol–Water Mixtures from Molecular Dynamics Simulations

    Science.gov (United States)

    2016-01-01

    Mixtures of ethylene glycol with water are a prominent example of media with variable viscosity. Classical molecular dynamics simulations at room temperature were performed for mixtures of ethylene glycol (EG) and water with EG mole fractions of xE = 0.0, 0.1, 0.2, 0.4, 0.6, 0.9, 1.0. The calculated dielectric loss spectra were in qualitative agreement with experiment. We found a slightly overestimated slowdown of the dynamics with increasing EG concentration compared to experimental data. Statistics of the hydrogen bond network and hydrogen bond lifetimes were derived from suitable time correlation functions and also show a slowdown in the dynamics with increasing xE. A similar picture is predicted for the time scales of EG conformer changes and for molecular reorientation. A slight blue shift was obtained for the power spectra of the molecular center of mass motion. The results were used to give a qualitative interpretation of the origin of three different relaxation times that appear in experimental complex dielectric spectra and of their change with xE. PMID:27649083

  9. Profiling of liquid crystal displays with Raman spectroscopy: Preprocessing of spectra.

    NARCIS (Netherlands)

    O. Stanimirovic; H.F.M. Boelens; A.J.G. Mank; H.C.J. Hoefsloot; A.K. Smilde

    2005-01-01

    Raman spectroscopy is applied for characterizing paintable displays. Few other options than Raman spectroscopy exist for doing so because of the liquid nature of functional materials. The challenge is to develop a method that can be used for estimating the composition of a single display cell on the

  10. Spectroscopy (FT-IR, FT-Raman), hydrogen bonding, electrostatic potential and HOMO-LUMO analysis of tioxolone based on DFT calculations

    Science.gov (United States)

    Tao, Yaping; Li, Xiaofeng; Han, Ligang; Zhang, Weiying; Liu, Zhaojun

    2016-10-01

    Tioxolone possess antipsoriatic and antibacterial properties. Therefore, it has been used in treating various skin and scalp disorders for many years. Spectroscopic analysis of tioxolone was presented by using density functional theory (DFT) calculations and experiments (FT-IR, FT-Raman and UV-Vis). Molecular geometry and vibrational wavenumbers of tioxolone were investigated by using B3LYP method with aug-cc-pVTZ basis set. A complete vibrational spectra was made to analyze the potential energy distributions (PED). In addition, analysis of frontier molecular orbitals, electrostatic potential (ESP) and thermodynamic properties (heat capacity, entropy, enthalpy and Gibbs free energy) was presented with the same basis-set. Furthermore, the nature of molecular association through hydrogen bonding were discussed using atoms in molecules (AIM) and reduced density gradient (RDG) methods.

  11. Rotational isomers, intramolecular hydrogen bond, and IR spectra of o-vinylphenol

    International Nuclear Information System (INIS)

    Absorption bands of OH stretching vibrations in IR spectra of o-vinylphenol (o-VP) in the weakly polar solvents CCl4 and n-hexane were studied. Several rotamers of the free OH group were observed for o-VP in n-hexane. The fraction of o-VP rotamers with an O–H…π intramolecular hydrogen bond (IHB) was less than 20% according to experimental estimates for CCl4 solutions and calculations in the gas phase and cyclohexane. The theoretical effective enthalpy of the o-VP IHB was estimated for rotamer A (–ΔH=0.20 kcal/mol). (authors)

  12. Raman and crystal field studies of Tb-O bonds in TbM n2O5

    Science.gov (United States)

    Mansouri, S.; Jandl, S.; Balli, M.; Laverdière, J.; Fournier, P.; Dimitrov, D. Z.

    2016-09-01

    We have studied the temperature dependence of TbM n2O5 Raman-active phonons and its T b3 + crystal field (CF) excitations. Interestingly, the Raman intensities of some phonons are significantly reduced below ˜180 K . Such behaviors are also observed in HoM n2O5 and YM n2O5 systems. A connection between the Raman intensities and the nearest-neighbor mean-square relative displacement σ2 is established. Also, some of the T b3 + and H o3 + CF excitations become broader below ˜180 K . These results are discussed in terms of the disorder induced by the Tb-O bond splitting.

  13. Discriminant Analysis of Raman Spectra for Body Fluid Identification for Forensic Purposes

    Directory of Open Access Journals (Sweden)

    Vitali Sikirzhytski

    2010-03-01

    Full Text Available Detection and identification of blood, semen and saliva stains, the most common body fluids encountered at a crime scene, are very important aspects of forensic science today. This study targets the development of a nondestructive, confirmatory method for body fluid identification based on Raman spectroscopy coupled with advanced statistical analysis. Dry traces of blood, semen and saliva obtained from multiple donors were probed using a confocal Raman microscope with a 785-nm excitation wavelength under controlled laboratory conditions. Results demonstrated the capability of Raman spectroscopy to identify an unknown substance to be semen, blood or saliva with high confidence.

  14. Density Functional Theoretical Analysis of the Molecular Structural Effects on Raman Spectra of β-Carotene and Lycopene

    Institute of Scientific and Technical Information of China (English)

    刘伟龙; 王志刚; 郑植仁; 蒋礼林; 杨延强; 赵连城; 苏文辉

    2012-01-01

    The molecular structural and Raman spectroscopic characteristics of fl-carotene and lycopene are investigated by density functional calculations. The effects of molecular structure and solvent environment on the Raman spectra are analyzed by comparing the calculated and measured results. It is found that the B3LYP/6-31G(d) method can predict the reasonable result for β-carotene, but the vl Raman activities of lycopene overflow at all the used theo- retical methods because of the longer conjugation length in β-carotene impedes the delocalization of ~r-electrons The calculated results indicate that the rotation of β-rings shortens the effective conjugation length, and results in higher frequency and lower activity of the vl mode in /q-carotene than lycopene. The measured vl bands of β-carotene and lycopene shift respectively to higher and lower frequencies in solution compared with that in crystals since the crystal packing forces can lead to different conformational variations in the carotenoids molecules. The polarized continuum model theoretical analysis suggests that solvent has slight (significant) effects on the Raman frequencies (intensities) of both carotenoids.

  15. FT-IR, FT-Raman, NMR and UV-Vis spectra and DFT calculations of 5-bromo-2-ethoxyphenylboronic acid (monomer and dimer structures)

    Science.gov (United States)

    Sas, E. B.; Kose, E.; Kurt, M.; Karabacak, M.

    2015-02-01

    In this study, the Fourier Transform Infrared (FT-IR) and Fourier Transform Raman (FT-Raman) spectra of 5-bromo-2-ethoxyphenylboronic acid (5Br2EPBA) are recorded in the solid phase in the region 4000-400 cm-1 and 3500-10 cm-1, respectively. The 1H, 13C and DEPT nuclear magnetic resonance (NMR) spectra are recorded in DMSO solution. The UV-Vis absorption spectrum of 5Br2EPBA is saved in the range of 200-400 nm in ethanol and water. The following theoretical calculations for monomeric and dimeric structures are supported by experimental results. The molecular geometry and vibrational frequencies in the ground state are calculated by using DFT methods with 6-31G(d,p) and 6-311G(d,p) basis sets. There are four conformers for the present molecule. The computational results diagnose the most stable conformer of 5Br2EPBA as Trans-Cis (TC) form. The complete assignments are performed on the basis of the total energy distribution (TED) of vibrational modes, calculated with scaled quantum mechanics (SQM) method in parallel quantum solutions (PQS) program. The 1H and 13C NMR chemical shifts of 5Br2EPBA molecule are calculated by using the Gauge Invariant Atomic Orbital (GIAO) method in DMSO and gas phase for monomer and dimer structures of the most stable conformer. Moreover, electronic properties, such as the HOMO and LUMO energies (by TD-DFT and CIS methods) and molecular electrostatic potential surface (MEPs) are investigated. Stability of the molecule arising from hyper-conjugative interactions, charge delocalization is analyzed using natural bond orbital (NBO) analysis. Nonlinear optical (NLO) properties and thermodynamic features are presented. All calculated results are compared with the experimental data of the title molecule. The correlation of theoretical and experimental results provides a detailed description of the structural and physicochemical properties of the title molecule.

  16. Absorption, phosphorescence and Raman spectra of IrQ(ppy){sub 2} organometallic compound

    Energy Technology Data Exchange (ETDEWEB)

    Polosan, Silviu, E-mail: silv@infim.ro [National Institute of Materials Physics, R-77125 Bucharest-Magurele (Romania); Ciobotaru, Iulia Corina [National Institute of Materials Physics, R-77125 Bucharest-Magurele (Romania); Tsuboi, Taiju [Kyoto Sangyo University, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan)

    2015-07-15

    The absorption and photoluminescence (PL) spectra, PL decays, Raman spectrum, cyclic voltammetry (CV) and nuclear magnetic resonance of heteroleptic Ir-compound IrQ(ppy){sub 2} compound with two phenylpyridine (ppy) ligands and one quinoline (Q) ligand have been investigated experimentally and theoretically. Two very weak absorption bands due to the transitions to the triplet states are found at about 560 and 595 nm in IrQ(ppy){sub 2} doped in CH{sub 2}Cl{sub 2} solution. IrQ(ppy){sub 2} exhibits a dual emission of red and green phosphorescence bands. The red emission intensity is much higher than the green one in IrQ(ppy){sub 2} powder, but much lower than the green one in lightly IrQ(ppy){sub 2}-doped CH{sub 2}Cl{sub 2} solution and PMMA film. The intensity ratio of the red emission to the green emission, however, is observed to increase with increasing the IrQ(ppy){sub 2} concentration in CH{sub 2}Cl{sub 2} solution and PMMA film. The enhancement of the red emission is suggested to be caused by the Forester energy transfer from Ir-ppy component to Ir–Q components between two neighboring IrQ(ppy){sub 2} molecules. The HOMO energy is estimated to be −4.865 eV from the CV measurement, which is close to the HOMO energy of −4.844 eV calculated using the time dependent density function theory (TD-DFT). The LUMO energy is estimated as −2.856 eV from the HOMO energy and the long-wavelength absorption edge found at 617 nm in the absorption spectrum. The absorption spectrum of IrQ(ppy){sub 2} is calculated by the TD-DFT. Discussion is given on a deviation of the calculated spectrum from the measured spectrum. - Graphical abstract: Display Omitted - Highlights: • IrQ(ppy){sub 2} has red and green emissions of different ratio between film and solution. • Intensity ratio of red to green emissions increases with IrQ(ppy){sub 2} concentration. • Enhancement of red emission is due to energy transfer in two neighboring IrQ(ppy){sub 2}. • Lowest-energy absorption

  17. Discriminant Analysis of Raman Spectra for Body Fluid Identification for Forensic Purposes

    OpenAIRE

    Vitali Sikirzhytski; Kelly Virkler; Lednev, Igor K.

    2010-01-01

    Detection and identification of blood, semen and saliva stains, the most common body fluids encountered at a crime scene, are very important aspects of forensic science today. This study targets the development of a nondestructive, confirmatory method for body fluid identification based on Raman spectroscopy coupled with advanced statistical analysis. Dry traces of blood, semen and saliva obtained from multiple donors were probed using a confocal Raman microscope with a 785-nm excitation wave...

  18. Interpretation of FTIR spectra of polymers and Raman spectra of car paints by means of likelihood ratio approach supported by wavelet transform for reducing data dimensionality.

    Science.gov (United States)

    Martyna, Agnieszka; Michalska, Aleksandra; Zadora, Grzegorz

    2015-05-01

    The problem of interpretation of common provenance of the samples within the infrared spectra database of polypropylene samples from car body parts and plastic containers as well as Raman spectra databases of blue solid and metallic automotive paints was under investigation. The research involved statistical tools such as likelihood ratio (LR) approach for expressing the evidential value of observed similarities and differences in the recorded spectra. Since the LR models can be easily proposed for databases described by a few variables, research focused on the problem of spectra dimensionality reduction characterised by more than a thousand variables. The objective of the studies was to combine the chemometric tools easily dealing with multidimensionality with an LR approach. The final variables used for LR models' construction were derived from the discrete wavelet transform (DWT) as a data dimensionality reduction technique supported by methods for variance analysis and corresponded with chemical information, i.e. typical absorption bands for polypropylene and peaks associated with pigments present in the car paints. Univariate and multivariate LR models were proposed, aiming at obtaining more information about the chemical structure of the samples. Their performance was controlled by estimating the levels of false positive and false negative answers and using the empirical cross entropy approach. The results for most of the LR models were satisfactory and enabled solving the stated comparison problems. The results prove that the variables generated from DWT preserve signal characteristic, being a sparse representation of the original signal by keeping its shape and relevant chemical information. PMID:25757825

  19. Resonance Raman spectra of an O2-binding H-NOX domain reveal heme relaxation upon mutation†

    OpenAIRE

    Tran, Rosalie; Boon, Elizabeth M.; Marletta, Michael A.; Mathies, Richard A.

    2009-01-01

    Resonance Raman spectra are measured for Tt H-NOX WT and three other Tt H-NOX proteins containing mutations at key conserved residues to determine the heme conformation in solution. The most dramatic changes in heme conformation occurred in the O2-bound forms, and the single Tt H-NOX P115A mutation was sufficient to generate a significant relaxation of the chromophore. Clear evidence of heme relaxation in the Tt H-NOX I5L, P115A, and I5L/P115A mutants in solution is demonstrated by the observ...

  20. Far-infrared reflectivity and Raman spectra of Ba5Nb4O15

    Science.gov (United States)

    Massa, Néstor E.; Pagola, Silvina; Carbonio, Raúl

    1996-04-01

    We report low-temperature, far-infrared reflectivity, and Raman-scattering measurements for layered Ba5Nb4O15. We find that this material is characterized by a strong anharmonic lattice where the symmetric stretching vibration of the empty octahedra, a singular feature of this layer compound, splits into two narrow Raman-active bands. We assign them to the same phonon in a slightly different environment, and suggest a small local departure of the reported centrosymmetric D33d-P3m1 space group. We think that the infrared and mainly the Raman band profiles indicate that the lattice of Ba5Nb4O15 is close to collapsing into a lower symmetry structure.

  1. Stress effect on Raman spectra of Ce-doped BaTiO3 films

    Science.gov (United States)

    Chen, M. S.; Shen, Z. X.; Tang, S. H.; Shi, W. S.; Cui, D. F.; Chen, Z. H.

    2000-08-01

    Ce-doped BaTiO3 (BTO:Ce) thin films prepared on MgO (100) substrates by pulsed laser deposition (PLD) at oxygen pressure of 1.2×10-3 and 17 Pa have been studied by micro-Raman spectroscopy, x-ray diffraction (XRD) and atomic force microscopy (AFM). The film deposited at lower oxygen pressure has a larger lattice parameter in the direction normal to the substrate surface, and the film has smaller grains and a smoother surface. The polarized Raman peaks of both as-deposited films show blue shifts and linewidth broadening in comparison to those of the BaTiO3 single crystal. The blue shifts are attributed to tensile stresses in the films. Our results indicate that the grain size increases and the tensile stress relaxes with annealing. We have shown that quantum confinement and oxygen vacancies are not the dominant factors for the observed Raman spectral changes.

  2. Surface Plasmons and Surface Enhanced Raman Spectra of Aggregated and Alloyed Gold-Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Y. Fleger

    2009-01-01

    Full Text Available Effects of size, morphology, and composition of gold and silver nanoparticles on surface plasmon resonance (SPR and surface enhanced Raman spectroscopy (SERS are studied with the purpose of optimizing SERS substrates. Various gold and silver films made by evaporation and subsequent annealing give different morphologies and compositions of nanoparticles and thus different position of the SPR peak. SERS measurements of 4-mercaptobenzoic acid obtained from these films reveal that the proximity of the SPR peak to the exciting laser wavelength is not the only factor leading to the highest Raman enhancement. Silver nanoparticles evaporated on top of larger gold nanoparticles show higher SERS than gold-silver alloyed nanoparticles, in spite of the fact that the SPR peak of alloyed nanoparticles is narrower and closer to the excitation wavelength. The highest Raman enhancement was obtained for substrates with a two-peak particle size distribution for excitation wavelengths close to the SPR.

  3. A detailed analysis of the Raman spectra in superconducting boron doped nanocrystalline diamond

    Energy Technology Data Exchange (ETDEWEB)

    Szirmai, Peter [Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Vienna (Austria); Department of Physics, Budapest University of Technology and Economics, PO Box 91, 1521 Budapest (Hungary); Pichler, Thomas [Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Vienna (Austria); Williams, Oliver A. [School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA (United Kingdom); Mandal, Soumen; Baeuerle, Christopher [Institut Neel - CNRS and Universite Joseph Fourier, 38042 Grenoble (France); Simon, Ferenc [Department of Physics, Budapest University of Technology and Economics, PO Box 91, 1521 Budapest (Hungary)

    2012-12-15

    The light scattering properties of superconducting (T{sub c} {approx} 3.8 K) heavily boron doped nanocrystalline diamond has been investigated by Raman spectroscopy using visible excitations. Fano type interference of the zone-center phonon line and the electronic continuum was identified. Lineshape analysis reveals Fano lineshapes with a significant asymmetry (q {approx} -2). An anomalous wavelength dependence and small value of the Raman scattering amplitude is observed in agreement with previous studies. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. A detailed analysis of the Raman spectra in superconducting boron doped nanocrystalline diamond

    International Nuclear Information System (INIS)

    The light scattering properties of superconducting (Tc ∼ 3.8 K) heavily boron doped nanocrystalline diamond has been investigated by Raman spectroscopy using visible excitations. Fano type interference of the zone-center phonon line and the electronic continuum was identified. Lineshape analysis reveals Fano lineshapes with a significant asymmetry (q ∼ -2). An anomalous wavelength dependence and small value of the Raman scattering amplitude is observed in agreement with previous studies. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. X-ray photoelectron spectra structure and chemical bonding in AmO2

    Directory of Open Access Journals (Sweden)

    Teterin Yury A.

    2015-01-01

    Full Text Available Quantitative analysis was done of the X-ray photoelectron spectra structure in the binding energy range of 0 eV to ~35 eV for americium dioxide (AmO2 valence electrons. The binding energies and structure of the core electronic shells (~35 eV-1250 eV, as well as the relativistic discrete variation calculation results for the Am63O216 and AmO8 (D4h cluster reflecting Am close environment in AmO2 were taken into account. The experimental data show that the many-body effects and the multiplet splitting contribute to the spectral structure much less than the effects of formation of the outer (0-~15 eV binding energy and the inner (~15 eV-~35 eV binding energy valence molecular orbitals. The filled Am 5f electronic states were shown to form in the AmO2 valence band. The Am 6p electrons participate in formation of both the inner and the outer valence molecular orbitals (bands. The filled Am 6p3/2 and the O 2s electronic shells were found to make the largest contributions to the formation of the inner valence molecular orbitals. Contributions of electrons from different molecular orbitals to the chemical bond in the AmO8 cluster were evaluated. Composition and sequence order of molecular orbitals in the binding energy range 0-~35 eV in AmO2 were established. The experimental and theoretical data allowed a quantitative scheme of molecular orbitals for AmO2, which is fundamental for both understanding the chemical bond nature in americium dioxide and the interpretation of other X-ray spectra of AmO2.

  6. Bonding and charge transfer in nitrogen-donor uranyl complexes: insights from NEXAFS spectra.

    Science.gov (United States)

    Pemmaraju, C D; Copping, Roy; Wang, Shuao; Janousch, Markus; Teat, Simon J; Tyliszcak, Tolek; Canning, Andrew; Shuh, David K; Prendergast, David

    2014-11-01

    We investigate the electronic structure of three newly synthesized nitrogen-donor uranyl complexes [(UO2)(H2bbp)Cl2], [(UO)2(Hbbp)(Py)Cl], and [(UO2)(bbp)(Py)2] using a combination of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy experiments and simulations. The complexes studied feature derivatives of the tunable tridentate N-donor ligand 2,6-bis(2-benzimidazyl)pyridine (bbp) and exhibit discrete chemical differences in uranyl coordination. The sensitivity of the N K-edge X-ray absorption spectrum to local bonding and charge transfer is exploited to systematically investigate the evolution of structural as well as electronic properties across the three complexes. A thorough interpretation of the measured experimental spectra is achieved via ab initio NEXAFS simulations based on the eXcited electron and Core-Hole (XCH) approach and enables the assignment of spectral features to electronic transitions on specific absorbing sites. We find that ligand-uranyl bonding leads to a signature blue shift in the N K-edge absorption onset, resulting from charge displacement toward the uranyl, while changes in the equatorial coordination shell of the uranyl lead to more subtle modulations in the spectral features. Theoretical simulations show that the flexible local chemistry at the nonbinding imidazole-N sites of the bbp ligand is also reflected in the NEXAFS spectra and highlights potential synthesis strategies to improve selectivity. In particular, we find that interactions of the bbp ligand with solvent molecules can lead to changes in ligand-uranyl binding geometry while also modulating the K-edge absorption. Our results suggest that NEXAFS spectroscopy combined with first-principles interpretation can offer insights into the coordination chemistry of analogous functionalized conjugated ligands. PMID:25330350

  7. Progress in the Raman spectra analysis of covalently functionalized multiwalled carbon nanotubes: unraveling disorder in graphitic materials.

    Science.gov (United States)

    Rebelo, Susana L H; Guedes, Alexandra; Szefczyk, Monika E; Pereira, André M; Araújo, João P; Freire, Cristina

    2016-05-14

    Raman spectroscopy is highly sensitive to the morphology and electronic structures of graphitic materials, but a convenient interpretation model has been lacking for multiwalled carbon nanotubes (MWCNTs), in particular for the discrimination of spectral changes induced by covalent functionalization. The present work describes a systematic investigation of the Raman analysis of covalently functionalized MWCNTs by diazonium chemistry and oxidation methodologies, with typically different mechanisms and reaction sites. A multi-peak deconvolution system and spectral band assignment were proposed based on the chemical and structural modifications identified by X-ray photoelectron spectroscopy, thermogravimetry, X-ray diffraction, specific surface areas and the comparative analysis of the first and second order regions of the Raman spectra. Diazonium functionalization takes place mainly in the π-system of the external sidewall, while oxidation occurs on defects and leads to structure burning. This allowed us to distinguish between spectral features related to aromaticity disruptions within the sidewalls and spectral features related to changes within the inner tubes. The model was validated extending the studies to the functionalization of MWCNTs by the Bingel reaction.

  8. FT-IR and Raman spectra and vibrational investigation of bis (4-acetylanilinium) hexachlorostannate using DFT (B3LYP) calculation

    Science.gov (United States)

    Tarchouna, S.; Chaabane, I.; Rahaiem, A. Ben

    2016-09-01

    4-acetylanilinium was used as a ligand for the synthesis of the organic/inorganic compound bis (4-acetylanilinium) hexachlorostannate. Vibrational study in the solid state was performed by FT-Raman of the free 4-acetylanilinium ligand C8H9ON+ and by FT-IR and FT-Raman spectroscopies of the [C8H10NO]2 SnCl6 compound. The comparative analysis of the Raman spectra of the title compound with that of the free ligand was discussed. The structure of the [C8H10NO]2SnCl6 was optimized by density functional theory (DFT) using B3LYP method and shows that the calculated values obtained by B3LYP/LanL2DZ basis are in a better agreement with the experimental data reported by Song et al. (2011) [1] than those obtained by B3LYP/LanL2MB basis. The vibrational frequencies are calculated using density functional theory (DFT) with the B3LYP/LanL2DZ basis, and scaled by various factors. Root mean square (RMS) value was calculated and the small difference between experimental and calculated modes has been interpreted by intermolecular interactions in the crystal.

  9. Raman and infrared spectra, structure, vibrational assignment, normal coordinate analysis, and ab initio calculations of trifluoromethyl isocyanate

    Science.gov (United States)

    Durig, J. R.; Guirgis, G. A.; Eltayeb, S.

    1994-07-01

    The Raman (2500 to 30 cm -1) and infrared (2500 to 60 cm 1) spectra of gaseous and solid trifluoromethyl isocyanate, CF 3NCO, have been recorded. The Raman spectrum of the liquid has also been obtained and qualitative depolarization ratios have been measured. The CNC bend has been observed in the low-frequency Raman spectrum of the gas at 130 cm -1 as a relatively strong line which is split in the spectrum of the solid. However, the CF 3 torsional mode was not observed. The infrared spectrum of CF 3NCO dissolved in liquid xenon was also obtained and the observed spectrum indicates a very small barrier to internal rotation. With the exception of the torsion, a complete assignment of the vibrational fundamentals is proposed. The structural parameters, force constants, and vibrational frequencies have been determined from ab initio calculations utilizing a variety of basis sets and the theoretical results are compared to the experimental values when appropriate. These results have been compared with the corresponding quantities obtained for some similar molecules.

  10. Raman spectra of terbium trichloride, phosphorus pentachloride and their molten mixtures

    International Nuclear Information System (INIS)

    Raman spectroscopy was used to study in situ the behavior of individual terbium trichloride and phosphorus pentachloride in different aggregative states as a function of temperature, and of solutions of PCl5 vapors in molten TbCl3. A conclusion is drawn about their structure and the nature of phase transformations and chemical reactions in wide ranges of temperature and saturated vapor pressures

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-09-15

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

  12. FT-IR, FT-Raman spectra, density functional computations of the vibrational spectra and molecular geometry of biomolecule 5-aminouracil

    Energy Technology Data Exchange (ETDEWEB)

    Alcolea Palafox, M.; Tardajos, G.; Guerrero-Martinez, A. [Departamento de Quimica-Fisica1, Facultad de Ciencias Quimicas, Universidad Complutense, Madrid 28040 (Spain); Rastogi, V.K. [Department of Physics, CCS University, Meerut 250 004 (India)], E-mail: v_krastogi@rediffmail.com; Mishra, D.; Ojha, S.P. [Department of Physics, CCS University, Meerut 250 004 (India); Kiefer, W. [Institut fuer Physikalische Chemie, Universitaet Wuerzburg, D-97074 Wuerzburg (Germany)

    2007-11-09

    FT-IR and FT-Raman spectra of the biomolecule 5-aminouracil were recorded in the regions 400-4000 cm{sup -1} and 10-3500 cm{sup -1}, respectively. The observed vibrational wavenumbers were analyzed and assigned to different normal modes of vibration of the molecule. Density functional calculations were performed to support wavenumber assignments of the observed bands. A comparison with the molecule of uracil was made, and specific scale factors were employed in the predicted wavenumbers of 5-aminouracil. With the purpose of study the important molecule 5-aminouracil, its equilibrium geometry and harmonic wavenumbers were calculated for the first time by the B3LYP DFT method. The vibrational wavenumbers were compared with IR and Raman experimental data. Also good reproduction of the experimental wavenumbers is obtained and the % error is very small. All the tautomeric forms of 5-aminouracil were determined and optimized. The dimer forms were also simulated. The energy, atomic charges and dipole moments were discussed and several general conclusions were underlined.

  13. Rotational spectra of propargyl alcohol dimer: A dimer bound with three different types of hydrogen bonds

    International Nuclear Information System (INIS)

    Pure rotational spectra of the propargyl alcohol dimer and its three deuterium isotopologues have been observed in the 4 to 13 GHz range using a pulsed-nozzle Fourier transform microwave spectrometer. For the parent dimer, a total of 51 transitions could be observed and fitted within experimental uncertainty. For two mono-substituted and one bi-substituted deuterium isotopologues, a total of 14, 17, and 19 transitions were observed, respectively. The observed rotational constants for the parent dimer [A = 2321.8335(4) MHz, B = 1150.4774(2) MHz, and C = 1124.8898(2) MHz] are close to those of the most stable structure predicted by ab initio calculations. Spectra of the three deuterated isotopologues and Kraitchman analysis positively confirm this structure. Geometrical parameters and “Atoms in Molecules” analysis on the observed structure reveal that the two propargyl alcohol units in the dimer are bound by three different types of hydrogen bonds: O–H⋯O, O–H⋯π, and C–H⋯π. To the best of our knowledge, propargyl alcohol seems to be the smallest molecule forming a homodimer with three different points of contact

  14. Rotational spectra of propargyl alcohol dimer: A dimer bound with three different types of hydrogen bonds

    Energy Technology Data Exchange (ETDEWEB)

    Mani, Devendra; Arunan, E., E-mail: arunan@ipc.iisc.ernet.in [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012 (India)

    2014-10-28

    Pure rotational spectra of the propargyl alcohol dimer and its three deuterium isotopologues have been observed in the 4 to 13 GHz range using a pulsed-nozzle Fourier transform microwave spectrometer. For the parent dimer, a total of 51 transitions could be observed and fitted within experimental uncertainty. For two mono-substituted and one bi-substituted deuterium isotopologues, a total of 14, 17, and 19 transitions were observed, respectively. The observed rotational constants for the parent dimer [A = 2321.8335(4) MHz, B = 1150.4774(2) MHz, and C = 1124.8898(2) MHz] are close to those of the most stable structure predicted by ab initio calculations. Spectra of the three deuterated isotopologues and Kraitchman analysis positively confirm this structure. Geometrical parameters and “Atoms in Molecules” analysis on the observed structure reveal that the two propargyl alcohol units in the dimer are bound by three different types of hydrogen bonds: O–H⋯O, O–H⋯π, and C–H⋯π. To the best of our knowledge, propargyl alcohol seems to be the smallest molecule forming a homodimer with three different points of contact.

  15. Effects of central metal on electronic structure, magnetic properties, infrared and Raman spectra of double-decker phthalocyanine

    Science.gov (United States)

    Suzuki, Atsushi; Oku, Takeo

    2016-09-01

    The effects of the central metal in double-decker metal phthalocyanine on the electronic structure, magnetic properties, and infrared and Raman spectra of the complex were investigated. Electron density distributions were delocalized on the phthalocyanine rings. The narrow energy gap and infrared peaks observed in the ultra-violet-visible-near infrared spectra of the systems were attributed to phthalocyanine ring-ring interactions the between overlapping π-orbitals on each ring. The chemical shift behavior of the phthalocyanine rings was separated by the deformation of their structure owing to nuclear magnetic interaction of the nuclear quadrupole interaction as determined by the electronic field gradient and asymmetric parameters. The magnetic parameters of principle g-tensors were dependent on the perturbation of the crystal field by the hybridization of the d-spin in the central metal conjugated with nitrogen ligands. In the case of the vanadyl system, the IR vibration modes were shifted by the soft vibration mode for resolving the symmetrical structure. Inactive Raman vibration modes arose from no-polarization on the phthalocyanine rings. Double-decker metal phthalocyanines have great advantages for the control of the magnetic mechanism for quantum spin entanglement in the relaxation process.

  16. FTIR and Raman spectra, DFT and normal coordinate computations of 2,4,5- and 2,4,6-tri-fluoroanilines

    Science.gov (United States)

    Mukherjee, V.; Singh, N. P.; Yadav, R. A.

    2009-07-01

    FTIR and Raman spectra of the 2,4,5- and 2,4,6-tri-fluoroaniline molecules have been reported. Density functional method has been employed to calculate the optimized geometrical parameters, atomic charges and vibrational frequencies. In addition, SQM force field method has also been employed to calculate potential energy distribution matrix. The observed and calculated IR and Raman spectra have been simulated. Each normal mode has been assigned using observed and calculated vibrational frequencies, IR and Raman intensities, depolarization ratios for the Raman lines, vector displacements and potential energy distributions. Optimized geometrical parameters, atomic charges and vibrational frequencies have been compared for the title molecules. The influences of presence of fluorine atoms to the geometries and normal modes of the aniline molecule have also been discussed.

  17. Growth and Raman spectra of single-crystal trilayer graphene with different stacking orientations.

    Science.gov (United States)

    Zhao, Haiming; Lin, Yung-Chang; Yeh, Chao-Hui; Tian, He; Chen, Yu-Chen; Xie, Dan; Yang, Yi; Suenaga, Kazu; Ren, Tian-Ling; Chiu, Po-Wen

    2014-10-28

    Understanding the growth mechanism of graphene layers in chemical vapor deposition (CVD) and their corresponding Raman properties is technologically relevant and of importance for the application of graphene in electronic and optoelectronic devices. Here, we report CVD growth of single-crystal trilayer graphene (TLG) grains on Cu and show that lattice defects at the center of each grain persist throughout the growth, indicating that the adlayers share the same nucleation site with the upper layers and these central defects could also act as a carbon pathway for the growth of a new layer. Statistics shows that ABA, 30-30, 30-AB, and AB-30 make up the major stacking orientations in the CVD-grown TLG, with distinctive Raman 2D characteristics. Surprisingly, a high level of lattice defects results whenever a layer with a twist angle of θ = 30° is found in the multiple stacks of graphene layers. PMID:25295851

  18. Double-Ended Calibration of Fiber-Optic Raman Spectra Distributed Temperature Sensing Data

    OpenAIRE

    John Selker; Mark B. Hausner; Scott Tyler; Jop Jansen; Olivier Hoes; Susan C. Steele-Dunne; Nick van de Giesen

    2012-01-01

    Over the past five years, Distributed Temperature Sensing (DTS) along fiber optic cables using Raman backscattering has become an important tool in the environmental sciences. Many environmental applications of DTS demand very accurate temperature measurements, with typical RMSE < 0.1 K. The aim of this paper is to describe and clarify the advantages and disadvantages of double-ended calibration to achieve such accuracy under field conditions. By measuring back...

  19. Raman scattering spectra and crystal structure of acid potassium-lithium sulfate

    International Nuclear Information System (INIS)

    Paper presents the results of the comprehensive investigation into Raman scattering in potassium-lithium acid sulfate crystal. A model of crystal structure is suggested on the basis of the study data. The suggested consistent model of the crystalline structure of potassium-lithium acid sulfate crystal describes well both spectrum high-frequency and low-frequency sections and may be used to analyze models of phase transformation

  20. Extended coupled cluster for Raman and infrared spectra of small molecules

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Sayali P.; Dutta, Achintya Kumar; Pal, Sourav [Physical Chemistry Division, National Chemical Laboratory (CSIR), Pune 411008 (India); Vaval, Nayana, E-mail: np.vaval@ncl.res.in [Physical Chemistry Division, National Chemical Laboratory (CSIR), Pune 411008 (India)

    2012-07-25

    Highlights: Black-Right-Pointing-Pointer We have used extended coupled cluster method to study IR and Raman spectroscopic properties for small molecules. Black-Right-Pointing-Pointer Our approach is semi-numerical. Black-Right-Pointing-Pointer Basis set dependence and electron correlation is studied. Black-Right-Pointing-Pointer Effect of partial triples makes the result closer to experimental and full CI values. -- Abstract: In this paper we study the harmonic vibrational frequencies, infrared (IR) intensities, Raman intensities and depolarization ratio using extended coupled cluster method. Raman and IR intensities are mixed derivatives of energy with respect to the electric field and geometric perturbation whereas vibrational frequencies are derivatives of energy with respect to electric field. We use semi-numerical approach to obtain these derivatives. We have studied the effect of electron correlation and basis set for the above properties. We compare our results with non-variational coupled cluster and experimental values, wherever available. We have studied HF, BH, CH{sup +}, CO and H{sub 2}CO molecules in different basis sets. For HF molecule, benchmarking is done with full CI values and basis set convergence is studied for this molecule. Effect of triples is studied for all the molecules.

  1. Raman and infrared spectra, normal coordinate analysis and ab initio calculations of 4-Amino-2-chloropyrimidine-5-carbonitrile

    Science.gov (United States)

    Abuelela, Ahmed M.; Mohamed, Tarek A.; Wilson, Lee D.; Zoghaib, Wajdi M.

    2016-07-01

    The present work reports an experimental and theoretical study of molecular structure of 4-Amino-2-chloropyrimidine-5-carbonitrile (ACPC) in solid phase. Raman and infrared (IR) spectra of ACPC have been recorded in the region of 3600-100 cm-1 and 4000-200 cm-1, respectively. Calculations with the methods of B3LYP and Møller-Plesset second perturbation (MP2) were carried out for structural and vibrational predictions. The computational approaches were tested and adapted by comparing the predicted spectra to results obtained experimentally. In order to assign the calculated frequencies for the recorded ones, a normal coordinate analysis has been performed for vibrations with respect to the nuclei displacements for all the fundamental frequencies. By computing and analyzing, in detail, the infrared and Raman spectra of ACPC, the changes in the vibrational features were probed by identifying two tautomers of ACPC; (i) amino ACPC which could exist in two conformational structures, and (ii) imino ACPC which could exist in four conformational structures. Both computational and spectral results were in favor of the amino tautomer with no evidence for the existence of interconversion between amino and imino forms. Moreover, only one of the amino ACPC conformers was found to be the most stable one where the hybridization of amino group was found to be sp3. The theoretical predictions agree well with the available experimental data, accounting for the interconversion process in the amino/imino functional groups. We demonstrate that vibrational spectroscopy constitutes a powerful tool for studying molecular structure due to its high sensitivity to changes in molecular geometry.

  2. Hydrogen-bonding and vibrational coupling of water in a hydrophobic hydration shell as observed by Raman-MCR and isotopic dilution spectroscopy.

    Science.gov (United States)

    Ahmed, Mohammed; Singh, Ajay K; Mondal, Jahur A

    2016-01-28

    Hydrogen-bonding and intra/intermolecular vibrational coupling of water next to a hydrophobic molecule (tert-butyl alcohol, TBA) have been studied by Raman multivariate curve resolution (Raman-MCR) and isotopic dilution spectroscopy. Raman-MCR provides the vibrational spectrum of water pertinent to the hydration shell of TBA, which shows a distinct Raman band at around 3660 cm(-1) corresponding to the dangling OH in the hydration shell. The presence of positive charge on the hydrophobe decreases the propensity of dangling OH in the hydration shell, presumably due to unfavorable electrostatic interaction. Analysis of the dangling OH band with isotopic dilution reveals that the 'dangling OH' is intramolecularly coupled with the 'H-bonded OH' of the same water molecule. The hydration water spectrum in the H-bonded OH stretch region (3000-3600 cm(-1)) shows a depletion of weakly H-bonded water (∼3580 cm(-1)) and an increase of strongly H-bonded water (∼3250 cm(-1)), making the average H-bonding stronger in a hydrophobic hydration shell than that in bulk. This strongly H-bonded hydration water exhibits weaker intra- and intermolecular vibrational coupling than that of bulk water. PMID:26725484

  3. Infrared, Raman, and ultraviolet absorption spectra and theoretical calculations and structure of 2,3,5,6-tetrafluoropyridine in its ground and excited electronic states

    Energy Technology Data Exchange (ETDEWEB)

    Sheu, Hong-Li; Boopalachandran, Praveenkumar [Department of Chemistry, Texas A& M University, College Station, TX 77843-3255 (United States); Kim, Sunghwan [National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Department of Health and Human Services, 8600 Rockville Pike, Bethesda, MD 20894 (United States); Laane, Jaan, E-mail: laane@chem.tamu.edu [Department of Chemistry, Texas A& M University, College Station, TX 77843-3255 (United States)

    2015-07-29

    Highlights: • The structures of 2,3,5,6-tetrafluoropyridine for its S{sub 0} and S{sub 1}(π, π{sup ∗}) states have been calculated. • TFPy is rigidly planar in its ground electronic state, but is quasi-planar and floppy in S{sub 1}. • The barrier to planarity is 30 cm{sup −1} in the excited state. • The observed vibrational frequencies for both states agree well with the computations. • A ring-bending potential energy function for the S{sub 1}(π, π{sup ∗}) state was proposed. - Abstract: Infrared and Raman spectra of 2,3,5,6-tetrafluoropyridine (TFPy) were recorded and vibrational frequencies were assigned for its S{sub 0} electronic ground states. Ab initio and density functional theory (DFT) calculations were used to complement the experimental work. The lowest electronic excited state of this molecule was investigated with ultraviolet absorption spectroscopy and theoretical CASSCF calculations. The band origin was found to be at 35,704.6 cm{sup −1} in the ultraviolet absorption spectrum. A slightly puckered structure with a barrier to planarity of 30 cm{sup −1} was predicted by CASSCF calculations for the S{sub 1}(π, π{sup ∗}) state. Lower frequencies for the out-of-plane ring bending vibrations for the electronic excited state result from the weaker π bonding within the pyridine ring.

  4. Vibrational (FT-IR and FT-Raman), electronic (UV-Vis), NMR (1H and 13C) spectra and reactivity analyses of 4,5-dimethyl-o-phenylenediamine

    Science.gov (United States)

    Atac, Ahmet; Karaca, Caglar; Gunnaz, Salih; Karabacak, Mehmet

    2014-09-01

    The structure of 4,5-dimethyl-o-phenylenediamine (C8H12N2, DMPDA) was investigated on the basis of spectroscopic data and theoretical calculations. The sterochemical structure was determined by FT-IR, FT-Raman, UV, 1H and 13C NMR spectra. An experimental study and a theoretical analysis were associated by using the B3LYP method with Gaussian09 package program. FT-IR and FT-Raman spectra were recorded in the region of 4000-400 cm-1 and 4000-10 cm-1, respectively. The vibrational spectra were calculated by DFT method and the fundamental vibrations were assigned on the basis of the total energy distribution (TED), calculated with scaled quantum mechanics (SQM) method with Parallel Quantum Solutions (PQS) program. The UV absorption spectrum of the compound that dissolved in ethanol solution were recorded in the range of 190-400 nm. Total density of state (TDOS) and partial density of state (PDOS) of the DMPDA in terms of HOMOs and LUMOs were calculated and analyzed. Chemical shifts were reported in ppm relative to tetramethylsilane (TMS) for 1H and 13C NMR spectra. The compound was dissolved in dimethyl sulfoxide (DMSO). Also, 1H and 13C chemical shifts calculated using the gauge independent atomic orbital (GIAO) method. Mullikan atomic charges and other thermo-dynamical parameters were investigated with the help of B3LYP (DFT) method using 6-311++G** basis set. On the basis of the thermodynamic properties of the title compound at different temperatures have been carried out, revealing the correlations between heat capacity (C), entropy (S), enthalpy changes (H) and temperatures. The optimized bond lengths, bond angles, chemical shifts and vibrational wavenumbers showed the best agreement with the experimental results.

  5. Raman Spectra of Interchanging β lactamase Inhibitor Intermediates on the Millisecond Time Scale

    OpenAIRE

    Torkabadi, Hossein Heidari; Che, Tao; Shou, Jingjing; Shanmugam, Sivaprakash; Crowder, Michael W.; Robert A Bonomo; Pusztai-Carey, Marianne; Carey, Paul R.

    2013-01-01

    Rapid mix - rapid freeze is a powerful method to study the mechanisms of enzyme-substrate reactions in solution. Here we report a protocol that combines this method with normal (non-resonance) Raman microscopy to enable us to define molecular details of intermediates at early time points. With this combined method, SHV-1, a class A β-lactamase, and tazobactam, a commercially available β-lactamase inhibitor, were rapidly mixed on the millisecond time-scale, then were flash-frozen by injecting ...

  6. Anomalous temperature dependence in the Raman spectra of l-alanine: Evidence for dynamic localization

    Energy Technology Data Exchange (ETDEWEB)

    Migliori, A.; Maxton, P.M.; Clogston, A.M.; Zirngiebl, E.; Lowe, M.

    1988-12-15

    We measured the temperature dependence of the intensity of the two lowest Raman modes in single crystals of l-alanine. The sum of the intensities obeys Maxwell-Boltzman statistics accurately from 20 to 340 K but the intensities of the individual lines are anomalous. This behavior is explained by assuming that both lines share the same degrees of freedom but that a mode instability is triggered abruptly at an occupation of seven quanta. This instability, which has an activation energy of 500 K, is observed at temperatures as low as 20 K, possibly indicating the existence of dynamic localization of vibrational energy.

  7. Resonance Raman spectroscopy reveals pH-dependent active site structural changes of lactoperoxidase compound 0 and its ferryl heme O-O bond cleavage products.

    Science.gov (United States)

    Mak, Piotr J; Thammawichai, Warut; Wiedenhoeft, Dennis; Kincaid, James R

    2015-01-14

    The first step in the enzymatic cycle of mammalian peroxidases, including lactoperoxidase (LPO), is binding of hydrogen peroxide to the ferric resting state to form a ferric-hydroperoxo intermediate designated as Compound 0, the residual proton temporarily associating with the distal pocket His109 residue. Upon delivery of this "stored" proton to the hydroperoxo fragment, it rapidly undergoes O-O bond cleavage, thereby thwarting efforts to trap it using rapid mixing methods. Fortunately, as shown herein, both the peroxo and the hydroperoxo (Compound 0) forms of LPO can be trapped by cryoradiolysis, with acquisition of their resonance Raman (rR) spectra now permitting structural characterization of their key Fe-O-O fragments. Studies were conducted under both acidic and alkaline conditions, revealing pH-dependent differences in relative populations of these intermediates. Furthermore, upon annealing, the low pH samples convert to two forms of a ferryl heme O-O bond-cleavage product, whose ν(Fe═O) frequencies reflect substantially different Fe═O bond strengths. In the process of conducting these studies, rR structural characterization of the dioxygen adduct of LPO, commonly called Compound III, has also been completed, demonstrating a substantial difference in the strengths of the Fe-O linkage of the Fe-O-O fragment under acidic and alkaline conditions, an effect most reasonably attributed to a corresponding weakening of the trans-axial histidyl imidazole linkage at lower pH. Collectively, these new results provide important insight into the impact of pH on the disposition of the key Fe-O-O and Fe═O fragments of intermediates that arise in the enzymatic cycles of LPO, other mammalian peroxidases, and related proteins.

  8. Raman and infrared spectroscopic study of turquoise minerals

    Science.gov (United States)

    Čejka, Jiří; Sejkora, Jiří; Macek, Ivo; Malíková, Radana; Wang, Lina; Scholz, Ricardo; Xi, Yunfei; Frost, Ray L.

    2015-10-01

    Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)2- units were observed.

  9. A study of vibrational spectra and investigations of charge transfer and chemical bonding features of 2-chloro benzimidazole based on DFT computations

    Science.gov (United States)

    Muthunatesan, S.; Ragavendran, V.

    2015-01-01

    Benzimidazoles are bicyclic heteroatomic molecules. Polycyclic heteroatomic molecules have extensive coupling of different modes leading to strong coupling of force constants associated with the various chemical bonds of the molecules. To carry out a detailed vibrational spectroscopic analysis of such a bicyclic heteroatomic molecule, FT-IR and FT-Raman spectra of 2-chloro benzimidazole (CBZ) have been recorded in the condensed phase. Density Functional Theory calculations in the B3LYP/6-31G* level have been carried out to determine the optimized geometry and vibrational frequencies. In order to obtain a close agreement between theoretical and observed frequencies and hence to perform a reliable assignment, the theoretical DFT force field was transformed from Cartesian to local symmetry co-ordinates and then scaled empirically using SQM methodology. The SQM treatment resulted in a RMS deviation of 9.4 cm-1. For visual comparison, the observed and calculated spectra are presented on a common wavenumber scale. From the NBO analysis, the electron density (ED) charge transfers in the σ* and π* antibonding orbitals and second order delocalization energies E(2) confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. The calculated Homo and Lumo energies show that charge transfer occurs within the molecule. The results obtained from the vibrational, NBO and HOMO-LUMO analyses have been properly tabulated.

  10. Davydov Splitting and Excitonic Resonance Effects in Raman Spectra of Few-Layer MoSe2.

    Science.gov (United States)

    Kim, Kangwon; Lee, Jae-Ung; Nam, Dahyun; Cheong, Hyeonsik

    2016-08-23

    Raman spectra of few-layer MoSe2 were measured with eight excitation energies. New peaks that appear only near resonance with various exciton states are analyzed, and the modes are assigned. The resonance profiles of the Raman peaks reflect the joint density of states for optical transitions, but the symmetry of the exciton wave functions leads to selective enhancement of the A1g mode at the A exciton energy and the shear mode at the C exciton energy. We also find Davydov splitting of intralayer A1g, E1g, and A2u modes due to interlayer interaction for some excitation energies near resonances. Furthermore, by fitting the spectral positions of interlayer shear and breathing modes and Davydov splitting of intralayer modes to a linear chain model, we extract the strength of the interlayer interaction. We find that the second-nearest-neighbor interlayer interaction amounts to about 30% of the nearest-neighbor interaction for both in-plane and out-of-plane vibrations. PMID:27479147

  11. The 2ν{sub 3} Raman overtone of sulfur hexafluoride: Absolute spectra, pressure effects, and polarizability properties

    Energy Technology Data Exchange (ETDEWEB)

    Chrysos, M., E-mail: michel.chrysos@univ-angers.fr; Rachet, F.; Kremer, D. [LUNAM Université, Université d’Angers, CNRS UMR 6200, Laboratoire MOLTECH-Anjou, 2 Bd Lavoisier, 49045 Angers (France)

    2014-03-28

    Of the six normal vibrations of SF{sub 6}, ν{sub 3} has a key role in the mechanisms of radiative forcing. This vibration, though inactive in Raman, shows up through the transition 2ν{sub 3} allowing for a complementary view on the asymmetric stretch of the molecule. Here, we look back into this topic, which has already caught some interest in the past but with some points been left out. We make a systematic incoherent-light-scattering analysis of the overtone with the use of different gas pressures and polarization orientations for the incident beam. Absolute-scale isotropic and anisotropic spectra are reported along with natural and pressure-induced widths and shifts, and other spectral features such as the peaks corresponding to the (experimentally indistinguishable) interfering channels E{sub g} and F{sub 2g} hitherto seen solely as two-photon IR-absorption features. We make the first-ever prediction of the SF{sub 6} polarizability second derivative with respect to the ν{sub 3}-mode coordinate and we develop a heuristic argument to explain why the superposition of the three degenerate stretching motions that are related to the ν{sub 3} mode cannot but generate a polarized Raman band.

  12. Analysis of serum from type II diabetes mellitus and diabetic complication using surface-enhanced Raman spectra (SERS)

    Science.gov (United States)

    Han, H. W.; Yan, X. L.; Dong, R. X.; Ban, G.; Li, K.

    2009-03-01

    In this paper, we show surface-enhanced Raman spectra (SERS) of serums from type II diabetes mellitus and diabetic complication (coronary disease, glaucoma and cerebral infarction), and analyze the SERS through the multivariate statistical methods of principal component analysis (PCA). In particular, we find that there exist many adenines in these serums, which maybe come from DNA (RNA) damage. The relative intensity of the band at 725±2 cm-1 assigned to adenine is higher for patients than for the healthy volunteers; therefore, it can be used as an important ‘fingerprint’ in order to diagnose these diseases. It is also shown that serums from type II diabetes mellitus group, diabetic complication group and healthy volunteers group can be discriminated by PCA.

  13. Raman spectroscopic determination of the length, strength, compressibility, Debye temperature, elasticity, and force constant of the C-C bond in graphene.

