WorldWideScience

Sample records for bond raman spectra

  1. Inter-tetrahedra bond angle of permanently densified silicas extracted from their Raman spectra

    Energy Technology Data Exchange (ETDEWEB)

    Hehlen, B, E-mail: bernard.hehlen@univ-montp2.f [Laboratoire des Colloides, Verres et Nanomateriaux, UMR 5587 CNRS and University of Montpellier II, F-34095 Montpellier (France)

    2010-01-20

    Relative Raman scattering intensities are obtained in three samples of vitreous silica of increasing density. The variation of the intensity upon densification is very different for bending and stretching modes. For the former we find a Raman coupling-to-light coefficient C{sub B}propor toomega{sup 2}. A comparative intensity and frequency dependence of the Raman spectral lines in the three glasses is performed. Provided the Raman spectra are normalized by C{sub B}, there exists a simple relation between the Si-O-Si bond angle and the frequency of all O-bending motions, including those of fourfold (n = 4) and threefold (n = 3) rings. For 20% densification we find a reduction of approx5.7 deg. of the maximum of the network angle distribution, a value in very close agreement with previous NMR experiments. The threefold and fourfold rings are weakly perturbed by the densification, with a bond angle reduction of approx0.5 deg. for the former.

  2. Molecular structure, vibrational spectra (FTIR and FT Raman) and natural bond orbital analysis of 4-Aminomethylpiperidine: DFT study.

    Science.gov (United States)

    Mahalakshmi, G; Balachandran, V

    2014-10-15

    The FT-IR and FT-Raman spectra of 4-Aminomethylpiperidine have been recorded using Perkin Elmer Spectrophotometer and Nexus 670 spectrophotometer. The equilibrium geometrical parameters, various bonding features, the vibrational wavenumbers, the infrared intensities and the Raman scattering activities were calculated using Hartree-Fock and density functional method (B3LYP) with 6-311+G(d,p) basis set. Detailed interpretations of the vibrational spectra have been carried out with the aid of the normal coordinate analysis. The spectroscopic and natural bonds orbital (NBO) analysis confirms the occurrence of intra molecular hydrogen bonds, electron delocalization and steric effects. The changes in electron density in the global minimum and in the energy of hyperconjugative interactions of 4-Aminomethylpiperidine (4AMP) were calculated. The theoretical UV-Visible spectrum of the compound was computed in the region 200-400nm by time-dependent TD-DFT approach. The calculated HOMO and LUMO energies show that charge transfer occur within the molecule. The dipole moment (μ) and polarizability (α), anisotropy polarizability (Δα) and hyperpolarizability (β) of the molecule have been reported. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Raman spectra of lithium compounds

    Science.gov (United States)

    Gorelik, V. S.; Bi, Dongxue; Voinov, Y. P.; Vodchits, A. I.; Gorshunov, B. P.; Yurasov, N. I.; Yurasova, I. I.

    2017-11-01

    The paper is devoted to the results of investigating the spontaneous Raman scattering spectra in the lithium compounds crystals in a wide spectral range by the fibre-optic spectroscopy method. We also present the stimulated Raman scattering spectra in the lithium hydroxide and lithium deuteride crystals obtained with the use of powerful laser source. The symmetry properties of the lithium hydroxide, lithium hydroxide monohydrate and lithium deuteride crystals optical modes were analyzed by means of the irreducible representations of the point symmetry groups. We have established the selection rules in the Raman and infrared absorption spectra of LiOH, LiOH·H2O and LiD crystals.

  4. Evaluation of the bond polarizabilities of zincblende-type semiconductors: Application to the Raman spectra of disordered GaSb/AlSb (001) superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Berdekas, D. [Direction of High Schools Education of Larissa, Lykeio of Giannouli, Larissa (Greece); Ves, S. [School of Physics, Aristotle University of Thessaloniki (Greece)

    2012-08-15

    We derive expressions for the bond polarizability (BP) parameters involving only directly measurable quantities, such as dielectric and elasto-optic constants of the bulk crystal and apply them to zincblende-type crystals. The vibrational modes are calculated on the basis of an eleven (11) parameter rigid-ion model approximation (RIM). Having estimated the BP parameters for GaSb and AlSb bulk crystals, we calculate the Raman spectra away of resonance conditions for the vibrations of perfect and disordered (GaSb)1/(AlSb)1 (001) superlattices (SL). The disordered SL is approximated with primitive cells much larger than the primitive cell of the perfect 1 x 1 SL. Furthermore, we show that disorder modifies the Raman spectra of the perfect SL by introducing asymmetry as well as by the formation of additional peaks in both the acoustic and optical range of the Raman spectra. Puzzlingly, even a small degree of disorder, results in a blueshift of all modes frequencies, especially the strongest optical ones. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. FTIR, FT-Raman, UV-Visible spectra and quantum chemical calculations of allantoin molecule and its hydrogen bonded dimers.

    Science.gov (United States)

    Alam, Mohammad Jane; Ahmad, Shabbir

    2015-02-05

    FTIR, FT-Raman and electronic spectra of allantoin molecule are recorded and investigated using DFT and MP2 methods with 6-311++G(d,p) basis set. The molecular structure, anharmonic vibrational spectra, natural atomic charges, non-linear optical properties, etc. have been computed for the ground state of allantoin. The anharmonic vibrational frequencies are calculated using PT2 algorithm (Barone method) as well as VSCF and CC-VSCF methods. These methods yield results that are in remarkable agreement with the experiment. The coupling strengths between pairs of modes are also calculated using coupling integral based on 2MR-QFF approximation. The simulations on allantoin dimers have been also performed at B3LYP/6-311++G(d,p) level of theory to investigate the effect of the intermolecular interactions on the molecular structure and vibrational frequencies of the monomer. Vibrational assignments are made with the great accuracy using PED calculations and animated modes. The combination and overtone bands have been also identified in the FTIR spectrum with the help of anharmonic computations. The electronic spectra are simulated in gas and solution at TD-B3LYP/6-311++G(d,p) level of theory. The important global quantities such as electro-negativity, electronic chemical potential, electrophilicity index, chemical hardness and softness based on HOMO, LUMO energy eigenvalues are also computed. NBO analysis has been performed for monomer and dimers of allantoin at B3LYP/6-311++G(d,p) level of theory. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Surface enhancement Raman scattering of tautomeric thiobarbituric acid. Natural bond orbitals and B3LYP/6-311+G (d, p) assignments of the Fourier Infrared and Fourier Raman Spectra.