    Science.gov (United States)

    Yang, X X; Li, J W; Zhou, Z F; Wang, Y; Yang, L W; Zheng, W T; Sun, Chang Q

    2012-01-21

    From the perspective of bond relaxation and bond vibration, we have formulated the Raman phonon relaxation of graphene, under the stimuli of the number-of-layers, the uni-axial strain, the pressure, and the temperature, in terms of the response of the length and strength of the representative bond of the entire specimen to the applied stimuli. Theoretical unification of the measurements clarifies that: (i) the opposite trends of the Raman shifts, which are due to the number-of-layers reduction, of the G-peak shift and arises from the vibration of a pair of atoms, while the D- and the 2D-peak shifts involve the z-neighbor of a specific atom; (ii) the tensile strain-induced phonon softening and phonon-band splitting arise from the asymmetric response of the C(3v) bond geometry to the C(2v) uni-axial bond elongation; (iii) the thermal softening of the phonons originates from bond expansion and weakening; and (iv) the pressure stiffening of the phonons results from bond compression and work hardening. Reproduction of the measurements has led to quantitative information about the referential frequencies from which the Raman frequencies shift as well as the length, energy, force constant, Debye temperature, compressibility and elastic modulus of the C-C bond in graphene, which is of instrumental importance in the understanding of the unusual behavior of graphene.

  14. c-Axis Raman scattering spectra of MgB2: observation of a dirty-limit gap in the pi bands.

    Science.gov (United States)

    Quilty, J W; Lee, S; Tajima, S; Yamanaka, A

    2003-05-23

    Raman scattering spectra from the ac face of thick MgB2 single crystals were measured in zz, xz, and xx polarizations. In zz and xz polarizations a threshold at around 29 cm(-1) forms in the below T(c) continuum but no pair-breaking peak is seen, in contrast to the sharp pair-breaking peak at around 100 cm(-1) in xx polarization. The zz and xz spectra are consistent with Raman scattering from a dirty superconductor while the sharp peak in the xx spectra argues for a clean system. Analysis of the spectra resolves this contradiction, placing the larger and smaller gap magnitudes in the sigma and pi bands and indicating that relatively strong impurity scattering is restricted to the pi bands.

  15. [Raman spectra study of thermal transformation of nephrite cat's eye from Sichuan province].

    Science.gov (United States)

    Lu, Bao-qi; Xia, Yi-ben; Qi, Li-jian; You, Jing-lin

    2005-11-01

    Raman spectrum and X-ray powder diffraction (XRD) were used to study the process andproduct of thermal transformation of nephrite cat's eye from Sichuan province. The results indicate that upon being heated till 900 degrees C, tremolite in the nephrite cat's eye is dehydrated completely and the appearance of a new characteristic band near 671 cm(-1) indicates the form of a new product. At 1 000 degrees C, the intensity of band near 1014 cm(-1) rises obviously, and the weak bands near 573 cm(-1) and 934 cm(-1) present. Up to 1100 degrees C, the band near 1033 cm(-1) appears. All these evidences show that the final thermal transformation product is identified as Ca-Mg pyroxene which is similar to diopside both in structure and in composition. This conclusion is confirmed by XRD.

  16. Vibrational assignments, spectroscopic investigation (FT-IR and FT-Raman), NBO, MEP, HOMO‒LUMO analysis and intermolecular hydrogen bonding interactions of 7-fluoroisatin, 7-bromoisatin and 1-methylisatin ‒ A comparative study

    Science.gov (United States)

    Polat, Turgay; Bulut, Fatih; Arıcan, Ilknur; Kandemirli, Fatma; Yildirim, Gürcan

    2015-12-01

    In this comprehensive study, theoretical and experimental studies were carried out on 7-fluoroisatin, 7-bromoisatin and 1-methylisatin using FT-Raman and FT-IR spectra. The optimized geometrical parameters and theoretical vibrational frequencies were calculated by means of density functional theory (DFT/B3LYP) with 6-311++G(d,p) basis set based on scaled quantum mechanical (SQM) method for the first time. The relative abundances of the possible tautomers or conformers found were calculated with respect to the Boltzmann distribution. Moreover, the harmonic vibrational frequencies including IR and Raman intensities, thermodynamic and electronic parameters were computed in detail. The effects of substituents -F, ‒Br and -CH3 on the crucial characteristics pertaining to the title compound of isatin were investigated, and the obtained data were compared with each other. Natural bond orbital (NBO) analysis was applied to study the stability arising from charge delocalization along with the compound. The chemical reactivity parameters (chemical hardness and softness, electronegativity, chemical potential and electrophilicity index) were discussed clearly. The HOMO and LUMO energies determined showed that the serious charge transfer occurs in the title molecules studied. Furthermore, the size, shape, charge density distributions and chemical reactivity sites belonging to the molecules were obtained by mapping electron density isosurface with electrostatic potential surfaces (ESP). Additionally, the hydrogen-bonded complexes were simulated to describe the roles of intermolecular hydrogen bonding on the molecular structures and vibrational frequencies.

  17. Signs of the Biological Effect of ~2 μm Low-Intensity Laser Radiation in Raman and Absorption Spectra of Blood

    Science.gov (United States)

    Batay, L. E.; Khodasevich, I. A.; Khodasevich, M. A.; Gorbunova, N. B.; Manina, E. Yu.

    2016-09-01

    Local exposure of experimental animals to low-intensity emission from a thulium laser (λ = 1.96 μm) leads to changes in the Raman and IR absorption spectra of blood. This indicates development of systemic effects caused by direct excitation of water molecules by radiation with wavelength ~2 μm, in particular modifi cation of the hemoglobin molecule.

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    In this work, we present the state of the art in the use of theory (first principles, molecular dynamics, and statistical methods) for interpreting and understanding the infrared (vibrational) absorption and Raman scattering spectra. It is discussed how they can be used in combination with purely...

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

    NARCIS (Netherlands)

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

    2010-01-01

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

  20. Quantum chemical calculations and analysis of FTIR, FT-Raman and UV-Vis spectra of temozolomide molecule

    Science.gov (United States)

    Bhat, Sheeraz Ahmad; Ahmad, Shabbir

    2015-11-01

    A combined experimental and theoretical study of the structure, vibrational and electronic spectra of temozolomide molecule, which is largely used in the treatment of brain tumours, is presented. FTIR (4000-400 cm-1) and FT-Raman spectra (4000‒50 cm-1) have been recorded and analysed using anharmonic frequency calculations using VPT2, VSCF and CC-VSCF levels of theory within B3LYP/6-311++G(d,p) framework. Anharmonic methods give accurate frequencies of fundamental modes, overtones as well as Fermi resonances and account for coupling of different modes. The anharmonic frequencies calculated using VPT2 and CC-VSCF methods show better agreement with the experimental data. Harmonic frequencies including solvent effects are also computed using IEF-PCM model. The magnitudes of coupling between pair of modes have been calculated using coupling integral based on 2MR-QFF approximation. Intermolecular interactions are discussed for three possible dimers of temozolomide. UV-Vis spectrum, examined in ethanol solvent, is compared with the calculated spectrum at TD-DFT/6-311++G(d,p) level of theory. The electronic properties, such as excitation energy, frontier molecular orbital energies and the assignments of the absorption bands are also discussed.

  1. An experimental and theoretical investigation of Acenaphthene-5-boronic acid: Conformational study, NBO and NLO analysis, molecular structure and FT-IR, FT-Raman, NMR and UV spectra

    Science.gov (United States)

    Karabacak, Mehmet; Sinha, Leena; Prasad, Onkar; Asiri, Abdullah M.; Cinar, Mehmet

    2013-11-01

    The solid state Fourier transform infrared (FT-IR) and FT-Raman spectra of Acenaphthene-5-boronic acid (AN-5-BA), have been recorded in the range 4000-400 cm-1 and 4000-10 cm-1, respectively. Density functional theory (DFT), with the B3LYP functional was used for the optimization of the ground state geometry and simulation of the infrared and Raman spectra of the molecule. The vibrational wave numbers and their assignments were examined theoretically using the Gaussian 09 set of quantum chemistry codes and the normal modes were assigned by a scaled quantum mechanical (SQM) force field approach. Hydrogen-bonded dimer of AN-5-BA, optimized by counterpoise correction, has also been studied by B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H⋯O hydrogen bonding have been discussed. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by Gauge-Including Atomic Orbital (GIAO) method. Natural bond orbital (NBO) analysis has been applied to study stability of the molecule arising from charge delocalization. UV spectrum of the title compound was also recorded and the electronic properties, such as frontier orbitals, and band gap energies were measured by TD-DFT approach. The first order hyperpolarizability , its components and associated properties such as average polarizability and anisotropy of the polarizability (α and Δα) of AN-5-BA was calculated using the finite-field approach.

  2. Raman Scattering at Plasmonic Junctions Shorted by Conductive Molecular Bridges

    Energy Technology Data Exchange (ETDEWEB)

    El-Khoury, Patrick Z.; Hu, Dehong; Apkarian, V. Ara; Hess, Wayne P.

    2013-04-10

    Intensity spikes in Raman scattering, accompanied by switching between line spectra and band spectra, can be assigned to shorting the junction plasmon through molecular conductive bridges. This is demonstrated through Raman trajectories recorded at a plasmonic junction formed by a gold AFM tip in contact with a silver surface coated either with biphenyl-4,4’-dithiol or biphenyl-4-thiol. The fluctuations are absent in the monothiol. In effect, the making and breaking of chemical bonds is tracked.

  3. Chemometric study of Andalusian extra virgin olive oils Raman spectra: Qualitative and quantitative information.

    Science.gov (United States)

    Sánchez-López, E; Sánchez-Rodríguez, M I; Marinas, A; Marinas, J M; Urbano, F J; Caridad, J M; Moalem, M

    2016-08-15

    Authentication of extra virgin olive oil (EVOO) is an important topic for olive oil industry. The fraudulent practices in this sector are a major problem affecting both producers and consumers. This study analyzes the capability of FT-Raman combined with chemometric treatments of prediction of the fatty acid contents (quantitative information), using gas chromatography as the reference technique, and classification of diverse EVOOs as a function of the harvest year, olive variety, geographical origin and Andalusian PDO (qualitative information). The optimal number of PLS components that summarizes the spectral information was introduced progressively. For the estimation of the fatty acid composition, the lowest error (both in fitting and prediction) corresponded to MUFA, followed by SAFA and PUFA though such errors were close to zero in all cases. As regards the qualitative variables, discriminant analysis allowed a correct classification of 94.3%, 84.0%, 89.0% and 86.6% of samples for harvest year, olive variety, geographical origin and PDO, respectively. PMID:27260451

  4. Chemometric study of Andalusian extra virgin olive oils Raman spectra: Qualitative and quantitative information.

    Science.gov (United States)

    Sánchez-López, E; Sánchez-Rodríguez, M I; Marinas, A; Marinas, J M; Urbano, F J; Caridad, J M; Moalem, M

    2016-08-15

    Authentication of extra virgin olive oil (EVOO) is an important topic for olive oil industry. The fraudulent practices in this sector are a major problem affecting both producers and consumers. This study analyzes the capability of FT-Raman combined with chemometric treatments of prediction of the fatty acid contents (quantitative information), using gas chromatography as the reference technique, and classification of diverse EVOOs as a function of the harvest year, olive variety, geographical origin and Andalusian PDO (qualitative information). The optimal number of PLS components that summarizes the spectral information was introduced progressively. For the estimation of the fatty acid composition, the lowest error (both in fitting and prediction) corresponded to MUFA, followed by SAFA and PUFA though such errors were close to zero in all cases. As regards the qualitative variables, discriminant analysis allowed a correct classification of 94.3%, 84.0%, 89.0% and 86.6% of samples for harvest year, olive variety, geographical origin and PDO, respectively.

  5. FTIR and FT-Raman spectra, vibrational assignments and density functional theory calculations of 2,6-dibromo-4-nitroaniline and 2-(methylthio)aniline

    Science.gov (United States)

    Krishnakumar, V.; Balachandran, V.

    2005-06-01

    The FTIR and FT-Raman spectra of 2,6-dibromo-4-nitroaniline (2,6-DB4NA) in solid phase and 2-(methylthio)aniline (2-MTA) in liquid phase were measured. The geometry and normal vibrations have been obtained from the density functional theory (DFT) with the B3LYP method employing the 6-31G* basis set. Scale factors, which bring computational frequencies in closer agreement with the experimental data, have been calculated for predominant vibrational motions of the normal modes. The effects of the amino, bromine, nitro, thio and methyl substituents on vibrational frequencies have been investigated. The infrared and Raman spectra were also predicted from the calculated intensities. The observed and the calculated spectra were found to be in good agreement.

  6. Resonance Raman spectra of organic molecules absorbed on inorganic semiconducting surfaces: Contribution from both localized intramolecular excitation and intermolecular charge transfer excitation

    International Nuclear Information System (INIS)

    The time-dependent correlation function approach for the calculations of absorption and resonance Raman spectra (RRS) of organic molecules absorbed on semiconductor surfaces [Y. Zhao and W. Z. Liang, J. Chem. Phys. 135, 044108 (2011)] is extended to include the contribution of the intermolecular charge transfer (CT) excitation from the absorbers to the semiconducting nanoparticles. The results demonstrate that the bidirectionally interfacial CT significantly modifies the spectral line shapes. Although the intermolecular CT excitation makes the absorption spectra red shift slightly, it essentially changes the relative intensities of mode-specific RRS and causes the oscillation behavior of surface enhanced Raman spectra with respect to interfacial electronic couplings. Furthermore, the constructive and destructive interferences of RRS from the localized molecular excitation and CT excitation are observed with respect to the electronic coupling and the bottom position of conductor band. The interferences are determined by both excitation pathways and bidirectionally interfacial CT

  7. [Study on the Recognition of Liquor Age of Gujing Based on Raman Spectra and Support Vector Regression].

    Science.gov (United States)

    Wang, Guo-xiang; Wang, Hai-yan; Wang, Hu; Zhang, Zheng-yong; Liu, Jun

    2016-03-01

    It is an important and difficult research point to recognize the age of Chinese liquor rapidly and exactly in the field of liquor analyzing, which is also of great significance to the healthy development of the liquor industry and protection of the legitimate rights and interests of consumers. Spectroscopy together with the pattern recognition technology is a preferred method of achieving rapid identification of wine quality, in which the Raman Spectroscopy is promising because of its little affection of water and little or free of sample pretreatment. So, in this paper, Raman spectra and support vector regression (SVR) are used to recognize different ages and different storing time of the liquor of the same age. The innovation of this paper is mainly reflected in the following three aspects. First, the application of Raman in the area of liquor analysis is rarely reported till now. Second, the concentration of studying the recognition of wine age, while most studies focus on studying specific components of liquor and studies together with the pattern recognition method focus more on the identification of brands or different types of base wine. The third one is the application of regression analysis framework, which cannot be only used to identify different years of liquor, but also can be used to analyze different storing time, which has theoretical and practical significance to the research and quality control of liquor. Three kinds of experiments are conducted in this paper. Firstly, SVR is used to recognize different ages of 5, 8, 16 and 26 years of the Gujing Liquor; secondly, SVR is also used to classify the storing time of the 8-years liquor; thirdly, certain group of train data is deleted form the train set and put into the test set to simulate the actual situation of liquor age recognition. Results show that the SVR model has good train and predict performance in these experiments, and it has better performance than other non-liner regression method such

  8. A novel europium (III) nitridoborate Eu3[B3N6]: Synthesis, crystal structure, magnetic properties, and Raman spectra

    Science.gov (United States)

    Aydemir, Umut; Kokal, Ilkin; Prots, Yurii; Förster, Tobias; Sichelschmidt, Jörg; Schappacher, Falko M.; Pöttgen, Rainer; Ormeci, Alim; Somer, Mehmet

    2016-07-01

    A novel europium (III) nitridoborate, Eu3[B3N6], was successfully synthesized by oxidation of Eu3II[BN2]2 with Br2 at 1073 K. The compound crystallizes in the trigonal space group R 3 barc (No:167) with a=11.9370(4) Å, c=6.8073(4) Å, and Z=6. The crystal structure of Eu3[B3N6] consists of isolated, planar cyclic [B3N6]9- units which are charge-balanced by Eu3+ cations. The oxidation state of Eu was investigated by Mössbauer spectroscopy, electron spin resonance (ESR) spectroscopy, and quantum chemical calculations. The 151Eu Mössbauer spectroscopic measurement at 77 K reveals that the main signal at δ=0.93(7) mm/s is originating from trivalent Europium. Eu3[B3N6] showed no ESR signal in accordance with a non-magnetic (J=0) 7F0 ground state of the 4f6 configuration. Quantum chemical calculations find six electrons in the 4f subshell (4f6) of Eu indicating an oxidation state of +3. We present for the first time the vibrational spectra of a compound with cyclic trimer [B3N6]9- moieties. The Raman spectrum of Eu3[B3N6] is in good agreement with the predicted number of modes for the spectroscopically relevant cyclic [B3N6]9- group with D3h symmetry.

  9. Phonon Raman spectra of colloidal CdTe nanocrystals: effect of size, non-stoichiometry and ligand exchange

    Directory of Open Access Journals (Sweden)

    Lokteva Irina

    2011-01-01

    Full Text Available Abstract Resonant Raman study reveals the noticeable effect of the ligand exchange on the nanocrystal (NC surface onto the phonon spectra of colloidal CdTe NC of different size and composition. The oleic acid ligand exchange for pyridine ones was found to change noticeably the position and width of the longitudinal optical (LO phonon mode, as well as its intensity ratio to overtones. The broad shoulder above the LO peak frequency was enhanced and sharpened after pyridine treatment, as well as with decreasing NC size. The low-frequency mode around 100 cm-1 which is commonly related with the disorder-activated acoustical phonons appears in smaller NCs but is not enhanced after pyridine treatment. Surprisingly, the feature at low-frequency shoulder of the LO peak, commonly assigned to the surface optical phonon mode, was not sensitive to ligand exchange and concomitant close packing of the NCs. An increased structural disorder on the NC surface, strain and modified electron-phonon coupling is discussed as the possible reason of the observed changes in the phonon spectrum of ligand-exchanged CdTe NCs. PACS: 63.20.-e, 78.30.-j, 78.67.-n, 78.67.Bf

  10. A comparative study of the infrared and Raman spectra of aniline and o-, m-, p-phenylenediamine isomers

    Science.gov (United States)

    Badawi, Hassan M.; Förner, Wolfgang; Ali, Shaikh A.

    2013-08-01

    The structural stabilities of o-, m- and p-phenylenediamine (PDA) isomers were investigated by DFT-B3LYP and ab initio MP2 calculations with the 6-311G** basis set. From the calculations the three isomers were predicted to exist predominantly in an anti (transoid) structure. In the o-isomer, the syn (cisoid) form is calculated to turn to the anti (transoid) form with the two HNCC torsional angles of about 44 and 10° and the NH2 inversion barrier of 3-4 kcal/mol. The CCNH torsional angles in the m-PDA and p-PDA isomers were calculated to be about 25-26° as compared to 20° in aniline. A comparison of the Raman spectra of the three PDA-s with those of aniline shows the high sensitivity of the ring breathing mode to the nature of substituents in the aniline ring. The vibrational wavenumbers were computed at the DFT-B3LYP for aniline and the o-, m- and p-PDA isomers for the purpose of comparison. Complete vibrational assignments were made on the basis of normal coordinate analyses and potential energy distributions for aniline and the o-, m- and p-PDA molecules.

  11. Raman spectra of Cu{sub 2}B{sup II}C{sup IV}X{sub 4}{sup VI} magnetic quaternary semiconductor compounds with tetragonal stannite type structure

    Energy Technology Data Exchange (ETDEWEB)

    Rincón, C., E-mail: crincon@ula.ve; Quintero, M.; Power, Ch.; Moreno, E.; Quintero, E.; Morocoima, M. [Centro de Estudios de Semiconductores, Departamento de Física, Facultad de Ciencias, Universidad de Los Andes, Mérida (Venezuela, Bolivarian Republic of); Henao, J. A.; Macías, M. A. [Grupo de Investigación en Química Estructural, Facultad de Ciencias, Escuela de Química, Universidad Industrial de Santander, Apartado Aéreo 678, Bucaramanga (Colombia)

    2015-05-28

    A comparative study of the Raman spectra of Cu{sub 2}B{sup II}C{sup IV}S{sub 4}{sup VI} and Cu{sub 2}B{sup II}C{sup IV}Se{sub 4}{sup VI}(where B = Mn or Fe) magnetic quaternary semiconductor compounds with stannite-type structure (I4{sup ¯}2m) has been done. Most of the fourteen Raman lines expected for these materials were observed in the spectra. The two strongest lines observed have been assigned to the IR inactive A{sub 1}{sup 1} and A{sub 1}{sup 2} stannite modes that originated from the motion of the S or Se anion around the Cu and C{sup IV} cations remaining at rest. The shift in the frequency of these two lines of about 150 cm{sup −1} to lower energies observed in Cu{sub 2}B{sup II}C{sup IV}Se{sub 4}{sup VI} compounds as compared to those in Cu{sub 2}B{sup II}C{sup IV}S{sub 4}{sup VI} ones, can then be explained as due to the anion mass effect. Based on the fact that values of these frequencies depend mainly on anion mass and bond-stretching forces between nearest-neighbor atoms, the vibrational frequencies v{sup ¯}(A{sub 1}{sup 2}) and v{sup ¯}(A{sub 1}{sup 2}) of both modes for several Cu{sub 2}B{sup II}C{sup IV}X{sub 4}{sup VI} stannite compounds (where X = S, Se, or Te) very close to the experimental data reported for these materials were calculated from a simple model that relates these stretching forces to the anion-cation bond-distances.

  12. Difference in effect of temperature on absorption and Raman spectra between all-trans-β-carotene and all-trans-retinol

    Institute of Scientific and Technical Information of China (English)

    Qu Guan-Nan; Li Zuo-Wei; Gao Shu-Qin; Li Shuo; Sun Cheng-Lin; Liu Tian-Yuan; Wu Yong-Ling; Sun Shang; Shan Xiao-Ning; Men Zhi-Wei; Chen Wei

    2012-01-01

    Temperature dependencies (81 ℃-18 ℃) of visible absorption and Raman spectra of all-trans-β-carotene and all-trans-retinol extremely diluted in dimethyl sulfoxide are investigated in order to clarify temperature effects on different polyenes.Their absorption spectra are identified to be redshifted with temperature decreasing.Moreover,all-trans-β-carotene is more sensitive to temperature due to the presence of a longer length of conjugated system.The characteristic energy responsible for the conformational changes in all-trans-β-carotene is smaller than that in all-trans-retinol.Both of the Raman scattering cross sections increase with temperature decreasing.The results are explained with electron-phonon coupling theory and coherent weakly damped electron-lattice vibrations model.

  13. Microwave, infrared and Raman spectra, r0 structural parameters, ab initio calculations and vibrational assignment of 1-fluoro-1-silacyclopentane.

    Science.gov (United States)

    Durig, James R; Panikar, Savitha S; Obenchain, Daniel A; Bills, Brandon J; Lohan, Patrick M; Peebles, Rebecca A; Peebles, Sean A; Groner, Peter; Guirgis, Gamil A; Johnston, Michael D

    2012-01-28

    The microwave spectrum (6500-18 ,500 MHz) of 1-fluoro-1-silacyclopentane, c-C(4)H(8)SiHF has been recorded and 87 transitions for the (28)Si, (29)Si, (30)Si, and (13)C isotopomers have been assigned for a single conformer. Infrared spectra (3050-350 cm(-1)) of the gas and solid and Raman spectrum (3100-40 cm(-1)) of the liquid have also been recorded. The vibrational data indicate the presence of a single conformer with no symmetry which is consistent with the twist form. Ab initio calculations with a variety of basis sets up to MP2(full)/aug-cc-pVTZ predict the envelope-axial and envelope-equatorial conformers to be saddle points with nearly the same energies but much lower energy than the planar conformer. By utilizing the microwave rotational constants for seven isotopomers ((28)Si, (29)Si, (30)Si, and four (13)C) combined with the structural parameters predicted from the MP2(full)/6-311+G(d,p) calculations, adjusted r(0) structural parameters have been obtained for the twist conformer. The heavy atom distances in Å are: r(0)(SiC(2)) = 1.875(3); r(0)(SiC(3)) = 1.872(3); r(0)(C(2)C(4)) = 1.549(3); r(0)(C(3)C(5)) = 1.547(3); r(0)(C(4)C(5)) = 1.542(3); r(0)(SiF) = 1.598(3) and the angles in degrees are: [angle]CSiC = 96.7(5); [angle]SiC(2)C(4) = 103.6(5); [angle]SiC(3)C(5) = 102.9(5); [angle]C(2)C(4)C(5) = 108.4(5); [angle]C(3)C(5)C(4) = 108.1(5); [angle]F(6)Si(1)C(2) = 110.7(5); [angle]F(6)Si(1)C(3) = 111.6(5). The heavy atom ring parameters are compared to the corresponding r(s) parameters. Normal coordinate calculations with scaled force constants from MP2(full)/6-31G(d) calculations were carried out to predict the fundamental vibrational frequencies, infrared intensities, Raman activities, depolarization values, and infrared band contours. These experimental and theoretical results are compared to the corresponding quantities of some other five-membered rings.

  14. The giant frequency shift of intramolecular O-H vibration band in the raman spectra of water on the silver surface

    CERN Document Server

    Kompan, Mikhail

    2016-01-01

    The giant frequency shift was observed in Raman spectra for inramolecular O-H vibration band. The effect was observed in SERS-condition experiment, when exciting light was focused by short-focus objective on the Ag-surface, merged in water. The shift was detected relatively to the regularl position of band, measured from the bulk of water under the same other conditions.

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

    Science.gov (United States)

    Todorov, Petar D; Jenneskens, Leonardus W; van Lenthe, Joop H

    2010-01-21

    The molecular geometry and the normal modes properties of coronene are investigated by means of DFT(B3LYP) and restricted/Hartree-Fock calculations utilizing basis sets of triple zeta+polarization quality. The interpretation of the infrared and Raman spectra of coronene, especially in solid state, is critically revised. The phantom bands in the solid state, previously not understood, are readily assigned after considering a minute out-of-plane molecular distortion from D(6h) to C(2h).

  16. NBO, NMR, UV, FT-IR, FT-Raman spectra and molecular structure (monomeric and dimeric structures) investigation of 4-Chloro-3,5-Xylenol: A combined experimental and theoretical study

    Science.gov (United States)

    Arivazhagan, M.; Gayathri, R.

    2013-12-01

    In this work, a joint experimental (FTIR and FT-Raman) and theoretical (DFT and ab initio) study on the structure and the vibrations of 4-Chloro-3,5-Xylenol (CXL) are compared and analyzed. CXL is a chlorinated phenolic antiseptic which is a bactericide against most gram-positive bacteria. The first hyperpolarizability (β0) of this novel molecular system and related non-linear properties of CXL are calculated using HF/6-311++G(d,p) method on the finite-field approach. The energy and oscillator strength calculated using absorption spectra (UV-Vis spectrum), this spectral analysis confirms the charge transfer of the molecule. The theoretical 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by Gauge Including Atomic Orbital (GIAO) method, to analyze the molecular environment as well as the delocalization activities of electron clouds. The directly calculated ionization potential (IP), electron affinity (EA), electronegativity (χ), chemical hardness (η), first electron excitation energy (τ) and electrophilicity index (ω) as well as local reactivity (S) analyzed using HOMO and LUMO energies; the energy band gap are also determined. NBO analysis shows that charge in electron density(ED) in the σ* and π* antibonding orbitals and E(2) energies confirms the occurrence of ICT (Intramolecular Charge Transfer) within the molecule. Inter molecular hydrogen bonds exist between -OH group, give the evidence for the formation of dimer entities in the title molecule. The influences of chlorine atom, hydroxyl group and methyl group on the geometry of benzene and its normal modes of vibrations (monomer and dimer of CXL) have also been discussed. Finally the calculated results were applied to simulate Infrared and Raman spectra of the title molecule which show good agreement with observed spectra.

  17. Vibration wavenumbers of 3-aminobenzotrifluoride in the ground and S1 electronic states from its infrared, Raman, and supersonic jet S1- S0 fluorescence spectra

    Science.gov (United States)

    Ribeiro-Claro, Paulo J. A.; Teixeira-Dias, JoséJ. C.; Gordon, Robert D.; Hollas, J. Michael

    1991-11-01

    Raman and infrared spectra of 3-aminobenzotrifluoride, in the liquid phase, and single vibronic level fluorescence spectra, in a supersonic jet, have been obtained and interpreted to give a fairly complete set of vibrational assignments in S0. These include the observation of the I 20 band in fluorescence, where ν1 is the NH 2-inversion vibration, in agreement with a previous interpretation of the gas phase far infrared spectrum. A strong Fermi resonance between one quantum of the a'CCF 3 bending vibration and two quanta of the a″CCF 3 bending vibration has been identified in S1.

  18. 拉曼光谱快速检测氨甲环酸注射液%Rapid Raman spectra identification and determination of Tranexamic acid injection

    Institute of Scientific and Technical Information of China (English)

    刘惠军; 吴丽红; 张继春; 傅莉萍

    2013-01-01

    OBJECTIVE To develop a method for the rapid identification,test and determine of Tranexamic acid injection using Raman spectra.METHODS Raman spectra was used to identify,test and determine the Tranexamic acid injection.RESULTS The result showed that the method of Raman spectra could identify,check pH value and determinate the Tranexamic acid injection.CONCLUSION Owing to its fast and nondestructive properties,the presented method can be developed as a analysis method for injection.%目的 运用拉曼光谱技术快速鉴别、检查和测定氨甲环酸注射液.方法 以氨甲环酸原料及注射液为研究对象,应用拉曼光谱方法快速检测氨甲环酸.结果 拉曼光谱方法可以鉴别氨甲环酸注射液,并进行pH值检查和含量测定.结论 所用方法操作简便、快速,可发展成为注射剂快速检测的分析方法.

  19. Accurate rotational constant and bond lengths of hexafluorobenzene by femtosecond rotational Raman coherence spectroscopy and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Den, Takuya S.; Frey, Hans-Martin; Leutwyler, Samuel, E-mail: leutwyler@dcb.unibe.ch [Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3000 Bern 9 (Switzerland)

    2014-11-21

    The gas-phase rotational motion of hexafluorobenzene has been measured in real time using femtosecond (fs) time-resolved rotational Raman coherence spectroscopy (RR-RCS) at T = 100 and 295 K. This four-wave mixing method allows to probe the rotation of non-polar gas-phase molecules with fs time resolution over times up to ∼5 ns. The ground state rotational constant of hexafluorobenzene is determined as B{sub 0} = 1029.740(28) MHz (2σ uncertainty) from RR-RCS transients measured in a pulsed seeded supersonic jet, where essentially only the v = 0 state is populated. Using this B{sub 0} value, RR-RCS measurements in a room temperature gas cell give the rotational constants B{sub v} of the five lowest-lying thermally populated vibrationally excited states ν{sub 7/8}, ν{sub 9}, ν{sub 11/12}, ν{sub 13}, and ν{sub 14/15}. Their B{sub v} constants differ from B{sub 0} by between −1.02 MHz and +2.23 MHz. Combining the B{sub 0} with the results of all-electron coupled-cluster CCSD(T) calculations of Demaison et al. [Mol. Phys. 111, 1539 (2013)] and of our own allow to determine the C-C and C-F semi-experimental equilibrium bond lengths r{sub e}(C-C) = 1.3866(3) Å and r{sub e}(C-F) = 1.3244(4) Å. These agree with the CCSD(T)/wCVQZ r{sub e} bond lengths calculated by Demaison et al. within ±0.0005 Å. We also calculate the semi-experimental thermally averaged bond lengths r{sub g}(C-C)=1.3907(3) Å and r{sub g}(C-F)=1.3250(4) Å. These are at least ten times more accurate than two sets of experimental gas-phase electron diffraction r{sub g} bond lengths measured in the 1960s.

  20. Comprehensive thermal characterization using ruby R fluorescence lines of sapphire and GaNE2-high Raman mode from Raman spectra in high-power flip-chip InGaN/GaN LEDs

    International Nuclear Information System (INIS)

    A comprehensive temperature characterization method based on the GaNE2-high Raman mode and sapphire ruby R fluorescence lines from Raman spectra was developed to analyse the thermal distribution and heat transfer process of high-power flip-chip InGaN/GaN LEDs (FC LEDs). Our analysis demonstrated that in addition to the known problem that the edges of mesa were always the hottest point of FC LEDs, which was due to the current crowding effect, a noteworthy temperature difference was first observed between the sapphire substrate and n-GaN when the injection current was above 300 mA. A 'heat reservoir' was suggested to occur at the interface between the sapphire and n-GaN due to poor thermal conductivity of sapphire when a large amount of heat from the hottest spot cannot be effectively transferred to the Si mount via the active region under high injection currents.

  1. Application of the Correlation Method to Vibrational Spectra of C60 and Other Fullerenes: Predicting the Number of IR- and Raman-Active Bands

    Science.gov (United States)

    Nakamoto, Kazuo; McKinney, Michael A.

    2000-06-01

    The C60 molecule (Buckyball/soccer ball) exhibits only 4 IR and 10 Raman bands although it possesses 174 (3 x 60 - 6) normal vibrations. This striking reduction in the number of observed bands is evidently due to the molecule's extremely high symmetry (Ih point group). First, the 120 symmetry elements of its truncated icosahedral structure are identified and the local (site) symmetry of the carbon atoms (Cc) is determined. Use of molecular models greatly facilitates the process in determining the local and molecular symmetries. Then the correlation method is used to derive a table that classifies the 174 normal vibrations into the respective symmetry species of the Ih point group. In this method, symmetry properties of atomic displacements in terms of the local point group (Cc) are correlated with those in terms of the molecular point group (Ih). After the normal vibrations are classified into respective symmetry species, the numbers of IR- and Raman-active vibrations can be determined by the symmetry selection rules for IR and Raman spectra. The vibrational spectra of C60 and C70 (rugby ball) are analyzed by the above procedure, and the results obtained for C28, C32, C50, and dodecahedrane are provided.

  2. A light-through-side cell and co-used furnace designed for micro-Raman spectra study on volatile melts

    Institute of Scientific and Technical Information of China (English)

    Xian Wei Hu; Huan Li; Bing Liang Gao; Jing Jing Liu; Zhong Ning Shi; Jiang Yu Yu; Zhao Wen Wang

    2012-01-01

    A new type of sample cell specially designed for micro-Raman spectra study on volatile melts is described.The cell is made of quartz.The lower section of the cell is circular ring-shaped and the one-end-closed hole in the cell is used for locating the heating body.The tube attached to the cell lid for placing the thermal couple is inserted into the sample,which ensures that the temperature measurement accuracy is good.The cell can be sealed for reducing the effect of the composition change caused by the inhomogeneous volatilization.During the Raman spectra scanning,the laser beam is transmitted into the cell through the side but not the top.Meanwhile,a furnace has been designed to match the cell.The heating body is closely coupled with the sample cell,and there is a hole on the side wall of the furnace for the entrance of the microlens.The assembly has performed well in the tested Raman spectrum measurement of molten NaNO3 at 602 ℃.

  3. Study of far-infrared reflection and Raman scattering spectra in reactive ion, etched ZnTe

    Institute of Scientific and Technical Information of China (English)

    吴森; 沈文忠; 小川博司; 郭其新

    2003-01-01

    Far-infrared reflection and Raman scattering measurements have been carried out on reactive ion,etched p-ZnTe samples.The averaged thickness of the surface damaged layer is found to be in the range of 1.0-1.5μm,and the,etch-induced defect density is in the order of 1018cm-3.The Raman intensity ratio between the second-order Raman peaks and the first-order longitudinal optical phonons reveals an increase trend with the radio frequency(rf)power.With the aid of related theories,we discuss the effects of the rf plasma power and the concentration of CH4/H2 on the damage,disorder,and the second-order Raman structures in p-ZnTe samples.

  4. SINGLE CRYSTAL GROWTH, X-RAY STRUCTURE ANALYSIS, OPTICAL BAND GAP, RAMAN SPECTRA, STRAIN TENSOR AND PHOTOLUMINSCENCE PROPERTIES IN [HgCl4]- [R]+ AND [ZnCl4]- [R]+ (R = 2-AMINO-5-CHLOROPYRIDINE HYBRID MATERIALS

    Directory of Open Access Journals (Sweden)

    A. Kumar

    2015-09-01

    Full Text Available The single crystal growth  of tetrachloromercurate (II [HM-1] and tetrachlorozincate (II [HM-2] with 2-amino-5-chloropyridine has been performed by slow cooling (SC crystal growth technique of solution growth methodin which needle shaped transparent single crystals (0.5 x 0.2 x 0.2mm were obtained. The crystal structures of these hybrid materials have been studied by X-ray diffraction, experimental and computational methods. [HgCl4]2- anions have a distorted tetrahedral geometry and the tetrahedra hybrid structure exhibit interwoven inorganic-organic layers mingled through N-Hδ+...Clδ- hydrogen bonding interactions. The mercurophilic interactions [Hg...Hg = 3.984(5Å] and halogen interactions [Cl...Cl = 3.406(2Å] form 2D parallelogram pattern of secondary interactions in [HM-1] whereas for [HM-2] crystal structure is stabilized by Cl...Cl = 3.357(2Å interactions. UV-vis absorption spectra depict the change in optical band gap from 3.01 eV to 3.42 eV on replacing the metal halide group, could be due to increase in optical absorption as a function of wavelength. The Raman and Hyper-Raman tensors calculations were performed based on single crystal X-ray data and the Lagrangian strain tensor calculations show the degree of lattice distortion = 1.794 between [HM-1] and [HM-2] which are useful tools for the optical response properties of inorganic-organic hybrid derivatives. The photoluminescence emission spectra peaks were observed in the wavelength range of 371 to 598 nm for material [HM-1] and  in the wavelength range of 384 to 600 nm for material [HM-2] and lie in the visible range for both materials.

  5. Infrared, Raman, and visible spectroscopic studies of Zn and Cd matrix reactions with ozone. Spectra of metal ozonides and oxides in solid argon and nitrogen

    Science.gov (United States)

    Prochaska, Eleanor S.; Andrews, Lester

    1980-06-01

    Reactions of zinc and cadmium atoms with ozone during condensation with excess nitrogen or argon produced B+O3- ion-pairs having infrared, Raman, and optical spectra similar to the analogous alkali and alkaline earth metal species. Additional infrared and Raman evidence was found for a different B+O3- ion-pair geometry. Mercury arc photolysis reduced ozonide absorptions and produced new 810 cm-1 zinc isotopic triplets which showed the appropriate 18O shifts for ZnO, and a new 719 cm-1 band which showed the proper 18O displacement for CdO. This nitrogen matrix work provides good measures of the yet-to-be-observed gas-phase fundamentals of these high temperature oxides.

  6. 6种新型香豆素类衍生物的拉曼光谱研究%Raman spectra studies on six new coumarin derivatives

    Institute of Scientific and Technical Information of China (English)

    刘婵; 周吉; 刘丽娜; 任华华; 叶勇

    2013-01-01

    The coumarins have been widely used as the organic heterocyclic compounds .It has very high medicine value duce to its biological activities in preventing HIV , preventing cancer , lowering blood pressure and preventing arrhythmia .In this study ,six new derivatives of coumarin were synthesized by using the tertiary amine as catalyst ,and then these coumarin derivatives were characterized by Raman spectra .Besides ,the characteristic spectra of the compound were assigned and we discussed the effects of structure in different components on the Raman spectra .%  香豆素是一类应用很广泛的有机杂环化合物,具有抗 HIV、抗癌、降压、抗心律失常等多种生物活性,具有很高的药用价值。本实验利用叔胺催化,合成了6种新型香豆素衍生物,采用激光显微拉曼光谱对其结构进行研究,归属各化合物拉曼谱峰,并探讨分子结构差异对拉曼光谱的影响。

  7. Raman spectra of R{sub 2}O{sub 3} (R—rare earth) sesquioxides with C-type bixbyite crystal structure: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Abrashev, M. V., E-mail: mvabr@phys.uni-sofia.bg [Instituto de Física, UFRGS, Porto Alegre, 91501-970 Rio Grande do Sul (Brazil); Faculty of Physics, University of Sofia, BG-1164 Sofia (Bulgaria); Todorov, N. D. [Faculty of Physics, University of Sofia, BG-1164 Sofia (Bulgaria); Geshev, J. [Instituto de Física, UFRGS, Porto Alegre, 91501-970 Rio Grande do Sul (Brazil)

    2014-09-14

    Raman spectra of R{sub 2}O{sub 3} (R—Sc, Er, Y, Ho, Gd, Eu, and Sm) powders with C-type bixbyite crystal structure are measured. With the help of these data and ones, previously published for other oxides from the same structural family, general dependencies of the frequencies of the Raman peaks on the cubic crystal unit cell parameter are constructed. Using these dependencies and knowing the symmetry of the peaks for one of the oxides, determined from previous single-crystal measurements, it is possible to find out the symmetry of the peaks from the spectra of all compounds. It was found that the frequency of the six lowest frequency peaks scales with the square root of the mass of the rare earth showing that mainly R ions take part in these vibrations. These results agree with performed here lattice dynamical calculations. The anomalous softening of the frequency of some peaks in the spectra of Eu{sub 2}O{sub 3} is discussed.

  8. Raman and FTIR spectra of CeO{sub 2} and Gd{sub 2}O{sub 3} in iron phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Yuanming, E-mail: laiyuanming@ipm.com.cn [State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming Institute of Precious Metals, Kunming 650106 (China); State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Liang, Xiaofeng; Yang, Shiyuan [State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Liu, Pei; Zeng, Yiming; Hu, Changyi [State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming Institute of Precious Metals, Kunming 650106 (China)

    2014-12-25

    Highlights: • The structure of the studied samples has been investigated by Raman and FTIR spectroscopy. • The structure for the all samples has similar features. • The structure consists of predominantly Q{sup 1} with a fraction of Q{sup 0} and Q{sup 2} units. • The Ce and Gd enters in the structure of studied glasses as a network modifier. - Abstract: In the present work, multicomponent oxide samples of composition x(CeO{sub 2} + Gd{sub 2}O{sub 3})–(40 − x)Fe{sub 2}O{sub 3}–60P{sub 2}O{sub 5} (0 ⩽ x ⩽ 8 mol%) were produced by conventional melting method. The samples were investigated to examine the effect of the CeO{sub 2} and Gd{sub 2}O{sub 3} composition on the structure of the iron phosphate glasses system. The X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) for the x ⩽ 6 mol% samples show all the samples formed homogeneous glass, but for the x = 8 mol% samples show the presence of randomly distributed crystalline phase embedded in an amorphous matrix. The x(CeO{sub 2} + Gd{sub 2}O{sub 3})–(40 − x)Fe{sub 2}O{sub 3}–60P{sub 2}O{sub 5} glass containing 8 mol% CeO{sub 2} and Gd{sub 2}O{sub 3} partially crystallized during annealing and Ce/Gd-rich were identified by EDS in the crystalline phase. The structure of the studied samples has been investigated using Raman and Fourier transform infrared spectroscopy (FTIR). The Raman and FTIR spectra for the samples have analogous spectral features. The Raman and FTIR spectra suggest that the structure is mainly constituted by the pyrophosphate glass based structure, with a part proportion of metaphosphate and orthophosphate structure. Raman and FTIR spectra allowed us to identify the structural units which appear in the structural network of these phosphate glasses and also the network modifier role of cerium and gadolinium ions.

  9. Electronic Raman scattering with excitation between localized states observed in the zinc M{sub 2,3} soft x-ray spectra of ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, L.; Callcott, T.A.; Jia, J.J. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

    1997-04-01

    Zn M{sub 2,3} soft x-ray fluorescence (SXF) spectra of ZnS and ZnS{sub .5}Se{sub .5} excited near threshold show strong inelastic scattering effects that can be explained using a simple model and an inelastic scattering theory based on second order perturbation theory. This scattering is often called electronic resonance Raman scattering. Tulkki and Aberg have developed this theory in detail for atomic systems, but their treatment can be applied to solid systems by utilizing electronic states characteristic of solids rather than of atomic systems.

  10. Raman spectra and cross sections of ammonia, chlorine, hydrogen sulfide, phosgene, and sulfur dioxide toxic gases in the fingerprint region 400-1400 cm−1

    Directory of Open Access Journals (Sweden)

    R. L. Aggarwal

    2016-02-01

    Full Text Available Raman spectra of ammonia (NH3, chlorine (Cl2, hydrogen sulfide (H2S, phosgene (COCl2, and sulfur dioxide (SO2 toxic gases have been measured in the fingerprint region 400-1400 cm−1. A relatively compact (<2′x2′x2′, sensitive, 532 nm 10 W CW Raman system with double-pass laser and double-sided collection was used for these measurements. Two Raman modes are observed at 934 and 967 cm−1 in NH3. Three Raman modes are observed in Cl2 at 554, 547, and 539 cm−1, which are due to the 35/35 35/37, and 37/37 Cl isotopes, respectively. Raman modes are observed at 870, 570, and 1151 cm−1 in H2S, COCl2, and SO2, respectively. Values of 3.68 ± 0.26x10−32 cm2/sr (3.68 ± 0.26x10−36 m2/sr, 1.37 ± 0.10x10−30 cm2/sr (1.37 ± 0.10x10−34 m2/sr, 3.25 ± 0.23x10−31 cm2/sr (3.25 ± 0.23x10−35 m2/sr, 1.63 ± 0.14x10−30 cm2/sr (1.63 ± 0.14x10−34 m2/sr, and 3.08 ± 0.22x10−30 cm2/sr (and 3.08 ± 0.22x10−34 m2/sr were determined for the differential Raman cross section of the 967 cm−1 mode of NH3, sum of the 554, 547, and 539 cm−1 modes of Cl2, 870 cm−1 mode of H2S, 570 cm−1 mode of COCl2, and 1151 cm-1 mode of SO2, respectively, using the differential Raman cross section of 3.56 ± 0.14x10−31 cm2/sr (3.56 ± 0.14x10−35 m2/sr for the 1285 cm−1 mode of CO2 as the reference.

  11. Raman spectra and cross sections of ammonia, chlorine, hydrogen sulfide, phosgene, and sulfur dioxide toxic gases in the fingerprint region 400-1400 cm-1

    Science.gov (United States)

    Aggarwal, R. L.; Farrar, L. W.; Di Cecca, S.; Jeys, T. H.

    2016-02-01

    Raman spectra of ammonia (NH3), chlorine (Cl2), hydrogen sulfide (H2S), phosgene (COCl2), and sulfur dioxide (SO2) toxic gases have been measured in the fingerprint region 400-1400 cm-1. A relatively compact (<2'x2'x2'), sensitive, 532 nm 10 W CW Raman system with double-pass laser and double-sided collection was used for these measurements. Two Raman modes are observed at 934 and 967 cm-1 in NH3. Three Raman modes are observed in Cl2 at 554, 547, and 539 cm-1, which are due to the 35/35 35/37, and 37/37 Cl isotopes, respectively. Raman modes are observed at 870, 570, and 1151 cm-1 in H2S, COCl2, and SO2, respectively. Values of 3.68 ± 0.26x10-32 cm2/sr (3.68 ± 0.26x10-36 m2/sr), 1.37 ± 0.10x10-30 cm2/sr (1.37 ± 0.10x10-34 m2/sr), 3.25 ± 0.23x10-31 cm2/sr (3.25 ± 0.23x10-35 m2/sr), 1.63 ± 0.14x10-30 cm2/sr (1.63 ± 0.14x10-34 m2/sr), and 3.08 ± 0.22x10-30 cm2/sr (and 3.08 ± 0.22x10-34 m2/sr) were determined for the differential Raman cross section of the 967 cm-1 mode of NH3, sum of the 554, 547, and 539 cm-1 modes of Cl2, 870 cm-1 mode of H2S, 570 cm-1 mode of COCl2, and 1151 cm-1 mode of SO2, respectively, using the differential Raman cross section of 3.56 ± 0.14x10-31 cm2/sr (3.56 ± 0.14x10-35 m2/sr) for the 1285 cm-1 mode of CO2 as the reference.

  12. 彩色珍珠致色成分的拉曼光谱研究%Reserach on Raman Spectra of Organic Ingredients on Colored Pearls

    Institute of Scientific and Technical Information of China (English)

    胡洋; 范陆薇; 黄艺兰

    2014-01-01

    Based on the visible spectra and Raman spectra test of a variety of colored pearls samples to study the relationship be-tween the organic component and the pearl’s color was studied .The study results show that both the freshwater and seawater pearls exhibit strong characteristic peaks in 1 121~1 132 and 1 506~1 524 cm-1 range ,which is respectively attributed to the C-C and C=C stretching vibration ;the peak intensity in 1 117~1 132 ,1 502~1 524 and 2 000~3 500 cm -1 range increases as the color deepens ,which is closely related to the pearl’s color ;The peak in the 1 475~1 575 cm-1 range is divided into 8~10 secondary peaks of purple freshwater pearl and deep orange seawater pearl .The number of C=C double bonds is N=9~27 and N=7~27 respectively after calculation .Polyene compound of different varieties and content could be the reason for the pearls’ color .%对多种彩色珍珠样品进行了可见光光谱和拉曼光谱测试,研究了珍珠致色成分的种类及其与颜色的关系。研究结果表明:(1)彩色淡水珍珠和海水珍珠样品均会在1121~1132和1506~1524cm-1范围出现强峰,该特征峰归属于多烯化合物的C-C和C=C伸缩振动;(2)随着珍珠颜色的加深,样品位于1117~1132,1502~1524和2000~3500cm-1范围的峰逐渐增强,特征峰所代表的有机质与珍珠颜色有关;(3)深紫色淡水珍珠和深橘红色海水珍珠样品在1475~1575cm-1范围的包络峰可分成8~10个次级峰,计算可知多烯化合物C=C双键数目分别为N=9~27和N=7~27。珍珠中不同种类和含量的多烯化合物,可能是彩色珍珠的致色原因。

  13. The effect of an anti-hydrogen bond on Fermi resonance:A Raman spectroscopic study of the Fermi doublet v1-v12 of liquid pyridine

    Institute of Scientific and Technical Information of China (English)

    Li Dong-Fei; Gao Shu-Qin; Sun Cheng-Lin; Li Zuo-Wei

    2012-01-01

    The effects of an anti-hydrogen bond on the v1-v12 Fermi resonance (FR) of pyridine are experimentally investigated by using Raman scattering spectroscopy.Three systems,pyridine/water,pyridine/formamide,and pyridine/carbon tetrachloride,provide varying degrees of strength for the diluent-pyridine anti-hydrogen bond complex.Water forms a stronger anti-hydrogen bond with pyridine than with formamide,and in the case of adding non-polar solvent carbon tetrachloride,which is neither a hydrogen bond donor nor an acceptor and incapable of forming a hydrogen bond with pyridine,the intermolecular distance of pyridine will increase and the interaction of pyridine molecules will reduce.The dilution studies are performed on the three systems.Comparing with the values of the Fermi coupling coefficient W of the ring breathing mode v1 and triangle mode v12 of pyridine at different volume concentrations,which are calculated according to the Bertran equations,in three systems,we find that the solution with the strongest anti-hydrogen bond,water,shows the fastest change in thev1-v12 Fermi coupling coefficient W with the volume concentration varying,followed by the formamide and carbon tetrachloride solutions.These results suggest that the stronger anti-hydrogen bond-forming effect will cause a greater reduction in the strength of the v1-v12 FR of pyridine.According to the mechanism of the formation of an anti-hydrogen bond in the complexes and the FR theory,a qualitative explanation for the anti-hydrogen bond effect in reducing the strength of the v1 - v12 FR of pyridine is given.