    Science.gov (United States)

    Soto, C A Téllez; Ramos, J M; Costa Junior, A C; Vieira, Laís S; Rangel, João L; Raniero, L; Fávero, Priscila P; Lemma, Tibebe; Ondar, Grisset F; Versiane, Otavio; Martin, A A

    2013-10-01

    Surface enhancement Raman scattering (SERS) of two tautomer of thiobarbituric acid was obtained using silver and gold nanoparticles. Large band enhancement in the region of the ν(C=S), ν(C=C), δ(CH2), and δ(CNH) vibrational modes was found. Natural bond analysis of the tautomer species revealed expressive values of charge transfer, principally from lone pair electron orbitals of the S, N, and O atoms. Complete vibrational assignment was done for the two tautomers using the B3LYP/6-311+G (d, p) procedure, band deconvolution analysis, and from a rigorous interpretation of the normal modes matrix. The calculated spectra agree well with the experimental ones. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. 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

  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. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. Raman spectra of deuteriated taurine single crystals

    Science.gov (United States)

    Souza, J. M. de; Lima, R. J. C.; Freire, P. T. C.; Sasaki, J. M.; Melo, F. E. A.; Filho, J. Mendes; Jones, Derry W.

    2005-05-01

    The polarized Raman spectra of partially deuteriated taurine [(ND 3+) 0.65(NH 3+) 0.35(CH 2) 2SO 3-] crystals from x( zz) x and x( zy) x scattering geometries of the A g and B g irreducible representations of the factor group C 2h are reported. The temperature-dependent Raman spectra of partially deuteriated taurine do not reveal any evidence of the structural phase transition undergone by normal taurine at about 250 K, but an anomaly observed in the 180 cm -1 band at ˜120 K implies a different dynamic for this band (which is involved in a pressure-induced phase transition) in the deuteriated crystal.

  10. 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

    Some ionic compounds (salts) form liquids when heated to temperatures in the range of 200-300 °C. They may be referred to as moderate temperature ionic liquids. An example of such a compound is the 1,1,3,3- tetramethylguanidinium chloride, [TMGH]Cl, melting at ∼212 °C. The chemistry of this compo......Some ionic compounds (salts) form liquids when heated to temperatures in the range of 200-300 °C. They may be referred to as moderate temperature ionic liquids. An example of such a compound is the 1,1,3,3- tetramethylguanidinium chloride, [TMGH]Cl, melting at ∼212 °C. The chemistry...... and the dimeric chloride ion-pair salt converged to give geometries near the established crystal structure of [TMGH]Cl. The structures and their binding energies are given as well as calculated vibrational harmonic normal modes (IR and Raman band wavenumbers and intensities). Experimentally obtained Raman...... scattering spectra are presented and assigned, by comparing to the quantum mechanical calculations. It is concluded that dimeric molecular ion pairs with four N-H+ · · · Cl- hydrogen bonds probably exist in the solutions and are responsible for the relatively high solubility of the “salt” in ethanol...

  11. Metal-metal bonding and structures of metal string complexes Cr3(dpa)4Cl2, Cr3(dpa)4(NCS)2, and [Cr3(dpa)4Cl2](PF6) from IR, Raman, and surface-enhanced Raman spectra.

    Science.gov (United States)

    Hsiao, Chung-Jen; Lai, Szu-Hsueh; Chen, I-Chia; Wang, Wen-Zhen; Peng, Shie-Ming

    2008-12-25

    We recorded infrared, Raman, and surface-enhanced Raman scattering (SERS) spectra of metal-string complexes Cr(3)(dpa)(4)X(2) (dpa = di(2-pyridyl)amido, X = Cl, NCS) and [Cr(3)(dpa)(4)Cl(2)](PF(6)) and dipyridylamine (Hdpa) to determine their vibrational frequencies and to study their structures. For the SERS measurements these complexes were adsorbed on silver nanoparticles in aqueous solution to eliminate the constraints of a crystal lattice. From the results of analysis of the vibrational normal modes we assign the infrared band at 346 cm(-1) to the Cr(3) asymmetric stretching vibration of the symmetric form and the Raman line at 570 cm(-1) to the Cr-Cr stretching mode for the unsymmetric form of Cr(3)(dpa)(4)Cl(2). Complex Cr(3)(dpa)(4)Cl(2) exhibits both symmetric (s-) and unsymmetric (u-) forms in solution but Cr(3)(dpa)(4)(NCS)(2) only the s-form. The structures for both complexes in their ground states have the s-form. The oxidized complex [Cr(3)(dpa)(4)Cl(2)](PF(6)) has only a u-form for which the Cr-Cr stretching mode is assigned to the band at 570 cm(-1). From the variation with temperature from 23 to 60 degrees C of the intensity of this line, we obtained the proportion of the u-form Cr(3)(dpa)(4)Cl(2); the enthalpy change is thus obtained to be DeltaH = 46.2 +/- 3.3 kJ mol(-1) and the entropy change is DeltaS = 138 +/- 10.3 J K(-1) mol(-1) for the reaction u-Cr(3)(dpa)(4)Cl(2) s-Cr(3)(dpa)(4)Cl(2). From the spectral intensities and band frequencies in SERS spectra, Hdpa is expected to adsorb on a silver nanoparticle with the amido nitrogen and pyridyl rings tilted from the silver surface, whereas the trichromium complex with the chromium ion line is orthogonal to the silver surface normal in aqueous silver solution.

  12. Raman spectra of selected transuranium trihalides in the solid state

    International Nuclear Information System (INIS)

    Wilmarth, W.R.; Begun, G.M.; Haire, R.G.; Peterson, J.R.

    1988-01-01

    Raman spectral data have been obtained from a number of transuranium trihalides in the solid state. The Raman spectra of these actinide compounds are reported and compared to the published Raman spectra of isostructural compounds. Tentative symmetry assignments have been made for the observed Raman-active lattice vibrations based on nuclear site symmetry analysis of their respective crystal structures and comparisons to the symmetry assignments made for isostructural lanthanide compounds. The Raman spectral data obtained in this study represent a partial data base for the use of Raman spectroscopy for identifying the crystal structures exhibited by these and isostructural compounds

  13. Adaptive estimation of Raman chemical mixture spectra

    Science.gov (United States)

    Burr, David J.; Chen, Carl G.; Sedlacek, Arthur J., III

    1996-11-01

    We introduce an adaptive mixing algorithm for estimating the relative ratios of chemicals in a mixture spectrum. This procedure is particularly well suited to mixtures with a large dynamic range of mixture weights. It has the advantage of being able to be used in conjunction with a band-pass (difference-to-Gaussian or DOG) filter, and a correction of baseline off-set and tilting of the spectrum. Output of these filtering techniques is a cleaner signal retaining most of the relevant Raman spectral signature while minimizing artifacts due primarily to Rayleigh, dust, and atmospheric aerosols. We will describe the results of applying these algorithm to mixture spectra with both real and simulated additive noise.

  14. [Raman spectra of fossil dinosaurs from different regions].

    Science.gov (United States)

    Yang, Qun; Wang, Yi-lin

    2007-12-01

    Raman microscopic spectra in the higher wave number region were obtained from 7 fossil dinosaurs specimens from different regions. The specimens of fossil dinosaurs are different parts of bone. The Raman spectra of fossil dinosaurs indicate the high similarity among peak positions of different fossil dinosaurs; but important differences exist in the spectral peak figures. In the wave number region of 1000-1800 cm(-1) the Raman spectra of the same bone part fossils from different regions are very similar, example similarities between spectra of Lufeing backbone head and Yua nmou backbone head; Lufeng limb bone and Wuding limb bone. There are relations between the same bone part spectra of different fossil dinosaurs. The characteristic does not relate to regions. Raman spectra of fossil dinosaurs cannot be used to distinguish fossil source, although the part of bone can be used as an indicator to narrow the range of possible geographical origins.

  15. Raman spectra of the transplutonium orthophosphates and trimetaphosphates

    International Nuclear Information System (INIS)

    Hobart, D.E.; Begun, G.M.; Haire, R.G.; Hellwege, H.E.

    1983-01-01

    Raman spectra have been obtained from multimicrogram samples of crystalline transplutonium (americium through einsteinium) orthophosphates. Spectra were also obtained for americium, curium, and californium trimetaphosphates. Assignments of the major Raman bands and confirmation of the compounds' stoichiometry were made by comparison with spectra obtained in previous studies on the lanthanide phosphates. The variation of transplutonium orthophosphate vibrational frequencies as a function of atomic number was found to be smaller in magnitude than that established for the lanthanide orthophosphates. (author)

  16. 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

  17. Raman Optical Activity and Raman Spectra of Amphetamine Species

    DEFF Research Database (Denmark)

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

    2012-01-01

    and ROA spectra. As predicted the experimental ROA spectra were found to depend on the chirality. Two street samples, provided by the London Police, were also measured and compared to the calculated ROA spectra. The street samples were found to contain different enantiomers of the protonated am- phetamine...

  18. Local Bi-O bonds correlated with infrared emission properties in triply doped Gd2.95Yb0.02Bi0.02Er0.01Ga5O12 via temperature-dependent Raman spectra and x-ray absorption fine structure analysis.

    Science.gov (United States)

    Tong, Liping; Saito, Katsuhiko; Guo, Qixin; Zhou, Han; Guo, Xingmei; Fan, Tongxiang; Zhang, Di

    2018-03-28

    A correlation function between the Raman intensities and the nearest-neighbor mean-square relative displacement (MSRD) [Formula: see text] of local Bi-O bonds is successfully established based on x-ray absorption fine structure (XAFS) and temperature-dependent Raman spectra in the temperature range 77-300 K in amorphous and crystalline Gd 2.95 Yb 0.02 Bi 0.02 Er 0.01 Ga 5 O 12 . The structural symmetries of Gd 2.95 Yb 0.02 Bi 0.02 Er 0.01 Ga 5 O 12 are described by using [Formula: see text] of local Bi-O bonds. More importantly, Gd 2.95 Yb 0.02 Bi 0.02 Er 0.01 Ga 5 O 12 is found to show excellent infrared (IR) emission properties due to changes in Bi-O bonds, and the IR emission intensities are found to depend on [Formula: see text], by using temperature-dependent photoluminescence spectroscopy. The maximum emission intensity at 1533 nm is obtained when [Formula: see text] [Formula: see text] at the lowest symmetry. This work shows that temperature-dependent Raman intensities can be used effectively to analyze the local covalent bonds around absorbing atoms as well as to study the emission properties of this visible-light-activated IR luminophor.

  19. Local Bi–O bonds correlated with infrared emission properties in triply doped Gd2.95Yb0.02Bi0.02Er0.01Ga5O12 via temperature-dependent Raman spectra and x-ray absorption fine structure analysis

    Science.gov (United States)

    Tong, Liping; Saito, Katsuhiko; Guo, Qixin; Zhou, Han; Guo, Xingmei; Fan, Tongxiang; Zhang, Di

    2018-03-01

    A correlation function between the Raman intensities and the nearest-neighbor mean-square relative displacement (MSRD) σ2 of local Bi–O bonds is successfully established based on x-ray absorption fine structure (XAFS) and temperature-dependent Raman spectra in the temperature range 77–300 K in amorphous and crystalline Gd2.95Yb0.02Bi0.02Er0.01Ga5O12. The structural symmetries of Gd2.95Yb0.02Bi0.02Er0.01Ga5O12 are described by using σ2 of local Bi–O bonds. More importantly, Gd2.95Yb0.02Bi0.02Er0.01Ga5O12 is found to show excellent infrared (IR) emission properties due to changes in Bi–O bonds, and the IR emission intensities are found to depend on σ2 , by using temperature-dependent photoluminescence spectroscopy. The maximum emission intensity at 1533 nm is obtained when σ^2∼0.003 {\\mathringA} at the lowest symmetry. This work shows that temperature-dependent Raman intensities can be used effectively to analyze the local covalent bonds around absorbing atoms as well as to study the emission properties of this visible-light-activated IR luminophor.

  20. [Micro-Raman and fluorescence spectra of several agrochemicals].

    Science.gov (United States)

    Xiao, Yi-lin; Zhang, Peng-xiang; Qian, Xiao-fan

    2004-05-01

    Raman and fluorescence spectra from several agrochemicals were measured, which are sold for the use in vegetables, fruits and grains. Characteristic vibration Raman peaks from some of the agrochemicals were recorded, hence the spectra can be used for their identification. Other marketed agrochemicals demonstrated strong fluorescence under 514.5 nm excitation. It was found that the fluorescence spectra of the agrochemicals are very different. According to these results one can detect the trace amount of agrochemicals left on the surface of fruits, vegetables and grains in situ and conveniently.

  1. Relationship between molecular structure and Raman spectra of quinolines

    Science.gov (United States)

    Frosch, Torsten; Popp, Jürgen

    2009-04-01

    DFT calculations were applied to investigate the relationship between the molecular structure and the Raman spectra of quinolines. A variety of different quinolines with increasing complexity was investigated and an aminoquinoline nucleus was found that describes the Raman spectrum of protonated chloroquine. It was discovered that the biological important, rigid C7-chloro group and C4-side chain of chloroquine significantly disturb certain molecular vibrations. The protonation at the N1 position causes dramatic changes of the Raman bands in the wavenumber region between 1500 cm -1 and 1650 cm -1. These bands are putative marker bands of the aminoquinoline drugs for π-π interactions to the hematin targets in malaria infected cells. The calculation of the normal modes and the illustration of the associated atomic displacements are very valuable for a deeper understanding of the associated bands in the Raman spectra.