  14. Anisotropy of Raman spectra measured in the xy-plane in nontwinned YBa sub 2 Cu sub 3 O sub 7 sub - sub x monocrystal

    CERN Document Server

    Misochko, O V

    2002-01-01

    The temperature dependence of the anisotropy of the phonon and electron Raman spectra, measured in the xy plane in the YBa sub 2 Cu sub 3 O sub 7 sub - sub x monocrystals is studied. It is shown, that the full-symmetrical phonons, generated by the CuO sub 2 -plane shift (modes 150, 340 and 435 cm sup - sup 1), have the sing of the orthorhombicity parameters gamma contrary to the sign for the phonons, generated by the shifts of the barium extraplane ions and bridge oxygen (modes 120 and 500 cm sup - sup 1). The value of the orthorhombicity parameter gamma in the superconducting state decreases in the low-frequency area, whereby the renormalization of the mode 340 cm sup - sup 1 frequency, measured from the xx- and yy-spectra, coincides with the accuracy up to the experimental error

  15. HOMO-LUMO, UV, NLO, NMR and vibrational analysis of 3-methyl-1-phenylpyrazole using FT-IR, FT-RAMAN FT-NMR spectra and HF-DFT computational methods.

    Science.gov (United States)

    Carthigayan, K; Xavier, S; Periandy, S

    2015-05-01

    In this paper, the spectral analysis of 3-methyl-1-phenylpyrazole is carried out using the FT-IR, FT Raman, FT NMR and UV-Vis spectra with the help of quantum mechanical computations using HF and density functional theories. The different conformers of the compound and their minimum energies are studied using B3LYP functional with 6-311+G (d,p) basis set and the most stable conformer with minimum energy was identified and the same conformer was used for further computations. The computed wave numbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the modes of vibrations are assigned and the structure the molecule is analyzed in terms of parameters like bond length, bond angle and dihedral angle predicted by both HF and B3LYP methods with 6-311+G (d,p) and 6-311++G (d,p) basis sets. The values of dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the molecule are reported, using which the non-linear property of the molecule is discussed. The HOMO-LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule. The isotropic chemical shifts predicted for (1)H and (13)C atoms using gauge invariant atomic orbital (GIAO) theory show good agreement with experimental shifts. NBO analysis is carried out to picture the charge transfer between the localized bonds and lone pairs. The thermodynamic properties (heat capacity, entropy and enthalpy) at different temperatures are also calculated. PMID:25710893

  16. Chemical Bonding of AlH3 Hydride by Al-L2,3 Electron Energy-Loss Spectra and First-Principles Calculations

    Directory of Open Access Journals (Sweden)

    Kazutaka Ikeda

    2012-03-01

    Full Text Available In a previous study, we used transmission electron microscopy and electron energy-loss (EEL spectroscopy to investigate dehydrogenation of AlH3 particles. In the present study, we systematically examine differences in the chemical bonding states of Al-containing compounds (including AlH3 by comparing their Al-L2,3 EEL spectra. The spectral chemical shift and the fine peak structure of the spectra were consistent with the degree of covalent bonding of Al. This finding will be useful for future nanoscale analysis of AlH3 dehydrogenation toward the cell.

  17. Line interference effects using a refined Robert-Bonamy formalism: The test case of the isotropic Raman spectra of autoperturbed N2

    International Nuclear Information System (INIS)

    A symmetrized version of the recently developed refined Robert-Bonamy formalism [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)] is proposed. This model takes into account line coupling effects and hence allows the calculation of the off-diagonal elements of the relaxation matrix, without neglecting the rotational structure of the perturbing molecule. The formalism is applied to the isotropic Raman spectra of autoperturbed N2 for which a benchmark quantum relaxation matrix has recently been proposed. The consequences of the classical path approximation are carefully analyzed. Methods correcting for effects of inelasticity are considered. While in the right direction, these corrections appear to be too crude to provide off diagonal elements which would yield, via the sum rule, diagonal elements in good agreement with the quantum results. In order to overcome this difficulty, a re-normalization procedure is applied, which ensures that the off-diagonal elements do lead to the exact quantum diagonal elements. The agreement between the (re-normalized) semi-classical and quantum relaxation matrices is excellent, at least for the Raman spectra of N2, opening the way to the analysis of more complex molecular systems

  18. Resonance Raman and electronic absorption spectra of O3- ions in γ-irradiated KC1O3 and NaC1O3

    International Nuclear Information System (INIS)

    Resonance Raman and electronic absorption spectra have been measured for the ozonide ion, O-3, produced in single crystals of KClO3 and NaClO3 by irradiation with γ rays. The O-3 ions are oriented in four to six symmetrically nonequivalent positions in KClO3 and appear to be oriented in two nonequivalent positions in NaClO3. Differences between the nonequivalent orientations affect both the ground and excited electronic states of O-3 as well as its ground vibrational states. The progressions of ν1 observed in the electronic spectra show that the vibrational spacing of ν1 in the excited electronic state is about 857 cm/sup -1/ as compared with the ground state spacing of about 1020 cm/sup -1/. Measurements of relative Raman intensities obtained with different exciting lines indicate that excitation near the center of a vibronic transition (0--n') produces extra enhancement of the intensity of the nν1 vibrational transition

  19. Development and integration of block operations for data invariant automation of digital preprocessing and analysis of biological and biomedical Raman spectra.

    Science.gov (United States)

    Schulze, H Georg; Turner, Robin F B

    2015-06-01

    High-throughput information extraction from large numbers of Raman spectra is becoming an increasingly taxing problem due to the proliferation of new applications enabled using advances in instrumentation. Fortunately, in many of these applications, the entire process can be automated, yielding reproducibly good results with significant time and cost savings. Information extraction consists of two stages, preprocessing and analysis. We focus here on the preprocessing stage, which typically involves several steps, such as calibration, background subtraction, baseline flattening, artifact removal, smoothing, and so on, before the resulting spectra can be further analyzed. Because the results of some of these steps can affect the performance of subsequent ones, attention must be given to the sequencing of steps, the compatibility of these sequences, and the propensity of each step to generate spectral distortions. We outline here important considerations to effect full automation of Raman spectral preprocessing: what is considered full automation; putative general principles to effect full automation; the proper sequencing of processing and analysis steps; conflicts and circularities arising from sequencing; and the need for, and approaches to, preprocessing quality control. These considerations are discussed and illustrated with biological and biomedical examples reflecting both successful and faulty preprocessing.

  20. 1H NMR, electronic-absorption and resonance-Raman spectra of isomeric okenone as compared with those of isomeric β-carotene, canthaxanthin, β-apo-8'-carotenal and spheroidene

    Science.gov (United States)

    Fujii, Ritsuko; Chen, Chun-Hai; Mizoguchi, Tadashi; Koyama, Yasushi

    1998-05-01

    Eleven cis- trans isomers of okenone were isolated by means of HPLC using a silica-gel column from an isomeric mixture which was obtained by iodine-sensitized photo-isomerization of the all- trans isomer. The configurations of eight isomers among them were determined by NMR spectroscopy using the isomerization shifts of the olefinic 1Hs and the 1H- 1H NOE correlations to be all- trans, 7- cis, 7- cis,8-s- cis, 9- cis, 9'- cis, 13- cis, 13'- cis and 9,9'-di- cis, and their electronic-absorption and resonance-Raman spectra were recorded. Based on the results: (1) the chemical shifts of the olefinic 1Hs in NMR; (2) the wavelength of the A g-→B u+ transition; and (3) the relative intensity of the A g-→A g+ versus the A g-→B u+ transition in electronic absorption; (4) the CC stretching frequency; and (5) the relative intensity of the C10-C11 (C10'-C11') versus the C14-C15 (C14'-C15') stretching vibration in resonance Raman were compared among the all- trans, 7- cis, 9- cis (9'- cis) and 13- cis (13'- cis) isomers of β-carotene, canthaxanthin, β-apo-8'-carotenal, neurosporene, spheroidene and okenone. Relevance of the systematic changes in the above five different parameters originally found in β-carotene was examined in the rest of the carotenoids, and the effects of the peripheral groups on them were explained in terms of the length and asymmetry of the conjugated system consisting of the CC and CO bonds.

  1. [The symmetric zero-area conversion adptive peak-seeking method research for LIBS/Raman spectra].

    Science.gov (United States)

    Bi, Yun-Feng; Li, Ying; Zheng, Rong-Er

    2013-02-01

    Automatic peak seeking is an indispensable link for in situ and real-time spectral detection and analysis, and has important significance for application of spectral technology to such fields as long-term marine monitoring and oil mud logging. Based on some typical LIBS/Raman spectrum data obtained from lab, three kinds of symmetric zero-area transformation functions respectively constructed from Gaussian, Lorentz and Voigt function were compared, and the results show that there exists an optimal symmetrical zero-area transformation function for peak seeking, but all the transformation functions obtain the same peak position and peak width under their optimal parameters. The proposed method is free from spectrum background and baseline trend influence, adaptive to the wide range of SNR, close to or even better than artificial recognition for weak peak, and could be used in future automatic in-situ analysis of LIBS and Raman. PMID:23697128

  2. Interaction of zirconium and hafnium tetrachlorides with cesium, rubidium and potassium chlorides and Raman spectra of reaction products

    International Nuclear Information System (INIS)

    Raman spectroscopy was used to reveal the formation of novel complexes involving [Zr2Cl9]- and [Hf2Cl9]- anions in molten mixtures of ZrCl4 and HfCl4 with CsCl, RbCl, and KCl. A prediction is made about the presence of the above-mentioned complex anions in poorly investigated melts of the corresponding binary systems at high concentrations of ZrCl4 or HfCl4

  3. Infrared and Raman spectra of bicyclic molecules using scaled noncorrelated and correlated {ital ab initio} force fields

    Energy Technology Data Exchange (ETDEWEB)

    Collier, W.B. [Department of Chemistry, Oral Roberts University, Tulsa, Oklahoma 74171 (United States); Magdo, I. [Gedeon Richter Ltd., Molecular Design Unit, P.O. Box 27, H-1475, Budapest (Hungary); Klots, T.D. [Bartlesville Thermodynamic Group, BDM Petroleum Technologies, P.O. Box 2543, Bartlesville, Oklahoma 74005 (United States)

    1999-03-01

    This paper reports the application of a scaled {ital ab initio} calculated harmonic force field to predict the frequencies, infrared intensities, Raman intensities, and depolarization ratios of benzofuran, benzothiophene, indole, benzothiazole, and benzoxazole. The theoretical calculations were made using the Hartree{endash}Fock HF/3-21G{sup {asterisk}} and HF/6-31G{sup {asterisk}} basis sets and density-functional theory (DFT)B3-LYP/6-31G{sup {asterisk}} levels. The equilibrium calculated force constants are scaled according to the method of Pulay and compared with the experimentally determined frequencies, intensities, and depolarization ratios to assess the accuracy and fit of the theoretical calculation. Methods for quantitative comparison of intensities were developed. The double numerical differentiation algorithm of Komornicki and McIver was analyzed and used to calculate the Raman intensities for the (DFT)B3-LYP/6-31G{sup {asterisk}} model. The (DFT)B3-LYP/6-31G{sup {asterisk}} model is approaching the harmonic limit in the planar and nonplanar refinement of these bicyclics with wave number fits of 5 and 4 cm{sup {minus}1}, respectively. It reduces the need for scale factors and increases their transfer accuracy, largely because the scale factors values cluster near unity. The Komornicki and McIver algorithm is still a viable method for calculating Raman intensity information for methods that do not have analytic routines programmed. The main shortcoming to this method may lie in the tighter self-consistent field (SCF) convergence criterion possibly needed to calculate Raman intensities for the totally symmetric modes of large molecules. The (DFT)B3-LYP/6-31G{sup {asterisk}} model was superior for calculating the planar intensities, but equal to the HF methods for predicting the nonplanar intensities. {copyright} {ital 1999 American Institute of Physics.}

  4. Raman spectroscopy as a screening tool for ancient life detection on Mars.

    Science.gov (United States)

    Marshall, Craig P; Marshall, Alison Olcott

    2014-12-13

    The search for sp(2)-bonded carbonaceous material is one of the major life detection strategies of the astrobiological exploration programmes of National Aeronautics and Space Administration and European Space Agency (ESA). The ESA ExoMars rover scheduled for launch in 2018 will include a Raman spectrometer with the goal of detecting sp(2)-bonded carbonaceous material as potential evidence of ancient life. However, sp(2)-bonded carbonaceous material will yield the same Raman spectra of well-developed G and D bands whether they are synthesized biologically or non-biologically. Therefore, the origin and source of sp(2)-bonded carbonaceous material cannot be elucidated by Raman spectroscopy alone. Here, we report the combined approach of Raman spectroscopy and gas chromatography-mass spectrometry biomarker analysis to Precambrian sedimentary rocks, which taken together, provides a promising new methodology for readily detecting and rapidly screening samples for immature organic material amenable to successful biomarker analysis.

  5. Triplet State Resonance Raman Spectrum of all-trans-diphenylbutadiene

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter; Grossman, W.E.L.; Killough, P.M;

    1984-01-01

    The resonance Raman spectrum of all-trans-diphenylbutadiene (DPB) in its ground state and the resonance Raman spectrum (RRS) of DPB in its short-lived electronically excited triplet state are reported. Transient spectra were obtained by a pump-probe technique using two pulsed lasers....... The preresonance spectrum of the ground state is not significantly changed from that of the nonresonance spectrum. In the resonance spectrum of the triplet state the double-bond stretching mode of the butadiene part is shifted by 43 cm-1 downward to 1582 cm-1 whereas the single-bond stretching mode is essentially...

  6. Vibrational (FT-IR and FT-Raman) spectra and quantum chemical studies on the molecular orbital calculations, chemical reactivity and thermodynamic parameters of 2-chloro-5-(trifluoromethyl) aniline

    Science.gov (United States)

    Karthick, T.; Balachandran, V.; Perumal, S.; Nataraj, A.

    2013-04-01

    In this work, the vibrational characteristics of 2-chloro-5-(trifluoromethyl) aniline have been investigated and both the experimental and theoretical vibrational data indicate the presence of various functional groups within the title molecule. The influence of chlorine substituent on the vibrational wavenumbers of a molecule in comparison with aniline and trifluoromethyl aniline has been discussed in detail. The density functional theoretical (DFT) computations were performed at the B3LYP/6-31++G(3df,3pd)/6-31G(3df,3pd) levels to derive the optimized geometry, vibrational wavenumbers with IR and Raman intensities. Furthermore, the molecular orbital calculations such as; natural bond orbitals (NBOs) and HOMO-LUMO energy gap and mapped molecular electrostatic potential (MEP) surfaces were also performed with the same level of DFT. The temperature dependence thermodynamic parameters of a molecule were illustrated on the basis of their correlation graphs. The detailed interpretation of the vibrational spectra has been carried out with the aid of potential energy distribution (PED) results obtained from MOLVIB program. The delocalization of electron density in various constituents of the molecule has been discussed with the aid of NBO and HOMO-LUMO energy gap analysis.

  7. Efficient second harmonic generation of double-end diffusion-bonded Nd:YVO4 self-Raman laser producing 7.9 W yellow light.

    Science.gov (United States)

    Zhu, Haiyong; Duan, Yanmin; Zhang, Ge; Huang, Chenghui; Wei, Yong; Shen, Hongyuan; Zheng, Yiqun; Huang, Lingxiong; Chen, Zhenqiang

    2009-11-23

    A high power and efficient 588 nm yellow light is demonstrated through intracavity frequency doubling of an acousto-optic Q-switched self-frequency Raman laser. A 30-mm-length double-end diffusion-bonded Nd:YVO(4) crystal was utilized for efficient self-Raman laser operation by reducing the thermal effects and increasing the interaction length for the stimulated Raman scattering. A 15-mm-length LBO with non-critical phase matching (theta = 90 degrees, phi = 0 degrees) cut was adopted for efficient second-harmonic generation. The focus position of incident pump light and both the repetition rate and the duty cycle of the Q-switch have been optimized. At a repetition rate of 110 kHz and a duty cycle of 5%, the average power of 588 nm light is up to 7.93 W while the incident pump power is 26.5 W, corresponding to an overall diode-yellow conversion efficiency of 30% and a slope efficiency of 43%. PMID:19997395

  8. Efficient and automatic calculation of optical band shapes and resonance Raman spectra for larger molecules within the independent mode displaced harmonic oscillator model.

    Science.gov (United States)

    Petrenko, Taras; Neese, Frank

    2012-12-21

    In this work, an improved method for the efficient automatic simulation of optical band shapes and resonance Raman (rR) intensities within the "independent mode displaced harmonic oscillator" is described. Despite the relative simplicity of this model, it is able to account for the intensity distribution in absorption (ABS), fluorescence, and rR spectra corresponding to strongly dipole allowed electronic transitions with high accuracy. In order to include temperature-induced effects, we propose a simple extension of the time dependent wavepacket formalism developed by Heller which enables one to derive analytical expressions for the intensities of hot bands in ABS and rR spectra from the dependence of the wavepacket evolution on its initial coordinate. We have also greatly optimized the computational procedures for numerical integration of complicated oscillating integrals. This is important for efficient simulations of higher-order rR spectra and excitation profiles, as well as for the fitting of experimental spectra of large molecules. In particular, the multimode damping mechanism is taken into account for efficient reduction of the upper time limit in the numerical integration. Excited state energy gradient as well as excited state geometry optimization calculations are employed in order to determine excited state dimensionless normal coordinate displacements. The gradient techniques are highly cost-effective provided that analytical excited state derivatives with respect to nuclear displacements are available. Through comparison with experimental spectra of some representative molecules, we illustrate that the gradient techniques can even outperform the geometry optimization method if the harmonic approximation becomes inadequate. PMID:23267471

  9. Theoretical calculation of the OH vibrational overtone spectra of 1-n alkane diols (n = 2-4): origin of disappearing hydrogen-bonded OH peak.

    Science.gov (United States)

    Cheng, Yu-Lung; Chen, Hui-Yi; Takahashi, Kaito

    2011-06-01

    In this theoretical study, we simulated the vibrational overtone spectrum of ethylene glycol (EG), 1-3 propanediol (PD), and 1-4 butanediol (BD). Using the local mode model along with the potential energy curve and dipole moment function calculated by B3LYP/6-31+G(d,p) and QCISD/6-311++G(3df,3pd), we obtained the theoretical peak position and integrated absorption coefficient. Furthermore, the vibrational spectra was simulated using a Voigt function using homogeneous and inhomogenous width obtained from quantum chemical calculation methods. Previously, Howard and Kjaergaard recorded the second and third overtone photoacoustic spectra of the three aforementioned alkane diols in the gas phase and observed that the intramolecular hydrogen bonded OH peak becomes difficult to observe as the intramolecular hydrogen bonding strength increased, that is, as the chain length was increased. In this paper we show that the disappearance of the hydrogen-bonded OH peak for the OH stretching overtone excitation for BD is partly due to the increase in homogeneous width due to the increase in the hydrogen bond strength and partly due to the decrease in the relative population of the intramolecular hydrogen-bonded conformers as the chain length is increased. This latter feature is a consequence of the unfavorable strained geometry needed to form the intramolecular hydrogen bond in longer alkane chains. PMID:21568300

  10. Structural peculiarities and Raman spectra of TeO{sub 2}/WO{sub 3}-based glasses: A fresh look at the problem

    Energy Technology Data Exchange (ETDEWEB)

    Mirgorodsky, Andreie; Colas, Maggy [Laboratoire Science des Procedes Ceramiques et de Traitements de Surface, UMR 6638 CNRS, Centre Europeen de la Ceramique, 12 rue Atlantis, 87068 Limoges Cedex (France); Smirnov, Mikhael [Fock Institute of Physics, Saint-Petersburg State University, 1 Ulyanovskaya street, 198504, Petrodvorets, Saint-Petersburg (Russian Federation); Merle-Mejean, Therese [Laboratoire Science des Procedes Ceramiques et de Traitements de Surface, UMR 6638 CNRS, Centre Europeen de la Ceramique, 12 rue Atlantis, 87068 Limoges Cedex (France); El-Mallawany, Raouf [Physics Department, Science College, Northern Borders University (Saudi Arabia); Thomas, Philippe, E-mail: philippe.thomas@unilim.fr [Laboratoire Science des Procedes Ceramiques et de Traitements de Surface, UMR 6638 CNRS, Centre Europeen de la Ceramique, 12 rue Atlantis, 87068 Limoges Cedex (France)

    2012-06-15

    Ideas currently dominating the field of structural studies of TeO{sub 2}-based glasses are critically considered. A new physically and chemically consistent approach to the constitution of binary TeO{sub 2}-WO{sub 3} glasses is proposed, in which the reasoning coming from the Raman spectra reexamination are correlated with the basic principles of thermodynamics. Separation into two phases is suggested in such glasses. One phase is TeO{sub 2}, and another is Te(WO{sub 4}){sub 2} consisting of tetrahedral [WO{sub 4}]{sup 2-} anions and of Te{sup 4+} cations. Supplementary M{sub n}O{sub k} oxides added to the glasses are found incorporated in the former phase, thus producing solid solutions (for M=Ti, Nb) or tellurite compounds (for M=Nd). - Graphical abstract: Raman scattering spectra of TeO{sub 2}-based glasses with the following compositions (mol%): (a) pure TeO{sub 2}, (b) 85TeO{sub 2}-15WO{sub 3}, (c) 80TeO{sub 2}-15WO{sub 3}-5TiO{sub 2} ,(d) 80TeO{sub 2}-10WO{sub 3}-5TiO{sub 2}-5Nb{sub 2}O{sub 5}, (e) 80TeO{sub 2}-12WO{sub 3}-5TiO{sub 2}-3 Nd{sub 2}O{sub 3}, (f) 80TeO{sub 2}-10WO{sub 3}-5TiO{sub 2}-5Nd{sub 2}O{sub 3}. Highlights: Black-Right-Pointing-Pointer Structural studies of TeO{sub 2}-WO{sub 3} glasses are critically considered. Black-Right-Pointing-Pointer The oxide glass formation is analyzed from Raman spectra and thermodynamic principles. Black-Right-Pointing-Pointer Separation into two phases, TeO{sub 2} and Te(WO{sub 4}){sub 2}, is intrinsic in such glasses. Black-Right-Pointing-Pointer TiO{sub 2} or Nb{sub 2}O{sub 5} addition to TeO{sub 2}-WO{sub 3} glasses leads to produce solid solutions. Black-Right-Pointing-Pointer Nd{sub 2}O{sub 3} addition to TeO{sub 2}-WO{sub 3} glasses leads to produce a tellurite compound.

  11. Infrared and Raman spectra, theoretical calculations, conformations, and two-dimensional potential energy surface of 2-cyclopenten-1-one ethylene ketal.

    Science.gov (United States)

    Sheu, Hong-Li; Meinander, Niklas; Laane, Jaan

    2015-03-01

    The infrared and Raman spectra of the bicyclic spiro molecule 2-cyclopenten-1-one ethylene ketal (CEK) have been recorded. Density functional theory (DFT) calculations were used to compute the theoretical spectra, and these agree well with the experimental spectra. The structures and conformational energies for the two pairs of conformational minima, which can be defined in terms of ring-bending (x) and ring-twisting (τ) vibrational coordinates, have also been calculated. Utilizing the results from ab initio MP2/cc-PVTZ computations, a two-dimensional potential energy surface (PES) was calculated. The energy levels and wave functions for this PES were then calculated, and the characteristics of these were analyzed. At lower energies, all of the quantum states are doubly degenerate and correspond to either the lower-energy conformation L or to conformation H, which is 154 cm(-1) higher in energy. At energies above the barrier to interconversion of 264 cm(-1), the wave functions show that the quantum levels have significant probabilities for both conformations. PMID:25133325

  12. Resonance raman spectroscopic study of alumina-supported vanadium oxide catalysts with 220 and 287 nm excitation.

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H. S.; Stair, P. C.; Chemical Sciences and Engineering Division; Northwestern Univ.

    2009-01-01

    We present detailed resonance Raman spectroscopic results excited at 220 and 287 nm for alumina-supported VO{sub x} catalysts. The anharmonic constant, harmonic wavenumber, anharmonic force constant, bond dissociation energy, and bond length change in the excited state for double bonded V{double_bond}O and single bonded V-O were obtained from fundamental and overtone frequencies. Totally symmetric and nontotally symmetric modes could be discerned and assigned on the basis of the overtone and combination progressions found in the resonance Raman spectra. Selective resonance enhancement of two different vibrational modes with two different excitation wavelengths was observed. This allowed us to establish a linear relationship between charge transfer energy and VO bond length and, consequently, to assign the higher-energy charge transfer band centered around 210?250 nm in the UV?vis spectra to the V{double_bond}O transition.

  13. The pH dependent Raman spectroscopic study of caffeine

    Science.gov (United States)

    Kang, Jian; Gu, Huaimin; Zhong, Liang; Hu, Yongjun; Liu, Fang

    2011-02-01

    First of all the surface enhanced Raman spectroscopy (SERS) and normal Raman spectra of caffeine aqueous solution were obtained at different pH values. In order to obtain the detailed vibrational assignments of the Raman spectroscopy, the geometry of caffeine molecule was optimized by density functional theory (DFT) calculation. By comparing the SERS of caffeine with its normal spectra at different pH values; it is concluded that pH value can dramatically affect the SERS of caffeine, but barely affect the normal Raman spectrum of caffeine aqueous solution. It can essentially affect the reorientation of caffeine molecule to the Ag colloid surface, but cannot impact the vibration of functional groups and chemical bonds in caffeine molecule.

  14. Quantum chemical vibrational study, molecular property, FTIR, FT-Raman spectra, NBO, HOMO-LUMO energies and thermodynamic properties of 1-methyl-2-phenyl benzimidazole

    Science.gov (United States)

    Karnan, M.; Balachandran, V.; Murugan, M.; Murali, M. K.

    2014-09-01

    The solid phase FT-IR and FT-Raman spectra of 1-methyl-2-phenyl benzimidazole (MPBZ) have been recorded in the condensed state. In this work, experimental and theoretical study on the molecular structure, quantum chemical calculations of energies and vibrational wavenumbers of MPBZ is presented. The vibrational frequencies of the title compound were obtained theoretically by DFT/B3LYP calculations employing the standard 6-311+G(d,p) and 6-311++G(d,p) basis set for optimized geometry and were compared with Fourier transform infrared spectrum (FTIR) in the region of 4000-400 cm-1 and with Fourier transform Raman spectrum in the region of 4000-100 cm-1. Complete vibrational assignments, analysis and correlation of the fundamental modes for the title compound were carried out. The vibrational harmonic frequencies were scaled using scale factor, yielding a good agreement between the experimentally recorded and the theoretically calculated values. The study is extended to calculate the HOMO-LUMO energy gap, NBO, mapped molecular electrostatic potential (MEP) surfaces, polarizability, Mulliken charges and thermodynamic properties of the title compound.

  15. Raman scattering spectra, magnetic and ferroelectric properties of BiFeO{sub 3}–CoFe{sub 2}O{sub 4} nanocomposite thin films structure

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, Mintu [School of Physics and Materials Science, Thapar University, Patiala 147004, Punjab (India); Kumari, Mukesh; Chatterjee, Ratnamala [Magnetics and Advanced Ceramics Laboratory, Department of Physics, Indian Institute of Technology, Delhi 110016 (India); Sharma, Puneet, E-mail: puneet.sharma@thapar.edu [School of Physics and Materials Science, Thapar University, Patiala 147004, Punjab (India)

    2014-09-01

    Multiferroic (1−x)BiFeO{sub 3}(BFO)–xCoFe{sub 2}O{sub 4}(CFO) (x=0 and 0.1) nanocomposite thin films were deposited on ITO coated glass using sol–gel spin coating technique. X-ray diffraction and transmission electron microscopy examinations confirm the coexistence of both perovskite BFO and spinel CFO phases. The effect of addition of CFO in BFO matrix has been studied on Raman spectra, magnetic and ferroelectric properties. BFO/CFO nanocomposite showed good magnetic behavior (M{sub s}∼40.3 emu/cm{sup 3}, M{sub r}∼12.9 emu/cm{sup 3}, H{sub c}∼90 Oe) with no change in ferroelectric properties. The strain analysis carried out by Raman spectroscopy reveals that both BFO and CFO bands are found to be strained in BFO/CFO composite nanostructure. The strain of the bands is discussed on the basis of lattice mismatch (interfacial stress) between CFO (a=0.839 nm) and BFO (a=0.396 nm) phases.

  16. Refractive index spectral dependence, Raman and transmission spectra of high-purity $^{28}$Si, $^{29}$Si, $^{30}$Si, and $^{nat}$Si single crystals

    CERN Document Server

    Plotnichenko, V G; Kryukova, E B; Koltashev, V V; Sokolov, V O; Dianov, E M; Gusev, A V; Gavva, V A; Kotereva, T V; Churbanov, M F

    2011-01-01

    Precise measurement of the refractive index of stable silicon isotopes $^{28}$Si, $^{29}$Si, $^{30}$Si single crystals with enrichments above 99.9 at.% and a silicon single crystal $^{nat}$Si of natural isotopic composition is performed with the Fourier-transform interference refractometry method from 1.06 to more than 80 mkm with 0.1 cm$^{-1}$ resolution and accuracy of $2 \\times 10^{-5} ... 1 \\times 10^{-4}$. The oxygen and carbon concentrations in all crystals are within $5 \\times 10^{15}$ cm$^{-3}$ and the content of metal impurities is $10^{-5} ... 10^{-6}$ at.%. The peculiar changes of the refractive index in the phonon absorption region of all silicon single crystals are shown. The coefficients of generalized Cauchy dispersion function approximating the experimental refractive index values all over the measuring range are given. The transmission and Raman spectra are also studied.

  17. Deep analysis of Raman spectra of ZnO:Mo and ZnO:In sprayed thin films along with LO and TA+LO bands investigation

    Science.gov (United States)

    Souissi, A.; Amlouk, M.; Khemakhem, H.; Guermazi, S.

    2016-04-01

    ZnO and Mo, In doped ZnO thin films with the molar ratios (Mo/Zn) and (In/Zn) were dosed at 1%, 2% and 3%, respectively. These films were deposited on amorphous SiO2 substrate at 460 °C by the spray-pyrolysis process. A useful and concise reminder of the spatial resolutions of Raman spectroscopy was presented. The vibrational responses of these films at high doping exhibited strong fluctuations that were resolved by successive digital processing, choice of the optimal profile of the baseline, suppression of fluorescence and/or photoluminescence, and noise reduction. These treated spectra have allowed to identify possible multi-modes in highly doped studied samples and revealed the presence of LO and TA+LO broad bands, whose second was at cascade and could be explored in optoelectronic and sensitive systems.

  18. UV resonance Raman analysis of trishomocubane and diamondoid dimers

    Energy Technology Data Exchange (ETDEWEB)

    Meinke, Reinhard, E-mail: rene@physik.tu-berlin.de; Thomsen, Christian; Maultzsch, Janina [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Richter, Robert; Merli, Andrea [Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Fokin, Andrey A. [Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 58, D-35392 Giessen (Germany); Department of Organic Chemistry, Kiev Polytechnic Institute, pr. Pobedy 37, 03056 Kiev (Ukraine); Koso, Tetyana V.; Schreiner, Peter R. [Institute of Organic Chemistry, Justus-Liebig University, Heinrich-Buff-Ring 58, D-35392 Giessen (Germany); Rodionov, Vladimir N. [Department of Organic Chemistry, Kiev Polytechnic Institute, pr. Pobedy 37, 03056 Kiev (Ukraine)

    2014-01-21

    We present resonance Raman measurements of crystalline trishomocubane and diamantane dimers containing a C=C double bond. Raman spectra were recorded with excitation energies between 2.33 eV and 5.42 eV. The strongest enhancement is observed for the C=C stretch vibration and a bending mode involving the two carbon atoms of the C=C bond, corresponding to the B{sub 2g} wagging mode of ethylene. This is associated with the localization of the π-HOMO and LUMO and the elongation of the C=C bond length and a pyramidalization of the two sp{sup 2}-hybridized carbon atoms at the optical excitation. The observed Raman resonance energies of the trishomocubane and diamantane dimers are significantly lower than the HOMO-LUMO gaps of the corresponding unmodified diamondoids.

  19. Assessment of mode-mixing and Herzberg-Teller effects on two-photon absorption and resonance hyper-Raman spectra from a time-dependent approach

    International Nuclear Information System (INIS)

    A time-dependent approach is presented to simulate the two-photon absorption (TPA) and resonance hyper-Raman scattering (RHRS) spectra including Duschinsky rotation (mode-mixing) and Herzberg-Teller (HT) vibronic coupling effects. The computational obstacles for the excited-state geometries, vibrational frequencies, and nuclear derivatives of transition dipole moments, which enter the expressions of TPA and RHRS cross sections, are further overcome by the recently developed analytical excited-state energy derivative approaches in the framework of time-dependent density functional theory. The excited-state potential curvatures are evaluated at different levels of approximation to inspect the effects of frequency differences, mode-mixing and HT on TPA and RHRS spectra. Two types of molecules, one with high symmetry (formaldehyde, p-difluorobenzene, and benzotrifluoride) and the other with non-centrosymmetry (cis-hydroxybenzylidene-2,3-dimethylimidazolinone in the deprotonated anion state (HDBI−)), are used as test systems. The calculated results reveal that it is crucial to adopt the exact excited-state potential curvatures in the calculations of TPA and RHRS spectra even for the high-symmetric molecules, and that the vertical gradient approximation leads to a large deviation. Furthermore, it is found that the HT contribution is evident in the TPA and RHRS spectra of HDBI− although its one- and two-photon transitions are strongly allowed, and its effect results in an obvious blueshift of the TPA maximum with respect to the one-photon absorption maximum. With the HT and solvent effects getting involved, the simulated blueshift of 1291 cm−1 agrees well with the experimental measurement

  20. Assessment of mode-mixing and Herzberg-Teller effects on two-photon absorption and resonance hyper-Raman spectra from a time-dependent approach

    Science.gov (United States)

    Ma, HuiLi; Zhao, Yi; Liang, WanZhen

    2014-03-01

    A time-dependent approach is presented to simulate the two-photon absorption (TPA) and resonance hyper-Raman scattering (RHRS) spectra including Duschinsky rotation (mode-mixing) and Herzberg-Teller (HT) vibronic coupling effects. The computational obstacles for the excited-state geometries, vibrational frequencies, and nuclear derivatives of transition dipole moments, which enter the expressions of TPA and RHRS cross sections, are further overcome by the recently developed analytical excited-state energy derivative approaches in the framework of time-dependent density functional theory. The excited-state potential curvatures are evaluated at different levels of approximation to inspect the effects of frequency differences, mode-mixing and HT on TPA and RHRS spectra. Two types of molecules, one with high symmetry (formaldehyde, p-difluorobenzene, and benzotrifluoride) and the other with non-centrosymmetry (cis-hydroxybenzylidene-2,3-dimethylimidazolinone in the deprotonated anion state (HDBI-)), are used as test systems. The calculated results reveal that it is crucial to adopt the exact excited-state potential curvatures in the calculations of TPA and RHRS spectra even for the high-symmetric molecules, and that the vertical gradient approximation leads to a large deviation. Furthermore, it is found that the HT contribution is evident in the TPA and RHRS spectra of HDBI- although its one- and two-photon transitions are strongly allowed, and its effect results in an obvious blueshift of the TPA maximum with respect to the one-photon absorption maximum. With the HT and solvent effects getting involved, the simulated blueshift of 1291 cm-1 agrees well with the experimental measurement.

  1. Assessment of mode-mixing and Herzberg-Teller effects on two-photon absorption and resonance hyper-Raman spectra from a time-dependent approach

    Energy Technology Data Exchange (ETDEWEB)

    Ma, HuiLi [State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, and Institute of Fujian Provincial Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Department of Chemical Physics, University of Science and Technology of China, Hefei 230026 (China); Zhao, Yi; Liang, WanZhen, E-mail: liangwz@xmu.edu.cn [State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, and Institute of Fujian Provincial Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)

    2014-03-07

    A time-dependent approach is presented to simulate the two-photon absorption (TPA) and resonance hyper-Raman scattering (RHRS) spectra including Duschinsky rotation (mode-mixing) and Herzberg-Teller (HT) vibronic coupling effects. The computational obstacles for the excited-state geometries, vibrational frequencies, and nuclear derivatives of transition dipole moments, which enter the expressions of TPA and RHRS cross sections, are further overcome by the recently developed analytical excited-state energy derivative approaches in the framework of time-dependent density functional theory. The excited-state potential curvatures are evaluated at different levels of approximation to inspect the effects of frequency differences, mode-mixing and HT on TPA and RHRS spectra. Two types of molecules, one with high symmetry (formaldehyde, p-difluorobenzene, and benzotrifluoride) and the other with non-centrosymmetry (cis-hydroxybenzylidene-2,3-dimethylimidazolinone in the deprotonated anion state (HDBI{sup −})), are used as test systems. The calculated results reveal that it is crucial to adopt the exact excited-state potential curvatures in the calculations of TPA and RHRS spectra even for the high-symmetric molecules, and that the vertical gradient approximation leads to a large deviation. Furthermore, it is found that the HT contribution is evident in the TPA and RHRS spectra of HDBI{sup −} although its one- and two-photon transitions are strongly allowed, and its effect results in an obvious blueshift of the TPA maximum with respect to the one-photon absorption maximum. With the HT and solvent effects getting involved, the simulated blueshift of 1291 cm{sup −1} agrees well with the experimental measurement.

  2. Raman Spectroscopy of Cocrystals

    Science.gov (United States)

    Rooney, Frank; Reardon, Paul; Ochoa, Romulo; Abourahma, Heba; Marti, Marcus; Dimeo, Rachel

    2010-02-01

    Cocrystals are a class of compounds that consist of two or more molecules that are held together by hydrogen bonding. Pharmaceutical cocrystals are those that contain an active pharmaceutical ingredient (API) as one of the components. Pharmaceutical cocrystals are of particular interest and have gained a lot of attention in recent years because they offer the ability to modify the physical properties of the API, like solubility and bioavailability, without altering the chemical structure of the API. The APIs that we targeted for our studies are theophylline (Tp) and indomethacin (Ind). These compounds have been mixed with complementary coformers (cocrystal former) that include acetamide (AcONH2), melamine (MLM), nicotinic acid (Nic-COOH), 4-cyanopyridine (4-CNPy) and 4-aminopyridine (4-NH2Py). Raman spectroscopy has been used to characterize these cocrystals. Spectra of the cocrystals were compared to those of the coformers to analyze for peak shifts, specifically those corresponding to hydrogen bonding. A 0.5 m CCD Spex spectrometer was used, in a micro-Raman setup, for spectral analysis. An Argon ion Coherent laser at 514.5 nm was used as the excitation source. )

  3. DFT calculations of 2,6-dimethylpyrazine (26DMP) and its complex with chloranilic acid (CLA): Comparison to INS, IR and Raman vibration spectra

    Science.gov (United States)

    Pawlukojć, A.; Sobczyk, L.; Prager, M.; Bator, G.; Grech, E.; Nowicka-Scheibe, J.

    2008-12-01

    The inelastic neutron scattering (INS), infrared and Raman spectra of crystalline 2,6-dimethylpyrazine (26DMP) and its complex with chloranilic acid (26DMP·CLA) were measured. Simultaneously the DFT calculations of the molecular structures and frequencies of the normal vibrations were performed by using various functionals. The INS spectra were simulated in the energy range up to 1200 cm -1, on the basis of the calculated frequencies. A very good conformity was obtained between experimental and calculated data with respect to the structure as well as to frequencies, with exception, however, of the CH 3 torsional modes. The structural analysis based on the deviation from the sum of the van der Waals radii showed that the packing of the methyl groups in the 26DMP·CLA complex was markedly stronger than that in the neat 26DMP. However, the DFT calculations overestimated the role of this effect that may be due to a limitation of the applied methods. In addition the anharmonicity of the rotational potential led to the librational energies different from those obtained using a harmonic potential.

  4. Ab Initio Calculations and Raman and SERS Spectral Analyses of Amphetamine Species

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Nørbygaard, Thomas; White, Peter C.;

    2011-01-01

    For the first time, the differences between the spectra of amphetamine and amphetamine-H+ and between different conformers are thoroughly studied by ab initio model calculations, and Raman and surface-enhanced Raman spectroscopy (SERS) spectra are measured for different species of amphetamine....... The spectra of amphetamine and amphetamine-H+ sampleswere obtained and assigned according to a comparison of the experimental spectra and the ab initio MO calculations, performed using the Gaussian 03W program (Gaussian, Inc., Pittsburgh, PA). The analyses were based on complete geometry minimization...... of the conformational energy of the S-plus-amphetamine molecule and the S-plus-amphetamine-H+ ion. The harmonic frequency calculations provide information about the characteristic features of the Raman spectra and the nature of the bonding in the molecule. It is concluded that vibrational bands from salt anions...

  5. Exploring the C-X…π Halogen Bonding Motif: An Infrared and Raman Study of the Complexes of CF3X (X = Cl, Br and I with the Aromatic Model Compounds Benzene and Toluene

    Directory of Open Access Journals (Sweden)

    Wouter A. Herrebout

    2013-06-01

    Full Text Available The formation of halogen bonded complexes formed between the trifluorohalomethanes CF3Cl, CF3Br and CF3I and the Lewis bases benzene and toluene at temperatures below 150K was investigated using FTIR and Raman spectroscopy. Experiments using liquid krypton as solvent show that for both CF3Br and CF3I substantial fractions of the monomers can be involved in 1:1 complexes. In addition, weak absorptions illustrating the formation of 2:1 complexes between CF3I and benzene are observed. Using spectra recorded at temperatures between 120 and 140 K, observed information on the relative stability was obtained for all complexes by determining the complexation enthalpies in solution. The resulting values for CF3Br.benzene, CF3I.benzene and (CF3I2.benzene are −6.5(3, −7.6(2 and −14.5(9 kJ mol−1. The values for CF3Br.toluene and CF3I.toluene are −6.2(5 and −7.4(5 kJ mol−1. The experimental complexation enthalpies are compared with theoretical data obtained by combining results from MP2/aug-cc-pVDZ(-PP and MP2/aug-cc-pVTZ(-PP ab initio calculations, from statistical thermodynamical calculations and from Monte Carlo Free Energy Perturbation simulations. The data are also compared with results derived for other C-X···π halogen bonded complexes involving unsaturated Lewis bases such as ethene and ethyne.

  6. Surface enhanced Raman spectra of the organic nonlinear optic material: Methyl 3-(4-methoxy phenyl)prop-2-enoate

    Indian Academy of Sciences (India)

    D Sajan; I Hubert Joe; V S Jayakumar; Jacek Zaleski

    2008-07-01

    The surface geometry of methyl 3-(4-methoxy phenyl)prop-2-enoate molecule was studied by analysis of the SERS spectra adsorbed on silver colloid surfaces. For a reliable analysis of the SERS spectrum, we also performed density functional theoretical calculations. The absence of a C-H stretching vibrations and the observed C-H out-of-plane bending modes suggest that the MMP molecule may be adsorbed in a flat on orientation to the surface. The SERS spectral studies predict a tilted orientation of ethylenic bridge with respect to the phenyl ring.

  7. Identification and discrimination of polycyclic aromatic hydrocarbons using Raman spectroscopy

    Science.gov (United States)

    Cloutis, Edward; Szymanski, Paul; Applin, Daniel; Goltz, Douglas

    2016-08-01

    Polycyclic aromatic hydrocarbons (PAHs) are widely present throughout the Solar System and beyond. They have been implicated as a contributor to unidentified infrared emission bands in the interstellar medium, comprise a substantial portion of the insoluble organic matter in carbonaceous chondrites, are expected stable components of organic matter on Mars, and are present in a wide range of terrestrial hydrocarbons and as components of biomolecules. However, PAH structures can be very complicated, making their identification challenging. Raman spectroscopy is known to be especially sensitive to the highly polarizable C-C and C=C bonds found in PAHs, and therefore, can be a powerful tool for PAH structural and compositional elucidation. This study examined Raman spectra of 48 different PAHs to determine the degree to which Raman spectroscopy could be used to uniquely identify different species, factors that control the positions of major Raman peaks, the degree to which induced fluorescence affects the intensity of Raman peaks, its usefulness for PAH discrimination, and the effects of varying excitation wavelength on some PAH Raman spectra. It was found that the arrangement and composition of phenyl (benzene) rings, and the type and position of functional groups can greatly affect fluorescence, positions and intensities of Raman peaks associated with the PAH backbone, and the introduction of new Raman peaks. Among the functional groups found on many of the PAHs that were analyzed, only a few Raman peaks corresponding to the molecular vibrations of these groups could be clearly distinguished. Comparison of the PAH Raman spectra that were acquired with both 532 and 785 nm excitation found that the longer wavelength resulted in reduced fluorescence, consistent with previous studies.

  8. The mechanism of N-Ag bonding determined tunability of surface-enhanced Raman scattering of pyridine on MAg (M = Cu, Ag, Au) diatomic clusters.

    Science.gov (United States)

    Chen, Lei; Gao, Yang; Xu, Haoran; Wang, Zhigang; Li, Zhengqiang; Zhang, Rui-Qin

    2014-10-14

    Binary coinage metal clusters can show a significantly different enhancement in surface-enhanced Raman scattering (SERS) from that of pure element clusters, owing to their tunable surface plasmon resonance energies affected by the composition and atomic ordering. Yet, the tunability by composition requires a deep understanding in order to further optimize the SERS-based detection technique. Here, to fill this deficiency, we conducted detailed analyses of the SERS of pyridine adsorbed through N-Ag bonding on the homonuclear diatomic metal cluster Ag2 and heteronuclear diatomic metal clusters of AuAg and CuAg, as well as the involved charge transfer under an intracluster excitation, based on calculations using time-dependent density functional theory with a short-time approximation for the Raman cross-section. We find that although the SERS enhancements for all complexes can reach the order of 10(3)-10(4), the corresponding wavelengths used for SERS excitation are significantly different. Our molecular orbital analysis reveals that the complexes based on heteronuclear metal clusters can produce varied electronic transitions owing to the polarization between different metal atoms, which tune the SERS enhancements with altered optical properties. Our analyses are expected to provide a theoretical basis for exploring the multi-composition SERS substrates applicable for single molecular detection, nanostructure characterization, and biological molecular identification. PMID:25157565

  9. Covalent Bond Formation of Uranium Ions in a LiCl-KCl Eutectic Melt at 450 .deg. C: Spectroscopic Evidence from Their UV-VIS Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Young Hwan; Bae, Sang Eun; Oh, Seung Yong; Kim, Jong Yun; Song, Kyu Seok; Yeon, Jei Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    Molten salt based electrochemical processes, so called pyroprocessing, have been proposed as a new option for the advanced spent nuclear fuel cycle. One of the important steps in the pyroprocessing of the spent nuclear fuel is the electrorefining of uranium in molten LiCl based media. The knowledge on the electronic states of uranium ions in molten salt media is essential for understanding their optical, electrochemical properties. Electronic absorption spectra may provide detailed information on the chemical state of the ions. Several studies have been reported for the past decades on the electronic absorption spectra of uranium ion species in high temperature molten salt media. However, no attempts have been made to interpret the spectra with respect to the electronic state and chemical bonding point of view. Here, report the results of insitu measurement and interpretation of the electronic spectra of the U(III) and U(IV) ion species in a LiCl- KCl eutectic melt at in terms of chemical bonding

  10. High resolution infrared and Raman spectra of {sup 13}C{sup 12}CD{sub 2}: The CD stretching fundamentals and associated combination and hot bands

    Energy Technology Data Exchange (ETDEWEB)

    Di Lonardo, G.; Fusina, L., E-mail: luciano.fusina@unibo.it; Canè, E.; Tamassia, F. [Dipartimento di Chimica Industriale “Toso Montanari,” Università di Bologna, Viale Risorgimento 4, I-40136 Bologna (Italy); Martínez, R. Z.; Bermejo, D. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, 28006 Madrid (Spain)

    2015-09-07

    Infrared and Raman spectra of mono {sup 13}C fully deuterated acetylene, {sup 13}C{sup 12}CD{sub 2}, have been recorded and analysed to obtain detailed information on the C—D stretching fundamentals and associated combination, overtone, and hot bands. Infrared spectra were recorded at an instrumental resolution ranging between 0.006 and 0.01 cm{sup −1} in the region 1800–7800 cm{sup −1}. Sixty new bands involving the ν{sub 1} and ν{sub 3} C—D stretching modes also associated with the ν{sub 4} and ν{sub 5} bending vibrations have been observed and analysed. In total, 5881 transitions have been assigned in the investigated spectral region. In addition, the Q branch of the ν{sub 1} fundamental was recorded using inverse Raman spectroscopy, with an instrumental resolution of about 0.003 cm{sup −1}. The transitions relative to each stretching mode, i.e., the fundamental band, its first overtone, and associated hot and combination bands involving bending states with υ{sub 4} + υ{sub 5} up to 2 were fitted simultaneously. The usual Hamiltonian appropriate to a linear molecule, including vibration and rotation l-type and the Darling–Dennison interaction between υ{sub 4} = 2 and υ{sub 5} = 2 levels associated with the stretching states, was adopted for the analysis. The standard deviation for each global fit is ≤0.0004 cm{sup −1}, of the same order of magnitude of the measurement precision. Slightly improved parameters for the bending and the ν{sub 2} manifold have been also determined. Precise values of spectroscopic parameters deperturbed from the resonance interactions have been obtained. They provide quantitative information on the anharmonic character of the potential energy surface, which can be useful, in addition to those reported in the literature, for the determination of a general anharmonic force field for the molecule. Finally, the obtained values of the Darling–Dennison constants can be valuable for understanding energy flows

  11. Raman and DFT Study on N-H+…Cl- Hydrogen Bonding in 1,1,3,3-Tetra-Methylguanidinium Chloride forming an Ion-pair Molecule in the Vapor Phase

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Riisager, Anders; Fehrmann, Rasmus

    The chemistry of 1,1,3,3-tetramethylguanidinium ([TMGH]+) chloride, a low temperature (molten) ionic liquid, is discussed, based on its Raman spectra associated with ab initio molecular orbital DFT-type quantum mechanical calculations (with 6-311+G(d,p) basis sets) on “molecules” in isolated gase...