  2. Magnetic measurements, Raman and infrared spectra of metal ...

    Indian Academy of Sciences (India)

    70

    Magnetic measurements, Raman and infrared spectra of metal- ligand complex derived from CoCl2·6H2Oand ... molecule derived transition metal (TM) ion based complexes have opened a wide research field in the interface of physics and ..... will give the proper value of the magnetic moment. The present value suggests.

  3. Infrared spectra, Raman laser, XRD, DSC/TGA and SEM ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 34; Issue 4. Infrared spectra, Raman laser, XRD, DSC/TGA and SEM investigations on the preparations of selenium metal, (Sb2O3, Ga2O3, SnO and HgO) oxides and lead carbonate with pure grade using acetamide precursors. Moamen S Refat Khaled M Elsabawy.

  4. Magnetic measurements, Raman and infrared spectra of metal ...

    Indian Academy of Sciences (India)

    2018-04-06

    Apr 6, 2018 ... [24] Bandyopadhyay A, Sutradhar S, Sarkar B J, Deb A. K and Chakbarti P K 2012 Appl. Phys. Lett. 100. 252411. [25] Nakamoto K 1997 Infrared and Raman spectra of inorganic and coordination compounds (New York: John Wiley & Sons. Inc.) 5th edn. [26] Faulques E, Perry D I, Lott S, Zubkowski J D and ...

  5. Investigation on tip enhanced Raman spectra of graphene

    Science.gov (United States)

    Li, Xinjuan; Liu, Yanqi; Zeng, Zhuo; Wang, Peijie; Fang, Yan; Zhang, Lisheng

    2018-02-01

    Tip-enhanced Raman scattering (TERS) is a promising analytical approach for some two-dimensional materials and offers the possibility to correlate imaging and chemical data. Tip-enhanced Raman spectra of graphene are discussed in some details, including substrate, gap between tip-apex and sample surface as well as Ag-nanowire. The TERS spectra give special emphasis to the possibility of TERS tip to induce a large number of defects only while got the tip attached to sample surface. Then the dependence of the TERS spectra of graphene and gap between the probe tip and sample surface was studied, and distribution features of electromagnetic (EM) field around tip were also simulated by finite-difference time-domain (FDTD). The Raman signal enhancement of graphene was further discussed with respect to experimental data. Furthermore, the Ag-nanowire as a nano-antenna could significantly enhance the weak Raman signal of D-band of monolayer graphene is shown, and the TERS spectra of graphene with regard to different regions of Ag-nanowires (endpoints, body) were obtained toward investigating into the distribution of electromagnetic field.

  6. Low-Cost Elimination of Plasma Lines in Raman Spectra.

    Science.gov (United States)

    Behlow, Herbert W., Jr.; Petersen, John D.

    1985-01-01

    Describes a low-cost ($120) device which eliminates plasma lines in Raman spectra. The device consists of two prisms and two mirrors which are held in a symmetrical relationship to one another so that a particular position will allow only one wavelength to pass through on a given axis. (JN)

  7. Determination of temperature and concentrations of main components in flames by fitting measured Raman spectra

    NARCIS (Netherlands)

    Sepman, A. V.; Toro, V.V.; Mokhov, A. V.; Levinsky, H. B.

    The procedure of deriving flame temperature and major species concentrations by fitting measured Raman spectra in hydrocarbon flames is described. The approach simplifies the calibration procedure to determine temperature and major species concentrations from the measured Raman spectra. The

  8. Electronic Raman spectra in iron-based superconductors with two-orbital model

    International Nuclear Information System (INIS)

    Lu Hongyan; Wang Da; Chen San; Wang Wei; Gong Pifeng

    2011-01-01

    Electronic Raman spectra were calculated in orbital space in a microscopic theory. Both Raman spectra and spectra weight were presented. Raman spectra for the gap symmetries are different from each other. The results can help decide the gap symmetry by comparing with experiments. Electronic Raman spectra in iron-based superconductors with two-orbital model is discussed. In the orbital space, some possible pairing symmetries of the gap are selected. To further discriminate them, electronic Raman spectra and spectra weight at Fermi surface (FS) which helps understand the Raman spectra are calculated in each case. From the low energy threshold, the number of Raman peaks, and the low frequency power law behavior, we can judge whether it is full gap or nodal gap, and even one gap or multi-gaps. The results provide useful predictions for comparison with experiments.

  9. Study of the Raman spectra of phonons in disordered GaSb/AlSb (001) superlattices

    International Nuclear Information System (INIS)

    Berdekas, D.

    2010-01-01

    In the present work, we study the influence of disorder in the Raman spectra of the phonons of (GaSb) n /(AlSb) n (001) superlattices (SLs), for n = 1, 2. The disordered superlattices are approximated with primitive cells that are much larger than the primitive cells of the corresponding perfect SLs. We propose that disorder appears because of deviations from the sequence of the GaSb and AlSb layers, which is imposed by symmetry, or because of intermixing of Ga and Al in the cation lattice planes. The dynamical matrix of each SL is constructed from the combination of the dynamical matrices of the bulk crystalline constituents, which have been calculated at certain points of the Brillouin zone with a ten-parameter valence overlap shell model. Further, we have calculated the Raman spectra of the disordered 1 x 1 and 2 x 2 superlattices grown along the (001) direction, using an eight-parameter bond polarizability model, away from resonance conditions. Our results show that intermixing of Ga and Al cations produce Raman activity that is not present in the phonon spectra of perfect superlattices. (author)

  10. Raman spectra of zinc phthalocyanine monolayers absorbed on glassy carbon and gold electrodes by application of a confocal Raman microspectrometer

    NARCIS (Netherlands)

    Palys-Staron, B.J.; Palys, B.J.; Puppels, G.J.; Puppels, G.J.; van den Ham, D.M.W.; van den Ham, D.M.W.; Feil, D.; Feil, D.

    1992-01-01

    Raman spectra of zinc phthalocyanine monolayers, adsorbed on gold and on glassy carbon surfaces (electrodes), are presented. These spectra have been recorded with the electrodes inside and outside an electrochemical cell filled with an aqueous electrolyte. A confocal Raman microspectrometer was

  11. 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

    2016-09-05

    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. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Micro-Raman Vibrational Identification of 10-MDP Bond to Zirconia and Shear Bond Strength Analysis.

    Science.gov (United States)

    De-Paula, Diego Martins; Loguercio, Alessandro D; Reis, Alessandra; Frota, Natasha Marques; Melo, Radamés; Yoshihara, Kumiko; Feitosa, Victor Pinheiro

    2017-01-01

    So far, there is no report regarding the micro-Raman vibrational fingerprint of the bonds between 10-methacryloyloxy-decyl dihydrogen phosphate (10-MDP) and zirconia ceramics. Thus, the aim of this study was to identify the Raman vibrational peaks related to the bonds of 10-MDP with zirconia, as well as the influence on microshear bond strength. Micro-Raman spectroscopy was employed to assess the vibrational peak of 10-MDP binding to zirconia. Microshear bond strength of the dual-cure resin cement to zirconia with the presence of 10-MDP in composition of experimental ceramic primer and self-adhesive resin cement was also surveyed. Statistical analysis was performed by one-way ANOVA and Tukey's test ( p MDP. The presence of 10-MDP in both experimental ceramic primer and self-adhesive resin cement improved microshear bond strength to zirconia ceramic. It can be concluded that the nondestructive method of micro-Raman spectroscopy was able to characterize chemical bonds of 10-MDP with zirconia, which improves the bond strengths of resin cement.

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

    Czech Academy of Sciences Publication Activity Database

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

    2007-01-01

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

  14. Raman Spectra of Nanodiamonds: New Treatment Procedure Directed for Improved Raman Signal Marker Detection

    Directory of Open Access Journals (Sweden)

    Raoul R. Nigmatullin

    2013-01-01

    Full Text Available Detonation nanodiamonds (NDs have shown to be promising agents in several industries, ranging from electronic to biomedical applications. These NDs are characterized by small particle size ranging from 3 to 6 nm, while having a reactive surface and a stable inert core. Nanodiamonds can exhibit novel intrinsic properties such as fluorescence, high refractive index, and unique Raman signal making them very attractive imaging agents. In this work, we used several nanodiamond preparations for Raman spectroscopic studies. We exposed these nanodiamonds to increasing temperature treatments at constant heating rates (425–575°C aiding graphite release. We wanted to correlate changes in the nanodiamond surface and properties with Raman signal which could be used as a detection marker. These observations would hold potential utility in biomedical imaging applications. First, the procedure of optimal linear smoothing was applied successfully to eliminate the high-frequency fluctuations and to extract the smoothed Raman spectra. After that we applied the secondary Fourier transform as the fitting function based on some significant set of frequencies. The remnant noise was described in terms of the beta-distribution function. We expect this data treatment to provide better results in biomolecule tracking using nanodiamond base Raman labeling.

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

    Directory of Open Access Journals (Sweden)

    Andrea Alparone

    2013-01-01

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

  16. Resonance Raman spectra of metal halide vapor complexes

    International Nuclear Information System (INIS)

    Paptheodorou, G.N.

    1978-01-01

    Resonance Raman spectra of complex vapor phase compounds formed by reacting ''acidic'' gases (A 2 X 6 = Al 2 Cl 6 , Al 2 Br 6 , In 2 Cl 6 ) with metal halides have been measured. Spectra obtained from equilibrium vapor mixtures of A 2 X 6 over solid MX 2 (= PdCl 2 , PdBr 2 , CuCl 2 , CoBr 2 , TiCl 2 , FeCl 2 , NiCl 2 , PtCl 2 ) were a superposition of the A 2 X 6 -AX 3 bands and in few cases of new resonance-enhanced polarized bands due to MA 2 X 8 and/or MAX 5 complexes. At temperatures above 800 0 K, characteristic bands due to MX 2 (g) (M = Fe, Co, Ni, Cu, Zn) and M 2 X 4 (g) (M = Cu) were observed. The predominant features of the PdAl 2 Cl 8 , CuAl 2 Cl 8 , and PdAl 2 Br 6 spectra were three high-intensity, polarized bands which were attributed to the vibrational modes of the complex coupled to the electronic state of the central atom. The spectra of CuAlCl 5 (g), CuInCl 5 (g) and Cu 2 Cl 4 (g) species showed resonance enhancement of selective fundamentals which were attributed to vibrational modes of trigonally coordinated Cu(II). Resonance Raman spectra of U 2 Cl 10 (g) and UCl 5 .AlCl 3 (g) were characterized by the presence of a strong band attributed to the U-Cl/sub t/ stretching frequency. Raman band intensity measurements were carried out for the iron(III) chloride vapors and for the vapor complexes of CuAl 2 Cl 8 , CuInCl 5 and UCl 5 .AlCl 3 using different laser powers and frequencies. The measurements suggested increasing spectroscopic temperatures and decomposition of the vapor complexes. The data are discussed in terms of the distribution of vibrational modes and the structure of the vapor species. 22 figs

  17. Raman spectra of acoustooptic NaBi(MoO4)2 crystals

    International Nuclear Information System (INIS)

    Moiseenko, V.N.; Bogatyrev, Yu.I.; Eremenko, A.M.; Akimov, S.V.

    2000-01-01

    Raman spectra of NaBi(MoO 4 ) 2 single crystals are measured and the frequencies of phonon modes are determined using a fitting procedure. The symmetry species are found by selection rules. The interpretation of the Raman spectra is made in terms of the influence of defects: Mo nonstoichiometry and disordered structure in dispositions of Na + and Bi 3+ ions. The peculiarity of Raman spectra is their large Raman scattering efficiency. The obtained value of the Raman scattering cross-section is 10 3 times more than that in CaCo 3 crystals. It can be a reason for a high acoustooptic efficiency of this material

  18. A relationship between Raman and infrared spectra: the case of push pull molecules

    Science.gov (United States)

    Del Zoppo, M.; Tommasini, M.; Castiglioni, C.; Zerbi, G.

    1998-04-01

    Vibrational spectra of push-pull polyenes show a peculiar feature namely, in infrared and Raman spectra strong, coincident bands appear, arising from vibrations localised on the polyene bridge. A simple model, based on the introduction of an effective internal field due to the charge transfer between end groups allows the infrared and Raman intensities of these bands to be related.

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

    Science.gov (United States)

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

    2015-01-05

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

  20. The spectroscopic (FTIR, FT-Raman and UV-Vis spectra), DFT and normal coordinate computations of m-nitromethylbenzoate.

    Science.gov (United States)

    Gnanasambandan, T; Gunasekaran, S; Seshadri, S

    2013-08-01

    A combined experimental and theoretical study on molecular structure, vibrational spectra, NBO and UV-spectral analysis of m-nitromethylbenzoate (MNMB) has been reported in the present work. The FT-IR solid phase (4000-400 cm(-1)) and FT-Raman spectra (3500-100 cm(-1)) of MNMB was recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of MNMB in the ground-state have been calculated by using the density functional method B3LYP with 6-31G (d,p) and 6-31+G(d,p) basis sets. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). Stability of the molecule arising from hyperconjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ* antibonding orbitals and E(2) energies confirms the occurrence of ICT (Intra-molecular Charge Transfer) within the molecule. The UV spectrum was measured in ethyl acetate solution. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) result complements the experimental findings. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally the calculation results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. 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...