  12. Temperature Effect on the Hydrogen Bonding Behavior between DMSO and Water in Aqueous DMSO Solutions Studied by Raman Spectroscopy%变温过程中二甲基亚砜与水之间氢键行为的拉曼光谱研究

    Institute of Scientific and Technical Information of China (English)

    欧阳顺利; 李正强; 吴楠楠; 里佐威; 孙成林; 范丽梅

    2013-01-01

    测量了在降温过程中体积比为1∶1的二甲基亚砜(DMSO)水溶液的拉曼光谱,并对DMSO水溶液的拉曼光谱进行了归属.对实验数据进行分析发现:在降温过程中DMSO分子与水分子的分子间氢键、DMSO分子与DMSO分子和水分子与水分子间氢键的作用行为引起了DMSO的S=O双键和水分子的O—H键的拉曼谱带的变化.进一步分析表明:在27~-30℃降温过程DMSO与水之间氢键加强,-30~-60℃降温过程水与水之间氢键代替DMSO与水之间的氢键.这为丰富水溶液的氢键理论提供了实验依据.%In the present paper,DMSO/H2O mixture with the ratio of volume 1 ∶ 1 was measured in the cooling process by Raman spectroscopy,and the Raman assignments was made to the DMSO molecular and water molecular.The results showed that the behavior between intra-molecular hydrogen bonds and inter-molecular hydrogen bonds of DMSO and water leads to the change in the Raman spectra of the S=O stretching vibration of DMSO and the O--H stretching vibration of water.Further analysis showed that the hydrogen bond between DMSO and water was enhanced in the course of temperature decreasing process (27 to-30 ℃),and the intramolecular hydrogen bonds between water and water replaced the intermolecular hydrogen bonds of DMSO and water in the course of temperature decreasing process (-30 to-60 ℃).The research provides experimental basis for hydrogen bonding theory in aqueous solution.

  13. Raman effect in icosahedral boron-rich solids

    Directory of Open Access Journals (Sweden)

    Helmut Werheit, Volodymyr Filipov, Udo Kuhlmann, Ulrich Schwarz, Marc Armbrüster, Andreas Leithe-Jasper, Takaho Tanaka, Iwami Higashi, Torsten Lundström, Vladimir N Gurin and Maria M Korsukova

    2010-01-01

    Full Text Available We present Raman spectra of numerous icosahedral boron-rich solids having the structure of α-rhombohedral, β-rhombohedral, α-tetragonal, β-tetragonal, YB66, orthorhombic or amorphous boron. The spectra were newly measured and, in some cases, compared with reported data and discussed. We emphasize the importance of a high signal-to-noise ratio in the Raman spectra for detecting weak effects evoked by the modification of compounds, accommodation of interstitial atoms and other structural defects. Vibrations of the icosahedra, occurring in all the spectra, are interpreted using the description of modes in α-rhombohedral boron by Beckel et al. The Raman spectrum of boron carbide is largely clarified. Relative intra- and inter-icosahedral bonding forces are estimated for the different structural groups and for vanadium-doped β-rhombohedral boron. The validity of Badger's rule is demonstrated for the force constants of inter-icosahedral B–B bonds, whereas the agreement is less satisfactory for the intra-icosahedral B–B bonds.

  14. Temperature dependent Raman spectra and micro-structure study of hexagonal MgTiO3 crystal%六方晶型MgTiO3温致微结构变化及其原位拉曼光谱研究

    Institute of Scientific and Technical Information of China (English)

    王丽红; 尤静林; 王媛媛; 郑少波; 西蒙·派特里克; 侯敏; 季自方

    2011-01-01

    Hexagonal MgTiO3 crystal powder is prepared by solid-phase sintering method and characterized by X-ray diffraction method.Temperature dependent crystal cell parameters(293—1473 K) are deduced from the results of in-situ X-ray diffraction measurement with temperature increasing.In-situ Raman spectra are recorded(293—1623 K) at various temperatures and all the vibrational modes were assigned with the aid of theoretical calculation of first principles.It is demonstrated that temperature dependent Raman spectra are sensitive and can show the delicate variations of different bond lengths and angles between various atoms of local structure.But the relationship between Raman shift and bond length and angle can be independent of temperature.Those observed Raman vibrational bands being wider and overlapped with the increasing temperature reveals the enhanced amplitude of atomic instantaneous movement,which leads atoms to diffuse more heavily and the stability of the crystal to decrease,although MgTiO3 remains hexagonal crystal type.%采用固相烧结法制备了六方晶型结构的MgTiO3粉体.经高温原位X射线衍射分析(293—1473K)进行了表征与确认,获得了晶胞参数及其随温度的变化,测量了高温原位拉曼光谱(273—1623K),并运用第一性原理理论计算方法对应核实了拉曼谱峰的归属.结果表明,随着温度升高,MgTiO3晶面间距和晶格常数增大,从而反映对于拉曼光谱较为敏感的键长和键角的变化;温致拉曼位移可以反映Ti—O,Mg—O等键长以及Ti—O—Ti,Ti—O—Mg与Mg—O—Mg等键角随温度的细微变化,相关关系则独立于温度,有效提升了原位拉曼光谱微探针诊断技术的分析能力;拉曼谱峰随温度升高而展宽,表明原子瞬间运动振幅加剧,弥散性增加,稳定性有所下降,但仍维持六方晶型.

  15. Confocal Raman Microscopy

    CERN Document Server

    Dieing, Thomas; Toporski, Jan

    2011-01-01

    Confocal Raman Microscopy is a relatively new technique that allows chemical imaging without specific sample preparation. By integrating a sensitive Raman spectrometer within a state-of-the-art microscope, Raman microscopy with a spatial resolution down to 200nm laterally and 500nm vertically can be achieved using visible light excitation. Recent developments in detector and computer technology as well as optimized instrument design have reduced integration times of Raman spectra by orders of magnitude, so that complete images consisting of tens of thousands of Raman spectra can be acquired in seconds or minutes rather than hours, which used to be standard just one decade ago. The purpose of this book is to provide the reader a comprehensive overview of the rapidly developing field of Confocal Raman Microscopy and its applications.

  16. Raman spectroscopic analysis of isomers of biliverdin dimethyl ester.

    Science.gov (United States)

    Matysik, J; Hildebrandt, P; Smit, K; Mark, F; Gärtner, W; Braslavsky, S E; Schaffner, K; Schrader, B

    1997-06-01

    The constitutional isomers of biliverdin dimethyl ester, IX alpha and XIII alpha, were studied by resonance Raman spectroscopy. The far-reaching spectral similarities suggest that despite the different substitution patterns, the compositions of the normal modes are closely related. This conclusion does not hold only for the parent state (ZZZ, sss configuration) but also for the configurational isomers which were obtained upon double-bond photoisomerization. Based on a comparison of the resonance Raman spectra, a EZZ configuration is proposed for one of the two photoisomers of biliverdin dimethyl ester IX alpha, while a ZZE, ssa configuration has been assigned previously to the second isomer. PMID:9226559

  17. Raman spectroscopy for the characterization of algal cells

    Science.gov (United States)

    Samek, Ota; Jonáš, Alexandr; Pilát, Zdeněk; Zemánek, Pavel; Nedbal, Ladislav; Tříska, Jan; Kotas, Petr; Trtílek, Martin

    2010-12-01

    Raman spectroscopy can elucidate fundamental questions about intercellular variability and what governs it. Moreover, knowing the metabolic response on single cell level this can significantly contribute to the study and use of microalgae in systems biology and biofuel technology. Raman spectroscopy is capable to measure nutrient dynamics and metabolism in vivo, in real-time, label free making it possible to monitor/evaluate population variability. Also, degree of unsaturation of the algae oil (iodine value) can be measured using Raman spectra obtained from single microalgae. The iodine value is the determination of the amount of unsaturation contained in fatty acids (in the form of double bonds). Here we demonstrate the capacity of the spatially resolved Raman microspectroscopy to determine the effective iodine value in lipid storage bodies of individual living algal cells. We employed the characteristic peaks in the Raman scattering spectra at 1,656 cm-1 (cis C=C stretching mode) and 1,445 cm-1 (CH2 scissoring mode) as the markers defining the ratio of unsaturated-to-saturated carbon-carbon bonds of the fatty acids in the algal lipids.

  18. Raman spectroscopic analysis of cyanogenic glucosides in plants: development of a Flow Injection Surface-Enhanced Raman Scatter (FI-SERS) method for determination of cyanide

    DEFF Research Database (Denmark)

    Thygesen, Lisbeth Garbrecht; Jørgensen, Kirsten; Møller, Birger Lindberg;

    2004-01-01

    /lotaustralin in leaves and roots from a medium cyanogenic cassava variety were obtained in situ using a Fourier transform near-infrared (FT-NIR) Raman interferometer with a 1064 nm laser, but the signal was very weak and difficult to obtain. A spectrum containing a signal from the CN bond of dhurrin in a freeze......Cyanogenic glucosides were studied using Raman spectroscopy. Spectra of the crystal forms of linamarin, linustatin, neolinustatin, amygdalin, sambunigrin, and dhurrin were obtained using a Raman spectrograph microscope equipped with a 532 nm laser. The position of the signal from the CdropN triple...... bond of the cyanohydrin group was influenced by the nature of the side group and was above 2240 cm(-1) for the three cyanogenic glucosides that contain a neigh- boring aromatic ring, and below or partially below 2240 cm-1 for the non-aromatic cyanoglucosides. Signals from the CN bond of linamarin...

  19. Raman spectral evidence for hydration forces between collagen triple helices

    OpenAIRE

    Leikin, S; Parsegian, V A; Yang, W.-H.; Walrafen, G. E.

    1997-01-01

    Hydration forces are thought to result from the energetic cost of water rearrangement near macromolecular surfaces. Raman spectra, collected on the same collagen samples on which these forces were measured, reveal a continuous change in water hydrogen-bonding structure as a function of separation between collagen triple helices. The varying spectral parameters track the force-distance curve. The energetic cost of water “restructuring,” estimated from the spectra, is consistent with the measur...

  20. Condition Assessment of Kevlar Composite Materials Using Raman Spectroscopy

    Science.gov (United States)

    Washer, Glenn; Brooks, Thomas; Saulsberry, Regor

    2007-01-01

    This viewgraph presentation includes the following main concepts. Goal: To evaluate Raman spectroscopy as a potential NDE tool for the detection of stress rupture in Kevlar. Objective: Test a series of strand samples that have been aged under various conditions and evaluate differences and trends in the Raman response. Hypothesis: Reduction in strength associated with stress rupture may manifest from changes in the polymer at a molecular level. If so, than these changes may effect the vibrational characteristics of the material, and consequently the Raman spectra produced from the material. Problem Statement: Kevlar composite over-wrapped pressure vessels (COPVs) on the space shuttles are greater than 25 years old. Stress rupture phenomena is not well understood for COPVs. Other COPVs are planned for hydrogen-fueled vehicles using Carbon composite material. Raman spectroscopy is being explored as an non-destructive evaluation (NDE) technique to predict the onset of stress rupture in Kevlar composite materials. Test aged Kevlar strands to discover trends in the Raman response. Strength reduction in Kevlar polymer will manifest itself on the Raman spectra. Conclusions: Raman spectroscopy has shown relative changes in the intensity and FWHM of the 1613 cm(exp -1) peak. Reduction in relative intensity for creep, fleet leader, and SIM specimens compared to the virgin strands. Increase in FWHM has been observed for the creep and fleet leader specimens compared to the virgin strands. Changes in the Raman spectra may result from redistributing loads within the material due to the disruption of hydrogen bonding between crystallites or defects in the crystallites from aging the Kevlar strands. Peak shifting has not been observed to date. Analysis is ongoing. Stress measurements may provide a tool in the short term.

  1. Co-localised Raman and force spectroscopy reveal the roles of hydrogen bonds and π-π interactions in defining the mechanical properties of diphenylalanine nano- and micro-tubes

    Science.gov (United States)

    Sinjab, Faris; Bondakov, Georgi; Notingher, Ioan

    2014-06-01

    An integrated atomic force and polarized Raman microscope were used to measure the elastic properties of individual diphenylalanine (FF) nano- and micro-tubes and to obtain quantitative information regarding the inter-molecular interactions that define their mechanical properties. For individual tubes, co-localised force spectroscopy and Raman spectroscopy measurements allowed the calculation of the Young's and shear moduli (25 ± 5 GPa and 0.28 ± 0.05 GPa, respectively) and the contribution of hydrogen bonding network to the Young's modulus (˜17.6 GPa). The π-π interactions between the phenyl rings, dominated by T-type arrangements, were estimated based on previously published X-ray data to only 0.20 GPa. These results provide experimental evidence obtained from individual FF tubes that the network of H-bonds dominates the elastic properties of the FF tubes.

  2. Co-localised Raman and force spectroscopy reveal the roles of hydrogen bonds and π-π interactions in defining the mechanical properties of diphenylalanine nano- and micro-tubes

    International Nuclear Information System (INIS)

    An integrated atomic force and polarized Raman microscope were used to measure the elastic properties of individual diphenylalanine (FF) nano- and micro-tubes and to obtain quantitative information regarding the inter-molecular interactions that define their mechanical properties. For individual tubes, co-localised force spectroscopy and Raman spectroscopy measurements allowed the calculation of the Young's and shear moduli (25 ± 5 GPa and 0.28 ± 0.05 GPa, respectively) and the contribution of hydrogen bonding network to the Young's modulus (∼17.6 GPa). The π-π interactions between the phenyl rings, dominated by T-type arrangements, were estimated based on previously published X-ray data to only 0.20 GPa. These results provide experimental evidence obtained from individual FF tubes that the network of H-bonds dominates the elastic properties of the FF tubes.

  3. Characterization of a superlubricity nanometer interface by Raman spectroscopy.

    Science.gov (United States)

    Shi, Yunsheng; Yang, Xing; Liu, Bingqi; Dong, Hualai; Zheng, Quanshui

    2016-08-12

    Despite being known for almost two decades, the use of micro-/nano-electromechanical systems in commercial applications remains a challenge because of stiction, friction, and the wear of the interface. Superlubricity may be the solution to these challenges. In this paper, we study factors affecting the realization of superlubricity. Raman spectroscopy and other methods were used to characterize a graphite interface which can realize superlubricity and another graphite interface which cannot realize superlubricity. Raman spectra of the interfaces were obtained with the mapping mode and then processed to obtain the Raman images of the characteristic peaks. The Raman spectra provided the distribution of the surface defects and probed defects. Combined with atomic force microscopy and x-ray photoelectron spectroscopy, the Raman spectra show that the sp(3) carbons and carbon-oxygen bond stuck at the edge of the graphite mesa are some of the determinants of large-area superlubricity realization. The characterization results can also be used to understand the friction and wear of large-area superlubricity, which are important for development and application of superlubricity. Furthermore, the methods used in this study are useful techniques and tools for the mechanism analysis of other nanometer interfaces. PMID:27348089

  4. Characterization of a superlubricity nanometer interface by Raman spectroscopy

    Science.gov (United States)

    Shi, Yunsheng; Yang, Xing; Liu, Bingqi; Dong, Hualai; Zheng, Quanshui

    2016-08-01

    Despite being known for almost two decades, the use of micro-/nano-electromechanical systems in commercial applications remains a challenge because of stiction, friction, and the wear of the interface. Superlubricity may be the solution to these challenges. In this paper, we study factors affecting the realization of superlubricity. Raman spectroscopy and other methods were used to characterize a graphite interface which can realize superlubricity and another graphite interface which cannot realize superlubricity. Raman spectra of the interfaces were obtained with the mapping mode and then processed to obtain the Raman images of the characteristic peaks. The Raman spectra provided the distribution of the surface defects and probed defects. Combined with atomic force microscopy and x-ray photoelectron spectroscopy, the Raman spectra show that the sp3 carbons and carbon–oxygen bond stuck at the edge of the graphite mesa are some of the determinants of large-area superlubricity realization. The characterization results can also be used to understand the friction and wear of large-area superlubricity, which are important for development and application of superlubricity. Furthermore, the methods used in this study are useful techniques and tools for the mechanism analysis of other nanometer interfaces.

  5. Raman and surface enhanced Raman spectroscopic investigation on Lamiaceae plants

    Science.gov (United States)

    Rösch, P.; Popp, J.; Kiefer, W.

    1999-05-01

    The essential oils of Thymus vulgaris and Origanum vulgaris are studied by means of micro-Raman spectroscopy. The containing monoterpenes can be identified by their Raman spectra. Further the essential oils are investigated in their natural environment, the so-called oil cells of these Lamiaceae plants, with surface enhanced Raman spectroscopy (SERS). This method has the advantage to enhance Raman signals and furthermore the SERS effect leads to fluorescence quenching.

  6. Raman imaging and spectroscopy of individual single-wall carbon nanotubes

    Science.gov (United States)

    Zhang, Li

    diameter dependent, which can be ascribed to the temperature dependence of carbon-carbon bond force constant in SWNTs and the nanotube curvature effect. At last, second-order Raman modes between 1650 and 2000 cm-1 of small-diameter SWNTs are characterized under different excitation wavelength. Excitation wavelength dependent Raman spectra of the same nanotube reveals that frequencies of the overtone M band and combination iTOLA mode of a single tube are insensitive to excitation energy, which is in contrast to the dispersive behavior observed in the ensemble measurement. It is also discovered that the relative intensity of these second-order modes depends on the chirality and family type of a nanotube.

  7. Matrix isolation infrared spectra of O-H· · · π Hydrogen bonded complexes of Acetic acid and Trifluoroacetic acid with Benzene

    Indian Academy of Sciences (India)

    PUJARINI BANERJEE; INDRANI BHATTACHARYA; TAPAS CHAKRABORTY

    2016-10-01

    Mid infrared spectra of two O–H· · · π hydrogen-bonded binary complexes of acetic acid (AA) and trifluoroacetic acid (F₃AA) with benzene (Bz) have been measured by isolating the complexes in an argon matrix at ∼8 K. In a matrix isolation condition, the O–H stretching fundamentals (νO−H) of the carboxylic acid groups of the two molecules are observed to have almost the same value. However, the spectral red-shifts of νO−H bands of the two acids on complexation with Bz are largely different, 90 and 150 cm⁻¹ for AA and F₃AA, respectively. Thus, the O–H bond weakening of the two acids upon binding with Bz in a non-interacting environment follows the sequence of their ionic dissociation tendencies (pKa) in aqueous media. Furthermore, ΔνO−H of the latter complex is the largest among the known π-hydrogen bonded binary complexes of prototypical O–H donors reported so far with respect to Bz as acceptor. It is also observed that the spectral shifts (ΔνO−H) of phenol-Bz and carboxylic acid-Bz complexes show similar dependence on the acidity factor (pKa). Electronic structure theory has been used to suggest suitable geometries of the complexes that are consistent with the measured IR spectral changes. Calculation at MP2/6-311++G (d, p) level predicts a T-shaped geometry for both AA-Bz and F₃AA-Bz complexes, and the corresponding binding energies are 3.0 and 4.5 kcal/mol, respectively. Natural Bond Orbital (NBO) analysis has been performed to correlate the observed spectral behavior of the complexes with the electronic structure parameters.

  8. Abnormal Raman spectral phenomenon of silicon nanowires

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The Raman spectra of two one-dimensional silicon nanowire samples with different excitation wavelengths were measured and an abnormal phenomenon was discovered that the Raman spectral features change with the wavelengths of excitation. Closer analysis of the crystalline structure of samples and the changes in Raman spectral features showed that the abnormal behavior is the result of resonance Raman scattering selection effect.

  9. Raman spectra of the solid-solution between Rb sub 2 La sub 2 Ti sub 3 O sub 1 sub 0 and RbCa sub 2 Nb sub 3 O sub 1 sub 0

    CERN Document Server

    Kim, H J; Yun, H S

    2001-01-01

    A site preference of niobium atom in Rb sub 2 sub - sub x La sub 2 Ti sub 3 sub - sub x Nb sub x O sub 1 sub 0 (0.0<=x<=1.0) and RbLa sub 2 sub - sub x Ca sub x Ti sub 2 sub - sub x Nb sub 1 sub + sub x O sub 1 sub 0 (0.0<=x<= 2.0), which are the solid-solutions between Rb sub 2 La sub 2 Ti sub 3 O sub 1 sub 0 are RbCa sub 2 Nb sub 3 O sub 1 sub 0 , has been investigated by Raman spectroscopy. The Raman spectra of Rb sub 2 sub - sub x La sub 2 Ti sub 3 sub - sub x Nb sub x O sub 1 sub 0 (0.0<=x<=1.0) gave an evidence that niobium atoms substituted for titanium atoms preferably occupy the highly distorted outer octahedral sites rather than the central ones in triple-octahedral perovskite layers. In contrast, the Raman spectra of RbLa sub 2 sub - sub x Ca sub x Ti sub 2 sub - sub x Nb sub 1 sub + sub x O sub 1 sub 0 (0.0<=x<= 2.0) showed no clear information for the cationic arrangement in perovskite slabs. This difference indicated that a site preference of niobium atoms is observed onl...

  10. Influence of the ordered structure of short-chain polymer molecule all-trans-β-carotene on Raman scattering cross section in liquid

    Institute of Scientific and Technical Information of China (English)

    Qu Guan-Nan; OuYang Shun-Li; Wang Wei-Wei; Li Zuo-Wei; Sun Cheng-Lin; Men Zhi-Wei

    2011-01-01

    We measured the resonant Raman spectra of all-trans-β-carotene in solvents with different densities and concentrations at different temperatures. The results demonstrated that the Raman scattering cross section (RSCS) of short-chain polymer all-trans-β-carotene is extremely high in liquid. Resonance and strong coherent weakly damped CC bond vibrating properties play important roles under these conditions. Coherent weakly damped CC bond vibration strength is associated with molecular ordered structure. All-trans-β-carotene has highly ordered structure and strong coherent weakly damped CC bond vibrating properties, which lead to large RSCS in the solvent with large density and low concentration at low temperature.

  11. Microwave, infrared, and Raman spectra, structural parameters, vibrational assignments and theoretical calculations of 1,1,3,3-tetrafluoro-1,3-disilacyclopentane

    Energy Technology Data Exchange (ETDEWEB)

    Pate, Brooks H.; Seifert, Nathan A. [Department of Chemistry, University of Virginia, Charlottesville, VA 22904 (United States); Guirgis, Gamil A. [Department of Chemistry and Biochemistry, College of Charleston, Charleston, SC 29424 (United States); Deodhar, Bhushan S.; Klaassen, Joshua J.; Darkhalil, Ikhlas D. [Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110 (United States); Crow, Joseph A. [Department of Physics, University of Missouri-Kansas City, Kansas City, MO 64110 (United States); Wyatt, Justin K.; Dukes, Horace W. [Department of Chemistry and Biochemistry, College of Charleston, Charleston, SC 29424 (United States); Durig, James R., E-mail: durigj@umkc.edu [Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110 (United States)

    2013-04-18

    Highlights: • Structural parameters have been determined for the stable twist conformer. • Rotational constants for the six isotopologues for the twist conformer were determined from the microwave spectra. • Vibrational assignments are given for the molecule. • Ab intio and density functional theory calculations have been carried out for all possible conformers. - Abstract: The FT-microwave spectrum of 1,1,3,3-tetrafluoro-1,3-disilacyclopentane (c-C{sub 3}H{sub 6}Si{sub 2}F{sub 4}) has been recorded and 339 transitions for 6 isotopologues have been assigned for the twist conformation. The ground state rotational constants were determined with values for the normal species: A = 2102.74026(68), B = 751.34319(32), C = 736.51478(31). Adjusted r{sub 0} parameters are reported with distances (Å): rC{sub α}–Si = 1.859(2), rSi–C{sub β} = 1.864(2), rSi–F{sub 1} = 1.583(3), rSi–F{sub 2} = 1.578(3), and rC{sub β}–C{sub β} = 1.559(3), and angles (°): ∠SiC{sub α}Si = 102.8(3), ∠C{sub α}SiC{sub β} = 104.3(3), ∠SiC{sub β}C{sub β′} = 106.6(3), τC{sub β}SiC{sub α}Si = 10.7(3), and τ SiC{sub β}C{sub β′}Si = 40.8(3). The conformational stabilities have been predicted from ab initio calculations utilizing several various basis sets. Vibrational assignments have been provided for the observed bands for the twist conformer which are supported by ab initio calculations to predict harmonic force constants, vibrational wavenumbers, infrared intensities, Raman activities and depolarization ratios. The results are discussed and compared to the corresponding properties of some related molecules.

  12. Atomic-scale microstructures, Raman spectra and dielectric properties of cubic pyrochlore-typed Bi1.5MgNb1.5O7 dielectric ceramics

    KAUST Repository

    Li, Yangyang

    2014-07-01

    Single-phase cubic pyrochlore-typed Bi1.5MgNb 1.5O7 (BMN) dielectric ceramics were synthesized at temperatures of 1050-1200 °C by solid-state reaction method. Their atomic-scale microstructures and dielectric properties were investigated. X-ray diffraction patterns revealed that the BMN ceramics had an average cubic pyrochlore structure, whereas the Raman spectra indicated that they had an essentially cubic symmetry with small local deviations at the A and O\\' sites of the cubic pyrochlore structure. This was confirmed by selected electron area diffraction (SAED) patterns, where the reflections of {442} (not allowed in the cubic pyrochlore with Fd3̄m symmetry) were clearly observed. SEM and TEM images revealed that the average grain size was increased with the sintering temperature, and an un-homogeneous grain growth was observed at high temperatures. HRTEM images and SAED patterns revealed the single-crystalline nature of the BMN ceramic grains. Energy dispersive spectroscopy (EDS) elemental mapping studies indicated that the compositional distributions of Bi, Mg, Nb and O elements in the ceramic grains were homogenous, and no elemental precipitation was observed at the grain boundary. Quantitative EDS data on ceramic grains revealed the expected cationic stoichiometry based on the initial composition of Bi1.5MgNb1.5O7. Dielectric constants of all the BMN samples exhibited almost frequency independent characteristic in the frequency range of 102-106 Hz, and the highest value was 195 for the BMN ceramics sintered at sintered at 1150 °C with the highest bulk density. The dielectric losses were stable and less than 0.002 in the frequency range of 102-105 Hz. The high dielectric constants of the present BMN samples can be ascribed to the local atomic deviations at the A and O\\' sites from the ideal atomic positions of the pyrochlore structure, which affect the different polarization mechanisms in the BMN ceramics, and which in turn enhance the dielectric

  13. Long-distance inter-hydrogen bond coupling effects in the polarized IR spectra of succinic acid crystals

    Science.gov (United States)

    Flakus, Henryk T.; Hachuła, Barbara; Hołaj-Krzak, Jakub T.

    2015-05-01

    The spectral properties of four different crystalline succinic acid (HOOC-(CH2)2-COOH) (SAC) isotopomer systems, h6, d2, d4 and d6, were examined by means of the IR spectroscopy in polarized light aided by numerical simulations of the νO-H and νO-D band contour shapes on utilizing the "strong-coupling" model. The abnormal IR spectral properties of SAC crystals in relation to the corresponding properties of glutaric, pimelic and adipic acid crystals were ascribed to the hyperconjugation electronic effects in the acid associated molecules. A vibronic coupling mechanism involving the proton stretching vibrations in the (COOH)2 cycles and the electronic motions in the molecular skeletons, the isotopic "H/D self-organization" mechanisms and a long-distance vibrational exciton coupling between the adjacent (COOH)2 cycles in the molecular chains are mainly responsible for the generation of the temperature effects in the crystalline IR spectra.

  14. Basis set dependence using DFT/B3LYP calculations to model the Raman spectrum of thymine.

    Science.gov (United States)

    Bielecki, Jakub; Lipiec, Ewelina

    2016-02-01

    Raman spectroscopy (including surface enhanced Raman spectroscopy (SERS) and tip enhanced Raman spectroscopy (TERS)) is a highly promising experimental method for investigations of biomolecule damage induced by ionizing radiation. However, proper interpretation of changes in experimental spectra for complex systems is often difficult or impossible, thus Raman spectra calculations based on density functional theory (DFT) provide an invaluable tool as an additional layer of understanding of underlying processes. There are many works that address the problem of basis set dependence for energy and bond length consideration, nevertheless there is still lack of consistent research on basis set influence on Raman spectra intensities for biomolecules. This study fills this gap by investigating of the influence of basis set choice for the interpretation of Raman spectra of the thymine molecule calculated using the DFT/B3LYP framework and comparing these results with experimental spectra. Among 19 selected Pople's basis sets, the best agreement was achieved using 6-31[Formula: see text](d,p), 6-31[Formula: see text](d,p) and 6-11[Formula: see text]G(d,p) sets. Adding diffuse functions or polarized functions for small basis set or use of a medium or large basis set without diffuse or polarized functions is not sufficient to reproduce Raman intensities correctly. The introduction of the diffuse functions ([Formula: see text]) on hydrogen atoms is not necessary for gas phase calculations. This work serves as a benchmark for further research on the interaction of ionizing radiation with DNA molecules by means of ab initio calculations and Raman spectroscopy. Moreover, this work provides a set of new scaling factors for Raman spectra calculation in the framework of DFT/B3LYP method.

  15. HYDROGEN-BOND DEFECT OF WATER IN PVA HYDROGELS BY RAMAN SPECTRAL ANALYSIS%不同结晶度聚乙烯醇水凝胶中水氢键缺损的拉曼光谱学研究

    Institute of Scientific and Technical Information of China (English)

    郭兴林; 李福绵; 张树霖

    2001-01-01

    The hydrogen-bond defect of water in PVA hydrogels was studied by Raman spectral analysis. The PVA hydrogels were prepared from PVA of different DP in different concentrations via freeze/thawed method.It was found that the hydrogen bond defect of water in PVA hydrogels is affected by their crystallinity which was depended on the molecular weight and concentration of PVA and also the number of freeze/thawed cycles.After swelling in water for 24?h,partial VA units were released from the crystalline regions,this means that more `free' VA units could bond with water in PVA hydrogels,causing the decrease of C value and the increase of N value.

  16. Absorption,fluorescence and resonance Rayleigh scattering spectra of hydrophobic hydrogen bonding of eosin Y/Triton X-100 nanoparticles and their analytical applications

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In a weak acidic medium(pH 2.4-2.8),eosin Y molecules(H2L) could replace water molecules to associate with Triton X-100 to form hydrophobic hydrogen bonding complexes.These complexes could further aggregate to form nanoparticles through the squeezing action of the water phase and Van Der Waals force,resulting in changes in the absorption spectrum and fluorescence quenching of EY as well as the significant enhancement of resonance Rayleigh scattering.This enables the sensitive determination of Triton X-100 using the fading spectrophotometry,fluorescence quenching method and RRS method.Among them,the RRS method shows the highest sensitivity with a detection limit of 20.6 ng mL-1 for Triton X-100.The optimum experimental conditions and factors that affect the absorption,fluorescence and RRS spectra were tested.The effects of coexisting substances were investigated and the results showed good selectivity.Based on these results,new spectrophotometric methods,fluorescence quenching method and RRS method for the determination of Triton X-100,were established.The hydrogen bonding association of eosin Y with Triton X-100 and the formation of nanoparticles as well as their effects on related spectral characteristics were discussed utilizing infrared,transmission electron microscope technique and quantum chemical method.

  17. Metallodrug induced apoptotic cell death and survival attempts are characterizable by Raman spectroscopy

    Science.gov (United States)

    le Roux, K.; Prinsloo, L. C.; Meyer, D.

    2014-09-01

    Chrysotherapeutics are under investigation as new or additional treatments for different types of cancers. In this study, gold complexes were investigated for their anticancer potential using Raman spectroscopy. The aim of the study was to determine whether Raman spectroscopy could be used for the characterization of metallodrug-induced cell death. Symptoms of cell death such as decreased peak intensities of proteins bonds and phosphodiester bonds found in deoxyribose nucleic acids were evident in the principal component analysis of the spectra. Vibrational bands around 761 cm-1 and 1300 cm-1 (tryptophan, ethanolamine group, and phosphatidylethanolamine) and 1720 cm-1 (ester bonds associated with phospholipids) appeared in the Raman spectra of cervical adenocarcinoma (HeLa) cells after metallodrug treatment. The significantly (p cancer cells under chemical stress. Cancer cells excrete chemotherapeutics to improve their chances of survival and utilize glucose to achieve this. Raman spectroscopy was able to monitor a survival strategy of cancer cells in the form of glucose uptake to alleviate chemical stress. Raman spectroscopy was invaluable in obtaining molecular information generated by biomolecules affected by anticancer metallodrug treatments and presents an alternative to less reproducible, conventional biochemical assays for cytotoxicity analyses.

  18. Metallodrug induced apoptotic cell death and survival attempts are characterizable by Raman spectroscopy

    Science.gov (United States)

    le Roux, K.; Prinsloo, L. C.; Meyer, D.

    2014-09-01

    Chrysotherapeutics are under investigation as new or additional treatments for different types of cancers. In this study, gold complexes were investigated for their anticancer potential using Raman spectroscopy. The aim of the study was to determine whether Raman spectroscopy could be used for the characterization of metallodrug-induced cell death. Symptoms of cell death such as decreased peak intensities of proteins bonds and phosphodiester bonds found in deoxyribose nucleic acids were evident in the principal component analysis of the spectra. Vibrational bands around 761 cm-1 and 1300 cm-1 (tryptophan, ethanolamine group, and phosphatidylethanolamine) and 1720 cm-1 (ester bonds associated with phospholipids) appeared in the Raman spectra of cervical adenocarcinoma (HeLa) cells after metallodrug treatment. The significantly (p treatment could be a molecular signature of induced apoptosis since both the co-regulated phosphatidylserine and phosphatidylethanolamine are externalized during cell death. Treated cells had significantly higher levels of glucose and glycogen vibrational peaks, indicative of a survival mechanism of cancer cells under chemical stress. Cancer cells excrete chemotherapeutics to improve their chances of survival and utilize glucose to achieve this. Raman spectroscopy was able to monitor a survival strategy of cancer cells in the form of glucose uptake to alleviate chemical stress. Raman spectroscopy was invaluable in obtaining molecular information generated by biomolecules affected by anticancer metallodrug treatments and presents an alternative to less reproducible, conventional biochemical assays for cytotoxicity analyses.

  19. H/D isotopic recognition and temperature effects in IR spectra of hydrogen-bonded cyclic dimers in crystals: 3-Methylcinnamic acid and 4-phenylbutyric acid

    Science.gov (United States)

    Hachuła, Barbara; Jabłońska-Czapla, Magdalena; Flakus, Henryk T.; Nowak, Maria; Kusz, Joachim

    2015-01-01

    In the present work, the experimental and theoretical study of the nature of the inter-hydrogen bond interactions in two different carboxylic acids, 3-methylcinnamic acid (3MCA) and 4-phenylbutyric acid (4PBA), were reported. The polarized IR spectra of 3MCA and 4PBA crystals were recorded at the frequency ranges of the νOsbnd H and νOsbnd D bands. The spectral properties of 3MCA and 4PBA interpreted with the aid of the calculations based on the "strong-coupling" model. The differences in the spectral properties of the two different dimeric systems in the crystals provide a valuable information about the existence of a direct relationship between the crystal spectral properties in IR and the electronic structure of the molecular systems. In 3MCA crystals strong vibrational exciton interactions favor a "tail-to-head" (TH)-type Davydov coupling widespread via the π-electrons, whereas in 4PBA crystals a weak "through-space" (SS) exciton coupling is responsible for a "side-to-side"-type coupling. The relative contribution of each individual exciton coupling mechanism in IR spectra generation strongly depends on temperature and molecular electronic structure. The H/D isotopic recognition effect, depending on a non-random distribution of protons and deuterons in the crystal hydrogen bridges, was also analyzed.

  20. Rapid Raman spectra identification and determination of levofloxacin hydrochloride injection%拉曼光谱快速检测盐酸左氧氟沙星注射液

    Institute of Scientific and Technical Information of China (English)

    陈斌; 张少敏; 余岳林; 陈桂良; 乐健; 张予敏

    2011-01-01

    Objective: To develop a method for the rapid identification, test and determination of levofloxacin hydrochloride injection using Raman spectra. Method: Raman spectra was used as the method of identifying, testing and determination the levofloxacin hydrochloride injection. Results: The result showed that the method of Raman spectra can identify the different of floxacin ( despinner) , levofloxacin and levofloxacin hydrochloride, test pH of levofloxacin hydrochloride injection, determinate the levofloxacin hydrochloride injection. Conclusion: Owing to its fast and nondestructive properties, the presented method can be developed as an analysis method for injection.%目的:建立一种运用拉曼光谱技术快速鉴别、检查和测定盐酸左氧氟沙星注射液的方法.方法:以氧氟沙星、左氧氟沙星、盐酸左氧氟沙星以及盐酸左氧氟沙星注射液为研究对象,运用拉曼光谱技术对盐酸左氧氟沙星注射液进行快速鉴别、检查和含量测定.结果:拉曼光谱法可以鉴别出氧氟沙星消旋体和左氧氟沙星,辨别出不同pH的左氧氟沙星注射液的图谱差异并可用于盐酸左氧氟沙星注射液的含量测定.结论:本方法操作简便、快速无损,可成为注射剂快速检测的分析方法.

  1. Blood analysis by Raman spectroscopy.

    Science.gov (United States)

    Enejder, Annika M K; Koo, Tae-Woong; Oh, Jeankun; Hunter, Martin; Sasic, Slobodan; Feld, Michael S; Horowitz, Gary L

    2002-11-15

    Concentrations of multiple analytes were simultaneously measured in whole blood with clinical accuracy, without sample processing, using near-infrared Raman spectroscopy. Spectra were acquired with an instrument employing nonimaging optics, designed using Monte Carlo simulations of the influence of light-scattering-absorbing blood cells on the excitation and emission of Raman light in turbid medium. Raman spectra were collected from whole blood drawn from 31 individuals. Quantitative predictions of glucose, urea, total protein, albumin, triglycerides, hematocrit, and hemoglobin were made by means of partial least-squares (PLS) analysis with clinically relevant precision (r(2) values >0.93). The similarity of the features of the PLS calibration spectra to those of the respective analyte spectra illustrates that the predictions are based on molecular information carried by the Raman light. This demonstrates the feasibility of using Raman spectroscopy for quantitative measurements of biomolecular contents in highly light-scattering and absorbing media. PMID:18033426

  2. Laser annealing effects of the Raman laser on nitrogen implanted glassy carbon

    Energy Technology Data Exchange (ETDEWEB)

    Barbara, D.; Prawer, S.; Jamieson, D.N. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1996-12-31

    Raman analysis is a popular method of investigating crystallite sizes, ordering and the types of bonds that exist in ion irradiated carbon materials, namely graphite, diamond and glassy carbon (G.C.). In particular Raman spectroscopy is used in determining the tetrahedral bonding required for the elusive and potentially important new material called carbon nitride. Carbon nitride, {beta}-C{sub 3}N{sub 4}, is predicted to exist in several forms. Forming the tetrahedral bond between C and N has proved troublesome bain of many experimenters. A proven method for synthesizing novel materials is ion implantation. Thus G.C. was implanted with N at low temperatures so that diffusion of the implanted N would be hindered. G.C. is a relatively hard, chemically inert, graphitic material. The opaque property of G.C. means that Raman spectroscopy will only give information about the structures that exist at the surface and near surface layers. It was decided, after observing conflicting Raman spectra at different laser powers, that an investigation of the laser annealing effects of the Raman laser on the N implanted G.C. was warranted. The results of the preliminary investigation of the effects of increasing the Raman laser power and determining a power density threshold for high dose N implanted G.C. are discussed. 4 refs., 4 figs.

  3. Raman Imaging Techniques and Applications

    CERN Document Server

    2012-01-01

    Raman imaging has long been used to probe the chemical nature of a sample, providing information on molecular orientation, symmetry and structure with sub-micron spatial resolution. Recent technical developments have pushed the limits of micro-Raman microscopy, enabling the acquisition of Raman spectra with unprecedented speed, and opening a pathway to fast chemical imaging for many applications from material science and semiconductors to pharmaceutical drug development and cell biology, and even art and forensic science. The promise of tip-enhanced raman spectroscopy (TERS) and near-field techniques is pushing the envelope even further by breaking the limit of diffraction and enabling nano-Raman microscopy.

  4. 拉曼光谱技术在恶性骨肿瘤患者红细胞中的研究应用%Raman Spectra of Red-Cell from the Malignant Tumors

    Institute of Scientific and Technical Information of China (English)

    李和仙; 刘伟; 赵元黎; 王丽君; 张彦陟

    2011-01-01

    对单晶态血红蛋白和红细胞的拉曼光谱进行了研究.发现在600~1 750 cm-1的范围内,红细胞与单晶态血红蛋白的拉曼谱图极其相似,只有小量的峰移和加宽.实验结果表明可以通过分析红细胞的拉曼谱图中与heme相关的特征峰来研究红细胞内血红蛋白的结构及功能.对正常人和恶性骨肿瘤患者红细胞的拉曼光谱进行了分析,发现恶性骨肿瘤患者红细胞的拉曼峰相对于正常人的相对强度的比值在1505cm-1、1228cm-1、1087cm-1、1001cm-1和747 cm-1显著减小,说明亚铁血红素、苯丙氨酸和脱氧核糖在红细胞内的含量减少.由统计分析可知Ⅰ1586/1228、Ⅰ1586/1001和Ⅰ1586/1169的峰-峰比的变化可为恶性骨肿瘤的早期诊断提供一定的依据.%The UV spectra and Raman spectra of Hb(Hemoglobin) in crystalline state and in red cells are obtained. From 600 to 1 750 cm-1, the Raman spectra of Hb in red cells are similar to those in crystalline state except little Shifts and broadening. The results show that we can get the information of the structure and function of Hb by studying the spectra of hemein red cells. The raman spectra of red-cell from the normal blood and the malignant osteoma blood are also obtained. The ratio of comparatively intensity of lines in red-cell between the malignant osteoma and the normal minish in 1 505 cm-1、1 228 cm-1、1 087 cm-1 、1 001 cm-1 and 747 cm-1, which show the contents of heme、phenylalanine and deoxyribose in red-cell reduces. According to the statistic analysis, the changes of I1 586/1228 、I1 586/1 001 and I1 586/169 can provide a method for diagnosing malignant osteoma.

  5. Brain metastasis detection by resonant Raman optical biopsy method

    Science.gov (United States)

    Zhou, Yan; Liu, Cheng-hui; Cheng, Gangge; Zhou, Lixin; Zhang, Chunyuan; Pu, Yang; Li, Zhongwu; Liu, Yulong; Li, Qingbo; Wang, Wei; Alfano, Robert R.

    2014-03-01

    Resonant Raman (RR) spectroscopy provides an effective way to enhance Raman signal from particular bonds associated with key molecules due to changes on a molecular level. In this study, RR is used for detection of human brain metastases of five kinds of primary organs of lung, breast, kidney, rectal and orbital in ex-vivo. The RR spectra of brain metastases cancerous tissues were measured and compared with those of normal brain tissues and the corresponding primary cancer tissues. The differences of five types of brain metastases tissues in key bio-components of carotene, tryptophan, lactate, alanine and methyl/methylene group were investigated. The SVM-KNN classifier was used to categorize a set of RR spectra data of brain metastasis of lung cancerous tissues from normal brain tissue, yielding diagnostic sensitivity and specificity at 100% and 75%, respectively. The RR spectroscopy may provide new moleculebased optical probe tools for diagnosis and classification of brain metastatic of cancers.

  6. Raman scattering in crystals

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, D.F.

    1988-09-30

    A tutorial presentation is given of Raman scattering in crystals. The physical concepts are emphasized rather than the detailed mathematical formalism. Starting with an introduction to the concepts of phonons and conservation laws, the effects of photon-phonon interactions are presented. This interaction concept is shown for a simple cubic crystal and is extended to a uniaxial crystal. The correlation table method is used for determining the number and symmetry of the Raman active modes. Finally, examples are given to illustrate the relative ease of using this group theoretical method and the predictions are compared with measured Raman spectra. 37 refs., 17 figs., 6 tabs.

  7. Raman spectroscopy of PIN hydrogenated amorphous silicon solar cells

    Science.gov (United States)

    Keya, Kimitaka; Torigoe, Yoshihiro; Toko, Susumu; Yamashita, Daisuke; Seo, Hyunwoong; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

    2015-09-01

    Light-induced degradation of hydrogenated amorphous silicon (a-Si:H) is a key issue for enhancing competitiveness in solar cell market. A-Si:H films with a lower density of Si-H2 bonds shows higher stability. Here we identified Si-H2 bonds in PIN a-Si:H solar cells fabricated by plasma CVD using Raman spectroscopy. A-Si:H solar cell has a structure of B-doped μc-SiC:H (12.5 nm)/ non-doped a-Si:H (250nm)/ P-doped μc-Si:H (40 nm) on glass substrates (Asahi-VU). By irradiating HeNe laser light from N-layer, peaks correspond to Si-H2 bonds (2100 cm-1) and Si-H bonds (2000 cm-1) have been identified in Raman scattering spectra. The intensity ratio of Si-H2 and Si-H ISiH2/ISiH is found to correlate well to light induced degradation of the cells Therefore, Raman spectroscopy is a promising method for studying origin of light-induced degradation of PIN solar cells.

  8. 基于药用辅料的拉曼光谱鉴别络活喜仿冒药研究%Identification of Norvasc and counterfeit drugs based on Raman spectra of phar-maceutical excipients

    Institute of Scientific and Technical Information of China (English)

    钱小峰; 柳艳; 陈辉; 陆峰

    2015-01-01

    Objective To build an identification method for Norvascand its counterfeit drugs based on the differences of their pharmaceutical excipients with the original and generic Amlodipine besylatetablets as tools .Methods Raman spectra of pharmaceutical excipients which were usually used in tablets were collected .Similarity algorithm and characteristic Raman bands were used to search the excipients contained in the tablets .If the excipients was not the same as excipients contained in Nor-vasc ,the tablet was judged as counterfeit drugs .Otherwise ,principal component analysis was used to identify counterfeit and generic .Results and conclusion The method based on Raman spectra of pharmaceutical excipients could identify Norvasc and counterfeit drugs efficiently and accurately .%目的:针对药物活性成分与原研药质量相同的一类仿冒药,以苯磺酸氨氯地平片原研药及仿冒药为工具药,建立基于两者所用药用辅料的差异,用于鉴别络活喜仿冒药的方法。方法收集络活喜片剂常用辅料的拉曼光谱,采用相似度算法及特征峰查找待检样品中辅料,若待检样品的辅料与原研药辅料不同则判为仿冒药;若待检品辅料与原研药辅料相同,则采用主成分分析法区分仿冒药与原研药。结果与结论该方法可快速、准确地鉴别络活喜仿冒药。

  9. Spectroscopic Raman characterization of rutherfordine: a combined DFT and experimental study.

    Science.gov (United States)

    Bonales, L J; Colmenero, F; Cobos, J; Timón, V

    2016-06-28

    A rutherfordine mineral was studied by means of Raman spectroscopy combined with first principle calculations based on the density functional theory (DFT) method. The pseudopotential of a uranium atom was generated and its performance was evaluated for a series of uranium-containing minerals. The structure of rutherfordine was determined for two symmetries (Pmmn and Imm2) and the resulting lattice parameters, bond lengths, bond angles, and X-ray powder diffractogram were found to be in very good agreement with experimental values. The Raman spectrum was experimentally determined in the range 0-1700 cm(-1) and calculated using density functional perturbation theory. The non-scaled theoretical wavenumbers also agreed with the experimental values, and therefore a detailed interpretation of the theoretical spectra allowed us to assign the Raman bands found in the experimental spectrum. PMID:27271869

  10. Ethanol monomers and dimers revisited: a Raman study of conformational preferences and argon nanocoating effects.

    Science.gov (United States)

    Wassermann, Tobias N; Suhm, Martin A

    2010-08-19

    The gauche-trans conformational distribution in ethanol can be determined from the OH stretching Raman spectrum of seeded supersonic jet expansions, which thus provides a sensitive conformational thermometer. Depending on the rare gas mixture, one, two or four ethanol dimer conformations are abundant. Their conformational assignment is facilitated by the observation of hydrogen bond acceptor modes, which have similar Raman cross sections but much inferior infrared intensities than donor modes. Ethanol monomers and dimers can be progressively Ar-coated, and the resulting spectra may be compared with those in a bulk argon matrix. The low frequency range of torsional transitions provides some evidence for conformation-changing transitions in Raman jet spectra. PMID:20701332

  11. Difference Raman spectroscopy of DNA molecules

    International Nuclear Information System (INIS)

    In this paper the micro-Raman spectra of calf DNA for different points of DNA sample have been recorded. The Raman spectra were made with help of difference Raman spectroscopy technique. Raman spectra were recorded with high spatial resolution from different points of the wet and dry samples in different spectral range (100÷4000cm−1) using two lasers: argon (514.5 nm) and helium -neon (632.8 nm). The significant differences in the Raman spectra for dry and wet DNA and for different points of DNA molecules were observed. The obtained data on difference Raman scattering spectra of DNA molecules may be used for identification of DNA types and for analysis of genetic information associated with the molecular structure of this molecule

  12. Environmental effects on the lignin model monomer, vanillyl alcohol, studied by raman spectroscopy

    DEFF Research Database (Denmark)

    Larsen, Kiki Lyster; Barsberg, Søren Talbro

    2011-01-01

    units, respectively. Raman spectroscopy gives valuable knowledge on lignin and has a large potential for further developments. Thus in the present work we show how the use of electronic structure theory can support the study of environmental effects on lignin Raman bands. Raman spectra of the lignin...... model monomer, vanillyl alcohol (G type), dissolved in different solvents were compared to investigate such effects on the Raman band shapes and positions. Density functional theory combined with the polarizable continuum model were applied to assign the observed bands and tested for prediction accuracy....... Two ring deformation modes at 1600 cm–1 showed strong dependency on solvent ability to act as hydrogen bond donor, and this has to be considered in addition to substitutional effects on these modes....

  13. Raman Spectroscopic Studies on L-histidine, aniline Doped Triglycine Sulphate Single Crystals

    Science.gov (United States)

    Benial, A. Milton Franklin; Ramakrishnan, V.; Parameswari, A.