  2. Raman Spectra and Bulk Modulus of Nanodiamond in a Size Interval of 2-5 nm

    Science.gov (United States)

    Popov, Mikhail; Churkin, Valentin; Kirichenko, Alexey; Denisov, Viktor; Ovsyannikov, Danila; Kulnitskiy, Boris; Perezhogin, Igor; Aksenenkov, Viktor; Blank, Vladimir

    2017-10-01

    Nanodiamond in a 2-5-nm size interval (which is typical for an appearance of quantum confinement effect) show Raman spectra composed of 3 bands at 1325, 1600, and 1500 cm-1 (at the 458-nm laser excitation) which shifts to 1630 cm-1 at the 257-nm laser excitation. Contrary to sp2-bonded carbon, relative intensities of the bands do not depend on the 458- and 257-nm excitation wavelengths, and a halfwidth and the intensity of the 1600 cm-1 band does not change visibly under pressure at least up to 50 GPa. Bulk modulus of the 2-5-nm nanodiamond determined from the high-pressure study is around 560 GPa. Studied 2-5-nm nanodiamond was purified from contamination layers and dispersed in Si or NaCl.

  3. Raman spectra of iodine-derivatives of tyrosine and thyronine

    International Nuclear Information System (INIS)

    Loh, E.

    1974-01-01

    The Raman spectra of the iodine derivatives of tyrosine and thyronine in the form of compressed crystalline powders have been excited by 4880 A Argon laser on rotating samples at room temperature. The strong peaks in the low-frequency, -1 , region may be described by analogous vibrations of benzene as: I. the C-I out-of-plane bendings of E 1 sub(g) mode from 100 cm -1 to 180 cm -1 ; II. the C-I in-plane bendings of E 2 sub(g) and A 2 sub(g) mode from 190 cm -1 to 330 cm -1 and III. the C-I stretchings of E 2 sub(g) mode from 330 cm -1 to 400 cm -1 . In 3,3',5-triiodo-derivatives, the number of both the C-I in-plane bendings and C-I stretchings on the inner phenyl ring approximately doubles from thet of diiodo-derivatives. This doubling in number of peaks is presumably due to the modulation caused by the libration, which is associated with the C-I out-of-plane bending at position 3', of the outer phenyl ring

  4. Rapid acquisition of mean Raman spectra of eukaryotic cells for a robust single cell classification.

    Science.gov (United States)

    Schie, Iwan W; Kiselev, Roman; Krafft, Christoph; Popp, Jürgen

    2016-11-14

    Raman spectroscopy has previously been used to identify eukaryotic and prokaryotic cells. While prokaryotic cells are small in size and can be assessed by a single Raman spectrum, the larger size of eukaryotic cells and their complex organization requires the acquisition of multiple Raman spectra to properly characterize them. A Raman spectrum from a diffraction-limited spot at an arbitrary location within a cell results in spectral variations that affect classification approaches. To probe whole cells with Raman imaging at high spatial resolution is time consuming, because a large number of Raman spectra need to be collected, resulting in low cell throughput and impairing statistical analysis due to low cell numbers. Here we propose a method to overcome the effects of cellular heterogeneity by acquiring integrated Raman spectra covering a large portion of a cell. The acquired spectrum represents the mean macromolecular composition of a cell with an exposure time that is comparable to acquisition of a single Raman spectrum. Data sets were collected from T lymphocyte Jurkat cells, and pancreatic cell lines Capan1 and MiaPaca2. Cell classification by support vector machines was compared for single spectra, spectra of images and integrated Raman spectra of cells. The integrated approach provides better and more stable prediction for individual cells, and in the current implementation, the mean macromolecular information of a cell can be acquired faster than with the acquisition of individual spectra from a comparable region. It is expected that this approach will have a major impact on the implementation of Raman based cell classification.

  5. 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.

  6. IR Spectra and Bond Energies Computed Using DFT

    Science.gov (United States)

    Bauschlicher, Charles; Andrews, Lester; Arnold, James (Technical Monitor)

    2000-01-01

    The combination of density functional theory (DFT) frequencies and infrared (IR) intensities and experimental spectra is a very powerful tool in the identification of molecules and ions. The computed and measured isotopic ratios make the identification much more secure than frequencies and intensities alone. This will be illustrated using several examples, such as Mn(CO)n and Mn(CO)n-. The accuracy of DFT metal-ligand bond energies will also be discussed.

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

    Science.gov (United States)

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

    2018-04-01

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

  9. 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...

  10. Thermal dissociation of molten KHSO4: Temperature dependence of Raman spectra and thermodynamics

    DEFF Research Database (Denmark)

    Knudsen, Christian B.; Kalampounias, Angelos G.; Fehrmann, Rasmus

    2008-01-01

    Raman spectroscopy is used to study the thermal dissociation of molten KHSO4 at temperatures of 240-450 degrees C under static equilibrium conditions. Raman spectra obtained at 10 different temperatures for the molten phase and for the vapors thereof exhibit vibrational wavenumbers and relative...

  11. Raman spectra of C{sub 60} dimer and C{sub 60} polymer confined inside a (10, 10) single-walled carbon nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Chadli, H; Rahmani, A [Laboratoire de Physique des Materiaux et Modelisation des Systemes (Unite Associee au CNRST-URAC 08), Universite MY Ismail, Faculte des Sciences, BP 11201, Zitoune, 50000 Meknes (Morocco); Sauvajol, J-L [Laboratoire des Colloides, Verres et Nanomateriaux (UMR CNRS 5587), Universite Montpellier II, 34095 Montpellier Cedex 5 (France)

    2010-04-14

    A new set of C-C interball force constant was developed in order to reproduce the low wavenumber density of states measured by neutron scattering and the Raman spectra of the C{sub 60} dimer and C{sub 60} polymer chain. The nonresonant Raman spectra of the C{sub 60} dimer and C{sub 60} polymer confined inside a (10, 10) single-walled carbon nanotube were calculated in the framework of the bond-polarization theory by using the spectral moments method. The main changes of the Raman spectrum as a function of the organization of the C{sub 60} molecules inside the nanotubes were identified. We found that the radial breathing modes of a (10, 10) single-walled carbon nanotube are more sensitive on the structure of the C{sub 60} molecules than the G-modes. These predictions are useful to interpret the experimental Raman spectrum of fullerene peapods.

  12. 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.

  13. Conformational states of N-acylalanine dithio esters: correlation of resonance Raman spectra with structures

    International Nuclear Information System (INIS)

    Lee, H.; Angus, R.H.; Storer, A.C.; Varughese, K.I.; Carey, P.R.

    1988-01-01

    The conformational states of N-acylalanine dithio esters, involving rotational isomers about the RC(=O)NH-CH(CH 3 ) and NHCH(CH 3 )-C(=S) bonds, are defined and compared to those of N-acylglycine dithio esters. The structure of N-(p-nitrobenzoyl)-DL-alanine ethyl dithio ester has been determined by X-ray crystallographic analysis; it is a B-type conformer with the amide N atom cis to the thiol sulfur. Raman and resonance Raman (RR) measurements on this compound and for the B conformers of solid N-benzoyl-DL-alanine ethyl dithio ester and N-(β-phenylpropionyl)-DL-alanine ethyl dithio ester and its NHCH(CD 3 )C(=S) and NHCH(CH 3 ) 13 C(=S) analogues are used to set up a library of RR data for alanine-based dithio esters in a B-conformer state. RR data for this solid material in its isotopically unsubstituted and CH(C-D 3 )C(=S) and CH(CH 3 ) 13 C(=S) forms provide information on the RR signatures of alanine dithio esters in A-like conformations. RR spectra are compared for the solid compounds, for N-(p-nitrobenzoyl)-DL-alanine, N-(β-phenylpropionyl)-DL-alanine, and (methyloxycarbonyl)-L-phenylalanyl-DL-alanine ethyl dithio ester, and for several 13 C=S- and CD 3 -substituted analogues in CCl 4 or aqueous solutions. The RR data demonstrate that the alanine-based dithio esters take up A, B, and C 5 conformations in solution. The RR spectra of these conformers are clearly distinguishable from those for the same conformers of N-acylglycine dithio esters. However, the crystallographic and spectroscopic results show that the results show that the conformational properties of N-acylglycine and N-acylalanine dithio esters are very similar

  14. Hydrostatic pressure and temperature effect on the Raman spectra of the molecular crystal 2-amine-1,3,4-thiadiazole

    Science.gov (United States)

    de Toledo, T. A.; da Costa, R. C.; Bento, R. R. F.; Pizani, P. S.

    2018-03-01

    The structural, thermal and vibrational properties of the molecular crystal 2-amine-1,3,4-thiadiazole (ATD) were investigated combining X-ray diffraction, infrared spectroscopy, Raman scattering (in solid and in solution) and thermal analysis as experimental techniques and first principle calculations based on density functional theory using PZ, BLYP in condensed-phase and B3LYP/cc-pVTZ in isolated molecule methods. The structural stability and phonon anharmonicity were also studied using Raman spectroscopy at different temperatures and hydrostatic pressures. A reasonable agreement was obtained between calculated and experimental results. The main difference between experimental and computed structural and vibrational spectra occurred in the intermolecular bond distance Nsbnd H⋯N and stretching modes of NH2. The vibrational spectra were interpreted and assigned based on group theory and functional group analysis assisted by theoretical results, which led to a more comprehensive knowledge about external and internal modes at different thermodynamic conditions. As temperature increases, it was observed the line-width increases and red-shifts, indicating a phonon anharmonicity without a temperature-induced phase transition in the range 10-413 K. However, ATD crystal undergoes a phase transition in the temperature range 413-475 K, as indicated by thermal analysis curve and Raman spectra. Furthermore, increasing pressure from ambient to 3.1 GPa, it was observed the splitting of the external Raman bands centered at 122 cm-1 (at 0.2 GPa), 112 cm-1 (1.1 GPa), 93 cm-1 (2.4 GPa) in two components as well as the appearance of new band near 50 cm-1 at 1.1 GPa, indicating a possible phase-transition. The blue-shift of the Raman bands was associated to anharmonicity of the interatomic potential caused by unit cell contraction.

  15. DFT study on the Raman spectra of Fe(II-porphin

    Directory of Open Access Journals (Sweden)

    Hovorun D. M.

    2009-02-01

    Full Text Available DFT quantum-chemical calculations of the Raman spectra of Fe(II-porphin in quintet (ground state were performed. Spin-unrestricted UB3LYP functional in 6-311G basis was used for geometry optimization and Raman calculation. All active modes of Raman spectrum were analyzed in detail. It was noted that the insertion of Fe(II ion into porphin leads to the considerable changes in frequencies and intensities for those vibrational modes which involve nitrogen atoms displacement. The Raman depolarization ratio for plane polarized incident light is discussed

  16. 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.

  17. Analytic calculations of hyper-Raman spectra from density functional theory hyperpolarizability gradients

    Energy Technology Data Exchange (ETDEWEB)

    Ringholm, Magnus; Ruud, Kenneth [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø – The Arctic University of Norway, 9037 Tromsø (Norway); Bast, Radovan [Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, AlbaNova University Center, S-10691 Stockholm (Sweden); PDC Center for High Performance Computing, Royal Institute of Technology, S-10044 Stockholm (Sweden); Oggioni, Luca [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø – The Arctic University of Norway, 9037 Tromsø (Norway); Department of Physics G. Occhialini, University of Milano Bicocca, Piazza della scienza 3, 20126 Milan (Italy); Ekström, Ulf [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, 0315 Oslo (Norway)

    2014-10-07

    We present the first analytic calculations of the geometrical gradients of the first hyperpolarizability tensors at the density-functional theory (DFT) level. We use the analytically calculated hyperpolarizability gradients to explore the importance of electron correlation effects, as described by DFT, on hyper-Raman spectra. In particular, we calculate the hyper-Raman spectra of the all-trans and 11-cis isomers of retinal at the Hartree-Fock (HF) and density-functional levels of theory, also allowing us to explore the sensitivity of the hyper-Raman spectra on the geometrical characteristics of these structurally related molecules. We show that the HF results, using B3LYP-calculated vibrational frequencies and force fields, reproduce the experimental data for all-trans-retinal well, and that electron correlation effects are of minor importance for the hyper-Raman intensities.

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

    Science.gov (United States)

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

    2008-11-01

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

  19. Analysis of disulphide bonds found in human hair by Raman spectroscopy

    Science.gov (United States)

    Pina-Ruiz, A. L.; Cordova-Fraga, T.; Plascencia-Castro, A. S.; Hernandez-Rayas, A.; Ruvalcaba, J. M.