    2015-02-01

    Single crystals of triglycine sulphate (TGS) doped with L-histidine and aniline were studied by Raman Spectroscopy. The structure and symmetry of molecules, the nature of bonding and the effect of crystalline field on molecular vibrations were studied for pure and doped TGS. The characteristic group frequencies were identified and analysed for H2SO4 and glycine. The skeletal motion, lattice vibrational peaks were observed in the low wavenumber region. The site symmetry effect and the correlation field effect were studied from the splitting of vibrational bands. The observed Raman shift towards higher wave number region reveals that the symmetry reduction in doped TGS crystals. The broadening of Raman spectral line showed that a decrease in the hardness value for the doped crystals. Comparative studies of the Raman Spectra of pure TGS and doped TGS were also carried out.

  14. Davydov coupling as a factor influencing the H-bond IR signature: Computational study of the IR spectra of 3-thiopheneacrylic acid crystal

    Science.gov (United States)

    Rekik, Najeh; Al-Agel, Faisal A.; Flakus, Henryk T.

    2016-03-01

    In this work, we have studied the role played by Davydov coupling in the evolution of the fine structure of the IR spectra of 3-thiopheneacrylic acid dimer crystal. For this purpose, we took into account the linear dependence of the Davydov coupling on the position coordinate Qi(i = 1, 2) of the slow frequency O←sbnd H …O→ mode of the two H-bond bridges of the cyclic dimer. The Davydov coupling VD term was expanded up to first order with respect to the slow mode coordinate Qi. We have considered: VD (Q1 ,Q2) =VD0 + Θ (Q1 +Q2). That leads to the anharmonic expression of the Davydov coupling parameter VD: VD(Qg) =VD0 +√{ 2} ΘQg within the symmetrized coordinates. The effect of the second order parameter (Θ) of Davydov coupling on to the spectral density was undertaken. The numerical calculations clearly show that the crystal spectral properties of the infrared υOsbnd H stretching band remain in a close relation with the new anharmonic coupling parameter and provide a direct evidence of the increase of the level density and the spectral broadening.

  15. The effect of Nd and Mg doping on the micro-Raman spectra of LiNbO{sub 3} single-crystals

    Energy Technology Data Exchange (ETDEWEB)

    Quispe-Siccha, R; Villagran-Muniz, M [Laboratorio de FotofIsica, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, AP 70-186, DF (Mexico); MejIa-Uriarte, E V [Laboratorio de Fotonica de Microondas, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, AP 70-186, DF (Mexico); Jaque, D; GarcIa Sole, J; Jaque, F [Laboratorio de Espectroscopia Laser, Departamentode Fisica de Materiales, Universidad Autonoma de Madrid, Madrid 28049 (Spain); Sato-Berru, R Y [Laboratorio de Materiales y NanotecnologIa, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, AP 70-186, DF (Mexico); Camarillo, E; Hernandez A, J; Murrieta S, H [Laboratorio Propiedades Opticas, Instituto de Fisica, Universidad Nacional Autonoma de Mexico, AP 20-364 (Mexico)], E-mail: rosa.quispe@gmail.com, E-mail: elsi.mejia@ccadet.unam.mx, E-mail: mayo.villagran@ccadet.unam.mx, E-mail: dani.jaque@uam.es, E-mail: jose.garcia_sole@uam.es, E-mail: francisco.jaque@uam.es, E-mail: roberto.sato@ccadet.unam.mx, E-mail: cgarcia@fisica.unam.mx, E-mail: josemh@fisica.unam.mx, E-mail: murrieta@fisica.unam.mx

    2009-04-08

    The LiNbO{sub 3} congruent crystals doped with small Nd concentrations, <1 mol% Nd, and co-doped with Mg ions, 0-9 mol% Mg, were systematically investigated by means of micro-Raman spectroscopy in the Y and Z crystal directions. Results obtained from an undoped congruent crystal, an Nd-doped crystal, a Mg-doped crystal and Nd, Mg-co-doped crystals are compared. From the analyses of the results obtained in the Y direction, the Nd and Mg content dependence of the two lowest-Raman A{sub 1}(TO{sub 1}) and A{sub 1}(TO{sub 2}) modes, the half-width composition and the area ratio of the A{sub 1}(TO{sub 4}) and E(TO{sub 8}) bands, we reached several conclusions about the incorporation mechanism of the Nd and Mg ions into the LiNbO{sub 3} lattice. Likewise the Raman shift and half-width of the E(TO{sub 1}) and E(TO{sub 7}) modes were investigated in the Z direction. Results indicate that Mg and Nd ions are located in the Li site for low doping concentrations and for larger concentrations there is a replacement in both Li and Nb ion sites.

  16. Direct observation of the cyclic dimer in liquid acetic acid by probing the C=O vibration with ultrafast coherent Raman spectroscopy.

    Science.gov (United States)

    Lütgens, Matthias; Friedriszik, Frank; Lochbrunner, Stefan

    2014-09-01

    We present a comparison of spontaneous Raman and ultrafast coherent anti-Stokes Raman scattering (CARS) spectra of the C=O vibration of liquid acetic acid. The former technique cannot clearly reveal the number of contributions in the spectrum. However, the additional time and spectrally resolved CARS experiment supports strictly the existence of four modes, which proves the coexistence of more than one H-bonded configuration in liquid acetic acid. A comparably slowly dephasing mode which is obscured by a broad band in the linear Raman spectrum is assigned to the cyclic dimer and can be observed freed from all other contributions by ultrafast CARS.

  17. Simulating two-dimensional infrared-Raman and Raman spectroscopies for intermolecular and intramolecular modes of liquid water.

    Science.gov (United States)

    Ito, Hironobu; Tanimura, Yoshitaka

    2016-02-21

    Full classical molecular dynamics (MD) simulations of two-dimensional (2D) infrared-Raman and 2D Raman spectroscopies of liquid water were carried out to elucidate a mode-mode coupling mechanism using a polarizable water model for intermolecular and intramolecular vibrational spectroscopy (POLI2VS). This model is capable of describing both infrared and Raman spectra. Second-order response functions, which consist of one molecular polarizability and two molecular dipole moments for 2D IR-Raman and three molecular polarizabilities for 2D Raman spectroscopies, were calculated using an equilibrium-non-equilibrium hybrid MD approach. The obtained signals were analyzed using a multi-mode Brownian oscillator (BO) model with nonlinear system-bath interactions representing the intramolecular OH stretching, intramolecular HOH bending, hydrogen bonded (HB)-intermolecular librational motion and HB-intermolecular vibrational (translational) motion of liquid water. This model was applied through use of hierarchal Fokker-Planck equations. The qualitative features of the peak profiles in the 2D spectra obtained from the MD simulations are accurately reproduced with the BO model. This indicates that this model captures the essential features of the intermolecular and intramolecular motion. We elucidate the mechanisms governing the 2D signal profiles involving anharmonic mode-mode coupling, the nonlinearities of the polarizability and dipole moment, and the vibrational dephasing processes of liquid water even in the case that the 2D spectral peaks obtained from the MD simulation overlap or are unclear. The mode coupling peaks caused by electrical anharmonic coupling (EAHC) and mechanical anharmonic coupling (MAHC) are observed in all of the 2D spectra. We find that the strength of the MAHC between the OH-stretching and HB-intermolecular vibrational modes is comparable to that between the OH-stretching and HOH bending modes. Moreover, we find that this OH-stretching and HB

  18. Co-localised Raman and force spectroscopy reveal the roles of hydrogen bonds and π-π interactions in defining the mechanical properties of diphenylalanine nano- and micro-tubes

    Energy Technology Data Exchange (ETDEWEB)

    Sinjab, Faris; Bondakov, Georgi; Notingher, Ioan, E-mail: ioan.notingher@nottingham.ac.uk [School of Physics and Astronomy, University of Nottingham, Nottingham (United Kingdom)

    2014-06-23

    An integrated atomic force and polarized Raman microscope were used to measure the elastic properties of individual diphenylalanine (FF) nano- and micro-tubes and to obtain quantitative information regarding the inter-molecular interactions that define their mechanical properties. For individual tubes, co-localised force spectroscopy and Raman spectroscopy measurements allowed the calculation of the Young's and shear moduli (25 ± 5 GPa and 0.28 ± 0.05 GPa, respectively) and the contribution of hydrogen bonding network to the Young's modulus (∼17.6 GPa). The π-π interactions between the phenyl rings, dominated by T-type arrangements, were estimated based on previously published X-ray data to only 0.20 GPa. These results provide experimental evidence obtained from individual FF tubes that the network of H-bonds dominates the elastic properties of the FF tubes.

  19. 阳离子对硅酸盐玻璃激光拉曼光谱影响的研究%Influence of Cations on the Laser Raman Spectra of Silicate Glasses

    Institute of Scientific and Technical Information of China (English)

    熊义; 赵虹霞; 干福熹

    2012-01-01

    Na2O(K2O)-CaO(MgO)-SiO2, Na2O(K2O)-A12O3-SiO2, Na2O(K2O)-B2Q3-SiOz, Na2O(K2O)-PbO-SiO2 and PbO-BaO-SiO2 glass systems were investigated using laser Raman spectroscopic technique. The modification of short-range structure of glass caused by network modifier cations will influence Raman signature. Alkali and alkali-earth ions can weaken the bridging oxygen bond, thus lower the frequency of Si-Ob-Si anti-symmetric stretching vibration. When coordinated by oxygen ions, B3+ can form [BO4] tetrahedron and enter the silicon-oxygen network, but this effect had little impact on the frequency of Raman peaks located in the high-frequency region. Al3+ can also be coordinated by oxygen ions to form [A1O4 ] tetrahedron. [ AlO4 ] will increase the disorder degree of network while entering network. Ba2+ can increase the density of electron cloud along the Si-Onb bond when it bonds with non-bridging oxygen, which will lead to a higher peak intensity of O-Si-O stretching vibration. The Raman peaks of alkli- and alkali-earth silicate glasses are mainly distributed in the region of 400~1 200 cm-1, while in the spectrum of Na2O(K2O)-PbO-SiO2 glass system a 131 cm-1 peak existed. The authors assigned it to the Pb-O symmetric stretching vibration. Some of the samples were produced in the laboratory according to the average compositions of ancient glasses, so this research is very significant to discriminating ancient silicate glasses of different systems by Laser Raman spectroscopic technique.%运用拉曼光谱技术研究了Na2O (K2O) CaO( MgO)-SiO2,Na2O (K2O)- Al2-O3-SiO2,Na2O(K2O)-B2O3-SiO2,Na2O(K2O)-PbO-SiO2和PbO-BaO-SiO2五个系统的玻璃.结果表明,阳离子对玻璃近程结构的改造会引起拉曼特征的变化.部分样品是根据古玻璃平均成分在实验室烧制的,这项研究对于运用激光拉曼光谱区分不同系统的古代硅酸盐玻璃有重要意义.

  20. FT-IR, FT-Raman, UV, NMR spectra and molecular structure investigation of (E)-2-(3-chloropyrazin-2-yl)-1-(3-ethyl-2, 6-diphenyl piperidin-4-ylidene) hydrazine: A combined experimental and theoretical study

    Science.gov (United States)

    Therasa Alphonsa, A.; Loganathan, C.; Athavan Alias Anand, S.; Kabilan, S.

    2015-11-01

    This work presents the characterization of (E)-2-(3-chloropyrazin-2-yl)-1-(3-ethyl-2, 6-diphenyl piperidin-4-ylidene) hydrazine (HDE) by quantum chemical calculations and spectral techniques. The structure was investigated by FT-IR, FT-Raman, UV-vis and NMR techniques. The geometrical parameters and energies have been obtained from Density functional theory (DFT) B3LYP (6-31G (d, p)) basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. 1H and 13C NMR chemical shifts of the molecule were calculated using Gauge-independent atomic orbital method (GIAO). The electronic properties such as excitation energies, wavelength, HOMO, LUMO energies performed by Time dependent density functional theory (TD-DFT) results complements with the experimental findings. NBO analysis has been performed for analyzing charge delocalization throughout the molecule. The calculation results were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. To provide information about the interactions between human cytochrome protein and the novel compound theoretically, docking studies were carried out using Schrödinger software.

  1. Radical Cations of the Monomer and van der Waals Dimer of a Methionine Residue as Prototypes of (2 Center-3 Electron) SN and SS Bonds. Molecular Simulations of Their Absorption Spectra in Water.

    Science.gov (United States)

    Archirel, Pierre; Bergès, Jacqueline; Houée-Lévin, Chantal

    2016-09-22

    Oxidation of peptides or proteins by the OH(•) radicals produced by pulse radiolysis yields species identified by their absorption spectra in the UV-visible domain. However, the case of methionine (Met) in peptides is complex because its oxidation can lead to various free radicals with 2 center-3 electron (2c-3e) bonds. We have performed Monte Carlo/density functional theory molecular simulations of the radical cation of the methylated methionine aminoacid, Met(•+), taken as a model of the methonine residue of peptides, and of the radical cation of its van der Waals dimer, Met2(•+). The cation of the methionine residue displays a 2c-3e SN bond. The cation of dimer Met2(•+) displays three quasidegenerate conformers, one stabilized by a 2c-3e SS bond and the other two stabilized by ion-molecule interactions and made up of a neutral and a cationic unit. These conformers are characterized by their charge and spin density localization and their UV-visible absorption spectra. These spectra enable a discussion of the absorption spectra of the literature; in particular, we emphasize the role of dimers before and after the oxidation process. PMID:27564585

  2. Characterization of two-photon polymerization process using Raman microspectroscopy

    Science.gov (United States)

    Jiang, L. J.; Zhou, Y. S.; Xiong, W.; Gao, Y.; Baldacchini, T.; Silvain, J.-F.; Jiang, L.; Lu, Y. F.

    2014-03-01

    Two-photon polymerization (TPP) is a promising micro/nanofabrication technique, which is capable of fabricating 3D micro/nanostructures beyond the diffraction limit of light. However, the study of TPP process with a focus on the dependence of degree of conversion on TPP parameters using a non-destructive and efficient method is still lacking. We studied the quantitative relationships between the TPP parameters and the cross-linking of an acrylic-based IP-L 780 photoresist via systematic Raman characterization. The differences in the Raman spectra between the non-polymerized and the polymerized IP-L 780 photoresists were observed by probing the excitation of carbon-carbon double bond (C=C) vibrations. We obtained the relationship between the degree of conversion in TPP and the Raman spectra of the IP-L 780 resin, in which the intensity of the characteristic Raman peak of IP-L 780 at 1635 cm-1 decreases with the increase of the TPP laser dose. A mathematic model of the degree of conversion with respective to the TPP parameters, including laser average power and writing speed, has been established. The method provides a simple and effective way to characterize and optimize the TPP micro/nanofabrication processes. The established model for the degree of conversion as the function of TPP parameters will contribute to the advanced 3D TPP micro/nanofabrication by providing a guidance to optimize the laser doses, voxel sizes, and the mechanical strength of the polymers.

  3. High resolution electronic spectra of anisole and anisole-water in the gas phase: hydrogen bond switching in the S1 state.

    Science.gov (United States)

    Ribblett, J W; Sinclair, W E; Borst, D R; Yi, J T; Pratt, D W

    2006-02-01

    Rotationally resolved S(1)spectrum of the complex suggests that hydrogen bond "switching" occurs when the complex absorbs light. The former O-H- - -O(CH(3)) bond is stronger in the ground (S(0)) state, whereas the latter H-O- - -H(ring) bond is stronger in the excited (S(1)) state. Dynamical consequences of this phenomenon are discussed.

  4. Raman Spectroscopy and Related Techniques in Biomedicine

    OpenAIRE

    Alistair Elfick; Andrew Downes

    2010-01-01

    In this review we describe label-free optical spectroscopy techniques which are able to non-invasively measure the (bio)chemistry in biological systems. Raman spectroscopy uses visible or near-infrared light to measure a spectrum of vibrational bonds in seconds. Coherent anti-Stokes Raman (CARS) microscopy and stimulated Raman loss (SRL) microscopy are orders of magnitude more efficient than Raman spectroscopy, and are able to acquire high quality chemically-specific images in seconds. We dis...

  5. Raman spectroscopy of transition metal dichalcogenides.

    Science.gov (United States)

    Saito, R; Tatsumi, Y; Huang, S; Ling, X; Dresselhaus, M S

    2016-09-01

    Raman spectroscopy of transition metal dichalcogenides (TMDs) is reviewed based on our recent theoretical and experimental works. First, we discuss the semi-classical and quantum mechanical description for the polarization dependence of Raman spectra of TMDs in which the optical dipole transition matrix elements as a function of laser excitation energy are important for understanding the polarization dependence of the Raman intensity and Raman tensor. Overviewing the symmetry of TMDs, we discuss the dependence of the Raman spectra of TMDs on layer thickness, polarization, laser energy and the structural phase. Furthermore, we discuss the Raman spectra of twisted bilayer and heterostructures of TMDs. Finally, we give our perspectives on the Raman spectroscopy of TMDs. PMID:27388703

  6. Influence of piezoelectric strain on the Raman spectra of BiFeO{sub 3} films deposited on PMN-PT substrates

    Energy Technology Data Exchange (ETDEWEB)

    Himcinschi, Cameliu, E-mail: himcinsc@physik.tu-freiberg.de; Talkenberger, Andreas; Kortus, Jens [TU Bergakademie Freiberg, Institute of Theoretical Physics, 09596 Freiberg (Germany); Guo, Er-Jia [Institute of Physics, Martin-Luther-University Halle-Wittenberg, 06099 Halle (Germany); Institute for Metallic Materials, IFW Dresden, 01069 Dresden (Germany); Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States); Dörr, Kathrin [Institute of Physics, Martin-Luther-University Halle-Wittenberg, 06099 Halle (Germany); Institute for Metallic Materials, IFW Dresden, 01069 Dresden (Germany)

    2016-01-25

    BiFeO{sub 3} epitaxial thin films were deposited on piezoelectric 0.72Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.28PbTiO{sub 3} (PMN-PT) substrates with a conductive buffer layer (La{sub 0.7}Sr{sub 0.3}MnO{sub 3} or SrRuO{sub 3}) using pulsed laser deposition. The calibration of the strain values induced by the electric field applied on the piezoelectric PMN-PT substrates was realised using X-Ray diffraction measurements. The method of piezoelectrically induced strain allows one to directly obtain a quantitative correlation between the strain and the shift of the Raman-active phonons. This is a prerequisite for making Raman scattering a strong tool to probe the strain coupling in multiferroic nanostructures. Using the Poisson's number for BiFeO{sub 3}, one can determine the volume change induced by strain, and therefore the Grüneisen parameters for specific phonon modes.

  7. Influence of piezoelectric strain on the Raman spectra of BiFeO3 films deposited on PMN-PT substrates

    Science.gov (United States)

    Himcinschi, Cameliu; Guo, Er-Jia; Talkenberger, Andreas; Dörr, Kathrin; Kortus, Jens

    2016-01-01

    BiFeO3 epitaxial thin films were deposited on piezoelectric 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 (PMN-PT) substrates with a conductive buffer layer (La0.7Sr0.3MnO3 or SrRuO3) using pulsed laser deposition. The calibration of the strain values induced by the electric field applied on the piezoelectric PMN-PT substrates was realised using X-Ray diffraction measurements. The method of piezoelectrically induced strain allows one to directly obtain a quantitative correlation between the strain and the shift of the Raman-active phonons. This is a prerequisite for making Raman scattering a strong tool to probe the strain coupling in multiferroic nanostructures. Using the Poisson's number for BiFeO3, one can determine the volume change induced by strain, and therefore the Grüneisen parameters for specific phonon modes.

  8. Combined linear response quantum mechanics and classical electrodynamics (QM/ED) method for the calculation of surface-enhanced Raman spectra.

    Science.gov (United States)

    Mullin, Jonathan; Schatz, George C

    2012-03-01

    A multiscale method is presented that allows for evaluation of plasmon-enhanced optical properties of nanoparticle/molecule complexes with no additional cost compared to standard electrodynamics (ED) and linear response quantum mechanics (QM) calculations for the particle and molecule, respectively, but with polarization and orientation effects automatically described. The approach first calculates the total field of the nanoparticle by ED using the finite difference time domain (FDTD) method. The field intensity in the frequency domain as a function of distance from the nanoparticle is calculated via a Fourier transform. The molecular optical properties are then calculated with QM in the frequency domain in the presence of the total field of the nanoparticle. Back-coupling due to dipolar reradiation effects is included in the single-molecule plane wave approximation. The effects of polarization and partial orientation averaging are considered. The QM/ED method is evaluated for the well-characterized test case of surface-enhanced Raman scattering (SERS) of pyridine bound to silver, as well as for the resonant Raman chromophore rhodamine 6G. The electromagnetic contribution to the enhancement factor is 10(4) for pyridine and 10(2) for rhodamine 6G.

  9. Size-Dependent Raman Shifts for nanocrystals.

    Science.gov (United States)

    Gao, Yukun; Zhao, Xinmei; Yin, Penggang; Gao, Faming

    2016-04-22

    Raman spectroscopy is a very sensitive tool for probing semiconductor nanocrystals. The underlying mechanism behind the size-dependent Raman shifts is still quite controversial. Here we offer a new theoretical method for the quantum confinement effects on the Raman spectra of semiconductor nanocrystals. We propose that the shift of Raman spectra in nanocrystals can result from two overlapping effects: the quantum effect shift and surface effect shift. The quantum effect shift is extracted from an extended Kubo formula, the surface effect shift is determined via the first principles calculations. Fairly good prediction of Raman shifts can be obtained without the use of any adjustable parameter. Closer analysis shows that the size-dependent Raman shifts in Si nanocrystals mainly result from the quantum effect shifts. For nanodiamond, the proportion of surface effect shift in Raman shift is up to about 40%. Such model can also provide a good baseline for using Raman spectroscopy as a tool to measure size.

  10. [Raman active vibrations of aluminosilicates].

    Science.gov (United States)

    Pan, Feng; Yu, Xue-hui; Mo, Xuan-xue; You, Jing-lin; Wang, Chen; Chen, Hui; Jiang, Guo-chang

    2006-10-01

    Raman spectra of aluminosilicate minerals, namely kyanite, andalusite, and sillimanite and K2O-Al2O3-SiO2 glasses were recorded. Four alumino-silicon tetrahedral model clusters were calculated by self-consistent (SCF) molecular orbital ab-ini-tio calculation of the quantum chem (QC) method. The result shows a decrease tendency in Raman frequencies in the 800-1200 cm(-1) frequency region with increase in four-coordinated Al content, which is assigned to the Si--Onb symmetry stretching vibrations. The Raman spectra in the 700-800 cm(-1) frequency region is attributed to Al-Onb symmetry stretching vibrations. PMID:17205741

  11. Raman spectroscopy as a tool for reagent free estimation

    CERN Document Server

    Kumar, S

    2014-01-01

    We present results of Raman spectroscopic studies of urine to determine the suitability of near-infrared Raman spectroscopy for quantitative estimation of urinary urea. The Raman spectra were acquired from the urine samples with an inbuilt Raman spectroscopy setup that employs a 785-nm diode laser as the Raman excitation source. A multivariate algorithm based on partial least square (PLS) regression was developed to predict the concentration of urea depending on the measured sets of Raman spectra and the reference urea concentration. The computed results shows that Raman spectroscopy in amalgamation with PLS-based multivariate chemometric algorithm can detect urea in urine samples with an accuracy of >90 %.

  12. Resonant excitation of Mn local vibrational modes in the higher order Raman spectra of nanocrystalline Ga{sub 1-x}Mn{sub x}N films

    Energy Technology Data Exchange (ETDEWEB)

    Dias da Silva, J H; Leite, D M G [Department of Physics, Advanced Materials Group, UNESP-Sao Paulo State University, Bauru SP, 17033-360 (Brazil); Zanatta, A R [Instituto de Fisica de Sao Carlos, USP, Sao Carlos 13560-250 (Brazil)], E-mail: jhdsilva@fc.unesp.br, E-mail: dmgleite@fc.unesp.br, E-mail: zanatta@ifsc.usp.br

    2008-06-25

    The effect of manganese on the vibrational properties of Ga{sub 1-x}Mn{sub x}N (0{<=}x{<=}0.18) films has been investigated by Raman scattering using 488.0 and 632.8 nm photon excitations. The first-order transverse and longitudinal optical GaN vibrational bands were observed in the whole composition range using both excitations, while the corresponding overtones, as well as a prominent peak located in 1238 cm{sup -1} (153.5 meV) were only observed in the Mn-containing films under 488.0 nm excitation. We propose that the peak observed at 1238 cm{sup -1} is due to resonant Mn local vibrational modes, the excitation process being related to electronic transitions involving the Mn acceptor band. (fast track communication)

  13. Effects of Micro-Raman Spectra of Porous Silicon on Laser Powers%激光功率对多孔硅微Raman谱的影响

    Institute of Scientific and Technical Information of China (English)

    任鹏; 孙立来; 廖家欣; 李君求; 万小军; 史向华; 刘小兵

    2007-01-01

    运用微Raman谱仪以不同功率的激光入射到用阳极脉冲腐蚀制备的多孔硅样品以研究多孔硅的稳定性.用斯托克斯与反斯托克斯散射强度的比率确定样品的温度.观察比较不同温度下多孔硅样品的Raman谱趋向,发现在激光功率和样品温度之间的关系曲线上有3个过程,与Raman频移和Raman强度的曲线相一致.所有现象都可以用Si-O键和非晶Si被氧化的机制进行解释.

  14. Theoretical Investigation on the Substituent Effect of Halogen Atoms at the C8 Position of Adenine: Relative Stability, Vibrational Frequencies, and Raman Spectra of Tautomers.

    Science.gov (United States)

    Chen, Yan-Li; Wu, De-Yin; Tian, Zhong-Qun

    2016-06-16

    We have theoretically investigated the substituent effect of adenine at the C8 position with a substituent X = H, F, Cl, and Br by using the density functional theory (DFT) at the B3LYP/6-311+G(d, p) level. The aim is to study the substituent effect of halogen atoms on the relative stability, vibrational frequencies, and solvation effect of tautomers. Our calculated results show that for substituted adenine molecules the N9H8X tautomer to be the most stable structure in gas phase at the present theoretical level. Here N9H8X denotes the hydrogen atom binds to the N9 position of imidazole ring and X denotes H, F, Cl, and Br atoms. The influence of the induced attraction of the fluorine substituent is significantly larger than chlorine and bromine ones. The halogen substituent effect has a significant influence on changes of vibrational frequencies and Raman intensities.

  15. Vibrational spectroscopy at very high pressures. Part 28. Raman and far-infrared spectra of some complex chlorides A2MCl6 under hydrostatic pressure

    DEFF Research Database (Denmark)

    Adams, David M.; Berg, Rolf W.; Williams, Alan D.

    1981-01-01

    Raman and far-IR mode frequency shifts with pressure have been observed under hydrostatic conditions in a gasketed diamond anvil cell (d.a.c.). Using compressibilities calculated from unit cell constants and lattice energies, Grüneisen parameters gammai have been obtained for all observed modes....... Where previous data exist for comparison, it is shown that use of a d.a.c. without gaskets (i.e., applying a shear stress to the sample) greatly underestimates the true shifts of IR modes in particular. The Grüneisen parameter gamma1 for a1g nu-tilde 1 of the complex ions is always greater than gamma2...

  16. 2-μm fluorescence and Raman spectra in high and low Al(PO3)3 content fluorophosphates glasses doped with Er-Tm-Ho

    Institute of Scientific and Technical Information of China (English)

    Meng Wang; Lixia Yi; Liyan Zhang; Guonian Wang; Lili Hu; Junjie Zhang

    2009-01-01

    @@ Thermal stability and 2-μm fluorescence of high and low Al(PO_3)_3 content of fluorophosphate glasses are investigated.Thermal stability of high Al(PO_3)_3 content of fluorophosphate glass is better than low Al(PO_3)_3 content of fluorophosphate glass.However, 2.04-μm fluorescence intensity of high Al(PO_3)_3 content of fluorophosphate glass is only 48.2, lower than low Al(PO_3)_3 content of fluorophosphate glass.Raman spectroscopy is employed to investigate the difference in thermal stability and 2-μm fluorescence.Moreover, fluorescence peak intensity ratios of 2.04 to 1.81 μm and 2.04 to 1.57 μm are calculated, which indicate that Er-Tm-Ho doped fluorophosphate glasses are suitable materials in 2-μm applications.

  17. Nucleobases and C2 and C4 Imidazolium Acetate Interactions: FTIR-ATR, Raman and NMR Spectra and ab Initio Calculations Insights

    DEFF Research Database (Denmark)

    Araújo, J. M. M.; Ferreira, Rui; Veiga, H.I.M.;

    a Nucleoside, and a nucleoside with one or more phosphate groups attached at the 5’ carbon is called a Nucleotide. Nucleotides comprise the structural units of RNA and DNA. The structural elements of the most common Nucleotides are depicted in the Figure 1. Uracil, a common and naturally occurring pyrimidine...... of the phase behavior. In the present work, we explore the use of RTILs to dissolve Nucleobases, Nucleosides and Nucleotides. Nucleobases are the parts of Nucleic Acids (DNA and RNA) that are involved in pairing. The system of a base covalently bound to the 1’ carbon of a ribose or deoxyribose is called....... The combined use of FTIR, FT-RAMAN and NMR-spectroscopy, as well as computer simulation, will be attain to better understand the solubility mechanism of nucleobases, nucleosides and nucleotides. The results here obtained show the enormous potential of the use of RTILs to dissolve nucleobases, nucleosides...

  18. Resonance Raman study of benzyl radical

    DEFF Research Database (Denmark)

    Langkilde, F.W.; Bajdor, K.; Wilbrandt, R.

    1992-01-01

    Time-resolved resonance Raman spectra are obtained of benzyl radicals created by laser flash photolysis of benzylchloride and diphenylacetone in solution. The spectra are obtained in resonance with the intense 2 2A2-1 B-2(2) transition of benzyl. The strong Raman bands are assigned to totally...... symmetric a1 modes. The remaining observed bands are tentatively assigned to fundamental modes of b1, a2, and b2 symmetry, and to overtones and combinations. The resonance Raman spectra are found to be quite different from previous fluorescence spectra of benzyl, and the origins of these differences are...

  19. Differentiation of Lipsticks by Raman Spectroscopy

    OpenAIRE

    Salahioglu, Fatma; Went, Michael J.

    2012-01-01

    Dispersive Raman spectra have been obtained using a Raman microscope and an excitation wavelength of 632.8 nm from 69 lipsticks of various colours and from a range of manufacturers without any pre-treatment of the samples. 10% of the samples were too fluorescent to give Raman spectra. 22% of the samples gave spectra which were unique to the brand and colour within the collected sample set. The remaining 68% of the samples gave spectra which could be classified into seven distinct groups. Dis...

  20. Raman Active Phonons in RCoO3 (R=La, Ce, Pr, Nd, Sm, Eu, Gd, and Dy) Perovskites

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-Ran; XU Da-Peng; SU Wen-Hui; DING Zhan-Hui; XUE Yan-Feng; SONG Geng-Xin

    2005-01-01

    @@ We examine RCoO3 (R=La, Ce, Pr, Nd, Sm, Eu, Gd, and Dy) perovskites prepared with the solid-state reaction method by Raman spectroscopy, and report the Raman active phonons in the RCoO3 perovskites crystallized in cubic symmetry for RCoO3 (R=La, Ce, Pr and Nd) and orthorhombic symmetry for RCoO3 (R=Sm, Eu, Gd,and Dy). It is found that the Raman spectra of RCoO3 perovskites are strongly dependent on the ionic radius.of the rare earth elements, and the frequency shift of the most intense modes of the orthorhombic samples are correlated with some structural parameters such as Co-O bond distances, ionic radius of the rare earth elements and Jahn-Teller distortion. It is clear that Raman spectroscopy has the advantage of sensitivity to structure distortion and oxygen motion.

  1. Fermi resonance and solvent dependence of the vC=O frequency shifts of Raman spectra: cyclohexanone and 2-cyclohexene-1-one

    CERN Document Server

    Nam, S I; Lee, M S; Jung, Y M

    2001-01-01

    The carbonyl stretching vibration, vC=O of 2-cyclohexene-1-one , is in Fermi resonance with a combination tone. The amount of Fermi resonance interaction between these two modes is dependent upon the amount of solute/solvent interaction due to hydrogen bonding between the carbonyl oxygen and the solvent proton. The corrected vC=O frequency of 2-cyclohexene-1-one occurs at a lower frequency than the observed vC=O mode of cyclohexanone, possibly caused by expanded conjugation effects. The carbonyl stretching modes of cyclic ketones were also affected by interaction with the ROH/CCl sub 4 mixed solvent system.

  2. Comparison of Bond Character in Hydrocarbons and Fullerenes

    OpenAIRE

    Snoke, D. W.; Cardona, M.; Sanguinetti, S.; Benedek, G

    1996-01-01

    We present a comparison of the bond polarizabilities for carbon-carbon bonds in hydrocarbons and fullerenes, using two different models for the fullerene Raman spectrum and the results of Raman measurements on ethane and ethylene. We find that the polarizabilities for single bonds in fullerenes and hydrocarbons compare well, while the double bonds in fullerenes have greater polarizability than in ethylene.

  3. Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography

    Institute of Scientific and Technical Information of China (English)

    Yin Jun; Yu Ling-Yao; Liu Xing; Wan Hui; Lin Zi-Yang; Niu Han-Ben

    2011-01-01

    In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of verious molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactious in the fields of biology, chemistry and naterial science.

  4. Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography

    International Nuclear Information System (INIS)

    In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of various molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactions in the fields of biology, chemistry and material science. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  5. A UV resonance Raman (UVRR) spectroscopic study on the extractable compounds of Scots pine ( Pinus sylvestris) wood . Part I: Lipophilic compounds

    Science.gov (United States)

    Nuopponen, M.; Willför, S.; Jääskeläinen, A.-S.; Sundberg, A.; Vuorinen, T.

    2004-11-01

    The wood resin in Scots pine ( Pinus sylvestris) stemwood and branch wood were studied using UV resonance Raman (UVRR) spectroscopy. UVRR spectra of the sapwood and heartwood hexane extracts, solid wood samples and model compounds (six resin acids, three fatty acids, a fatty acid ester, sitosterol and sitosterol acetate) were collected using excitation wavelengths of 229, 244 and 257 nm. In addition, visible Raman spectra of the fatty and resin acids were recorded. Resin compositions of heartwood and sapwood hexane extracts were determined using gas chromatography. Raman signals of both conjugated and isolated double bonds of all the model compounds were resonance enhanced by UV excitation. The oleophilic structures showed strong bands in the region of 1660-1630 cm -1. Distinct structures were enhanced depending on the excitation wavelength. The UVRR spectra of the hexane extracts showed characteristic bands for resin and fatty acids. It was possible to identify certain resin acids from the spectra. UV Raman spectra collected from the solid wood samples containing wood resin showed a band at ˜1650 cm -1 due to unsaturated resin components. The Raman signals from extractives in the resin rich branch wood sample gave even more strongly enhanced signals than the aromatic lignin.

  6. Raman spectroscopic evidence of low temperature stability of D,L-glycolic and L-(+)-lactic acid crystals.

    Science.gov (United States)

    Mohaček-Grošev, Vlasta; Šoštarić, Vladimir; Maksimović, Aleksandar

    2015-04-01

    Raman and infrared spectra of polycrystalline D,L-glycolic and L-(+) lactic acid are presented and assigned both by an ab initio calculation of normal modes of free conformers and by self-consistent-charge density-functional-theory computational program DFTB+. Temperature dependent Raman spectra from 295 K to 10 K reveal great stability of crystal lattices, since no soft modes and no band splittings that could be attributed to changes of the number of molecules per unit cell were observed. A semiempirical calculation with GULP program was used to estimate the strength of hydrogen bonds in crystals: in glycolic acid they have energies of -0.337 eV/mol, -0.329 eV/mol, -0.262 eV/mol and -0.242 eV/mol, while in lactic acid two hydrogen bonds have energies of -0.283 eV/mol and -0.202 eV/mol.

  7. Raman spectroscopy of the system iron(III)-sulfuric acid-water: an approach to Tinto River's (Spain) hydrogeochemistry.

    Science.gov (United States)

    Sobron, P; Rull, F; Sobron, F; Sanz, A; Medina, J; Nielsen, C J

    2007-12-15

    Acid mine drainage is formed when pyrite (FeS(2)) is exposed and reacts with air and water to form sulfuric acid and dissolved iron. Tinto River (Huelva, Spain) is an example of this phenomenon. In this study, Raman spectroscopy has been used to investigate the speciation of the system iron(III)-sulfuric acid-water as an approach to Tinto River's aqueous solutions. The molalities of sulfuric acid (0.09 mol/kg) and iron(III) (0.01-1.5 mol/kg) were chosen to mimic the concentration of the species in Tinto River waters. Raman spectra of the solutions reveal a strong iron(III)-sulfate inner-sphere interaction through the nu(1) sulfate band at 981 cm(-1) and its shoulder at 1005 cm(-1). Iron(III)-sulfate interaction may also be facilitated by hydrogen bonds and monitored in the Raman spectra through the symmetric stretching band of bisulfate at 1052 cm(-1) and a shoulder at 1040 cm(-1). Other bands in the low-frequency region of the Raman spectra are attributed to the hydrogen-bonded complexes formation as well. PMID:17869164

  8. Preresonance Raman studies of metal-to-ligand charge transfer in (NH sub 3 ) sub 4 Ru(2,2 prime -bpy) sup 2+. In situ bond length changes, force constants, and reorganization energies

    Energy Technology Data Exchange (ETDEWEB)

    Doorn, S.K.; Hupp, J.T. (Northwestern Univ., Evanston, IL (USA))

    1989-06-21

    As a prototype for charge-transfer reactions in general, the intense metal-to-ligand charge-transfer transition occurring in Ru(NH{sub 3}){sub 4}(bpy){sup 2+} (bpy = 2,2{prime}-bipyridine) has been examined experimentally by resonance and preresonance Raman spectroscopy and analytically by time-dependent scattering theory. To their knowledge, the present example represents the first application of the theory to charge-transfer problems. From the experiments and corresponding theory, the normal-coordinate changes accompanying the transition have been calculated. Both metal-ligand and intraligand bonds are found to distort significantly. When the distortion data are combined with the observed vibrational frequencies, a mode-by-mode assessment of the inner-shell reorganization energy is possible. Further experiments, in which the nature of the solvent is systematically varied, show that selected force constants (and therefore selected components of the internal reorganization energy) are modulated significantly (ca. 6-11 %) by ligand-solvent hydrogen bonding. Finally, variations in the nature of the solvent are found to shift ground- and/or excited-state energies in such a way as to either enhance or attenuate the occurrence of net photochemistry.

  9. 拉曼光谱研究脉冲电场作用下磷脂脂质体构象的变化%Effect of pulsed electric fields on phospholipid vesicle conformation by Raman spectra

    Institute of Scientific and Technical Information of China (English)

    贾晓; 曾新安

    2012-01-01

    In order to study the sterilization mechanism of pulsed electric fields(PEF) on microorganisms and the interaction between PEF conditions and cell membrane composed of phospholipids,the phospholipid vesicle conformation changing under various electric field strength treatments was analyzed by Raman spectra.It was demonstrated from the Raman spectra that the intensity ratio of I1085/I1064 increased while I1085/I1123 increased firstly and then decreased later with increasing electric field strength,but the ratio was still higher than the control sample.It indicated a little increase of the gauche/trans population compared with control sample.On the other hand,the ratio of I2885/I2850 decreased with increasing electric field strength.The result showed that the intermolecular disordering in hydrocarbon chain of the lipid lattice increased and the membrane fluidity enhanced after being subjected PEF treatment.%为深入研究脉冲电场的灭菌机理,探讨电场与细胞膜的作用机制,利用拉曼光谱谱图分析了不同电场场强下磷脂脂质体构象的变化。结果表明,拉曼峰值比I1085/I1064随着电场场强的增加而相应增大,而I1085/I1123随着电场场强的增加而先增加后减少,但比值仍高于空白样,说明经过电场处理后,脂质体C-C扭曲构象的数目增多;而I2885/I2850随着场强的增加呈现递减的趋势。由此可以说明经电场处理后的脂质体磷脂分子间烃链的无序度增加,导致细胞膜流动性增强。

  10. Low temperature FTIR, Raman, NMR spectroscopic and theoretical study of hydroxyethylammonium picrate

    Science.gov (United States)

    Sudharsana, N.; Sharma, A.; Kuş, N.; Fausto, R.; Luísa Ramos, M.; Krishnakumar, V.; Pal, R.; Guru Row, T. N.; Nagalakshmi, R.

    2016-01-01

    A combined experimental (infrared, Raman and NMR) and theoretical quantum chemical study is performed on the charge-transfer complex hydroxyethylammonium picrate (HEAP). The infrared (IR) spectra for HEAP were recorded at various temperatures, ranging from 16 K to 299 K, and the Raman spectrum was recorded at room temperature. A comparison of the experimental IR and Raman spectra with the corresponding calculated spectra was done, in order to facilitate interpretation of the experimental data. Formation of the HEAP complex is evidenced by the presence of the most prominent characteristic bands of the constituting groups of the charge-transfer complex [e.g., NH3+, CO- and NO2]. Vibrational spectroscopic analysis, together with natural bond orbital (NBO) and theoretical charge density analysis in the crystalline phase, was used to shed light on relevant structural details of HEAP resulting from deprotonation of picric acid followed by formation of a hydrogen bond of the N-H⋯OC type between the hydroxyethylammonium cation and the picrate. 13C and 1H NMR spectroscopic analysis are also presented for the DMSO-d6 solution of the compound revealing that in that medium the HEAP crystal dissolves forming the free picrate and hydroxyethylammonium ions. Finally, the electron excitation analysis of HEAP was performed in an attempt to determine the nature of the most important excited states responsible for the NLO properties exhibited by the compound.

  11. Experimental and theoretical studies on the vibrational spectra of trans-3-phenylacryloyl chloride

    Science.gov (United States)

    Tao, Yaping; Han, Ligang; Han, Yunxia; Liu, Zhaojun

    2015-02-01

    The infrared and Raman spectra of trans-3-phenylacryloyl chloride (TPC) were reported and compared with the theoretical results calculating at B3LYP/6-311++G (d, p) level. Both wavenumbers and intensities obtained from the experimental and theoretical spectra were in good agreement. A complete spectral assignment was made with the aid of potential energy distribution (PED) based on the scaled quantum mechanical (SQM) force field method. This study provided valuable insight for understanding the observed spectral features of TPC. Additionally, the HOMO-LUMO gap, molecular electrostatic potential (MEP) atomic charge distribution, and natural bond orbitals (NBO) were studied theoretically on the same basis set.

  12. Ab initio MO calculations on the Structure and Raman and Infrared Spectra of the [Al4O2Cl10]2- oxide species in chloroaluminate melts

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    2007-01-01

    The oxide complexation chemistry in molten tetrachloroaluminate salts and ionic liquids is discussed with respect to what possible structures that may be formed in addition to [AlCl4]-: [Al2OCl6]2-, [Al3OCl8]-, [Al2O2Cl4]2-, [Al3O2Cl6]- and [Al4O2Cl10]2-. Ab initio Molecular Orbital (MO) calculat......The oxide complexation chemistry in molten tetrachloroaluminate salts and ionic liquids is discussed with respect to what possible structures that may be formed in addition to [AlCl4]-: [Al2OCl6]2-, [Al3OCl8]-, [Al2O2Cl4]2-, [Al3O2Cl6]- and [Al4O2Cl10]2-. Ab initio Molecular Orbital (MO......) calculations were carried out on these various aluminium chloride and oxochloride ions, in assumed isolated gaseous free ionic state, by use of the Gaussian-03W program at the restricted Hartree-Fock (HF) level and with the 6-31+G(d,p) basis set [1]. Without any pre-assumed symmetries and with tight...... optimization convergence criteria and by using the modified GDIIS algorithm, the model calculations generally converged. The structures and their binding energies are presented. The expected geometries are supported, with one exception perhaps being the [Al2OCl6]2- ion, that gave a linear Al-O-Al bonding...

  13. Graphitic carbon nanospheres: A Raman spectroscopic investigation of thermal conductivity and morphological evolution by pulsed laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Radhe; Sahoo, Satyaprakash, E-mail: satya504@gmail.com, E-mail: rkatiyar@hpcf.upr.edu; Chitturi, Venkateswara Rao; Katiyar, Ram S., E-mail: satya504@gmail.com, E-mail: rkatiyar@hpcf.upr.edu [Department of Physics, University of Puerto Rico, San Juan, Puerto Rico 00936-8377 (United States)

    2015-12-07

    Graphitic carbon nanospheres (GCNSs) were prepared by a unique acidic treatment of multi-walled nanotubes. Spherical morphology with a narrow size distribution was confirmed by transmission electron microscopy studies. The room temperature Raman spectra showed a clear signature of D- and G-peaks at around 1350 and 1591 cm{sup −1}, respectively. Temperature dependent Raman scattering measurements were performed to understand the phonon dynamics and first order temperature coefficients related to the D- and G-peaks. The temperature dependent Raman spectra in a range of 83–473 K were analysed, where the D-peak was observed to show a red-shift with increasing temperature. The relative intensity ratio of D- to G-peaks also showed a significant rise with increasing temperature. Such a temperature dependent behaviour can be attributed to lengthening of the C-C bond due to thermal expansion in material. The estimated value of the thermal conductivity of GCNSs ∼0.97 W m{sup −1} K{sup −1} was calculated using Raman spectroscopy. In addition, the effect of pulsed laser treatment on the GCNSs was demonstrated by analyzing the Raman spectra of post irradiated samples.

  14. Raman and coherent anti-Stokes Raman scattering microspectroscopy for biomedical applications

    Science.gov (United States)

    Krafft, Christoph; Dietzek, Benjamin; Schmitt, Michael; Popp, Jürgen

    2012-04-01

    A tutorial article is presented for the use of linear and nonlinear Raman microspectroscopies in biomedical diagnostics. Coherent anti-Stokes Raman scattering (CARS) is the most frequently applied nonlinear variant of Raman spectroscopy. The basic concepts of Raman and CARS are introduced first, and subsequent biomedical applications of Raman and CARS are described. Raman microspectroscopy is applied to both in-vivo and in-vitro tissue diagnostics, and the characterization and identification of individual mammalian cells. These applications benefit from the fact that Raman spectra provide specific information on the chemical composition and molecular structure in a label-free and nondestructive manner. Combining the chemical specificity of Raman spectroscopy with the spatial resolution of an optical microscope allows recording hyperspectral images with molecular contrast. We also elaborate on interfacing Raman spectroscopic tools with other technologies such as optical tweezing, microfluidics and fiber optic probes. Thereby, we aim at presenting a guide into one exciting branch of modern biophotonics research.

  15. Effects of anisotropic interaction-induced properties of hydrogen-rare gas compounds on rototranslational Raman scattering spectra: Comprehensive theoretical and numerical analysis.

    Science.gov (United States)

    Głaz, Waldemar; Bancewicz, Tadeusz; Godet, Jean-Luc; Gustafsson, Magnus; Haskopoulos, Anastasios; Maroulis, George

    2016-07-21

    A comprehensive study is presented of many aspects of the depolarized anisotropic collision induced (CI) component of light scattered by weakly bound compounds composed of a dihydrogen molecule and a rare gas (Rg) atom, H2-Rg. The work continues a series of earlier projects marking the revival of interest in linear light scattering following the development of new highly advanced tools of quantum chemistry and other theoretical, computational, and experimental means of spectral analyses. Sophisticated ab initio computing procedures are applied in order to obtain the anisotropic polarizability component's dependence on the H2-Rg geometry. These data are then used to evaluate the CI spectral lines for all types of Rg atoms ranging from He to Xe (Rn excluded). Evolution of the properties of CI spectra with growing polarizability/masses of the complexes studied is observed. Special attention is given to the heaviest, Kr and Xe based, scatterers. The influence of specific factors shaping the spectral lines (e.g., bound and metastable contribution, potential anisotropy) is discussed. Also the share of pressure broadened allowed rotational transitions in the overall spectral profile is taken into account and the extent to which it is separable from the pure CI contribution is discussed. We finish with a brief comparison between the obtained results and available experimental data. PMID:27448883

  16. Effects of anisotropic interaction-induced properties of hydrogen-rare gas compounds on rototranslational Raman scattering spectra: Comprehensive theoretical and numerical analysis

    Science.gov (United States)

    Głaz, Waldemar; Bancewicz, Tadeusz; Godet, Jean-Luc; Gustafsson, Magnus; Haskopoulos, Anastasios; Maroulis, George

    2016-07-01

    A comprehensive study is presented of many aspects of the depolarized anisotropic collision induced (CI) component of light scattered by weakly bound compounds composed of a dihydrogen molecule and a rare gas (Rg) atom, H2-Rg. The work continues a series of earlier projects marking the revival of interest in linear light scattering following the development of new highly advanced tools of quantum chemistry and other theoretical, computational, and experimental means of spectral analyses. Sophisticated ab initio computing procedures are applied in order to obtain the anisotropic polarizability component's dependence on the H2-Rg geometry. These data are then used to evaluate the CI spectral lines for all types of Rg atoms ranging from He to Xe (Rn excluded). Evolution of the properties of CI spectra with growing polarizability/masses of the complexes studied is observed. Special attention is given to the heaviest, Kr and Xe based, scatterers. The influence of specific factors shaping the spectral lines (e.g., bound and metastable contribution, potential anisotropy) is discussed. Also the share of pressure broadened allowed rotational transitions in the overall spectral profile is taken into account and the extent to which it is separable from the pure CI contribution is discussed. We finish with a brief comparison between the obtained results and available experimental data.

  17. Raman facility

    Data.gov (United States)

    Federal Laboratory Consortium — Raman scattering is a powerful light scattering technique used to diagnose the internal structure of molecules and crystals. In a light scattering experiment, light...

  18. Synthesis, single-crystal structure determination and Raman spectra of the tricyanomelaminates NaA{sub 5}[C{sub 6}N{sub 9}]{sub 2} . 4 H{sub 2}O (A = Rb, Cs)

    Energy Technology Data Exchange (ETDEWEB)

    Reckeweg, Olaf; DiSalvo, Francis J. [Cornell Univ., Ithaca, NY (United States). Baker Lab.; Schulz, Armin [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany)

    2016-07-01

    Transparent colorless crystals of NaA{sub 5}[C{sub 6}N{sub 9}]{sub 2} . 4 H{sub 2}O (A = Rb, Cs) were obtained by blending aqueous solutions of Na{sub 3}[C{sub 6}N{sub 9}] and RbF or CsF, respectively, and subsequent evaporation of the water under ambient conditions. Both compounds crystallize in the space group P2{sub 1}/m (no. 11) with the cell parameters a = 815.56(16), b = 1637.7(4) and c = 1036.4(3) pm, and β = 110.738(12) for NaRb{sub 5}[C{sub 6}N{sub 9}]{sub 2} . 4 H{sub 2}O and a = 843.32(6), b = 1708.47(11) and c = 1052.42(7) pm, and β = 112.034(2) for NaCs{sub 5}[C{sub 6}N{sub 9}]{sub 2} . 4 H{sub 2}O, respectively. Raman spectra of the title compounds complement our results.

  19. Raman spectroscopy under extreme conditions

    Energy Technology Data Exchange (ETDEWEB)

    Goncharov, A F; Crowhurst, J C

    2004-11-05

    We report the results of Raman measurements of various materials under simultaneous conditions of high temperature and high pressure in the diamond anvil cell (DAC). High temperatures are generated by laser heating or internal resistive (ohmic) heating or a combination of both. We present Raman spectra of cubic boron nitride (cBN) to 40 GPa and up to 2300 K that show a continuous pressure and temperature shift of the frequency of the transverse optical mode. We have also obtained high-pressure Raman spectra from a new noble metal nitride, which we synthesized at approximately 50 GPa and 2000 K. We have obtained high-temperature spectra from pure nitrogen to 39 GPa and up to 2000 K, which show the presence of a hot band that has previously been observed in CARS measurements. These measurements have also allowed us to constrain the melting curve and to examine changes in the intramolecular potential with pressure.

  20. Raman scattering from superhard rhenium diboride under high pressure

    International Nuclear Information System (INIS)

    Lattice vibrational properties of superhard rhenium diboride (ReB2) were examined up to 8 GPa in a diamond anvil cell using Raman spectroscopy techniques. Linear pressure coefficients and mode Grüneisen parameters are obtained. Good agreement is found between the experimental and theoretical calculated Grüneisen parameters. Examination of the calculated mode Grüneisen parameters reveals that both B-B and Re-B covalent bonds play a dominant role in supporting the applied load under pressure. A comparison of vibrations parallel and perpendicular to the c-axis indicates that bonds along the c-axis tend to take greater loads. Our results agree with observations of elastic lattice anisotropy obtained from both in situ X-ray diffraction measurements and ultrasonic resonance spectra

  1. High-temperature Raman study of L-alanine, L-threonine and taurine crystals related to thermal decomposition

    Science.gov (United States)

    Cavaignac, A. L. O.; Lima, R. J. C.; Façanha Filho, P. F.; Moreno, A. J. D.; Freire, P. T. C.

    2016-03-01

    In this work high-temperature Raman spectra are used to compare temperature dependence of the lattice mode wavenumber of L-alanine, L-threonine and taurine crystals. Anharmonic effects observed are associated with intermolecular N-H· · ·O hydrogen bond that plays an important role in thermal decomposition process of these materials. Short and strong hydrogen bonds in L-alanine crystal were associated with anharmonic effects in lattice modes leading to low thermal stability compared to taurine crystals. Connection between thermal decomposition process and anharmonic effects is furnished for the first time.

  2. High-pressure investigation of CaTiO3 up to 60 GPa using x-ray diffraction and Raman spectroscopy

    Science.gov (United States)

    Guennou, Mael; Bouvier, Pierre; Krikler, Benjamin; Kreisel, Jens; Haumont, Raphaël; Garbarino, Gaston

    2010-10-01

    In this work, we investigate calcium titanate [CaTiO3(CTO)] using x-ray diffraction and Raman spectroscopy up to 60 GPa and 55 GPa, respectively. Both experiments show that the orthorhombic Pnma structure remains stable up to the highest pressures measured, in contradiction to ab initio predictions. A fit of the compression data with a second-order Birch-Murnaghan equation of state yields a bulk modulus K0 of 181.0(6) GPa. The orthorhombic distortion is found to increase slightly with pressure, in agreement with previous experiments at lower pressures and the general rules for the evolution of perovskites under pressure. High-pressure polarized Raman spectra also enable us to clarify the Raman mode assignment of CTO and identify the modes corresponding to rigid rotation of the octahedra, A -cation shifts, and Ti-O bond stretching. The Raman signature is then discussed in terms of compression mechanisms.

  3. Near-forward Raman scattering by bulk and surface phonon-polaritons in the model percolation-type ZnBeSe alloy

    OpenAIRE

    Hussein, Rami Hajj; Pagès, Olivier; Firszt, Franciszek; Paszkowicz, Wojtek; Maillard, Alain

    2013-01-01

    We study the bulk and surface phonon-polaritons of the Zn0.67Be0.33Se zincblende alloy by near-forward Raman scattering. The short (Be-Se) bond exhibits a distinct percolation doublet in the conventional backscattering Raman spectra, corresponding to a three-mode behavior in total [1(Zn-Se),2(Be-Se)] for Zn0.67Be0.33Se. This offers an opportunity to achieve a refined understanding of the phonon-polariton modes of a zincblende alloy beyond the current two-mode approximation, corresponding to a...

  4. Raman spectral characterization of NH4H2PO4 single crystals: Effect of pH on microstructure

    Science.gov (United States)

    Zhou, Hailiang; Wang, Fang; Xu, Mingxia; Liu, Baoan; Liu, Fafu; Zhang, Lisong; Xu, Xinguang; Sun, Xun; Wang, Zhengping

    2016-09-01

    Single crystals of ammonium dihydrogen phosphate (NH4H2PO4, ADP) were grown from aqueous solutions using "point seeds" method. The Raman spectra of the NH4H2PO4 single crystals were recorded as a function of pH. The band intensities and frequencies were monitored to determine the diagnostic bands for the crystals grown from the solutions of different pH values of aqueous solution. In the Raman spectra of ADP crystal samples at different pH, the position and intensity of the peaks in the range 300-900 cm-1 did not change; the peaks in the range 1400-1700 cm-1 shifted their position, although they had the same intensity. This indicates that the structure of (PO4) 3 - did not change with pH, whereas the structure of NH4+ changed with pH. In the Raman study in the range 1700-4000 cm-1, the primary discrimination occurred for the intensity of the peaks at 3050 cm-1 and 3147 cm-1, which is attributed to the vibration of O-H⋯O hydrogen bond, it can be inferred that pH slightly affected the O-H⋯O hydrogen bonding. This Raman spectral characterization may help to better understand the microstructural change under different conditions and optimize the growth and property of this type of material.

  5. A mixed quantum-classical molecular dynamics study of the hydroxyl stretch in methanol/carbon tetrachloride mixtures III: nonequilibrium hydrogen-bond dynamics and infrared pump-probe spectra.

    Science.gov (United States)

    Kwac, Kijeong; Geva, Eitan

    2013-06-27

    We present a mixed quantum-classical molecular dynamics study of the nonequilibrium hydrogen-bond dynamics following vibrational energy relaxation of the hydroxyl stretch in a 10 mol % methanol/carbon tetrachloride mixture and pure methanol. The ground and first-excited energy levels and wave functions are identified with the eigenvalues and eigenfunctions of the hydroxyl's adiabatic Hamiltonian and as such depend parametrically on the configuration of the remaining, classically treated, degrees of freedom. The dynamics of the classical degrees of freedom are in turn governed by forces obtained by taking the expectation value of the force with respect to the ground or excited vibrational wave functions. Polarizable force fields and nonlinear mapping relations between the hydroxyl transition frequencies and dipole moments and the electric field along the hydroxyl bond are used, which were previously shown to quantitatively reproduce the experimental infrared steady-state absorption spectra and excited state lifetime [Kwac, K.; Geva, E. J. Phys. Chem. B 2011, 115, 9184; 2012, 116, 2856]. The relaxation from the first-excited state to the ground state is treated as a nonadiabatic transition. Within the mixed quantum-classical treatment, relaxation from the excited state to the ground state is accompanied by a momentum-jump in the classical degrees of freedom, which is in turn dictated by the nonadiabatic coupling vector. We find that the momentum jump leads to breaking of hydrogen bonds involving the relaxing hydroxyl, thereby blue-shifting the transition frequency by more than the Stokes shift between the steady-state emission and absorption spectra. The subsequent nonequilibrium relaxation toward equilibrium on the ground state potential energy surface is thereby accompanied by red shifting of the transition frequency. The signature of this nonequilibrium relaxation process on the pump-probe spectrum is analyzed in detail. The calculated pump-probe spectrum is found

  6. 通过向量角转换校正拉曼光谱中乘性干扰%Correction Multiplicative Effects in Raman Spectra through Vector Angle Transformation

    Institute of Scientific and Technical Information of China (English)

    姚志湘; 孙增强; 粟晖; 袁洪福

    2016-01-01

    spectrum intensity/amplitude corresponding to the module shifts for a vector ,doesn't impact the vector direction which is the essence of the vector ,so it is reasonable to rewrite the data form on module to on space angle for the same measurement .This thesis employed a data transformation to eliminate the multiplicative effects within spectra ,i .e .,the spectrum signal on its amplitude has been transformed to be on the vector angles .The first step of the transformation is the se-lection of a stand vector which is near to the analyte and almost orthogonal to the background within the sample space ;and the next step is to define a moving window ,then to find out the angle between the sample vector (i .e .the transformed spectrum ) and the stand vector within the window ;while the window is moved along the spectrum data series ,the transformation for vector angle (VA) series has been finished .The thesis has proved that an approximate linear quantitative relationship has been re-mained in the VA series .Multivariate calibration need full rank matrix which is combined by spectrum from variety samples ,and variety VA series also can combine a full rank VA matrix ,so the approximate linear VA matrix still perfectly meeting the de-mand for multivariate calibration .A mixed system consisted by methanol-ethanol-isopropanol has been employed to verify the eliminations to the multiplicative effects .These measuring values of the system are obtained at different Raman integral times and have remarkable multiplicative effects .In predicting results ,the correlation coefficient (r) and the root mean squared error of prediction (RMSEP) from class PLS respectively are 0.911 9 and 0.110 2 ,and 0.906 0 and 0.100 8 are for the preprocessing by multiplicative scatter correction (MSC) .In contrast ,r and RMSEP under the VAPLS ,presented by this thesis ,respectively are 0.998 7 and 0.015 2 and are significantly better than others .The VAPLS has eliminated the multiplicative effects of Raman

  7. Single crystal electron paramagnetic resonance spectra of Cu(II) ions in Cu(tyrosine)(2): a study of weak exchange interactions mediated by resonance assisted hydrogen bonds (RAHB).

    Science.gov (United States)

    Paredes-García, Verónica; Santana, Ricardo C; Madrid, Rosa; Baldo, Bianca; Vega, Andrés; Spodine, Evgenia

    2012-09-01

    EPR measurements have been performed on single crystals of [Cu(L-tyrosine)(2)](∞) at 33.8 GHz and at room temperature. The EPR spectra display partially resolved EPR lines for most orientations of the magnetic field in the ab plane, and only one resonance for orientations close to the crystal axes, while only a single line is observed along any direction in the ca and cb crystal planes. This behavior is a result of the selective collapse of the resonances corresponding to the four copper sites in the unit cell produced by the exchange interactions between the copper ions. The magnitudes of the exchange interactions between the copper ions were evaluated from the angular variation of the line width and the collapse of the EPR lines. The value |J(AD)/k(B)|=0.8 K between neighboring copper atoms at 4.942 Å is assigned to a syn-anti equatorial-apical carboxylate bridge with a total bond length of 6.822 Å, while the small value |J(AB)/k(B)|=0.004 K is assigned to a long bridge of 11 atoms with a total bond length of 19.186 Å, that includes one resonance assisted hydrogen bond (RAHB). This finding is discussed in terms of values obtained for similar paths in other model compounds and in proteins.

  8. Single-pulse stimulated Raman scattering spectroscopy

    CERN Document Server

    Frostig, Hadas; Natan, Adi; Silberberg, Yaron

    2010-01-01

    We demonstrate the acquisition of stimulated Raman scattering spectra with the use of a single femtosecond pulse. High resolution vibrational spectra are obtained by shifting the phase of a narrow band of frequencies in the broadband input pulse spectrum, using spectral shaping. The vibrational spectrum is resolved by examining the amplitude features formed in the spectrum after interaction with the sample. Using this technique, low frequency Raman lines (<100cm^-1) are resolved in a straightforward manner.

  9. Surface enhanced raman spectroscopy on chip

    DEFF Research Database (Denmark)

    Hübner, Jörg; Anhøj, Thomas Aarøe; Zauner, Dan;

    2007-01-01

    In this paper we report low resolution surface enhanced Raman spectra (SERS) conducted with a chip based spectrometer. The flat field spectrometer presented here is fabricated in SU-8 on silicon, showing a resolution of around 3 nm and a free spectral range of around 100 nm. The output facet...... fiber. The obtained spectra show that chip based spectrometer together with the SERS active surface can be used as Raman sensor....

  10. Raman and Surface-enhanced Raman Scattering of Chlorophenols

    Institute of Scientific and Technical Information of China (English)

    SONG Wei; SHANG Xiao-hong; LU Yong; LIU Bing-bing; WANG Xu

    2011-01-01

    Raman spectrum is a powerful analytical tool for determining the chemical information of compounds.In this study,we obtained analytical results of chlorophenols(CPs) molecules including 4-chlorophenol(4-CP),2,6-dichlorophenol(2,6-DCP) and 2,4,6-trichlorophenol(2,4,6-TCP) on the surface of Ag dendrites by surface-enhanced Raman scattering(SERS) spectra.SEM images indicate that the SERS substrate of Ag dendrites is composed of a large number of polygonal nanocrystallites,which self-assembled into a 3D hierarchical structure.It was found that there were distinct differences for those three molecules from Raman and SERS spectra.This indicates that SERS could be a new tool of detection technique regarding trace amounts of CPs.

  11. Raman spectroscopy of magnetoliposomes

    International Nuclear Information System (INIS)

    In this study Raman spectroscopy was used to investigate monolayer and bilayer magnetite-based magnetoliposomes (MLs). The Raman probe is the hydroxyl (OH) group chemisorbed at the magnetite nanoparticle surface. Measurements were performed at room temperature in the typical OH stretching region. The data gathered for both samples are compared to each other and with those obtained for pure water. In comparison to liquid water (2.74 kcal/mol), it was found that the hydrogen bond strength between the chemisorbed OH-group and the polar headgroup of the inner phospholipid layer was reduced in both the monolayer (2.22 kcal/mol) and the bilayer (1.83 kcal/mol) ML samples

  12. Raman spectroscopic investigation of urinary calculi and salivary stones

    International Nuclear Information System (INIS)

    Full text: The capabilities and limitations of determining the composition of urinary calculi (34 patients) and salivary stones (27 patients) by Raman spectroscopy have been investigated by analysing Raman spectra obtained with 1064 nm laser excitation, and comparing them with Raman spectra both from specific reference substances and from a commercial Raman database. The composition results were also compared with those obtained by other analytical methods e.g. powder diffraction. Raman spectroscopy proves to be an analytical method which provides reliable results on the composition of urinary calculi and salivary stones quickly, non-destructively and without any need of sample preparation. (author)

  13. FT-Raman, FT-IR spectroscopic and DFT studies of hexaphenoxycyclotriphosphazene

    Science.gov (United States)

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

    2016-07-01

    The FTIR and FT Raman measurements of zero Gc0‧ -H and first Gc1‧ -H generations of phosphorus dendrimer built from cyclotriphosphazene core with phenoxy and deuterophenoxy terminal groups have been performed. In order to evaluate how much the frequencies, shift when changing the electronics of the system the FTIR and FT Raman spectra of phosphorus‒containing dendron with five terminal oxybenzaldehyde and one ester function Gci‧ have been also studied. Structural optimization and normal mode analysis were obtained for Gc0‧ -H and Gc0‧ -D by the density functional theory (DFT). It is discovered that dendrimer molecule exists in a stable conformation with six phenoxy terminal groups spaced above and below the flat cyclotriphosphazene core. Optimized geometric bond length and angles obtained by DFT show good agreement with a previously-published X-ray study. The phenoxy terminal groups are characterized by the well-defined line at 993 cm-1 in the experimental Raman spectrum of Gc0‧ -H and by line at 960 cm-1 in the Raman spectrum of Gc0‧ -D. Relying on DFT calculations a complete vibrational assignment is proposed for the studied dendrimers. The frequencies and relative intensity of the bands at 1589, 1487 cm-1 in the IR spectra show marked difference in dependence of the substituents on the aromatic ring.

  14. Infrared and Raman spectra of organic materials

    Science.gov (United States)

    Baratta, G. A.; Spinella, F.; Strazzulla, G.

    Ion-processing of such materials as frozen gases, graphite, aliphatic, and aromatic polymers, complex molecules, and biological compounds is studied by using vibrational spectroscopy. In particular, frozen methane, diamond, high-oriented pyrolitic graphite, microcrystalline graphite, polyethylene pristine, and ion-produced hydrogenated amorphous carbon (IPHAC) are investigated. Focus is placed on effects induced by fast ions colliding with different organic targets. It is demonstrated that IPHAC as well as other organic materials, exhibits dehydrogenation demonstrated by changes in its IR spectrum.

  15. Sensitivity of Raman spectroscopy to normal patient variability

    Science.gov (United States)

    Vargis, Elizabeth; Byrd, Teresa; Logan, Quinisha; Khabele, Dineo; Mahadevan-Jansen, Anita

    2011-11-01

    Many groups have used Raman spectroscopy for diagnosing cervical dysplasia; however, there have been few studies looking at the effect of normal physiological variations on Raman spectra. We assess four patient variables that may affect normal Raman spectra: Race/ethnicity, body mass index (BMI), parity, and socioeconomic status. Raman spectra were acquired from a diverse population of 75 patients undergoing routine screening for cervical dysplasia. Classification of Raman spectra from patients with a normal cervix is performed using sparse multinomial logistic regression (SMLR) to determine if any of these variables has a significant effect. Results suggest that BMI and parity have the greatest impact, whereas race/ethnicity and socioeconomic status have a limited effect. Incorporating BMI and obstetric history into classification algorithms may increase sensitivity and specificity rates of disease classification using Raman spectroscopy. Studies are underway to assess the effect of these variables on disease.

  16. Differentiation of lipsticks by Raman spectroscopy.

    Science.gov (United States)

    Salahioglu, Fatma; Went, Michael J

    2012-11-30

    Dispersive Raman spectra have been obtained using a Raman microscope and an excitation wavelength of 632.8 nm from 69 lipsticks of various colours and from a range of manufacturers without any pre-treatment of the samples. 10% of the samples were too fluorescent to give Raman spectra. 22% of the samples gave spectra which were unique to the brand and colour within the collected sample set. The remaining 68% of the samples gave spectra which could be classified into seven distinct groups. Discrimination of red lipsticks by this technique was the most difficult. The spectra of deposited lipstick samples remained unchanged over a period of a least a year. PMID:22959771

  17. Observation of the low frequency vibrational modes of bacteriophage M13 in water by Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Tsen Shaw-Wei D

    2006-09-01

    Full Text Available Abstract Background Recently, a technique which departs radically from conventional approaches has been proposed. This novel technique utilizes biological objects such as viruses as nano-templates for the fabrication of nanostructure elements. For example, rod-shaped viruses such as the M13 phage and tobacco mosaic virus have been successfully used as biological templates for the synthesis of semiconductor and metallic nanowires. Results and discussion Low wave number (≤ 20 cm-1 acoustic vibrations of the M13 phage have been studied using Raman spectroscopy. The experimental results are compared with theoretical calculations based on an elastic continuum model and appropriate Raman selection rules derived from a bond polarizability model. The observed Raman mode has been shown to belong to one of the Raman-active axial torsion modes of the M13 phage protein coat. Conclusion It is expected that the detection and characterization of this low frequency vibrational mode can be used for applications in nanotechnology such as for monitoring the process of virus functionalization and self-assembly. For example, the differences in Raman spectra can be used to monitor the coating of virus with some other materials and nano-assembly process, such as attaching a carbon nanotube or quantum dots.

  18. Quantitative detection of astaxanthin and cantaxanthin in Atlantic salmon by resonance Raman spectroscopy

    Science.gov (United States)

    Ermakov, Igor V.; Ermakova, Maia R.; Gellermann, Werner

    2006-02-01

    Two major carotenoids species found in salmonids muscle tissues are astaxanthin and cantaxanthin. They are taken up from fish food and are responsible for the attractive red-orange color of salmon filet. Since carotenoids are powerful antioxidants and biomarkers of nutrient consumption, they are thought to indicate fish health and resistance to diseases in fish farm environments. Therefore, a rapid, accurate, quantitative optical technique for measuring carotenoid content in salmon tissues is of economic interest. We demonstrate the possibility of using fast, selective, quantitative detection of astaxanthin and cantaxanthin in salmon muscle tissues, employing resonance Raman spectroscopy. Analyzing strong Raman signals originating from the carbon-carbon double bond stretch vibrations of the carotenoid molecules under blue laser excitation, we are able to characterize quantitatively the concentrations of carotenoids in salmon muscle tissue. To validate the technique, we compared Raman data with absorption measurements of carotenoid extracts in acetone. A close correspondence was observed in absorption spectra for tissue extract in acetone and a pure astaxanthin solution. Raman results show a linear dependence between Raman and absorption data. The proposed technique holds promise as a method of rapid screening of carotenoid levels in fish muscle tissues and may be attractive for the fish farm industry to assess the dietary status of salmon, risk for infective diseases, and product quality control.

  19. Raman Spectroscopic Studies of Clathrate Hydrate Formation in the Presence of Hydrophobized Particles.

    Science.gov (United States)

    Li, Huijuan; Stanwix, Paul; Aman, Zachary; Johns, Michael; May, Eric; Wang, Liguang

    2016-01-28

    In the present work, Raman spectroscopy was used to study the structure of water molecules in the vicinity of glass particles with different hydrophobicity, immersed in water and in tetrahydrofuran and cyclopentane hydrates. The glass particle surfaces were clean (hydrophilic), coated with N,N-dimethyl-N-octadecyl-3-aminopropyl trimethoxysilyl chloride (partially hydrophobic), or coated with octadecyltrichlorosilane (hydrophobic). The Raman spectra indicate that, prior to nucleation, water molecules in the vicinity of hydrophobic surfaces are more ice-like ordered than those in the bulk liquid or near either hydrophilic or partially hydrophobic surfaces. Furthermore, the degree of hydrogen-bond ordering of water observed prior to hydrate nucleation, as measured by the ratio of the inter- and intramolecular Raman OH bands, was found to have an inverse relationship with the mean induction time for hydrate formation. Following hydration formation, no significant difference in the water molecule structure was observed in the hydrate phase based on their Raman OH bands, irrespective of surface hydrophobicity. These observations made with Raman spectroscopy provide the foundations for a quantitative link between hydrate nucleation promotion and water-ordering near solid surfaces, which could enable direct comparisons with results from corresponding molecular dynamics simulations. PMID:26731126

  20. Structural study, NCA, FT-IR, FT-Raman spectral investigations, NBO analysis, thermodynamic functions of N-acetyl-L-phenylalanine

    Science.gov (United States)

    Raja, B.; Balachandran, V.; Revathi, B.

    2015-03-01

    The FT-IR and FT-Raman spectra of N-acetyl-L-phenylalanine were recorded and analyzed. Natural bond orbital analysis has been carried out for various intramolecular interactions that are responsible for the stabilization of the molecule. HOMO-LUMO energy gap has been computed with the help of density functional theory. The statistical thermodynamic functions (heat capacity, entropy, vibrational partition function and Gibbs energy) were obtained for the range of temperature 100-1000 K. The polarizability, first hyperpolarizability, anisotropy polarizability invariant has been computed using quantum chemical calculations. The infrared and Raman spectra were also predicted from the calculated intensities. Comparison of the experimental and theoretical spectra values provides important information about the ability of the computational method to describe the vibrational modes.

  1. Primidone - An antiepileptic drug - characterisation by quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR and UV-Visible) investigations

    Science.gov (United States)

    Arjunan, V.; Santhanam, R.; Subramanian, S.; Mohan, S.

    2013-05-01

    The solid phase FTIR and FT-Raman spectra of primidone were recorded in the regions 4000-400 cm-1 and 4000-100 cm-1, respectively. The vibrational spectra were analysed and the observed fundamentals were assigned and analysed. The experimental wavenumbers were compared with the theoretical scaled vibrational wavenumbers determined by DFT methods. The Raman intensities were also determined with B3LYP/6-31G(d,p) method. The total electron density and molecular electrostatic potential surface of the molecule were constructed by using B3LYP/6-311++G(d,p) method to display electrostatic potential (electron + nuclei) distribution. The HOMO and LUMO energies were measured. Natural bond orbital analysis of primidone has been performed to indicate the presence of intramolecular charge transfer. The 1H and 13C NMR spectra were recorded and the chemical shifts of the molecule were calculated.

  2. Resonance Raman study on indoleamine 2,3-dioxygenase: Control of reactivity by substrate-binding

    International Nuclear Information System (INIS)

    Highlights: • Indoleamine 2,3-dioygenase has been studied by resonance Raman spectroscopy. • Trp-binding to the enzyme induces high frequency shift of the Fe–His stretching mode. • Increased imidazolate character of histidine promotes the O–O bond cleavage step. • A fine-tuning of the reactivity of the O–O bond cleavage reaction is identified. • The results are consistent with the sequential oxygen-atom-transfer mechanism. - Abstract: Resonance Raman spectra of ligand-bound complexes including the 4-phenylimidazole complex and of free and L-Trp-bound forms of indoleamine 2, 3-dioxygenase in the ferric state were examined. Effects on the vinyl and propionate substituent groups of the heme were detected in a ligand-dependent fashion. The effects of phenyl group of 4-phenylimidazole on the vinyl and propionate Raman bands were evident when compared with the case of imidazole ligand. Substrate binding to the ferrous protein caused an upshift of the iron–histidine stretching mode by 3 cm−1, indicating an increase in negativity of the imidazole ring, which favors the O–O bond cleavage. The substrate binding event is likely to be communicated from the heme distal side to the iron–histidine bond through heme substituent groups and the hydrogen-bond network which includes water molecules, as identified in an X-ray structure of a 4-phenylimidazole complex. The results provide evidence for fine-tuning of the reactivity of O–O bond cleavage by the oxygenated heme upon binding of L-Trp

  3. Rotational spectra and properties of complexes B···ICF3 (B = Kr or CO) and a comparison of the efficacy of ICl and ICF3 as iodine donors in halogen bond formation.

    Science.gov (United States)

    Stephens, Susanna L; Walker, Nicholas R; Legon, Anthony C

    2011-12-14

    The ground-state rotational spectra of two weakly bound complexes B···ICF(3) (B = Kr or CO) formed by trifluoroiodomethane have been observed in pulsed jets by using two types of Fourier-transform microwave spectroscopy (chirped-pulse and Fabry-Perot cavity). Both complexes exhibit symmetric-top type spectra, thus indicating that the Kr atom in Kr···ICF(3) and both the C and O atoms in OC···ICF(3) lie along the C(3) axis of ICF(3). The rotational constant B(0), the centrifugal distortion constants D(J) and D(JK), and the iodine nuclear quadrupole coupling constant χ(aa)(I) were determined for each of the isotopologues (84)Kr···ICF(3), (86)Kr···ICF(3), (16)O(12)C···ICF(3), (16)O(13)C···ICF(3), and (18)O(12)C···ICF(3). Interpretation of the spectroscopic constants reveals that the carbon atom of CO is adjacent to I and participates in the weak bond in OC···ICF(3). Simple models based on unperturbed component geometries lead to the distances r(Kr···I) = 3.830(1) Å and r(C···I) = 3.428(1) Å in Kr···ICF(3) and OC···ICF(3), respectively, and to the quadratic force constants for stretching of the weak bond k(σ) = 2.80 N m(-1) and 3.96 N m(-1), respectively. The distances r(Z···I) (Z is the acceptor atom in B), the k(σ) values, and the angular geometries of the pair of complexes B···ICF(3) and B···ICl for a given B are compared when B = Kr, CO, H(2)O, H(2)S, or NH(3). The comparison reveals that the iodine bond in B···ICF(3) is systematically longer and weaker than that of B···ICl, while the angular geometry of the B···I moiety is isomorphic in B···ICF(3) and B···ICl for a given B. It is concluded that -CF(3) is less effective than -Cl as an electron-withdrawing group when attached to an I atom and that the angular geometries of the B···ICF(3) can be predicted by means of a simple rule that holds for many hydrogen- and halogen-bonded complexes.

  4. Spectral interferometric polarised coherent anti-Stokes Raman spectroscopy

    CERN Document Server

    Littleton, Brad; Festy, Frederic; Richards, David

    2013-01-01

    We have developed an interferometric implementation of coherent anti-Stokes Raman scattering (CARS) which enables broadband coherent Raman spectroscopy free from non-resonant background (NRB), with a signal strength proportional to concentration. Spectra encode mode symmetry information into the amplitude response which can be directly compared to polarised spontaneous Raman spectra. The method requires only passive polarisation optics and is suitable for a wide range of laser linewidths and pulse durations

  5. Raman Microspectroscopy of Individual Algal Cells: Sensing Unsaturation of Storage Lipids in vivo

    Directory of Open Access Journals (Sweden)

    Ladislav Nedbal

    2010-09-01

    Full Text Available Algae are becoming a strategic source of fuels, food, feedstocks, and biologically active compounds. This potential has stimulated the development of innovative analytical methods focused on these microorganisms. Algal lipids are among the most promising potential products for fuels as well as for nutrition. The crucial parameter characterizing the algal lipids is the degree of unsaturation of the constituent fatty acids quantified by the iodine value. Here we demonstrate the capacity of the spatially resolved Raman microspectroscopy to determine the effective iodine value in lipid storage bodies of individual living algal cells. The Raman spectra were collected from three selected algal species immobilized in an agarose gel. Prior to immobilization, the algae were cultivated in the stationary phase inducing an overproduction of lipids. We employed the characteristic peaks in the Raman scattering spectra at 1,656 cm−1 (cis C=C stretching mode and 1,445 cm−1 (CH2 scissoring mode as the markers defining the ratio of unsaturated-to-saturated carbon-carbon bonds of the fatty acids in the algal lipids. These spectral features were first quantified for pure fatty acids of known iodine value. The resultant calibration curve was then used to calculate the effective iodine value of storage lipids in the living algal cells from their Raman spectra. We demonstrated that the iodine value differs significantly for the three studied algal species. Our spectroscopic estimations of the iodine value were validated using GC-MS measurements and an excellent agreement was found for the Trachydiscus minutus species. A good agreement was also found with the earlier published data on Botryococcus braunii. Thus, we propose that Raman microspectroscopy can become technique of choice in the rapidly expanding field of algal biotechnology.

  6. Raman and surface-enhanced Raman scattering (SERS) studies of the thrombin-binding aptamer.

    Science.gov (United States)

    Wu, Tsai-Chin; Vasudev, Milana; Dutta, Mitra; Stroscio, Michael A

    2013-06-01

    Surface-enhanced Raman scattering is used to study the Raman spectra and peak shifts the thrombin-binding aptamer (TBA) on substrates having two different geometries; one with a single stranded sequence and one with double stranded sequence. The Raman signals of the deoxyribonucleic acids on both substrates are enhanced and specific peaks of bases are identified. These results are highly reproducible and have promising applications in low cost nucleic acid detection.

  7. Condensing Raman spectrum for single-cell phenotype analysis

    KAUST Repository

    Sun, Shiwei

    2015-12-09

    Background In recent years, high throughput and non-invasive Raman spectrometry technique has matured as an effective approach to identification of individual cells by species, even in complex, mixed populations. Raman profiling is an appealing optical microscopic method to achieve this. To fully utilize Raman proling for single-cell analysis, an extensive understanding of Raman spectra is necessary to answer questions such as which filtering methodologies are effective for pre-processing of Raman spectra, what strains can be distinguished by Raman spectra, and what features serve best as Raman-based biomarkers for single-cells, etc. Results In this work, we have proposed an approach called rDisc to discretize the original Raman spectrum into only a few (usually less than 20) representative peaks (Raman shifts). The approach has advantages in removing noises, and condensing the original spectrum. In particular, effective signal processing procedures were designed to eliminate noise, utilising wavelet transform denoising, baseline correction, and signal normalization. In the discretizing process, representative peaks were selected to signicantly decrease the Raman data size. More importantly, the selected peaks are chosen as suitable to serve as key biological markers to differentiate species and other cellular features. Additionally, the classication performance of discretized spectra was found to be comparable to full spectrum having more than 1000 Raman shifts. Overall, the discretized spectrum needs about 5storage space of a full spectrum and the processing speed is considerably faster. This makes rDisc clearly superior to other methods for single-cell classication.

  8. SERS, FT-Raman and FT-IR studies of dithiocarbamates

    Science.gov (United States)

    Mylrajan, M.

    1995-03-01

    Surface-enhanced Raman scattering (SERS) spectra of dimethyl and diehtyldithiocarbamate (DMDTC and DEDTC) ions were obtained with different wavelength excitations in citrate reduced silver sol and compared with FT-Raman and FT-IR spectra. The red wavelength excitation shows large enhancement compared to green excitation. SERS spectra were compared with normal Raman spectra in both solid and solution form and assignments were made.

  9. Temperature dependent Raman spectroscopy of melamine and structural analogs in milk powder

    Science.gov (United States)

    Hyperspectral Raman imaging has the potential for rapid screening of solid-phase samples for potential adulterants. We found that the Raman spectra of melamine analogs changed dramatically and uniquely as a function of elevated temperature. Raman spectra were acquired for urea, biuret, cyanuric acid...

  10. On-Line Multichannel Raman Spectroscopic Detection System For Capillary Zone Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An on-line multichannel Raman spectroscopic detection system for capillary electrophoresis was established by using an Ar+ laser and a cryogenically cooled ICCD. Resonant excitation Raman spectra of methyl red and methyl orange were employed to test the system. The result shows that it could yield on-line electrophoretogram and time series of Raman spectra.

  11. Raman study of the molecular motions of pivalic acid: the liquid—plastic phase transition

    Science.gov (United States)

    Balevičius, V.; Orel, B.; Hadži, D.

    Raman spectra of pivalic acid in the plastic and liquid phase have been measured. The reorientational correlation times have been evaluated from the ν asCH, νCO and νCC bands as a function of temperature. The reorientational correlation time corresponding to ν as CH and νCC bands is τ 4ps ( T = 20°C). The calculated activation energy is 26 KJ mol -1. The reorientation of the carboxylic groups which may be assisted by the proton transfer along the hydrogen bonds in dimers is discussed.

  12. A Study on Raman Spectra of Bis (Saliaylaldehyde 1,2-Cyclohexanediiminato) in Fingerpoint Region%N,N‘-双水杨醛缩环己二胺指纹区拉曼光谱研究

    Institute of Scientific and Technical Information of China (English)

    杨国玉; 陈钢; 金显春; 赵仲麟; 苏同福

    2011-01-01

    The Raman spectra of bis (saliaylaldehyde 1,2-cyclohexanediiminato) were measured by excited wavelength 633 nm in fingerprint rang: below 1 000 cm-1 and its theoretical curves were simulated by B3LYP/3-21G*basis set according to density functional theory. The results of comparison between theoretical and observed values show that there is in agreement in fingerprint region, and there is a characteristic vibrational peak at 800 cm-1,which could be assigned scissor vibration of C-N=C with stretching vibrations of C =C in benzene ring. In addition,there are some differences in intensities between observed and theoretical curves due to differences of aggregations. the observed values were detected at solid powder which was composed of many molecules while calculated values were simulated according to a single molecular in gas phase conditions and the effects of the inter-or/and intra-molecule were not considered.%采用633 nm激光器,检测了合成的N,N'-双水杨醛缩环己二胺产物在指纹区的拉曼光谱,并根据密度泛函理论对其拉曼光谱进行理论模拟.该分子拉曼光谱检测值和理论值比较表明:在位移800 cm-1,该物质有一特征峰,初步将其归属为C-N-C两碳原子围绕N原子的剪式振动和苯环碳骨架伸缩振动的协同振动,这是该物质多个原子的集体振动模.拉曼图谱检测值和理论值相比表明,在指纹区,两者总的来说是一致的,但也有一定的差异,其主要原因是检测样品是多个分子的聚集体,分子基团的振动受到分子间相互作用的影响,而理论值计算的只是根据该物质气态的一个分子.

  13. Variability in automated assignment of NOESY spectra and three-dimensional structure determination: A test case on three small disulfide-bonded proteins

    International Nuclear Information System (INIS)

    Three independent runs of automatic assignment and structure calculations were performed on three small proteins, calcicludine from the venom of the green mamba Dendroaspis angusticeps, κ-conotoxin PVIIA from the purple cone Conus purpurascens and HsTX1, a short scorpion toxin from the venom of Heterometrus spinnifer. At the end of all the runs, the number of cross peaks which remained unassigned (0.6%, 1.4% and 2% for calcicludine, κ-conotoxin and HsTX1, respectively), as well as the number of constraints which were rejected as producing systematic violations (2.7%, 1.0%, and 1.4% for calcicludine, κ-conotoxin and HsTX1, respectively) were low. The conformation of the initial model used in the procedure (linear model or constructed by homology) has no influence on the final structures. Mainly two parameters control the procedure: the chemical shift tolerance and the cut-off distance. Independent runs of structure calculations, using the same parameters, yield structures for which the rmsd between averaged structures and the rmsd around each averaged structure were of the same order of magnitude. A different cut-off distance and a different chemical shift tolerance yield rmsd values on final average structures which did not differ more than 0.5 A compared to the rmsd obtained around the averaged structure for each calculation. These results show that the procedure is robust when applied to such a small disulfide-bonded protein

  14. Structure and vibrational modes of AgI-doped AsSe glasses: Raman scattering and ab initio calculations

    International Nuclear Information System (INIS)

    We report an investigation of the structure and vibrational modes of (AgI)x (AsSe)100-x, bulk glasses using Raman spectroscopy and first principles calculations. The short- and medium-range structural order of the glasses was elucidated by analyzing the reduced Raman spectra, recorded at off-resonance conditions. Three distinct local environments were revealed for the AsSe glass including stoichiometric-like and As-rich network sub-structures, and cage-like molecules (As4Sen, n=3, 4) decoupled from the network. To facilitate the interpretation of the Raman spectra ab initio calculations are employed to study the geometric and vibrational properties of As4Sen molecular units that are parts of the glass structure. The incorporation of AgI causes appreciable structural changes into the glass structure. AgI is responsible for the population reduction of molecular units and for the degradation of the As-rich network-like sub-structure via the introduction of As-I terminal bonds. Ab initio calculations of mixed chalcohalide pyramids AsSemI3-m provided useful information augmenting the interpretation of the Raman spectra. -- Graphical abstract: Raman scattering and ab initio calculations are employed to study the structure of AgI-AsSe superionic glasses. The role of mixed chalcohalide pyramidal units as illustrated in the figure is elucidated. Display Omitted Research highlights: → Doping binary As-Se glasses with AgI cause dramatic changes in glass structure. → Raman scattering and ab initio calculations determine changes in short- and medium-range order. → Three local environments exist in AsSe glass including a network sub-structure and cage-like molecules. → Mixed chalcohalide pyramids AsSemI3-m dominate the AgI-doped glass structure.

  15. Raman Imaging

    Science.gov (United States)

    Stewart, Shona; Priore, Ryan J.; Nelson, Matthew P.; Treado, Patrick J.

    2012-07-01

    The past decade has seen an enormous increase in the number and breadth of imaging techniques developed for analysis in many industries, including pharmaceuticals, food, and especially biomedicine. Rather than accept single-dimensional forms of information, users now demand multidimensional assessment of samples. High specificity and the need for little or no sample preparation make Raman imaging a highly attractive analytical technique and provide motivation for continuing advances in its supporting technology and utilization. This review discusses the current tools employed in Raman imaging, the recent advances, and the major applications in this ever-growing analytical field.

  16. FT-IR, FT-Raman and Computational Study of Ethyl Methyl Ketone Semicarbazone

    Directory of Open Access Journals (Sweden)

    P. S. Binil

    2011-01-01

    Full Text Available FT-IR and FT-Raman spectra of ethyl methyl ketone semicarbazone were recorded and analyzed. The vibrational wavenumbers were computed using HF/6-31G*, B3PW91/6-31G* and B3LYP/6-31G* basis and compared with experimental data. The first hyperpolarizability, infrared intensities and Raman activities are reported. The calculated first hyperpolarizability is comparable with the reported values of similar derivatives and is an attractive object for future studies of non-linear optics. The extended π-electron delocalization over the carbazone moiety is responsible for the nonlinearity of the molecule. The geometrical parameters of the title compound are in agreement with that of similar derivatives. The red shift of the NH stretching wavenumber in the infrared spectrum from the computed wavenumber indicates the weakening of the NH bond resulting in proton transfer to the neighboring oxygen atom.

  17. Using Raman spectroscopy to characterize biological materials.

    Science.gov (United States)

    Butler, Holly J; Ashton, Lorna; Bird, Benjamin; Cinque, Gianfelice; Curtis, Kelly; Dorney, Jennifer; Esmonde-White, Karen; Fullwood, Nigel J; Gardner, Benjamin; Martin-Hirsch, Pierre L; Walsh, Michael J; McAinsh, Martin R; Stone, Nicholas; Martin, Francis L

    2016-04-01

    Raman spectroscopy can be used to measure the chemical composition of a sample, which can in turn be used to extract biological information. Many materials have characteristic Raman spectra, which means that Raman spectroscopy has proven to be an effective analytical approach in geology, semiconductor, materials and polymer science fields. The application of Raman spectroscopy and microscopy within biology is rapidly increasing because it can provide chemical and compositional information, but it does not typically suffer from interference from water molecules. Analysis does not conventionally require extensive sample preparation; biochemical and structural information can usually be obtained without labeling. In this protocol, we aim to standardize and bring together multiple experimental approaches from key leaders in the field for obtaining Raman spectra using a microspectrometer. As examples of the range of biological samples that can be analyzed, we provide instructions for acquiring Raman spectra, maps and images for fresh plant tissue, formalin-fixed and fresh frozen mammalian tissue, fixed cells and biofluids. We explore a robust approach for sample preparation, instrumentation, acquisition parameters and data processing. By using this approach, we expect that a typical Raman experiment can be performed by a nonspecialist user to generate high-quality data for biological materials analysis. PMID:26963630

  18. 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.

  19. Thin Film Substrates from the Raman spectroscopy point of view

    OpenAIRE

    Gasparov, L.; Jegorel, T.; Loetgering, L.; Middey, S.; Chakhalian, J.

    2013-01-01

    We have investigated ten standard single crystal substrates of complex oxides on the account of their applicability in the Raman spectroscopy based thin film research. In this study we suggest a spectra normalization procedure that utilizes a comparison of the substrate Raman spectra to those of well-established Raman reference materials. We demonstrate that MgO, LaGaO3, (LaAlO3)_0.3(Sr2AlTaO6)_0.7 (LSAT), DyScO3, YAlO3, and LaAlO3 can be of potential use for a Raman based thin film research....

  20. Optical remote sensing of water temperature using Raman spectroscopy.

    Science.gov (United States)

    Artlett, C P; Pask, H M

    2015-12-14

    A detailed investigation into the use of Raman spectroscopy for determining water temperature is presented. The temperature dependence of unpolarized Raman spectra is evaluated numerically, and methods based on linear regression are used to determine the accuracy with which temperature can be obtained from Raman spectra. These methods were also used to inform the design and predict the performance of a two-channel Raman spectrometer, which can predict the temperature of mains supply water to an accuracy of ± 0.5 °C. PMID:26698976

  1. THz-Raman: accessing molecular structure with Raman spectroscopy for enhanced chemical identification, analysis, and monitoring

    Science.gov (United States)

    Heyler, Randy A.; Carriere, James T. A.; Havermeyer, Frank

    2013-05-01

    Structural analysis via spectroscopic measurement of rotational and vibrational modes is of increasing interest for many applications, since these spectra can reveal unique and important structural and behavioral information about a wide range of materials. However these modes correspond to very low frequency (~5cm-1 - 200cm-1, or 150 GHz-6 THz) emissions, which have been traditionally difficult and/or expensive to access through conventional Raman and Terahertz spectroscopy techniques. We report on a new, inexpensive, and highly efficient approach to gathering ultra-low-frequency Stokes and anti-Stokes Raman spectra (referred to as "THz-Raman") on a broad range of materials, opening potential new applications and analytical tools for chemical and trace detection, identification, and forensics analysis. Results are presented on explosives, pharmaceuticals, and common elements that show strong THz-Raman spectra, leading to clear discrimination of polymorphs, and improved sensitivity and reliability for chemical identification.

  2. Raman properties of GaSb nanoparticles embedded in SiO2 films

    Institute of Scientific and Technical Information of China (English)

    Liu Fa-Min; Wang Tian-Min; Zhang Li-De

    2004-01-01

    The Raman shifts of nanocrystalline GaSb excited by an Ar+ ion laser at wavelengths 514.5, 496.5, 488.0, 476.5,and 457.9nm are studied by an SPEX-1403 laser Raman spectrometer respectively, and they are explained by phonon confinement, tensile stress, resonant Raman scattering and quantum size effects. The Stokes and anti-Stokes Raman spectra of GaSb nanocrystals strongly support the Raman feature of GaSb nanocrystals. The calculated optical spectra compare well with experimental data on Raman scattering GaSb nanocrystals.

  3. Infrared and Raman studies on polylactide acid and polyethylene glycol-400 blend

    Science.gov (United States)

    Yuniarto, Kurniawan; Purwanto, Yohanes Aris; Purwanto, Setyo; Welt, Bruce A.; Purwadaria, Hadi Karia; Sunarti, Titi Candra

    2016-04-01

    As a biodegradableplastic, polylactideacid (PLA) can be blended with polyethylene glycol (PEG) to form a polymer blend because PEG has a good miscibility with PLA. Furthermore, this paper study the functional groups of PLA-PEG400 blend using direct casting to produce matrix film. Fourier Transform Infrared (FTIR) and Raman spectroscopy was used to identify alteration of functional group PLA-PEG400 blend. Absorbance and frequency wavenumber were used to observe any changing among functional group. In general, PLA-PEG blend did not produce a new configuration or chemical properties although some functional groups tended to decrease. PLA-PEG400 film spectra showed a similaritycompared to those of neat PLA because of each pristine polymer. However, FTIR and Raman investigated reducing carbonyl group of PLA with PEG400 addition and followed improving CH-COC bonding. Methyl group represented CH3symmetricchanged both the shift and absorbance.FTIR and Raman spectroscopy observed increasing hydrogen bonding with increasing PEG400 addition where a largest was found at PEG 10% and appeared at frequency range from 3400 cm-1 to 3600 cm-1. According to PEG400 addition, a FTIR measuredenhancing crystalline region.

  4. Hydrogen Bonding in Ionic Liquids Probed by Linear and Nonlinear Vibrational Spectroscopy

    CERN Document Server

    Roth, C; Kerlé, D; Friedriszik, F; Lütgens, M; Lochbrunner, S; Kühn, O; Ludwig, R

    2012-01-01

    Three imidazolium-based ionic liquids of the type [Cnmim][NTf2] with varying alkyl chain lengths (n = 1, 2 and 8) at the 1 position of the imidazolium ring were studied applying IR, linear Raman, and multiplex CARS spectroscopy. The focus has been on the CH-stretching region of the imidazolium ring, which is supposed to carry information about a possible hydrogen bonding network in the ionic liquid. The measurements are compared to calculations of the corresponding anharmonic vibrational spectra for a cluster of [C2mim][NTf2] consisting of four ion pairs. The results support the hypothesis of moderate hydrogen bonding involving the C(4)-H and C(5)-H groups and somewhat stronger hydrogen bonds of the C(2)-H groups.

  5. X-ray Crystal Structure, Raman Spectroscopy and Ab Initio Density Functional Theory Calculations on 1,1,3,3-Tetramethylguanidinium Bromide

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Riisager, Anders; Nguyen van Buu, Olivier;

    2010-01-01

    and Raman evidence to show that also the bromide salt contains dimeric ion pair “molecules” in the crystalline state and probably also in the liquid state. The structure of [tmgH]Br determined at 120(2) K was found to be monoclinic, space group P21/n, with a = 7.2072(14), b = 13.335(3), c = 9.378(2) Å, beta...... = 104.31(3)°, Z = 2, based on 11769 reflections, measured from θ = 2.71-28.00° on a small colorless needle crystal. Raman and IR spectra are presented and assigned. When heated, both the chloride and the bromide salts form vapor phases. The Raman spectra of the vapors are surprisingly alike, showing......). The Raman spectra of all gas phases were quite identical and fitted the calculated spectrum of dimethylcyanamide. It is concluded that monomeric ion pair “molecules” held together by single N-H+ · · ·X- hydrogen bonds probably do not exist in the vapor phase over the solids at about 200-230 °C....

  6. Co-localised Raman and force spectroscopy reveal the roles of hydrogen bonds and π-π interactions in defining the mechanical properties of diphenylalanine nano- and micro-tubes

    OpenAIRE

    Sinjab, Faris; Bondakov, Georgi; Notingher, Ioan

    2014-01-01

    An integrated atomic force and polarized Raman microscope were used to measure the elastic properties of individual diphenylalanine (FF) nano- and micro-tubes and to obtain quantitative information regarding the inter-molecular interactions that define their mechanical properties. For individual tubes, co-localised force spectroscopy and Raman spectroscopy measurements allowed the calculation of the Young’s and shear moduli (2565 GPa and 0.2860.05 GPa, respectively) and the contribution of hy...

  7. Combined fiber probe for fluorescence lifetime and Raman spectroscopy

    Science.gov (United States)

    Dochow, Sebastian; Ma, Dinglong; Latka, Ines; Bocklitz, Thomas; Hartl, Brad; Bec, Julien; Fatakdawala, Hussain; Marple, Eric; Urmey, Kirk; Wachsmann-Hogiu, Sebastian; Schmitt, Michael; Marcu, Laura; Popp, Jürgen

    2016-01-01

    In this contribution we present a dual modality fiber optic probe combining fluorescence lifetime imaging (FLIm) and Raman spectroscopy for in vivo endoscopic applications. The presented multi-spectroscopy probe enables efficient excitation and collection of fluorescence lifetime signals for FLIm in the UV/visible wavelength region, as well as of Raman spectra in the near-IR for simultaneous Raman/FLIm imaging. The probe was characterized in terms of its lateral resolution and distance dependency of the Raman and FLIm signals. In addition, the feasibility of the probe for in vivo FLIm and Raman spectral characterization of tissue was demonstrated. PMID:26093843

  8. Anomalous junctions characterized by Raman spectroscopy in SixGe1−x nanowires with axially degraded components

    International Nuclear Information System (INIS)

    The characterization of junctions in nanowires by high-resolution transmission electron microscopy with spherical aberration correction is tricky and tedious. Many disadvantages also exist, including rigorous sample preparation and structural damage inflicted by high-energy electrons. In this work, we present a simple, low-cost, and non-destructive Raman spectroscopy method of characterizing anomalous junctions in nanowires with axially degraded components. The Raman spectra of SixGe1−x nanowires with axially degraded components are studied in detail using a confocal micro-Raman spectrometer. Three Raman peaks (νSi–Si = 490 cm−1, νSi–Ge = 400 cm−1, and νGe–Ge = 284 cm−1) up-shift with increased Si content. This up-shift originates in the bond compression induced by a confined effect on the radial direction of nanowire. The anomalous junctions in SixGe1−x nanowires with axially degraded components are then observed by Raman spectroscopy and verified by transmission electron microscopy energy-dispersive X-ray spectroscopy. The anomalous junctions of SixGe1−x nanowires with axially degraded components are due to the vortex flow of inlet SiH4 and GeH4 gas in their synthesis. The anomalous junctions can be used as raw materials for fabricating devices with special functions.

  9. Self-assembly of mildly reduced graphene oxide monolayer for enhanced Raman scattering

    Science.gov (United States)

    Yin, Fenping; Wu, Shang; Wang, Yanbin; Wu, Lan; Yuan, Peilin; Wang, Xia

    2016-05-01

    Graphene-enhanced Raman scattering (GERS) has attracted much attention recently. In present study, monolayer of chemically reduced graphene oxide (RGO) nanosheets was chemically bonded on Si substrates and their possible applications in Raman scattering were investigated. In comparison with the mechanically exfoliated graphene, mildly reduced graphene oxide (MR-GO) monolayer is a better substrate to quench the fluorescence (FL) signals and simultaneously enhance the Raman signals of adsorbed Rhodamin 6G (R6G) molecules. Raman and X-ray photoelectron spectra indicate that π-π stacking and the residual polarized oxygen groups on MRGO surface, which can produce a strong local electric field under laser excitation, are mainly responsible for the excellent GERS effect of MR-GO substrate, while the charge transfer between R6G and MR-GO has a relatively low contribution for GERS effect. Our results not only provide a new approach to realize sensitive GERS substrate, but also are helpful for improving the fundamental understanding of GERS effect on RGO substrate.

  10. Ice thickness measurements by Raman scattering

    CERN Document Server

    Pershin, Sergey M; Klinkov, Vladimir K; Yulmetov, Renat N; Bunkin, Alexey F

    2014-01-01

    A compact Raman LIDAR system with a spectrograph was used for express ice thickness measurements. The difference between the Raman spectra of ice and liquid water is employed to locate the ice-water interface while elastic scattering was used for air-ice surface detection. This approach yields an error of only 2 mm for an 80-mm-thick ice sample, indicating that it is promising express noncontact thickness measurements technique in field experiments.

  11. Raman spectral research on MPCVD diamond film

    Institute of Scientific and Technical Information of China (English)

    YAN Yan; ZHANG Shulin; ZHAO Xinsheng; HAN Yisong; HOU Li

    2003-01-01

    Raman spectra of MPCVD diamond film have been studied. Based on the resonance size selection effect, we think that there is no nano-crystalline diamond in the sample and the Raman peak at 1145 cm-1 can not be considered as the characteristic peak of nano-crystalline diamond though it has been used as the characteristic peak of nano-crystalline diamond widely for many years.

  12. Candida parapsilosis Biofilm Identification by Raman Spectroscopy

    OpenAIRE

    Ota Samek; Katarina Mlynariková; Silvie Bernatová; Jan Ježek; Vladislav Krzyžánek; Martin Šiler; Pavel Zemánek; Filip Růžička; Veronika Holá; Martina Mahelová

    2014-01-01

    Colonies of Candida parapsilosis on culture plates were probed directly in situ using Raman spectroscopy for rapid identification of specific strains separated by a given time intervals (up to months apart). To classify the Raman spectra, data analysis was performed using the approach of principal component analysis (PCA). The analysis of the data sets generated during the scans of individual colonies reveals that despite the inhomogeneity of the biological samples unambiguous associations to...

  13. Confocal Raman microscopy of frozen bread dough

    OpenAIRE

    Huen, Julien; Weikusat, Christian; Bayer-Giraldi, Maddalena; Weikusat, Ilka; Ringer, Linda; Lösche, Klaus

    2014-01-01

    The use of freezing technology is well established in industrial and craft bakeries and is still gaining importance. In order to optimize recipes and processes of frozen baked goods, it is essential to be able to investigate the products' microstructure. Especially ice crystals and their interaction with the other components of the frozen products are of interest. In this study, frozen wheat bread dough was investigated by confocal Raman microscopy. The Raman spectra measured within the dough...

  14. Determination of ripeness stages of Mazafati variety of date fruit by Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    R Khodabakhshian

    2016-04-01

    with a Deuterated Triglycine Sulfate (DTGS detector and a solid substrate beam splitter. The spectra were collected with rapid scan software running under OMNIC (Nicolet, Madion, Wis., U.S.A and a resolution of 4 cm-1 by coadding of 128 scans. FT-Raman has three main advantages over dispersive Raman systems: (1 reducing the laser-induced fluorescence that a number of samples exhibit; (2 easing the operation as with a Fourier transform infrared (FTIR spectrometer; and (3 showing a high spectral resolution with a good wavelength accuracy (Yang and Ying, 2011. Furthermore, the Raman spectra of pure tannin were measured as a reference spectrum. The original data were used for further analysis only after subtracting dark current spectra. For obtaining dark current spectra, the laser was set to zero. Results and Discussion: Physical properties of date fruits: The results of some physical parameters of the studied date fruit are shown in Table1. The changes in the physical properties were dependent on the internal quality in different ripeness stages. This justification also was revealed for date fruits by Al-Hooti et al. (1995. The obtained relations between ripening stages and internal quality of studied samples are represented in the next part. Raman spectra of tannin: Raman features of the tannin in the wavelength range of 200-2500 cm-1 are shown in Figure 3. As shown in the figure, major Raman features of the tannin were observed in the spectral region of 600-1600 cm-1. Three main Raman peaks were identified in this region. The tannin showed its highest Raman intensity at 1590 cm-1, which was higher than that at 1357 cm-1. The other peak (650 cm-1 showed low intensity. As stated by many researchers (Shahidi and Naczk, 2004; Al-Farsi et al., 2005; Biglari et al., 2008, these bands are assigned to stretching C-C, C=C and C-H bonds which compose the structure of phytochemicals. Beyond 1600 cm-1, no notable Raman scattering signals were observed. Themain Raman features of

  15. Visualizing cell state transition using Raman spectroscopy.

    Directory of Open Access Journals (Sweden)

    Taro Ichimura

    Full Text Available System level understanding of the cell requires detailed description of the cell state, which is often characterized by the expression levels of proteins. However, understanding the cell state requires comprehensive information of the cell, which is usually obtained from a large number of cells and their disruption. In this study, we used Raman spectroscopy, which can report changes in the cell state without introducing any label, as a non-invasive method with single cell capability. Significant differences in Raman spectra were observed at the levels of both the cytosol and nucleus in different cell-lines from mouse, indicating that Raman spectra reflect differences in the cell state. Difference in cell state was observed before and after the induction of differentiation in neuroblastoma and adipocytes, showing that Raman spectra can detect subtle changes in the cell state. Cell state transitions during embryonic stem cell (ESC differentiation were visualized when Raman spectroscopy was coupled with principal component analysis (PCA, which showed gradual transition in the cell states during differentiation. Detailed analysis showed that the diversity between cells are large in undifferentiated ESC and in mesenchymal stem cells compared with terminally differentiated cells, implying that the cell state in stem cells stochastically fluctuates during the self-renewal process. The present study strongly indicates that Raman spectral morphology, in combination with PCA, can be used to establish cells' fingerprints, which can be useful for distinguishing and identifying different cellular states.

  16. Raman, IR and DFT studies of mechanism of sodium binding to urea catalyst

    Science.gov (United States)

    Kundu, Partha P.; Kumari, Gayatri; Chittoory, Arjun K.; Rajaram, Sridhar; Narayana, Chandrabhas

    2015-12-01

    Bis-camphorsulfonyl urea, a newly developed hydrogen bonding catalyst, was evaluated in an enantioselective Friedel-Crafts reaction. We observed that complexation of the sulfonyl urea with a sodium cation enhanced the selectivity of reactions in comparison to reactions performed with urea alone. To understand the role of sodium cation, we performed Infrared and Raman spectroscopic studies. The detailed band assignment of the molecule was made by calculating spectra using Density Functional theory. Our studies suggest that the binding of the cation takes place through the oxygen atoms of carbonyl and sulfonyl groups. Natural Bond Orbital (NBO) analysis shows the expected charge distribution after sodium binding. The changes in the geometrical parameter and charge distribution are in line with the experimentally observed spectral changes. Based on these studies, we conclude that binding of the sodium cation changes the conformation of the sulfonyl urea to bring the chiral camphor groups closer to the incipient chiral center.

  17. An ultraviolet resonance Raman study of dehydrogenase enzymes and their interactions with coenzymes and substrates.

    Science.gov (United States)

    Austin, J C; Wharton, C W; Hester, R E

    1989-02-21

    Ultraviolet resonance Raman (UVRR) spectra, with 260-nm excitation, are reported for oxidized and reduced nicotinamide adenine dinucleotides (NAD+ and NADH, respectively). Corresponding spectra are reported for these coenzymes when bound to the enzymes glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and liver and yeast alcohol dehydrogenases (LADH and YADH). The observed differences between the coenzyme spectra are interpreted in terms of conformation, hydrogen bonding, and general environment polarity differences between bound and free coenzymes and between coenzymes bound to different enzymes. The possibility of adenine protonation is discussed. UVRR spectra with 220-nm excitation also are reported for holo- and apo-GAPDH (GAPDH-NAD+ and GAPDH alone, respectively). In contrast with the 260-nm spectra, these show only bands due to vibrations of aromatic amino acid residues of the protein. The binding of coenzyme to GAPDH has no significant effect on the aromatic amino acid bands observed. This result is discussed in the light of the known structural change of GAPDH on binding coenzyme. Finally, UVRR spectra with 240-nm excitation are reported for GAPDH and an enzyme-substrate intermediate of GAPDH. Perturbations are reported for tyrosine and tryptophan bands on forming the acyl enzyme.

  18. Surface-Enhanced Raman Spectroscopy for Heterogeneous Catalysis Research

    NARCIS (Netherlands)

    Harvey, C.E.

    2013-01-01

    Raman spectroscopy is valuable characterization technique for the chemical analysis of heterogeneous catalysts, both under ex-situ and in-situ conditions. The potential for Raman to shine light on the chemical bonds present in a sample makes the method highly desirable for detailed catalyst characte

  19. Raman and mid-infrared spectroscopic imaging: applications and advancements

    NARCIS (Netherlands)

    Gautam, R.; Samuel, A.; Sil, S.; Chaturvedi, D.; Dutta, A.; Ariese, F.; Umapathy, S.

    2015-01-01

    Using Raman and Mid-Infrared (MIR) spectroscopic imaging techniques one can examine the spatial distribution of various molecular constituents in a heterogeneous sample at a microscopic scale. Raman and MIR spectroscopy techniques provide bond-specific vibrational frequencies to characterize molecul

  20. On surface Raman scattering and luminescence radiation in boron carbide.

    Science.gov (United States)

    Werheit, H; Filipov, V; Schwarz, U; Armbrüster, M; Leithe-Jasper, A; Tanaka, T; Shalamberidze, S O

    2010-02-01

    The discrepancy between Raman spectra of boron carbide obtained by Fourier transform Raman and conventional Raman spectrometry is systematically investigated. While at photon energies below the exciton energy (1.560 eV), Raman scattering of bulk phonons of boron carbide occurs, photon energies exceeding the fundamental absorption edge (2.09 eV) evoke additional patterns, which may essentially be attributed to luminescence or to the excitation of Raman-active processes in the surface region. The reason for this is the very high fundamental absorption in boron carbide inducing a very small penetration depth of the exciting laser radiation. Raman excitations essentially restricted to the boron carbide surface region yield spectra which considerably differ from bulk phonon ones, thus indicating structural modifications.

  1. Effect of nonstoichiometry on Raman scattering of VO2 films

    Institute of Scientific and Technical Information of China (English)

    Yuan Hong-Tao; Feng Ke-Cheng; Wang Xue-Jin; Li Chao; He Chen-Juan; Nie Yu-Xin

    2004-01-01

    @@ We report on Raman scattering of VO2 films prepared by radio frequency magnetron sputtering under different conditions. Our investigations revealed that the dominated Raman peaks shift towards high frequency for both V-rich and O-rich VO2 films, compared with the stoichiometry VO2 films. The experimental evidence is presented and the cause for nonstoichiometry dependence of Raman spectra of VO2 films is discussed.

  2. Single-Molecule Surface-Enhanced Raman Scattering Spectrum of Non-Resonant Aromatic Amine Showing Raman Forbidden Bands

    CERN Document Server

    Yamamoto, Yuko S; Ozaki, Yukihiro; Zhang, Zhenglong; Kozu, Tomomi; Itoh, Tamitake; Nakanishi, Shunsuke

    2016-01-01

    We present the experimentally obtained single-molecule (SM) surface-enhanced Raman scattering (SERS) spectrum of 4-aminibenzenethiol (4-ABT), also known as para-aminothiophenol (PATP). Measured at a 4-ABT concentration of 8 * 10^-10 M, the spectra show Raman forbidden modes. The SM-SERS spectrum of 4-ABT obtained using a non-resonant visible laser is different from the previously reported SERS spectra of 4-ABT, and could not be reconstructed using quantum mechanical calculations. Careful classical assignments (not based on quantum-mechanical calculations) are reported, and indicate that differences in the reported spectra of 4-ABT are mainly due to the appearance of Raman forbidden bands. The presence of Raman forbidden bands can be explained by the charge-transfer (CT) effect of 4-ABT adsorbed on the silver nanostructures, indicating a breakdown of Raman selection rules at the SERS hotspot.

  3. Study of Density Functional Theory for Surface-Enhanced Raman Spectra of Furfural%糠醛分子表面增强拉曼光谱的密度泛函理论研究

    Institute of Scientific and Technical Information of China (English)

    陈艳; 陈善俊; 易早; 罗江山; 易有根; 唐永建

    2012-01-01

    采用密度泛函理论(density functional theory,DFT),在B3LYP/6-31+G** (C,H,O)/LANL2DZ(Ag)水平上,对糠醛(furfural,FUR)分子进行了几何结构优化,并计算了FUR分子的常规拉曼散射(normal Raman scattering,NRS)光谱和FUR与Ag原子以及Ag2和Ag4团簇吸附的表面增强拉曼散射(surface-enhanced Raman scattering,SERS)光谱.结果表明,理论值与已有的实验值符合得较好,采用FUR-Ag4吸附构型的计算结果比FUR-Ag和FUR-Ag2吸附构型的计算结果更符合已有实验值.最后,通过Gauss View可视化软件,对FUR分子的振动频率进行了更为全面地归属.通过FUR分子SERS与NRS的比较,可得出FUR分子与Ag原子发生了相互作用,且被吸附的糠醛分子的杂五环是与银表面垂直的.%In the present paper, DFT method at the B3LYP/6-31+G" * (C, H, O)/LANL2DZ(Ag) level was used to optimize molecular configurations of furfural. Based on the optimized structure, the normal Raman spectrum (NRS) of FUR and the surface-enhanced Raman spectrum (SERS) of FUR adsorbed on Ag, Ag2 and Ag4 were all calculated, which were compared with the experimental values. The calculation results indicated that a good conformity was found between the computed and the experimental results. The results of furfural adsorbed on Ag4 were more approximate to the ever reported experimental date than those of furfural adsorbed on Ag and Ag2. At the end, detailed analysis of the Raman spectrum and more comprehensive assignments of the vibration mode for furfural were studied by the software of Gauss View. The data of the SERS by comparing with the one of NRS show that furfural molecule and Ag atoms interact with each other. And we suppose that the molecular plane with the ring of adsorbed furfural molecule is vertically orientated to the silver surface. The work in this paper offers a theory evidence for detection and trace analysis of drinks containing furfural.

  4. Simultaneous Spectral Temporal Adaptive Raman Spectrometer - SSTARS

    Science.gov (United States)

    Blacksberg, Jordana

    2010-01-01

    Raman spectroscopy is a prime candidate for the next generation of planetary instruments, as it addresses the primary goal of mineralogical analysis, which is structure and composition. However, large fluorescence return from many mineral samples under visible light excitation can render Raman spectra unattainable. Using the described approach, Raman and fluorescence, which occur on different time scales, can be simultaneously obtained from mineral samples using a compact instrument in a planetary environment. This new approach is taken based on the use of time-resolved spectroscopy for removing the fluorescence background from Raman spectra in the laboratory. In the SSTARS instrument, a visible excitation source (a green, pulsed laser) is used to generate Raman and fluorescence signals in a mineral sample. A spectral notch filter eliminates the directly reflected beam. A grating then disperses the signal spectrally, and a streak camera provides temporal resolution. The output of the streak camera is imaged on the CCD (charge-coupled device), and the data are read out electronically. By adjusting the sweep speed of the streak camera, anywhere from picoseconds to milliseconds, it is possible to resolve Raman spectra from numerous fluorescence spectra in the same sample. The key features of SSTARS include a compact streak tube capable of picosecond time resolution for collection of simultaneous spectral and temporal information, adaptive streak tube electronics that can rapidly change from one sweep rate to another over ranges of picoseconds to milliseconds, enabling collection of both Raman and fluorescence signatures versus time and wavelength, and Synchroscan integration that allows for a compact, low-power laser without compromising ultimate sensitivity.

  5. Raman scattering or fluorescence emission? Raman spectroscopy study on lime-based building and conservation materials.

    Science.gov (United States)

    Kaszowska, Zofia; Malek, Kamilla; Staniszewska-Slezak, Emilia; Niedzielska, Karina

    2016-12-01

    This work presents an in-depth study on Raman spectra excited with 1064 and 532nm lasers of lime binders employed in the past as building materials and revealed today as valuable conservation materials. We focus our interest on the bands of strong intensity, which are present in the spectra of all binders acquired with laser excitation at 1064nm, but absent in the corresponding spectra acquired with laser excitation at 532nm. We suggest, that the first group of spectra represents fluorescence phenomena of unknown origin and the second true Raman scattering. In our studies, we also include two other phases of lime cycle, i.e. calcium carbonate (a few samples of calcite of various origins) and calcium oxide (quicklime) to assess how structural and chemical transformations of lime phases affect the NIR-Raman spectral profile. Furthermore, we analyse a set of carbonated limewashes and lime binders derived from old plasters to give an insight into their spectral characteristics after excitation with the 1064nm laser line. NIR-Raman micro-mapping results are also presented to reveal the spatial distribution of building materials and fluorescent species in the cross-section of plaster samples taken from a 15th century chapel. Our study shows that the Raman analysis can help identify lime-based building and conservation materials, however, a caution is advised in the interpretation of the spectra acquired using 1064nm excitation. PMID:27314909

  6. Vibrational spectra of 3,5-diamino-6-chloro-N-(diaminomethylene) pyrazine-2-carboxamide: Combined experimental and theoretical studies

    Science.gov (United States)

    Sakthivel, S.; Alagesan, T.; Al-Saadi, Abdulaziz A.; Renuga, S.; Muthu, S.

    2014-06-01

    In this work, the vibrational spectral analysis of 3,5-diamino-6-chloro-N-(diaminomethylene)pyrazine-2-carboxamide(3DCNDPC) was carried out using FT-Raman and FT-IR spectroscopy in the range 4000-50 cm-1 and 4000-500 cm-1 respectively. The experimental spectra were recorded in the solid phase. The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT) B3LYP with the standard basis set 6-311++G(d,p). The optimized geometric parameters (bond lengths and bond angles) were compared with experimental values. Normal co-ordinate calculations were performed with the DFT force field corrected by a recommended set of scaling factors yielding fairly good agreement between observed and calculated frequencies. Simulation of infrared and Raman spectra utilizing the results of these calculations led to excellent overall agreement with the observed spectral patterns. The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The stability of the molecule arising from hyper conjugative interactions and the charge delocalization has been analyzed by using Natural Bond Orbital (NBO) analysis. UV-Vis spectrum of the compound was recorded. The calculated HOMO and LUMO energies show that chemical activity of the molecule.

  7. Electron paramagnetic resonance and Raman spectroscopy studies on carbon-doped MgB{sub 2} superconductor nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Bateni, Ali; Somer, Mehmet, E-mail: emre.erdem@physchem.uni-freiburg.de, E-mail: msomer@ku.edu.tr [Department of Chemistry, Koc University, RumelifeneriYolu, Sariyer, Istanbul (Turkey); Erdem, Emre, E-mail: emre.erdem@physchem.uni-freiburg.de, E-mail: msomer@ku.edu.tr; Repp, Sergej; Weber, Stefan [Institut für Physikalische Chemie, Universität Freiburg, Albertstr. 21, 79104 Freiburg (Germany); Acar, Selcuk; Kokal, Ilkin [Pavezyum Kimya Sanayi Dış Ticaret LTD. ŞTI., Tuzla, Istanbul (Turkey); Häßler, Wolfgang [Leibniz Institute for Solid State and Materials Research Dresden (IFW), P.O. Box 270116, 01171 Dresden (Germany)

    2015-04-21

    Undoped and carbon-doped magnesium diboride (MgB{sub 2}) samples were synthesized using two sets of mixtures prepared from the precursors, amorphous nanoboron, and as-received amorphous carbon-doped nanoboron. The microscopic defect structures of carbon-doped MgB{sub 2} samples were systematically investigated using X-ray powder diffraction, Raman and electron paramagnetic resonance spectroscopy. Mg vacancies and C-related dangling-bond active centers could be distinguished, and sp{sup 3}-hybridized carbon radicals were detected. A strong reduction in the critical temperature T{sub c} was observed due to defects and crystal distortion. The symmetry effect of the latter is also reflected on the vibrational modes in the Raman spectra.

  8. Identification of bacteria in drinking water with Raman spectroscopy

    NARCIS (Netherlands)

    van de Vossenberg, J.; Tervahauta, H.; Maquelin, K.; Blokker-Koopmans, C.H.W.; Uytewaal-Aaarts, M.; Kooij, D.; van Wezel, A.P.; van der Gaag, B.

    2013-01-01

    Raman spectroscopy was used to discriminate between Legionella strains and between E. coli and coliform strains. The relationship between triplicate Raman spectra derived from Legionella bacteria was compared with that derived from a blind set of samples and amplified fragment length polymorphism (A

  9. In and ex vivo breast disease study by Raman spectroscopy

    DEFF Research Database (Denmark)

    Raniero, L.; Canevari, R. A.; Ramalho, L. N. Z.;

    2011-01-01

    (with skin) and skin-removed tissues. To identify the spectral differences between normal and cancer breast tissue, the paired t-test was carried out for each wavenumber using the whole spectral range from both groups. Quadratic discriminate analysis based on principal component analysis (PCA) was also...... used to determine and evaluate differences in the Raman spectra for the various samples as a basis for diagnostic purposes. The differences in the Raman spectra of the samples were due to biochemical changes at the molecular, cellular and tissue levels. The sensitivity and specificity...... of the classification scheme based on the differences in the Raman spectra obtained by PCA were evaluated using the receiver operating characteristic (ROC) curve. The in vivo transcutaneous normal and abnormal tissues were correctly classified based on their measured Raman spectra with a discriminant proportion of 73...

  10. Monitoring defect-induced perturbations of the ideal crystal structure of ZnO and Cu2O by Raman spectroscopy

    OpenAIRE

    Sander, Thomas

    2015-01-01

    Deviations from the ideal crystal structure, i.e., intrinsic or extrinsic defects, modify the dynamics of a crystalline lattice among many other material properties. As a consequence, additional modes may occur in Raman spectra, Raman-forbidden modes may become Raman active, and the shape as well as the position in the frequency of the Raman signals may change. The impacts of perturbations of the ideal crystal structure on Raman spectra are addressed within the framework of this thesis. Cr...

  11. Cavity-enhanced Raman Microscopy of Individual Carbon Nanotubes

    CERN Document Server

    Hümmer, Thomas; Hofmann, Matthias S; Hänsch, Theodor W; Högele, Alexander; Hunger, David

    2015-01-01

    Raman spectroscopy reveals chemically specific information, and combined with imaging provides label-free insight into the molecular world. However, the signals are intrinsically weak and call for enhancement techniques. Here we use a tunable high-finesse optical microcavity to demonstrate Purcell enhancement of Raman scattering in combination with high-resolution scanning-cavity imaging. We detect cavity-enhanced Raman spectra of individual single-walled carbon nanotubes, expand the technique to hyperspectral imaging, and co-localize measurements with cavity-enhanced absorption microscopy. Direct comparison with confocal Raman microscopy yields a 550-times enhanced collectable Raman scattering spectral density and a 11-fold enhancement of the integrated count rate. The quantitative character, the inherent spectral filtering, and the absence of intrinsic background in cavity-vacuum stimulated Raman scattering renders our technique a promising tool for molecular imaging. Furthermore, cavity-enhanced Raman tran...

  12. MicroRaman Spectroscopy and Raman Imaging of Basal Cell Carcinoma

    Science.gov (United States)

    Short, M. A.; Zeng, H.; Lui, H.

    2005-03-01

    We have measured the Raman spectra of normal and cancerous skin tissues using a confocal microRaman spectrograph with a sub-micron spatial resolution. We found that the Raman spectrum of a cell nucleolus is different from the spectra measured outside the nucleolus and considerably different from those measured outside the nucleus. In addition, we found significant spectroscopic differences between normal and cancer-bearing sites in the dermis region. In order to utilize these differences for non-invasive skin cancer diagnosis, we have developed a Raman imaging system that clearly demonstrates the structure, location and distribution of cells in unstained skin biopsy samples. Our method is expected to be useful for the detection and characterization of skin cancer based on the known distinct cellular differences between normal and malignant skin.

  13. COMBINED RAMAN AND SEM STUDY ON CAF2 FORMED ON/IN ENAMEL BY APF TREATMENTS

    NARCIS (Netherlands)

    TSUDA, H; JONGEBLOED, WL; STOKROOS, [No Value; ARENDS, J

    1993-01-01

    Raman spectra containing the distinct band at 322 cm(-1) due to CaF2 or CaF2-like material formed in/on fluoridated bovine enamel were recorded using a micro-Raman spectrograph. Due to increasing levels of background fluorescence with increasing thickness of enamel, the Raman measurements were carri

  14. Raman microspectroscopy of fixed rabbit and human lenses and lens slices: New potentialities

    NARCIS (Netherlands)

    Bot, Annet C.C.; Huizinga, Alex; Mul, de Frits F.M.; Vrensen, Gijs F.J.M.; Greve, Jan

    1989-01-01

    Raman spectroscopy is a non-invasive, non-destructive technique for the study of the macromolecular composition of tissues. Raman spectra were obtained from intact fresh and paraformaldehyde fixed rabbit lenses and from thin slices prepared from these lenses. In addition the Raman spectrum of an int

  15. Local variation in absolute water content of human and rabbit eye lenses measured by Raman microspectroscopy

    NARCIS (Netherlands)

    Huizinga, Alex; Bot, Annet C.C.; Mul, de Frits F.M.; Vrensen, Gijs F.J.M.; Greve, Jan

    1989-01-01

    Raman spectra were obtained from fresh, fixed and sliced rabbit lenses and from human lens slices. For all lenses and lens slices the ratio R, defined as the Raman intensity at 3390 cm−1 divided by the Raman intensity at 2935 cm−1, was measured at different locations along the visual and equatorial

  16. Electronic Raman Scattering in Graphene

    Institute of Scientific and Technical Information of China (English)

    LU Hong-Yan; WANG Qiang-Hua

    2008-01-01

    Linear dispersion near the Dirac points in the band structure of graphenes can give rise to novel physical properties.We calculate the electronic contribution to the Raman spectra in graphenes, which also shows novel features.In the clean limit, the Raman spectrum in the undoped graphene is linear (with a universal slope against impurity scattering) at low energy due to the linear dispersion near the Dirac points, and it peaks at a position corresponding to the van Hove singularity in the band structure. In a doped graphene, the electronic Raman absorption is forbidden up to a vertical inter-band particle-hole gap. Beyond the gap the spectrum follows the undoped case. In the presence of impurities, absorption within the gap (in the otherwise clean case) is induced, which is identified as the intra-band contribution. The Drude-like intra-band contribution is seen to be comparable to the higher energy inter-band Raman peak. The results are discussed in connection to experiments.

  17. In vivo Coherent Raman Imaging for Neuroscience Applications

    Science.gov (United States)

    Cote, Daniel

    2010-08-01

    The use of coherent Raman imaging is described for applications in neuroscience. Myelin imaging of the spinal cord can be performed with Raman imaging through the use of the vibration in carbon-hydrogen bonds, dominant in lipids. First, we demonstrate in vivo histomorphometry in live animal for characterization of myelin-related nervous system pathologies. This is used to characterize spinal cord health during multiple sclerosis. Second, Raman spectroscopy of tissue is discussed. We discuss the challenges that live animal imaging brings, together with important aspects of coherent Raman imaging in tissue.

  18. Raman and surface-enhanced Raman spectroscopy for renal condition monitoring

    Science.gov (United States)

    Li, Jingting; Li, Ming; Du, Yong; Santos, Greggy M.; Mohan, Chandra; Shih, Wei-Chuan

    2016-03-01

    Non- and minimally-invasive techniques can provide advantages in the monitoring and clinical diagnostics in renal diseases. Although renal biopsy may be useful in establishing diagnosis in several diseases, it is an invasive approach and impractical for longitudinal disease monitoring. To address this unmet need, we have developed two techniques based on Raman spectroscopy. First, we have investigated the potential of diagnosing and staging nephritis by analyzing kidney tissue Raman spectra using multivariate techniques. Secondly, we have developed a urine creatinine sensor based on surface-enhanced Raman spectroscopy with performance near commercial assays which require relatively laborious sample preparation and longer time.

  19. Spectroscopic, electronic structure and natural bond analysis of 2-aminopyrimidine and 4-aminopyrazolo[3,4-d]pyrimidine: A comparative study

    Science.gov (United States)

    Prabavathi, N.; Nilufer, A.; Krishnakumar, V.; Akilandeswari, L.

    2012-10-01

    The FTIR and FT-Raman spectra of 2-aminopyrimidine (2-AP) and 4-aminopyrazolo[3,4-d]pyrimidine (4-APP) has been recorded in the region 4000-400 and 3500-100 cm-1, respectively. The tautomeric stability, optimized geometry, frequency and intensity of the vibrational bands of 2-AP and 4-APP were obtained by the DFT level using 6-31G(d) and 6-31G(d,p) basis sets. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FTIR and FT-Raman spectra. A detailed interpretation of the infrared and Raman spectra of 2-AP and 4-APP are also reported based on total energy distribution (TED). The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically simulated spectra. The 1H and 13C NMR spectra have been simulated using the gauge independent atomic orbital (GIAO) method. The theoretical UV-Vis spectrum of the compound using CIS method and 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 molecule. The first order hyperpolarizability (β0) of these novel molecular system and related properties (β, α0 and Δα) of 2-AP and 4-APP are calculated using DFT/6-31G(d) method on the finite-field approach. The Mulliken charges, the values of electric dipole moment (μ) of the molecule were computed using DFT calculations. The change in electron density (ED) in the σ∗ antibonding orbitals and stabilization energies E(2) have been calculated by natural bond (NBO) analysis to give clear evidence of stabilization originating in the hyper conjugation of hydrogen-bonded interactions.

  20. Hydrogen bonding and solution state structure of salicylaldehyde-4-phenylthiosemicarbazone: A combined experimental and theoretical study

    Science.gov (United States)

    Novak, Predrag; Pičuljan, Katarina; Hrenar, Tomica; Biljan, Tomislav; Meić, Zlatko

    2009-02-01

    Hydrogen bonding in salicylaldehyde-4-phenylthiosemicarbazone ( 1) has been studied by using experimental (NMR, Raman and UV spectroscopies) and quantum chemical (DFT) methods. It has been demonstrated that 1 adopted the hydroxy-thione tautomeric form in solution as found also in the solid state and previously indicated by secondary deuterium isotope effects. Apart from the intra-molecular hydrogen bonds new interactions between 1 and solvent molecules were formed as well. Changes in NMR chemical shifts and calculations have pointed towards a formation of inter-molecular three-centered hydrogen bonds in each of the studied complexes involving OH and NH groups of 1 and associated solvent molecules. Stabilization energies of intra-molecular hydrogen bonds were found to decrease with the increase of the solvent polarity. Two-dimensional NOESY spectra indicated conformational changes in solution with respect to the structure observed in the solid state. These were accounted for by a relatively low barrier of the rotation of the N sbnd N single bond thus enabling a molecule to posses a higher conformational flexibility in solution with portions of skewed conformations. The results presented here can help in a better understanding of the role hydrogen bonds can play in bioactivity of related thiosemicarbazone derivatives and their metal complexes.

  1. Raman tweezers spectroscopy of live, single red and white blood cells.

    Directory of Open Access Journals (Sweden)

    Aseefhali Bankapur

    Full Text Available An optical trap has been combined with a Raman spectrometer to make high-resolution measurements of Raman spectra of optically-immobilized, single, live red (RBC and white blood cells (WBC under physiological conditions. Tightly-focused, near infrared wavelength light (1064 nm is utilized for trapping of single cells and 785 nm light is used for Raman excitation at low levels of incident power (few mW. Raman spectra of RBC recorded using this high-sensitivity, dual-wavelength apparatus has enabled identification of several additional lines; the hitherto-unreported lines originate purely from hemoglobin molecules. Raman spectra of single granulocytes and lymphocytes are interpreted on the basis of standard protein and nucleic acid vibrational spectroscopy data. The richness of the measured spectrum illustrates that Raman studies of live cells in suspension are more informative than conventional micro-Raman studies where the cells are chemically bound to a glass cover slip.

  2. Mobile Raman spectroscopy in astrobiology research.

    Science.gov (United States)

    Vandenabeele, Peter; Jehlička, Jan

    2014-12-13

    Raman spectroscopy has proved to be a very useful technique in astrobiology research. Especially, working with mobile instrumentation during fieldwork can provide useful experiences in this field. In this work, we provide an overview of some important aspects of this research and, apart from defining different types of mobile Raman spectrometers, we highlight different reasons for this research. These include gathering experience and testing of mobile instruments, the selection of target molecules and to develop optimal data processing techniques for the identification of the spectra. We also identify the analytical techniques that it would be most appropriate to combine with Raman spectroscopy to maximize the obtained information and the synergy that exists with Raman spectroscopy research in other research areas, such as archaeometry and forensics.

  3. Raman microspectroscopic study of biomolecular structure inside living adhesive cells

    Institute of Scientific and Technical Information of China (English)

    LI; Guang; (李光); YANG; Hongying(杨红英); XU; Yiming; (许以明); ZHANG; Zhiyi(张志义)

    2002-01-01

    Cells adhesion is very important for many physiological processes. Using advanced Raman microspectroscopic technique, we selected T Leukemia cells (Jurkat) as the materials and obtained simultaneously conformation information of various biomolecules inside the whole living cells. By comparing the Raman microspectroscopic spectra of single and adhesive cancer cells, we found for the first time that when cells adhered, the conformation of the biomolecules (DNA, protein, carbohydrates and lipids) inside the cells had different changes: (i) the backbone of double-stranded DNA maintained orderly B-form or modified B-form conformation, whereas the groups of its deoxyribose and bases were modified; (ii) the conformational changes of the main chain and the side chain in the protein were obviously variant. The lines intensity belonging to α-helix andβ-sheet decreased, while that ofβ-turn increased. Tyrosine and tryptophane residues of the protein changed from "buried state" to "exposed state"; the lines intensity of its sulfhydryl group also increased; the conformation of its disulfide bond changed from two kinds to three kinds. These facts suggest that the cells adhesion causes changes in H-bonds organization of the main chain and environment of the side chain in the protein; (iii) the groups of the carbohydrates were also modified simultaneously; (iv) the conformation of the lipids bilayers of the membranes changed obviously; the order parameter for lateral interaction between chains decreased gradually with the increase of number of the adhesive cells. So cells adhesion resulted in an increase in fluidity of the membrane and ion permeability on the membrane.

  4. Surface enhanced Raman optical activity (SEROA)

    DEFF Research Database (Denmark)

    Abdali, Salim; Blanch, E.W.

    2008-01-01

    Raman optical activity (ROA) directly monitors the stereochemistry of chiral molecules and is now an incisive probe of biomolecular structure. ROA spectra contain a wealth of information on tertiary folding, secondary structure and even the orientation of individual residues in proteins and nucle...

  5. Resonance raman studies of phenylcyclopropane radical cations

    NARCIS (Netherlands)

    Godbout, J.T.; Zuilhof, H.; Heim, G.; Gould, I.R.; Goodman, J.L.; Dinnocenzo, J.P.; Myers Kelley, A.

    2000-01-01

    Resonance Raman spectra of the radical cations of phenylcyclopropane and trans-1-phenyl-2-methylcyclopropane are reported. A near-UV pump pulse excites a photosensitizer which oxidizes the species of interest, and a visible probe pulse delayed by 35 ns obtains the spectrum of the radical ion. The tr

  6. Raman Spectroscopy for Analysis of Thorium Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Su, Yin-Fong; Johnson, Timothy J.; Olsen, Khris B.

    2016-05-12

    The thorium fuel cycle is an alternative to the uranium fuel cycle in that when 232Th is irradiated with neutrons it is converted to 233U, another fissile isotope. There are several chemical forms of thorium which are used in the Th fuel cycle. Recently, Raman spectroscopy has become a very portable and facile analytical technique useful for many applications, including e.g. determining the chemical composition of different materials such as for thorium compounds. The technique continues to improve with the development of ever-more sensitive instrumentation and better software. Using a laboratory Fourier-transform (FT)-Raman spectrometer with a 785 nm wavelength laser, we were able to obtain Raman spectra from a series of thorium-bearing compounds of unknown origin. These spectra were compared to the spectra of in-stock-laboratory thorium compounds including ThO2, ThF4, Th(CO3)2 and Th(C2O4)2. The unknown spectra showed very good agreement to the known standards, demonstrating the applicability of Raman spectroscopy for detection and identification of these nuclear materials.

  7. Raman spectroscopy for analysis of thorium compounds

    Science.gov (United States)

    Su, Yin-Fong; Johnson, Timothy J.; Olsen, Khris B.

    2016-05-01

    The thorium fuel cycle is an alternative to the uranium fuel cycle in that when 232Th is irradiated with neutrons it is converted to 233U, another fissile isotope. There are several chemical forms of thorium which are used in the Th fuel cycle. Recently, Raman spectroscopy has become a very portable and facile analytical technique useful for many applications, including e.g. determining the chemical composition of different materials such as for thorium compounds. The technique continues to improve with the development of ever-more sensitive instrumentation and better software. Using a laboratory Fourier-transform (FT)-Raman spectrometer with a 785 nm wavelength laser, we were able to obtain Raman spectra from a series of thorium-bearing compounds of unknown origin. These spectra were compared to the spectra of in-stock-laboratory thorium compounds including e.g. ThO2, ThF4, Th(CO3)2 and Th(C2O4)2. The unknown spectra showed very good agreement to the known standards, demonstrating the applicability of Raman spectroscopy for detection and identification of these nuclear materials.

  8. A combined Raman- and infrared jet study of mixed methanol-water and ethanol-water clusters.

    Science.gov (United States)

    Nedić, Marija; Wassermann, Tobias N; Larsen, René Wugt; Suhm, Martin A

    2011-08-21

    The vibrational dynamics of vacuum-isolated hydrogen-bonded complexes between water and the two simplest alcohols is characterized at low temperatures by Raman and FTIR spectroscopy. Conformational preferences during adaptive aggregation, relative donor/acceptor strengths, weak secondary hydrogen bonding, tunneling processes in acceptor lone pair switching, and thermodynamic anomalies are elucidated. The ground state tunneling splitting of the methanol-water dimer is predicted to be larger than 2.5 cm(-1). Two types of alcohol-water trimers are identified from the spectra. It is shown that methanol and ethanol are better hydrogen bond donors than water, but even more so better hydrogen bond acceptors. As a consequence, hydrogen bond induced red shifts of OH modes behave non-linearly as a function of composition and the resulting cluster excess quantities correspond nicely to bulk excess enthalpies at room temperature. The effects of weak C-H···O hydrogen bonds are quantified in the case of mixed ethanol-water dimers. PMID:21491035

  9. Raman spectroscopic identification of normal and malignant hepatocytes

    Institute of Scientific and Technical Information of China (English)

    Jianyu Guo; Bing Du; Min Qian; Weiying Cai; Zugeng Wang; Zhenrong Sun

    2009-01-01

    Raman spectroscopy has strong potential for providing non-invasion diagnosis of cancers. In this paper, micro-Raman spectroscopy is used to diagnose one most common liver cancer, hepatocellular carcinoma (HCC). The statistical analyzes, including i-test, principal component analysis (PCA), and linear discrim inant analysis (LDA), are performed on the Raman spectra of malignant and normal hepatocytes. The t-test-LDA results show that the 786- and 1004-cm-1 bands of the malignant and normal hepatocytes are significantly different, and PCA-LDA results show an overall accuracy of 100% for the Raman spectro scopic identification of normal and malignant hepatocytes in our experiment.

  10. L-glutamine: Dynamical properties investigation by means of INS, IR, RAMAN, 1H NMR and DFT techniques

    Science.gov (United States)

    Pawlukojć, A.; Hołderna-Natkaniec, K.; Bator, G.; Natkaniec, I.

    2014-10-01

    Vibrational spectra of L-glutamine in the solid state were studied using the inelastic neutron scattering (INS), infrared (IR), Raman and 1H NMR spectroscopy techniques. DFT calculation using CASTEP code with the periodic boundary conditions was used to determine and describe the normal modes in the vibrational spectra of pure L-glutamine. An excellent agreement between the calculated and experimental INS, IR and Raman data has been found. Bands assigned to the stretching vibrations of the NH3+ group in hydrogen bonds are observed at 2400, 2618 and 2619 cm-1, while the NH3+ torsion vibration mode is observed at 441 cm-1. The band at 2041 cm-1 is assigned to combinations of the NH3+ bending symmetry vibration and the CO2- rocking vibration and can be used as an "indicator band" for the identification of the NH3+ groups in amino acid. For the L-glutamine an activation energy needed for the NH3+ group reorientation was obtained as 7.4 kcal/mol. It was found, that the combination three spectroscopic methods (INS, IR and Raman) with calculations for the crystal state proved to be an effective tool to investigate dynamical properties of amino acid crystals.

  11. Single-shot Raman spectroscopy and time-resolved reflectivity of a shocked TATB-based explosive

    Science.gov (United States)

    Hebert, Philippe; Saint-Amans, Charles; Doucet, Michel; de Resseguier, Thibaut

    2015-06-01

    Single-shot Raman spectroscopy experiments under shockwave loading were performed in order to get information on the initiation mechanisms that can lead to sustained detonation of a TATB-based explosive. Shocks up to 30 GPa were generated using a two-stage laser-driven flyer plate generator. The samples were confined by an optical window and shock pressure was maintained for at least 30 ns. Photon Doppler Velocimetry measurements were performed at the explosive/window interface to determine the shock pressure profile. Raman spectra were recorded as a function of shock pressure and the shifts of the principal modes were compared to static high-pressure measurements performed in a diamond anvil cell. Our shock data indicate the role of temperature effects on the H-bonding network present in TATB. Our Raman spectra also show a progressive extinction of the signal which disappears around 9 GPa. High-speed photography images reveal a simultaneous progressive darkening of the sample surface up to total opacity at 9 GPa. Time-resolved reflectivity measurements under shock compression seem to indicate that this opacity is due to a broadening of the absorption spectrum over the entire visible region.

  12. L-glutamine: Dynamical properties investigation by means of INS, IR, RAMAN, {sup 1}H NMR and DFT techniques

    Energy Technology Data Exchange (ETDEWEB)

    Pawlukojć, A., E-mail: andrzej@jinr.ru [Institute of Nuclear Chemistry and Technology, Dorodna 16 str., 03-195 Warsaw (Poland); Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Hołderna-Natkaniec, K. [Faculty of Physics, A. Mickiewicz University, 61-614 Poznań (Poland); Bator, G. [Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw (Poland); Natkaniec, I. [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Faculty of Physics, A. Mickiewicz University, 61-614 Poznań (Poland)

    2014-10-31

    Graphical abstract: - Highlights: • The L-glutamine was investigated by INS, IR, Raman and {sup 1}H NMR spectroscopy. • DFT calculations for the solids state model were performed. • The NH{sub 3}{sup +} torsional vibration mode is observed in the INS spectra. • Activation energy for the NH{sub 3}{sup +} group reorientation is obtained. - Abstract: Vibrational spectra of L-glutamine in the solid state were studied using the inelastic neutron scattering (INS), infrared (IR), Raman and {sup 1}H NMR spectroscopy techniques. DFT calculation using CASTEP code with the periodic boundary conditions was used to determine and describe the normal modes in the vibrational spectra of pure L-glutamine. An excellent agreement between the calculated and experimental INS, IR and Raman data has been found. Bands assigned to the stretching vibrations of the NH{sub 3}{sup +} group in hydrogen bonds are observed at 2400, 2618 and 2619 cm{sup −1}, while the NH{sub 3}{sup +} torsion vibration mode is observed at 441 cm{sup −1}. The band at 2041 cm{sup −1} is assigned to combinations of the NH{sub 3}{sup +} bending symmetry vibration and the CO{sub 2}{sup -} rocking vibration and can be used as an “indicator band” for the identification of the NH{sub 3}{sup +} groups in amino acid. For the L-glutamine an activation energy needed for the NH{sub 3}{sup +} group reorientation was obtained as 7.4 kcal/mol. It was found, that the combination three spectroscopic methods (INS, IR and Raman) with calculations for the crystal state proved to be an effective tool to investigate dynamical properties of amino acid crystals.

  13. Raman spectroscopic characterization of ZrO2 and yttrium stabilized zirconias

    DEFF Research Database (Denmark)

    Kjerulf-Jensen, N.; Berg, Rolf W.; Poulsen, Finn Willy

    1996-01-01

    forward. The spectral features of the Raman spectra do furthermore not only depend on the phase composition, but also depend on the frequency of the excitation, temperature of experiment and texture/orientation of zirconia crystallites under investigation. These effects are illustrated by Raman spectra...

  14. The spectroscopic (FT-IR, FT-Raman, dispersive Raman and NMR) study of ethyl-6-chloronicotinate molecule by combined density functional theory

    Science.gov (United States)

    Karabacak, Mehmet; Calisir, Zuhre; Kurt, Mustafa; Kose, Etem; Atac, Ahmet

    2016-01-01

    In this study, ethyl-6-chloronicotinate (E-6-ClN) molecule is recorded in the region 4000-400 cm- 1 and 3500-100 cm- 1 (FT-IR, FT-Raman and dispersive Raman, respectively) in the solid phase. 1H and 13C nuclear magnetic resonance (NMR) spectra are recorded in DMSO solution. The structural and spectroscopic data of the molecule are obtained for two possible isomers (S1 and S2) from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule is fully optimized, vibrational spectra are calculated and fundamental vibrations are assigned on the basis of the potential energy distribution (PED) of the vibrational modes. 1H and 13C NMR chemical shifts are calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strengths, wavelengths, HOMO and LUMO energies, are performed by time-dependent density functional theory (TD-DFT). Total and partial density of state and overlap population density of state diagrams analysis are presented for E-6-ClN molecule. Furthermore, frontier molecular orbitals (FMO), molecular electrostatic potential, and thermodynamic features are performed. In addition to these, reduced density gradient of the molecule is performed and discussed. As a conclusion, the calculated results are compared with the experimental spectra of the title compound. The results of the calculations are applied to simulate the vibrational spectra of the molecule, which show excellent agreement with the observed ones. The theoretical and tentative results will give us a detailed description of the structural and physicochemical properties of the molecule. Natural bond orbital analysis is done to have more information stability of the molecule arising from charge delocalization, and to reveal the information regarding charge transfer within the molecules.

  15. Formation of an Ion-Pair Molecule with a Single NH+...Cl- Hydrogen Bond: Raman spectra of 1,1,3,3-Tetramethylguanidinium chloride in the solid state, in solution and in the vapor phase

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Riisager, Anders; Fehrmann, Rasmus

    2008-01-01

    of this compoundscontaining a dimeric ion-pair “molecule”swas investigated in the solid state, in solutions in water and ethanol, and in the vapor phase, based on ab initio molecular orbital density functional theory (DFT)-type calculations with 6-311+G(d,p) basis sets. Calculations on the monomeric [TMGH]+ ion...

  16. Spectral interferometric Implementation with Passive Polarization Optics of Coherent Anti-Stokes Raman Spectroscopy

    OpenAIRE

    Littleton, Bradley; KAVANAGH, THOMAS; Festy, Frederic; Richards, David

    2013-01-01

    We have developed an interferometric implementation of coherent anti-Stokes Raman scattering which enables broadband coherent Raman spectroscopy free from the nonresonant background, with a signal strength proportional to concentration. Spectra encode mode symmetry information into the amplitude response, which can be directly compared to polarized spontaneous Raman spectra. The method requires only passive polarization optics and is suitable for a wide range of laser linewidths and pulse dur...

  17. The evaluation of temporal electronic structures of nonresonant Raman excited virtual state of thiourea

    Institute of Scientific and Technical Information of China (English)

    Fang Chao; Sun Li-Feng

    2011-01-01

    An algorithm has been introduced to calculate molecular bond polarizabilities of thiourea, which supply essential electronic information about the nonresonant Raman excited virtual states.The main dynamical behaviour of the excited virtual states of thiourea is that the Raman excited electrons tend to flow to the N-H bonds and C-N bonds from the S-C bonds because of the electronic repulsion effect. The difference in Raman excited electron relaxation time of thiourea under 514.5-nm and 325-nm excitations has been observed, which quantitatively shows that the Raman scattering process is dependent on the wavelength of the pumping laser. Finally, the distribution of the electrons at the final stage of relaxation is given out through the comparison between the bond electronic densities of the ground states and the bond polarizabilities after deexcitation.

  18. Spectroscopic and bond-topological investigation of interstitial volatiles in beryl from Slovakia

    Science.gov (United States)

    Fridrichová, Jana; Bačík, Peter; Bizovská, Valéria; Libowitzky, Eugen; Škoda, Radek; Uher, Pavel; Ozdín, Daniel; Števko, Martin

    2016-06-01

    Nine beryl samples from Western Carpathians, Slovakia, were investigated by infrared and Raman spectroscopy and differential thermal analysis. Two types of water H2O I and H2O II were detected. Infrared spectroscopy proved the presence of water type I and II in the presence of alkali cations with several bands: (1) symmetric stretching vibration—ν1; (2) antisymmetric stretching mode—ν3; (3) bending vibration—ν2. The presence of singly and doubly coordinated type II water (IIs and IId) was confirmed by single-crystal IR spectroscopy. From Raman spectra a band at 3606 cm-1 was assigned to ν1 of water type I and the range of 3597-3600 cm-1 to water type II. The presence of doubly coordinating water indicates a relatively highly hydrated environment with the presence of alkali ions including Na as the dominant cation coordinated by H2O II. CO2 bands were detected only by single-crystal IR spectroscopy. Thermal analysis proved total water loss in the range of 1.4-2.0 wt% and three main dehydration events. Based on the study of bond-topological arrangements two molecules of H2O IId are each bound with two H···O1 bonds and one Na-OW bond with an angular distortion, and by releasing one H2O molecule more stable H2O IIs is produced. The H2O I molecule is bound only by two equivalent hydrogen bonds. The H2O IIs molecule with a Na-OW bond strength of 0.28 vu and two H···O1 bonds of 0.14 vu without any forced angular distortion is the most stable of all.

  19. Raman spectroscopy of bone metastasis

    Science.gov (United States)

    Esmonde-White, Karen A.; Sottnik, Joseph; Morris, Michael; Keller, Evan

    2012-02-01

    Raman spectroscopy of bone has been used to characterize chemical changes occurring in diseases such as osteoporosis, osteoarthritis and osteomyelitis. Metastasis of cancer into bone causes changes to bone quality that are similar to those observed in osteoporosis, such as decreased bone strength, but with an accelerated timeframe. In particular, osteolytic (bone degrading) lesions in bone metastasis have a marked effect on patient quality of life because of increased risk of fractures, pain, and hypercalcemia. We use Raman spectroscopy to examine bone from two different mouse models of osteolytic bone metastasis. Raman spectroscopy measures physicochemical information which cannot be obtained through standard biochemical and histological measurements. This study was reviewed and approved by the University of Michigan University Committee on the Care and Use of Animals. Two mouse models of prostate cancer bone metastasis, RM1 (n=3) and PC3-luc (n=4) were examined. Tibiae were injected with RM1 or PC3-luc cancer cells, while the contralateral tibiae received a placebo injection for use as controls. After 2 weeks of incubation, the mice were sacrificed and the tibiae were examined by Raman microspectroscopy (λ=785 nm). Spectroscopic markers corresponding to mineral stoichiometry, bone mineralization, and mineral crystallinity were compared in spectra from the cancerous and control tibiae. X-ray imaging of the tibia confirmed extensive osteolysis in the RM1 mice, with tumor invasion into adjoining soft tissue and moderate osteolysis in the PC3-luc mice. Raman spectroscopic markers indicate that osteolytic lesions are less mineralized than normal bone tissue, with an altered mineral stoichiometry and crystallinity.

  20. Raman microspectrometric identification of corrosion products formed on UO2 nuclear fuel during leaching experiments

    International Nuclear Information System (INIS)

    The corrosion of directly disposed spent nuclear fuel by contact with intruding groundwater will alter the physical and chemical properties of this material. Secondary phases which formed during alteration of UO2 surfaces were measured with Raman microspectrometry and the characteristic vibrational spectra of the materials were recorded. U phases were synthesized in hydrothermal autoclave syntheses. A Raman spectral library of UO2 corrosion phases was set up for the identification of unknown products found on altered nuclear fuel samples. In a case study, U peroxide (UO4) was identified by comparison with a natural sample as the main alteration phase by its characteristic O-O Raman vibration at 870 cm-1. The results demonstrate the differentiation between UO2 and its alteration products U(VI) oxyhydroxide and U(VI) peroxide (UO4) on one sample with a relatively quick, non-destructive, spatially resolving measurement method which delivers oxidation state and molecular bonding information. Implications for the analysis of complex heterogenous matrices are discussed

  1. Laser Raman Spectra Study on Co-Mo/Al2 O3 Hydrodesulphurization Catalysts%激光拉曼光谱在加氢脱硫催化剂Co-Mo/Al2 O3中的应用研究

    Institute of Scientific and Technical Information of China (English)

    袁蕙; 徐广通; 齐和日玛; 李会峰; 卢立军; 杨行远; 塔娜

    2014-01-01

    Due to the implementation of more stringent specifications in sulfur content for gasoline ,a deep understanding of the active phase of Co-Mo/Al2 O3 catalysts is necessary to the development of hydrodesulphurization (HDS) catalysts .A series of Co-Mo/Al2 O3 HDS catalysts with different metal loading were studied by laser Raman spectra .The existence form and the con-tent of the active component of the catalyst were obtained by Raman spectra .The result shows that the percentage of characteris-tic Raman bands 940 cm -1 correlates linearly with the HDS selectivity ,which can be used as an experimental evidence for develo-ping industrial selective HDS catalysts .Raman spectra of sulfided catalysts show that the bands of oxidic catalysts at 839 and 940 cm -1 disappeared ,and simultaneously ,the bands of Mo-S at 372 and 408 cm -1 emerged ,which indicate that the oxidic sample is sulfided completely .%为减少汽车尾气排放和提高燃油质量,对催化裂化汽油进行选择性加氢脱硫是生产低硫汽油的重要技术。加氢脱硫催化剂活性金属的存在形态直接关系到催化剂的活性和选择性。利用激光拉曼光谱方法研究了Co-Mo/Al2 O3系加氢脱硫催化剂。通过拉曼峰的归属给出其活性组元的存在形态,合理的分峰给出活性金属各种存在形式的含量及其在载体表面的分散状态,并将表征结果与微反加氢脱硫活性和选择性的评价结果进行了关联分析。结果表明,二维钼多聚物在940 cm -1左右特征峰的百分比与催化剂HDS选择性存在良好的线性关系,940 cm -1处拉曼特征峰的百分比可作为选择性 HDS催化剂制备和改进的实验依据。硫化态样品的激光拉曼表征分析表明,样品经硫化后,氧化态M o物种谱带839和940 cm -1己消失,而在369和405 cm -1位置出现归属于M o-S键的振动谱峰,表明样品已基本完全硫化。这为加氢脱硫催化剂的开发和研究提供了重要实验依据和指导。

  2. Raman study of a work of art fragment

    CERN Document Server

    Scremin, Barbara Federica

    2016-01-01

    The purpose of the present report was the study and identification of an unspecified sample on a work of art by means only of a microscope coupled to a Raman spectrometer. The origin of the fragment was unknown. The Raman spectra on the virgin sample were giving no results because of a deteriorated surface treatment, in spite of the evident blue color identified by microscopic visual inspection. The sample fragmentation and the preparation of a KBr pellet allowed the distribution of the painting layers of the different components on a flat substrate reducing surface effects. Selecting the areas of different color and focusing there it was possible to identify the pigments from their Raman spectra locally acquired by selective excitation. Raman spectra were assigned by comparison with published databases. It was possible to connect Carbon Black and Orange iron oxide, as documented historically, as constituents of Azurite preparatory layer Morellone, according to a technique generally employed to allow the use ...

  3. Bond Issues.

    Science.gov (United States)

    Pollack, Rachel H.

    2000-01-01

    Notes trends toward increased borrowing by colleges and universities and offers guidelines for institutions that are considering issuing bonds to raise money for capital projects. Discussion covers advantages of using bond financing, how use of bonds impacts on traditional fund raising, other cautions and concerns, and some troubling aspects of…

  4. FT-Raman, FT-IR and UV-visible spectral investigations and ab initio computations of anti-epileptic drug: Vigabatrin

    Science.gov (United States)

    Edwin, Bismi; Joe, I. Hubert

    2013-10-01

    Vibrational analysis of anti-epileptic drug vigabatrin, a structural GABA analog was carried out using NIR FT-Raman and FTIR spectroscopic techniques. The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers were studied using density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA.4 program. Vibrational spectra, natural bond orbital analysis and optimized molecular structure show clear evidence for the effect of electron charge transfer on the activity of the molecule. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. The Mulliken population analysis on atomic charges and the HOMO-LUMO energy were also calculated. Good consistency is found between the calculated results and experimental data for the electronic absorption as well as IR and Raman spectra. The blue-shifting of the Csbnd C stretching wavenumber reveals that the vinyl group is actively involved in the conjugation path. The NBO analysis confirms the occurrence of intramolecular hyperconjugative interactions resulting in ICT causing stabilization of the system.

  5. Raman Scattering by Molecular Hydrogen and Nitrogen in Exoplanetary Atmospheres

    CERN Document Server

    Oklopčić, Antonija; Heng, Kevin

    2016-01-01

    An important source of opacity in the atmospheres of exoplanets at short visible and near-UV wavelengths is Rayleigh scattering of light on molecules. It is accompanied by a related, albeit weaker process -- Raman scattering. In this paper, we analyze the signatures of Raman scattering imprinted in the reflected light and the geometric albedo of exoplanets, which could provide valuable information about planetary atmospheres. Raman scattering affects the geometric albedo spectra of planets in two main ways. Firstly, it causes filling-in of strong absorption lines in the incident radiation, thus producing sharp peaks in the albedo. Secondly, it shifts the wavelengths of spectral features in the reflected light causing the so-called Raman ghost lines. Observing the Raman peaks in the albedo could be used to measure the column density of the scattering molecule, thus providing constrains on the presence of clouds and hazes in the atmosphere. Observing the Raman ghost lines could be used to spectroscopically iden...

  6. Coherently controlling Raman-induced grating in atomic media

    CERN Document Server

    Arkhipkin, V G; Timofeev, I V

    2015-01-01

    We consider dynamically controllable periodic structures, called Raman induced gratings, in three- and four-level atomic media, resulting from Raman interaction in a standing-wave pump. These gratings are due to periodic spatial modulation of the Raman nonlinearity and fundamentally differ from the ones based on electromagnetically induced transparency. The transmission and reflection spectra of such gratings can be simultaneously amplified and controlled by varying the pump field intensity. It is shown that a transparent medium with periodic spatial modulation of the Raman gain can be opaque near the Raman resonance and yet at the same time it can be a non-linear amplifying mirror. We also show that spectral properties of the Raman induced grating can be controlled with the help of an additional weak control field.

  7. 基于最小二乘支持向量机的橄榄油掺杂拉曼快速鉴别方法%Fast Discrimination of Olive Oil Adulteration Based on Raman Spectra Using Least Squares Support Vector Machine

    Institute of Scientific and Technical Information of China (English)

    周秀军; 戴连奎

    2013-01-01

    提出了一种基于最小二乘支持向量机(LS-SVM)的橄榄油掺杂拉曼快速鉴别方法.首先,收集若干已知类别的橄榄油样作为训练样本,获取其拉曼谱图,并对其谱图进行预处理和波段选择,进而构建LSSVM分类器;对于未知类别的油样,获取其拉曼谱图,并进行相应的预处理和波段选择,由LSSVM分类器获得鉴别结果.实验以7种已知的特级初榨橄榄油为基础,分别掺入4种其它植物油(大豆油、菜籽油、玉米油、葵花籽油),获得112个掺杂油样.将全部样本随机分成训练集和测试集,对测试集样本的预测实验结果表明,本文方法能有效鉴别橄榄油掺杂,且掺杂量最低检测限为5%.与其它分类方法相比,LSSVM分类法具有最佳的分类性能.该方法快速、简便,为橄榄油掺杂鉴别提供了一种全新的方法.%A fast discrimination method to olive oil adulteration based on Raman spectra using least squares support vector machine LSSVM was presented.Firstly,some known class olive oil samples were chosen randomly as training samples and their original Raman spectra were obtained,then a pretreatment and band selection were made for those spectra,and then,the LSSVM classifier was built.Secondly,for the Raman spectra of unknown test samples,the same pretreatment and band selection were used.Finally,the discrimination results were attained through the LSSVM classifier.The experiment was based on seven known Extra virgin olive oil and 112 adulterated samples were acquired by mixing four other vegetable oils (soybean,rapeseed,corn and sunflower oil) into the basic oils.The whole samples were divided into training test and testing test randomly,the test result shows that this method was able to discriminate olive oil adulteration and the lowest detection limit of the doping amount was 5 %.Compared with other classification methods,LSSVM classifier has the best classification performance.The above method provided a new

  8. Raman Barcode for Counterfeit Drug Product Detection.

    Science.gov (United States)

    Lawson, Latevi S; Rodriguez, Jason D

    2016-05-01

    Potential infiltration of counterfeit drug products-containing the wrong or no active pharmaceutical ingredient (API)-into the bona fide drug supply poses a significant threat to consumers worldwide. Raman spectroscopy offers a rapid, nondestructive avenue to screen a high throughput of samples. Traditional qualitative Raman identification is typically done with spectral correlation methods that compare the spectrum of a reference sample to an unknown. This is often effective for pure materials but is quite challenging when dealing with drug products that contain different formulations of active and inactive ingredients. Typically, reliable identification of drug products using common spectral correlation algorithms can only be made if the specific product under study is present in the library of reference spectra, thereby limiting the scope of products that can be screened. In this paper, we introduce the concept of the Raman barcode for identification of drug products by comparing the known peaks in the API reference spectrum to the peaks present in the finished drug product under study. This method requires the transformation of the Raman spectra of both API and finished drug products into a barcode representation by assigning zero intensity to every spectral frequency except the frequencies that correspond to Raman peaks. By comparing the percentage of nonzero overlap between the expected API barcode and finished drug product barcode, the identity of API present can be confirmed. In this study, 18 approved finished drug products and nine simulated counterfeits were successfully identified with 100% accuracy utilizing this method. PMID:27043140

  9. Distinctions in the Raman Spectroscopy Features of WO3 Materials with Increasing Temperature

    Science.gov (United States)

    Garcia-Sanchez, Raul F.; Misra, Prabhakar

    2014-06-01

    Metal oxides are widely used in gas sensor applications due to their low cost, easy production and selectivity. Tungsten Oxide (WO3) is one of the most used metal oxides in the detection of Nitrogen gases (NOx). The purpose of this research is to determine if the Raman features of a metal oxide gas sensor can serve as tools to make estimates regarding the sensor capabilities related to the target gases. This research will be used for gas sensing of oxidizing/reducing toxic gases (i.e. H2S, NOx, SO2, etc.) and finding the effect that temperature, gas concentration, type of gas, exposure time and other variables have on the Raman spectra of metal oxides. In this experiment, the temperature was increased from 30-160 °C and the Raman data was taken using a 780 nm infrared laser. In two of the samples, WO3 on Silicon substrate and WO3 nanopowder, we found vibrational modes at 807, 716 and 271 cm-1, which are indicators of a monoclinic WO3 structure. The WO3 nanowires samples exhibit the O-W-O bond stretching feature is present and asymmetric stretching of the W-O bonds occurs, resulting in a 750 cm-1 band. The intensity of Raman features such as 750 cm-1 for nanowires and 492 and 670 cm-1 for WO3 on Silicon substrate begins to decay as temperature increases. Additionally, the vibrational modes related to O-H and W-OH become more pronounced as temperature increases due to those bonds reacting more strongly to the temperature change than the normal W-O bonds related to the original lattice structure. Finally, all samples have low-frequency phonon mode markers associated with temperature change, and in most cases these change as temperature increases. The understanding of the thermal effects will help develop theoretical models for the identification of specific metal oxide-gas relationships and provide a supplemental way of observing gas adsorption in addition to current conductivity measurements.

  10. Raman and impedance spectroscopy methods of P{sub 2}O{sub 5}–Li{sub 2}O–Al{sub 2}O{sub 3} glass system doped with MgO

    Energy Technology Data Exchange (ETDEWEB)

    Jlassi, I., E-mail: ifa.jlassi@fst.rnu.tn [Laboratoire Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, Université de Tunis ElManar, Campus Universitaire Farhat Hachad, ElManar 2092 (Tunisia); Sdiri, N. [Laboratoire Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Elhouichet, H. [Laboratoire Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, Université de Tunis ElManar, Campus Universitaire Farhat Hachad, ElManar 2092 (Tunisia); Ferid, M. [Laboratoire Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95, Hammam-Lif 2050 (Tunisia)

    2015-10-05

    Highlights: • We have prepared a new lithium diphosphate glasses doped MgO. • Investigate structural and electrical properties at room temperature. • Investigate relation between structure and electrical conductivity of the glass. - Abstract: Lithium diphosphate glasses doped MgO was prepared via a melt quenching technique. The samples were characterized by X-ray diffraction (XRD), Raman and impedance spectroscopy. XRD spectra reflected the amorphous nature of the glasses Raman spectra show structural network modifications with the composition variations of the studied glasses. Raman spectra of the studied glasses contain also typical phosphate glasses bands. Thus the band at ∼698 cm{sup −1} assigned to symmetric stretching vibrations of P−O−P groups and that from ∼1168 cm{sup −1} is attributed to symmetric stretching motions of the non-bridging oxygen (NBO) atoms bonded to phosphorous atoms (PO{sub 2}) in phosphate tetrahedron. Electric properties were investigated using complex impedance spectroscopy in a frequency range from 40 Hz to 6 MHz at room temperature. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE). Constant-phase elements (CPE) are used in equivalent electrical circuits for the fitting of experimental impedance data. The AC conductivity exhibited a Jonscher’s universal power law according with the relation σ(ω) = σ(0) + Aω{sup s} and it is observed that as the MgO content increases, frequency exponent (s) decreases.

  11. Raman Fingerprints of Atomically Precise Graphene Nanoribbons

    Science.gov (United States)

    Verzhbitskiy, Ivan A.; Corato, Marzio De; Ruini, Alice; Molinari, Elisa; Narita, Akimitsu; Hu, Yunbin; Schwab, Matthias G.; Bruna, Matteo; Yoon, Duhee; Milana, Silvia; Feng, Xinliang; Müllen, Klaus; Ferrari, Andrea C.; Casiraghi, Cinzia; Prezzi, Deborah

    2016-06-01

    Bottom-up approaches allow the production of ultra-narrow and atomically precise graphene nanoribbons (GNRs), with electronic and optical properties controlled by the specific atomic structure. Combining Raman spectroscopy and ab-initio simulations, we show that GNR width, edge geometry and functional groups all influence their Raman spectra. The low-energy spectral region below 1000 cm-1 is particularly sensitive to edge morphology and functionalization, while the D peak dispersion can be used to uniquely fingerprint the presence of GNRs, and differentiates them from other sp2 carbon nanostructures.

  12. Blood proteins analysis by Raman spectroscopy method

    Science.gov (United States)

    Artemyev, D. N.; Bratchenko, I. A.; Khristoforova, Yu. A.; Lykina, A. A.; Myakinin, O. O.; Kuzmina, T. P.; Davydkin, I. L.; Zakharov, V. P.

    2016-04-01

    This work is devoted to study the possibility of plasma proteins (albumin, globulins) concentration measurement using Raman spectroscopy setup. The blood plasma and whole blood were studied in this research. The obtained Raman spectra showed significant variation of intensities of certain spectral bands 940, 1005, 1330, 1450 and 1650 cm-1 for different protein fractions. Partial least squares regression analysis was used for determination of correlation coefficients. We have shown that the proposed method represents the structure and biochemical composition of major blood proteins.

  13. Theory of Acoustic Raman Modes in Proteins

    Science.gov (United States)

    DeWolf, Timothy; Gordon, Reuven

    2016-09-01

    We present a theoretical analysis that associates the resonances of extraordinary acoustic Raman (EAR) spectroscopy [Wheaton et al., Nat. Photonics 9, 68 (2015)] with the collective modes of proteins. The theory uses the anisotropic elastic network model to find the protein acoustic modes, and calculates Raman intensity by treating the protein as a polarizable ellipsoid. Reasonable agreement is found between EAR spectra and our theory. Protein acoustic modes have been extensively studied theoretically to assess the role they play in protein function; this result suggests EAR spectroscopy as a new experimental tool for studies of protein acoustic modes.

  14. Conformational study of neutral histamine monomer and their vibrational spectra.

    Science.gov (United States)

    Mukherjee, V; Yadav, T

    2016-08-01

    Molecular modeling and potential energy scanning of histamine molecule, which is an important neurotransmitter, with respect to the dihedral angle of methylamine side chain have done which prefer three different conformers of histamine monomer. We have calculated molecular structures and vibrational spectra with IR and Raman intensities of these conformers using Density Functional Theory (DFT) with the exchange functional B3LYP incorporated with the basis set 6-31++G(d,p) and Hartree-Fock (HF) with the same basis set. We have also employed normal coordinate analysis (NCA) to scale the theoretical frequencies and to calculate potential energy distributions (PEDs) for the conspicuous assignments. Normal modes assignments of some of the vibrational frequencies of all the three conformers are in good agreement with the earlier reported experimental frequencies of histamine whereas others have modified. The standard deviations between the theoretical and experimental frequencies fall in the region 13-20cm(-1) for the three conformers. NBO analyses of histamine conformers were also performed. The net charge transfers from ethylamine side chain to the imidazole ring. The intensive interactions between bonding and anti-bonding orbitals are found in imidazole ring. The HOMO-LUMO energy gap is nearly 5.50eV. PMID:27155558

  15. Conformational study of neutral histamine monomer and their vibrational spectra

    Science.gov (United States)

    Mukherjee, V.; Yadav, T.

    2016-08-01

    Molecular modeling and potential energy scanning of histamine molecule, which is an important neurotransmitter, with respect to the dihedral angle of methylamine side chain have done which prefer three different conformers of histamine monomer. We have calculated molecular structures and vibrational spectra with IR and Raman intensities of these conformers using Density Functional Theory (DFT) with the exchange functional B3LYP incorporated with the basis set 6-31 ++G(d,p) and Hartree-Fock (HF) with the same basis set. We have also employed normal coordinate analysis (NCA) to scale the theoretical frequencies and to calculate potential energy distributions (PEDs) for the conspicuous assignments. Normal modes assignments of some of the vibrational frequencies of all the three conformers are in good agreement with the earlier reported experimental frequencies of histamine whereas others have modified. The standard deviations between the theoretical and experimental frequencies fall in the region 13-20 cm- 1 for the three conformers. NBO analyses of histamine conformers were also performed. The net charge transfers from ethylamine side chain to the imidazole ring. The intensive interactions between bonding and anti-bonding orbitals are found in imidazole ring. The HOMO-LUMO energy gap is nearly 5.50 eV.

  16. Raman spectroscopic studies on bacteria

    Science.gov (United States)

    Maquelin, Kees; Choo-Smith, Lin-P'ing; Endtz, Hubert P.; Bruining, Hajo A.; Puppels, Gerwin J.

    2000-11-01

    Routine clinical microbiological identification of pathogenic micro-organisms is largely based on nutritional and biochemical tests. Laboratory results can be presented to a clinician after 2 - 3 days for most clinically relevant micro- organisms. Most of this time is required to obtain pure cultures and enough biomass for the tests to be performed. In the case of severely ill patients, this unavoidable time delay associated with such identification procedures can be fatal. A novel identification method based on confocal Raman microspectroscopy will be presented. With this method it is possible to obtain Raman spectra directly from microbial microcolonies on the solid culture medium, which have developed after only 6 hours of culturing for most commonly encountered organisms. Not only does this technique enable rapid (same day) identifications, but also preserves the sample allowing it to be double-checked with traditional tests. This, combined with the speed and minimal sample handling indicate that confocal Raman microspectroscopy has much potential as a powerful new tool in clinical diagnostic microbiology.

  17. Vibrational spectra and ab initio molecular orbital calculations of the novel anti-cancer drug combretastatin A-4 prodrug

    Science.gov (United States)

    James, C.; Pettit, G. R.; Nielsen, O. F.; Jayakumar, V. S.; Joe, I. Hubert

    2008-10-01

    The NIR-FT Raman and FT-IR spectral studies of the novel antineoplastic and antiangiogenesis substance comprestatin A-4 prodrug (CA4P) were carried out. The equilibrium geometry, various bonding features and harmonic vibrational frequencies of CA4P have been investigated with the help of B3LYP density functional theory (DFT) method. The most preferred cis-configuration for its bioactivity has been demonstrated on the basis of torsional potential energy surface (PES) scan studies. Stability of the molecule arising from hyperconjugative interactions leading to its bioactivity, charge delocalization and mesomeric effects have been analyzed using natural bond orbital (NBO) analysis. Detailed assignments of the vibrational spectra have been made with the aid of theoretically predicted vibrational frequencies. The optimized geometry shows near-planarity of phenyl rings and perpendicular conformation of meta substituted methoxy group. The vibrational analysis confirms the differently acting ring modes, steric repulsion, π conjugation and back-donation.

  18. Coherent Raman spectroscopy

    CERN Document Server

    Eesley, G L

    1981-01-01

    Coherent Raman Spectroscopy provides a unified and general account of the fundamental aspects of nonlinear Raman spectroscopy, also known as coherent Raman spectroscopy. The theoretical basis from which coherent Raman spectroscopy developed is described, along with its applications, utility, and implementation as well as advantages and disadvantages. Experimental data which typifies each technique is presented. This book is comprised of four chapters and opens with an overview of nonlinear optics and coherent Raman spectroscopy, followed by a discussion on nonlinear transfer function of matter

  19. Time-encoded Raman scattering (TICO-Raman) with Fourier domain mode locked (FDML) lasers

    Science.gov (United States)

    Karpf, Sebastian; Eibl, Matthias; Wieser, Wolfgang; Klein, Thomas; Huber, Robert

    2015-07-01

    We present a new concept for performing stimulated Raman spectroscopy and microscopy by employing rapidly wavelength swept Fourier Domain Mode locked (FDML) lasers [1]. FDML lasers are known for fastest imaging in swept-source optical coherence tomography [2, 3]. We employ this continuous and repetitive wavelength sweep to generate broadband, high resolution stimulated Raman spectra with a new, time-encoded (TICO) concept [4]. This allows for encoding and detecting the stimulated Raman gain on the FDML laser intensity directly in time. Therefore we use actively modulated pump lasers, which are electronically synchronized to the FDML laser, in combination with a fast analog-to-digital converter (ADC) at 1.8 GSamples/s. We present hyperspectral Raman images with color-coded, molecular contrast.

  20. Beryl-II, a high-pressure phase of beryl: Raman and luminescence spectroscopy to 16.4 GPa

    Science.gov (United States)

    O'Bannon, Earl; Williams, Quentin

    2016-10-01

    The Raman and Cr3+ and V2+ luminescence spectra of beryl and emerald have been characterized up to 15.0 and 16.4 GPa, respectively. The Raman spectra show that an E 1g symmetry mode at 138 cm-1 shifts negatively by -4.57 (±0.55) cm-1/GPa, and an extrapolation of the pressure dependence of this mode indicates that a soft-mode transition should occur near 12 GPa. Such a transition is in accord with prior theoretical results. Dramatic changes in Raman mode intensities and positions occur between 11.2 and 15.0 GPa. These changes are indicative of a phase transition that primarily involves tilting and mild distortion of the Si6O18 rings. New Raman modes are not observed in the high-pressure phase, which indicates that the local bonding environment is not altered dramatically across the transition (e.g., changes in coordination do not occur). Both sharp line and broadband luminescence are observed for both Cr3+ and V2+ in emerald under compression to 16.4 GPa. The R-lines of both Cr3+ and V2+ shift to lower energy (longer wavelength) under compression. Both R-lines of Cr3+ split at ~13.7 GPa, and the V2+ R1 slope changes at this pressure and shifts more rapidly up to ~16.4 GPa. The Cr3+ R-line splitting and FWHM show more complex behavior, but also shift in behavior at ~13.7 GPa. These changes in the pressure dependency of the Cr3+ and V2+ R-lines and the changes in R-line splitting and FWHM at ~13.7 GPa further demonstrate that a phase transition occurs at this pressure, in good agreement with our Raman results. The high-pressure phase of beryl appears to have two Al sites that become more regular under compression. Hysteresis is not observed in our Raman or luminescence spectra on decompression, suggesting that this transition is second order in nature: The occurrence of a second-order transition near this pressure is also in accord with prior theoretical results. We speculate that the high-pressure phase (beryl-II) might be a mildly modulated structure, and/or that

  1. Beryl-II, a high-pressure phase of beryl: Raman and luminescence spectroscopy to 16.4 GPa

    Science.gov (United States)

    O'Bannon, Earl; Williams, Quentin

    2016-08-01

    The Raman and Cr3+ and V2+ luminescence spectra of beryl and emerald have been characterized up to 15.0 and 16.4 GPa, respectively. The Raman spectra show that an E 1g symmetry mode at 138 cm-1 shifts negatively by -4.57 (±0.55) cm-1/GPa, and an extrapolation of the pressure dependence of this mode indicates that a soft-mode transition should occur near 12 GPa. Such a transition is in accord with prior theoretical results. Dramatic changes in Raman mode intensities and positions occur between 11.2 and 15.0 GPa. These changes are indicative of a phase transition that primarily involves tilting and mild distortion of the Si6O18 rings. New Raman modes are not observed in the high-pressure phase, which indicates that the local bonding environment is not altered dramatically across the transition (e.g., changes in coordination do not occur). Both sharp line and broadband luminescence are observed for both Cr3+ and V2+ in emerald under compression to 16.4 GPa. The R-lines of both Cr3+ and V2+ shift to lower energy (longer wavelength) under compression. Both R-lines of Cr3+ split at ~13.7 GPa, and the V2+ R1 slope changes at this pressure and shifts more rapidly up to ~16.4 GPa. The Cr3+ R-line splitting and FWHM show more complex behavior, but also shift in behavior at ~13.7 GPa. These changes in the pressure dependency of the Cr3+ and V2+ R-lines and the changes in R-line splitting and FWHM at ~13.7 GPa further demonstrate that a phase transition occurs at this pressure, in good agreement with our Raman results. The high-pressure phase of beryl appears to have two Al sites that become more regular under compression. Hysteresis is not observed in our Raman or luminescence spectra on decompression, suggesting that this transition is second order in nature: The occurrence of a second-order transition near this pressure is also in accord with prior theoretical results. We speculate that the high-pressure phase (beryl-II) might be a mildly modulated structure, and/or that

  2. Parental Bonding

    Directory of Open Access Journals (Sweden)

    T. Paul de Cock

    2014-08-01

    Full Text Available Estimating the early parent–child bonding relationship can be valuable in research and practice. Retrospective dimensional measures of parental bonding provide a means for assessing the experience of the early parent–child relationship. However, combinations of dimensional scores may provide information that is not readily captured with a dimensional approach. This study was designed to assess the presence of homogeneous groups in the population with similar profiles on parental bonding dimensions. Using a short version of the Parental Bonding Instrument (PBI, three parental bonding dimensions (care, authoritarianism, and overprotection were used to assess the presence of unobserved groups in the population using latent profile analysis. The class solutions were regressed on 23 covariates (demographics, parental psychopathology, loss events, and childhood contextual factors to assess the validity of the class solution. The results indicated four distinct profiles of parental bonding for fathers as well as mothers. Parental bonding profiles were significantly associated with a broad range of covariates. This person-centered approach to parental bonding has broad utility in future research which takes into account the effect of parent–child bonding, especially with regard to “affectionless control” style parenting.

  3. Qualitative study of ethanol content in tequilas by Raman spectroscopy and principal component analysis

    Science.gov (United States)

    Frausto-Reyes, C.; Medina-Gutiérrez, C.; Sato-Berrú, R.; Sahagún, L. R.

    2005-09-01

    Using Raman spectroscopy, with an excitation radiation source of 514.5 nm, and principal component analysis (PCA) was elaborated a method to study qualitatively the ethanol content in tequila samples. This method is based in the OH region profile (water) of the Raman spectra. Also, this method, using the fluorescence background of the Raman spectra, can be used to distinguish silver tequila from aged tequilas. The first three PCs of the Raman spectra, that provide the 99% of the total variance of the data set, were used for the samples classification. The PCA1 and PCA2 are related with the water (or ethanol) content of the sample, whereas the PCA3 is related with the fluorescence background of the Raman spectra.

  4. Effect of Cefazolin Treatment on the Nonresonant Raman Signatures of the Metabolic State of Individual Escherichia coli Cells

    NARCIS (Netherlands)

    Moritz, T.; Taylor, D.; Polage, C.; Krol, D.M.; Lane, S.; Chan, J.

    2010-01-01

    Laser tweezers Raman spectroscopy (LTRS) was used to characterize the Raman fingerprints of the metabolic states of Escherichia coli (E. coli) cells and to determine the spectral changes associated with cellular response to the antibiotic Cefazolin. The Raman spectra of E. coli cells sampled at diff

  5. Applications of Raman Spectroscopy to Inorganic Chemistry

    Institute of Scientific and Technical Information of China (English)

    RobinJHClarkFRS

    1995-01-01

    The renaissance in Raman spectroscopy some 25-30 years ago had particular and immediate impact on Inorganic Chemistry,viz in areas such as the study of deeply coloued compounds,structural changes on change of state,equilibria,vapour phase band contour analysis,Raman band intensities and the nature of the chemical bond,metal-metal bonding,species in melts,identification of species in solution and of radicals by time-resolved techniques,in bioinorganic chemistry,and of linear-chain semiconductors.More recently,much attention has been directed at the quantitative level at the evaluation of geometric changes in molecules on excitation by resonance Raman spectroscopy.At the qualitative level Raman microscopy is now recognised to be the most effective technique for the identification of pigments-particularly the inorganic ones-on medieval manuscripts and especially of the components(down to grain sizes of -1 um)of pigment mixtures,It is thus a very important technique at the Arts/Science borderling in conservation science.

  6. Experimental and theoretical studies of the infrared spectra and bonding properties of NgBeCO₃ and a comparison with NgBeO (Ng = He, Ne, Ar, Kr, Xe).

    Science.gov (United States)

    Zhang, Qingnan; Chen, Mohua; Zhou, Mingfei; Andrada, Diego M; Frenking, Gernot

    2015-03-19

    The novel neon complex NeBeCO3 has been prepared in a low-temperature neon matrix via codeposition of laser-evaporated beryllium atoms with O2 + CO/Ne. Doping by the heavier noble gas atoms argon, krypton and xenon yielded the associated adducts NgBeCO3 (Ng = Ar, Kr, Xe). The noble gas complexes have been identified via infrared spectroscopy. Quantum chemical calculations of NgBeCO3 and NgBeO (Ng = He, Ne, Ar, Kr, Xe) using ab initio methods and density functional theory show that the Ng-BeCO3 bonds are slightly longer and weaker than the Ng-BeO bonds. The energy decomposition analysis of the Ng-Be bonds suggests that the attractive interactions come mainly from the Ng → BeCO3 and Ng → BeO σ donation.

  7. Evidence of low intermolecular coupling in rubrene single crystals by Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Weinberg-Wolf, J R [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27713 (United States); McNeil, L E [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27713 (United States); Liu Shubin [Division of Research Computing, Information Technology Services, University of North Carolina, Chapel Hill, NC 27713 (United States); Kloc, Christian [Bell Laboratories, Lucent Technologies, 600 Mountain Avenue, Murray Hill, NJ 07974 (United States)

    2007-07-11

    The observed Raman spectra for single crystals of rubrene and tetracene are compared with the calculated spectra for the isolated molecules. The Raman measurements presented are of the bulk properties of the material, and they confirmed that the vapour growth process yields very pure, unstrained rubrene crystals. Finally, Raman measurements indicate that rubrene, unlike many other oligoacenes, has very weak intermolecular coupling and no observable intermolecular Raman vibrational modes. We discuss the apparent conflict between the high mobility and the weak {pi}-electron overlap in this material.

  8. Subsurface Raman analysis of thin painted layers.

    Science.gov (United States)

    Conti, Claudia; Colombo, Chiara; Realini, Marco; Zerbi, Giuseppe; Matousek, Pavel

    2014-01-01

    Here we present, for the first time, an extension of spatially offset Raman spectroscopy to thin (tens of micrometers thick), highly turbid stratified media such as those encountered in paintings. The method permits the non-destructive interrogation of painted layers in situations where conventional Raman microscopy is not applicable due to high turbidity of the top layer(s). The concept is demonstrated by recovering the pure Raman spectra of paint sub-layers that are completely obscured by paint over-layers. Potential application areas include the analysis of paintings in art preservation and restoration avoiding the cross-sectional analysis used currently with this type of samples. The technique also holds promise for the development as a non-destructive subsurface tool for in situ analysis using portable instruments.

  9. Raman gain of Ge-Sb-Se chalcogenide glass%Ge-Sb-Se硫系玻璃拉曼增益特性研究∗

    Institute of Scientific and Technical Information of China (English)

    徐航; 彭雪峰; 戴世勋; 徐栋; 张培晴; 许银生; 李杏; 聂秋华

    2016-01-01

    of the Raman gain characteristics in a particular glass component glass. In this work, four chalcogenide glasses, respectively, with compositions of As2S3, As2Se3, Ge20Sb15Se65 and Ge28Sb12Se60 (mol%) are prepared. Refractive indices, infrared transmission and Raman spectra of these glass samples are measured. By using spontaneous Raman scattering theory combined with the measured Raman spectral data, the values of Raman gain coefficient gR of the chalcogenide glasses are calculated and calibrated by a quartz glass sample. Results show that the gR of As2S3 glass is 60 × 10−13 m/W at 230 cm−1 Raman shift and the gR of As2Se3 glass is 223 × 10−13 m/W at 340 cm−1 Raman shift, which are consistent with the experimental results reported in the literature. Compared with the traditional method, the present method used for calculating the fiber Raman gain coefficient provides great convenience for exploring new chalcogenide glasses with high Raman gain. By using this method, we obtain the gR values of Ge20Sb15Se65 and Ge28Sb12Se60 glasses at 200 cm−1 Raman shift, which are 215 × 10−13 m/W and 111 × 10−13 m/W respectively. Meanwhile, we analyze the effects of composition and network structure of chalcogenide glass samples on the Raman gain coefficient and gain spectrum. There are two Raman peaks at 165 cm−1 and 200 cm−1 Raman shift, which are attributed to Ge—Ge bond vibration and Ge—Se bond vibration of common apex GeSe4/2 tetrahedral structure respectively. It could be found that the Raman gain coefficient of Ge20Sb15Se65 glass is bigger than that of Ge28Sb12Se60 glass at 200 cm−1 Raman shift because of more Ge—Se bonds. By further optimizing the ratio of components of Ge-Sb-Se chalcogenide glass, we could obtain higher Raman gain coefficient at a particular frequency shift. These results show that the Raman gain coefficient of Ge-Sb-Se chalcogenide glass without poisonous element is up to over 200 times that of the ordinary quartz glass, which

  10. Surface-enhanced Raman spectroscopy of morphine in silver colloid

    Institute of Scientific and Technical Information of China (English)

    Shangyuan Feng; Weiwei Chen; Wei Huang; Min Cheng; Juqiang Lin; Yongzeng Li; Rong Chen

    2009-01-01

    @@ We report the surface-enhanced Raman (SERS) spectra of morphine in silver colloid, and study the silver colloid enhanced effects on the Raman scattering of morphine.The Raman bands of morphine are assigned to certain molecule vibrations.The broad band in the long-wavelength region of the electronic absorption spectra of the sol with added adsorbent at certain concentrations has been explained in terms of the ag-gregation of the colloidal silver particles.The potential applications of SERS in quantitative measurement of the morphine samples are demonstrated.By using a proper Raman band of morphine, the detection limit of morphine in silver sol is found to be 1.5 ng/ml.The result suggests that it is of great significance to use SERS in illicit drug morphine inspection.

  11. Analysis of polymer surfaces and thin-film coatings with Raman and surface enhanced Raman scattering

    CERN Document Server

    McAnally, G D

    2001-01-01

    This thesis investigates the potential of surface-enhanced Raman scattering (SERS) for the analysis and characterisation of polymer surfaces. The Raman and SERS spectra from a PET film are presented. The SERS spectra from the related polyester PBT and from the monomer DMT are identical to PET, showing that only the aromatic signals are enhanced. Evidence from other compounds is presented to show that loss of the carbonyl stretch (1725 cm sup - sup 1) from the spectra is due to a chemical interaction between the silver and surface carbonyl groups. The interaction of other polymer functional groups with silver is discussed. A comparison of Raman and SERS spectra collected from three faces of a single crystal shows the SERS spectra are depolarised. AFM images of the silver films used to obtain SERS are presented. They consist of regular islands of silver, fused together to form a complete film. The stability and reproducibility and of these surfaces is assessed. Band assignments for the SERS spectrum of PET are ...

  12. The structure and vibrational spectra of the 2,5-dimethylpyrazine (2,5-DMP) 1:1 adduct with 2,5-dichloro-3,6-dihydroxy-p-benzoquinone (CLA)

    International Nuclear Information System (INIS)

    Graphical abstract: The infrared, Raman and inelastic neutron scattering (INS) spectra of 2,5-DMP with CLA, its crystal structure, the DFT method applied to the crystalline state, the hydrogen bonded OH...N infinite chains without any proton transfer. Research highlights: → A novel complex of 2,5-dimethylpyrazine with 2,5-dichloro-3,6-dihydroxy-p-benzoquinone. → The crystal structure at 100 K is presented. → The infrared, Raman and inelastic neutron scattering spectra are shown. → They are compared with calculated by using the DFT methods applied to the crystalline state. → The calculated structure and the frequencies are well consistent, except of the CH3 torsional mode. - Abstract: The complexation of 2,5-dimethylpyrazine (2,5-DMP) with 2,5-dichloro-3,6-dihydroxy-p-benzoquinone (CLA) leads to the formation of the hydrogen bonded OH...N infinite chains without any proton transfer. In the high and medium frequency region of the IR spectra a characteristic Hadzi's trio with maxima at ca. 2400, 1800 and 1150 cm-1 is observed. The infrared, Raman and inelastic neutron scattering (INS) spectra are compared with those calculated by using the DFT methods applied to the crystalline state. The optimization of the structure by using this theoretical approach is also performed. Very good conformity of the experimental and theoretical structures is visible. The reproduction of vibrational spectra is also good except for the low frequency bands related to the CH3 torsional modes. One gets relatively good agreement by using PWC(dnp) approach. Applications of other theoretical models leads to much higher values of CH3 torsional frequency.

  13. Raman Spectroscopy of Garnet—group Minerals

    Institute of Scientific and Technical Information of China (English)

    彭明生; H.K.MAO; 等

    1994-01-01

    The Raman spectra of the natural end members of the garnet-group minerals,which include pyrope, almandine and spessarite of Fe-Al garnet series and grossularite ,andradite and uvarovite of Ca-Fe garnet series, have been strdied.Measured Raman spectra of these minerals are reasonably and qualitatively assigned to the internal modes, translational and rotatory modes of SiO4 tetrahedra, as well as the translational motion of bivalent cations in the X site.The stretch and rotatory A1g modes for the Fe-Al garnet series show obvious Raman shifts as compared with those for the Ca-Fe garnet series ,owing to the cations residing in the Xsite connected with SiO4 tetrahedra by sharing the two edges.The Raman shifts of all members within either of the series are attributed mainly to the properties of cations in the X site for the Fe-Al garnet series andin the Y site for the Ca-Fe garnet series.

  14. A Comparative Study on Surface-Enhanced Raman Spectra of Thymine onto Silver Colloids and Island Films%银胶和银岛膜上胸腺嘧啶的表面增强拉曼光谱对比研究

    Institute of Scientific and Technical Information of China (English)

    郭浩; 丁丽; 莫育俊

    2011-01-01

    Surface-enhanced Raman scattering (SERS) spectra of thymine obtained on silver colloids and island films were studied comparatively. The spectroscopic characterization showed that the molecule configuration of thymine hydrolyzed ion compound was transformed from keto-amino to enol-amino after adsorption. On either silver surface, the N(3)-deprotonated tautomer was favorable. Thymine adsorbed on the silver colloids surfaces as enolate through the 0(7) and N(3) atoms while through the 0(8) and N(3) atoms in the case of silver island films surfaces.%利用表面增强拉曼光谱对胸腺嘧啶在银胶和银岛膜上的吸附状态进行了对比研究.光谱分析表明,胸腺嘧啶吸附在银胶和银岛膜表面后其分子结构发生了互变异构,由原来的酮式结构变成了烯醇式结构.在银胶和银岛膜表面胸腺嘧啶主要以N(3)去质子化异构体的形式存在.胸腺嘧啶通过O(7)和N(3)倾斜地吸附在银胶颗粒表面,通过O(8)和N(3)倾斜地吸附在银岛膜表面.

  15. FT-Raman signatures of genomic DNA from plant tissues

    OpenAIRE

    Cristina M. Muntean; Adela HALMAGYI; Puia, Mircea D.; Pavel, Ioana

    2009-01-01

    The vibrational spectra of eight genomic DNAs from leaf tissues (sword fern (Nephrolepis exaltata L.), chrysanthemum (Dendranthema grandiflora Ramat.), redwood (Sequoia sempervirens D. Don. Endl.), orchids (Cymbidium × hybrida), common sundew (Drosera rotundifolia L.), potato (Solanum tuberosum L.) and scopolia (Scopolia carniolica Jacq.)) have been analyzed using FT-Raman spectroscopy, in the wavenumber range 500–1800 cm–1.FT-Raman signatures, spectroscopic assignments and structural interpr...

  16. Novel Raman instrumentation for characterizing 2D nanomaterials

    Science.gov (United States)

    Hight Walker, Angela

    2015-03-01

    We have designed and constructed a unique Raman microscope system to enable diffraction limited measurements of graphene and two-dimensional transition-metal dichalcogenides (TMD). The design enables low frequency phonon measurements down to ten wavenumbers through a triple grating Raman spectrometer, as well as resonance Raman spectroscopy through multiple laser excitation lines throughout the visible region. Through coupling to a cryogen-free magnet system, Raman spectra can be collected while the sample is in fields up 9 Tesla and at temperatures from 4 K to 400 K. Uniquely, both Farady and Voight geometries are accessible. Furthermore, multiple electronic feedthroughs permit collecting Raman scatter from devices at varying voltages. Proof of concept measurements on TMDs will highlight the full capabilities of the instrumentation. Collaborations are sought to demonstrate the utility of the new instrumentation.

  17. Raman spectroscopy of human saliva for acute myocardial infarction detection

    Science.gov (United States)

    Chen, Maowen; Chen, Yuanxiang; Wu, Shanshan; Huang, Wei; Lin, Jinyong; Weng, Guo-Xing; Chen, Rong

    2014-09-01

    Raman spectroscopy is a rapidly non-invasive technique with great potential for biomedical research. The aim of this study was to evaluate the feasibility of using Raman spectroscopy of human saliva for acute myocardial infarction (AMI) detection. Raman spectroscopy measurements were performed on two groups of saliva samples: one group from patients (n=30) with confirmed AMI and the other group from healthy controls (n=31). The diagnostic performance for differentiating AMI saliva from normal saliva was evaluated by multivariate statistical analysis. The combination of principal component analysis (PCA) and linear discriminate analysis (LDA) of the measured Raman spectra separated the spectral features of the two groups into two distinct clusters with little overlaps, rendering the sensitivity of 80.0% and specificity of 80.6%. The results from this exploratory study demonstrated that Raman spectroscopy of human saliva can serve as a potentially clinical tool for rapid AMI detection and screening.

  18. Remote Raman Spectroscopy of Minerals at Elevated Temperature Relevant to Venus Exploration

    Science.gov (United States)

    Sharma, Shiv K.; Misra, Anupam K.; Singh, Upendra N.

    2008-01-01

    We have used a remote time-resolved telescopic Raman system equipped with 532 nm pulsed laser excitation and a gated intensified CCD (ICCD) detector for measuring Raman spectra of a number of minerals at high temperature to 970 K. Remote Raman measurements were made with samples at 9-meter in side a high-temperature furnace by gating the ICCD detector with 2 micro-sec gate to minimize interference from blackbody emission from mineral surfaces at high temperature as well as interference from ambient light. A comparison of Raman spectra of gypsum (CaSO4.2H2O), dolomite (CaMg(CO3)2), and olivine (Mg2Fe2-xSiO4), as a function of temperature shows that the Raman lines remains sharp and well defined even in the high-temperature spectra. In the case of gypsum, Raman spectral fingerprints of CaSO4.H2O at 518 K were observed due to dehydration of gypsum. In the case of dolomite, partial mineral dissociation was observed at 973 K at ambient pressure indicating that some of the dolomite might survive on Venus surface that is at approximately 750 K and 92 atmospheric pressure. Time-resolved Raman spectra of low clino-enstatite (MgSiO3) measured at 75 mm from the sample in side the high-temperature furnace also show that the Raman lines remains sharp and well defined in the high temperature spectra. These high-temperature remote Raman spectra of minerals show that time-resolved Raman spectroscopy can be used as a potential tool for exploring Venus surface mineralogy at shorter (75 mm) and long (9 m) distances from the samples both during daytime and nighttime. The remote Raman system could also be used for measuring profiles of molecular species in the dense Venus atmosphere during descent as well as on the surface.

  19. NIR-FT Raman, FT-IR and surface-enhanced Raman scattering and DFT based theoretical studies on the adsorption behaviour of (S)-Phenylsuccinic acid on silver nanoparticles

    Indian Academy of Sciences (India)

    D Sajan; V Bena Jothy; Thomas Kuruvilla; I Hubert Joe

    2010-07-01

    Single crystals of ()-phenylsuccinic acid (SPSA) were grown by the slow evaporation technique and vibrational spectral analysis was carried out using near-IR Fourier transform Raman and Fourier transform IR spectroscopy. The density functional theoretical (DFT) computations were also performed at the B3LYP/6-311G(d, p) level to derive the equilibrium geometry, vibrational wavenumbers and intensities. Vibrational spectral investigation confirmed the formation of cyclic dimers in the crystal, with the carboxyl groups of each acid molecule being hydrogen bonded to those of the adjacent molecules. The Raman vibrational wavenumbers of the adsorption geometry of (S)-phenylsuccinic acid (SPSA) on a silver surface have been simulated using DFT-B3PW91 with lanl2dz basis set and it compared with the experimental spectrum. The large enhancement of in-plane bending and ring breathing modes in the surface-enhanced Raman scattering spectrum indicates that the molecule is adsorbed on the silver surface in an `at least vertical’ or slightly tilted orientation, with the ring perpendicular to the silver surface. The calculated vibrational spectra are in agreement with experimental values confirming the validity of the proposed adsorption configurations.

  20. Raman spectroscopy of boron carbides and related boron-containing materials

    International Nuclear Information System (INIS)

    Raman spectra of crystalline boron, boron carbide, boron arsenide (B12As2), and boron phosphide (B12P2) are reported. The spectra are compared with other boron-containing materials containing the boron icosahedron as a structural unit. The spectra exhibit similar features some of which correlate with the structure of the icosahedral units of the crystals. The highest Raman lines appear to be especially sensitive to the B-B distance in the polar triangle of the icosahedron. Such Raman structural markers are potentially useful in efforts to tailor electronic properties of these high temperature semiconductors and thermoelectrics