    2017-04-01

    Raman spectroscopy offers information-rich spectra, making it a technique easy to use in areas such as biology, chemistry, and in the field. Human hair spectra has been recorded obtaining interesting information about its composition. Correlating information obtained from these spectra to bone health and determining if Raman spectroscopy could be used as a diagnostic tool of bone health is proposed. Spectra from healthy women were compared to the spectra of women who have suffered a bone fracture, all which were aged 39-60. This technique has potential to become a regular diagnostic tool and further investigation to improve and validate this method are needed.

  20. 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.

  1. Crystal structure, vibrational spectra and DFT studies of hydrogen bonded 1,2,4-triazolium hydrogenselenate

    Science.gov (United States)

    Arjunan, V.; Thirunarayanan, S.; Marchewka, M. K.; Mohan, S.

    2017-10-01

    The new hydrogen bonded molecular complex 1,2,4-triazolium hydrogenselenate (THS) is prepared by the reaction of 1H-1,2,4-triazole and selenic acid. This complex is stabilised by N-H⋯O and C-H⋯O hydrogen bonding and electrostatic attractive forces between 1H and 1,2,4-triazolium cations and hydrogen selenate anions. The XRD studies revealed that intermolecular proton transfer occur from selenic acid to 1H-1,2,4-triazole molecule, results in the formation of 1,2,4-triazolium hydrogenselenate which contains 1,2,4-triazolium cations and hydrogenselenate anions. The molecular structure of THS crystal has also been optimised by using Density Functional Theory (DFT) using B3LYP/cc-pVTZ and B3LYP/6-311++G** methods in order to find the whole characteristics of the molecular complex. The theoretical structural parameters such as bond length, bond angle and dihedral angle determined by DFT methods are well agreed with the XRD parameters. The atomic charges and thermodynamic properties are also calculated and analysed. The energies of frontier molecular orbitals HOMO, LUMO, HOMO-1, LUMO+1 and LUMO-HUMO energy gap are calculated to understand the kinetic stability and chemical reactivity of the molecular complex. The natural bond orbital analysis (NBO) has been performed in order to study the intramolecular bonding interactions and delocalisation of electrons. These intra molecular charge transfer may induce biological activities such as antimicrobials, antiinflammatory, antifungal etc. The complete vibrational assignments of THS have been performed by using FT-IR and FT-Raman spectra.

  2. Different level of fluorescence in Raman spectra of montmorillonites

    Czech Academy of Sciences Publication Activity Database

    Ritz, M.; Vaculíková, Lenka; Kupková, J.; Plevová, Eva; Bartoňová, L.

    2016-01-01

    Roč. 84, May 2016 (2016), s. 7-15 ISSN 0924-2031 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : Raman spectroscopy * fluorescence * montmorillonite Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.740, year: 2016

  3. Different level of fluorescence in Raman spectra of montmorillonites

    Czech Academy of Sciences Publication Activity Database

    Ritz, M.; Vaculíková, Lenka; Kupková, J.; Plevová, Eva; Bartoňová, L.

    2016-01-01

    Roč. 84, May 2016 (2016), s. 7-15 ISSN 0924-2031 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : Raman spectroscopy * fluorescence * montmorillonite Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 1.740, year: 2016

  4. Surface enhanced Raman spectra of the organic nonlinear optic ...

    Indian Academy of Sciences (India)

    Wintec

    Institute of Chemistry, University of Opole, Olesksa 48 45-052 Opole, Poland. 1. Present Address: Department of Physics, V.P.S.H.S.S. for ... co-ordination chemistry. Surface-enhanced Raman scattering (SERS), using .... numbers were calculated using analytic second de- rivatives to confirm the convergence to minima on.

  5. Raman spectra of hot-pressed boron suboxide

    CSIR Research Space (South Africa)

    Machaka, R

    2011-01-01

    Full Text Available press. 59 LIPS/LIBS technique (laser induced plasma/breakdown spectroscopy) for laser synthesis of single-wall CNTs and their growth mechanism. akovos Sigalas is currently Element Six Professor... show an overall good agreement. Copyright ? 2011 VBRI press. Keywords: Hot-pressed boron suboxide; B6O; Raman spectroscopy; fluorescence background subtraction. Ronald Machaka is a Ph.D candidate at the University of the Witwatersrand...

  6. New model of Raman spectra in laser produced plasma

    International Nuclear Information System (INIS)

    Some experimental observations of Raman scattering in laser produced plasma have been previously attributed to the onset of the convective Stimulated Raman Instability (SRS-C). This interpretation has had a number of difficulties, associated with the calculated threshold for onset of the SRS-C, the existence of gaps in the frequency spectrum near the incident frequency ω 0 and near ω 0 /2, and with the angular distribution. We now propose a new explanation based on ordinary incoherent Thompson scattering, with a greatly enhanced plasma line. Transient local reversed-slope velocity distributions in the underdense region can be produced by pulses of hot electrons arising from the two-plasmon (2ω/sub p/) or absolute stimulated Raman instabilities (SRS-A) occurring near the quarter critical surface. A simple model yields the observed spectral gaps near ω 0 and near ω 0 /2. It also explains the correlation of onset of this scattering with onset of the SRS-A, its transient localization in frequency and time, and the weak azimuthal angular variation. The existence of upscattered light is also predicted

  7. Study of high-temperature multiplex HCl coherent anti-Stokes Raman spectroscopy spectra.

    Science.gov (United States)

    Singh, J P; Yueh, F Y; Kao, W; Cook, R L

    1993-02-20

    A feasibility study of temperature measurement with multiplex HCl coherent anti-Stokes Raman spectroscopy (CARS) is investigated. The HCl CARS spectra of a 100% HCl gas sample are recorded in a quartz sample cell placed in a furnace at 1 atm pressure and at different temperatures. The nonlinear susceptibility of HCl (chi(nr)(HCl)), which is measured with the present CARS experimental setup, is reported. The experimental spectra are fit by using a library of simulated HCl CARS spectra with a least-squares-fitting program to infer the temperature. The inferred temperatures from HCl CARS spectra are in agreement with thermocouple temperatures.

  8. Insight into boron-doped diamond Raman spectra characteristic features

    Czech Academy of Sciences Publication Activity Database

    Mortet, Vincent; Vlčková Živcová, Zuzana; Taylor, Andrew; Frank, Otakar; Hubík, Pavel; Trémouilles, D.; Jomard, F.; Barjon, J.; Kavan, Ladislav

    2017-01-01

    Roč. 115, May (2017), s. 279-284 ISSN 0008-6223 R&D Projects: GA ČR GA13-31783S; GA MŠk 7AMB16FR004 Grant - others:AV ČR(CZ) Fellowship J. E. Purkyně Institutional support: RVO:68378271 ; RVO:61388955 Keywords : diamond * boron doping * Raman spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism; CG - Electrochemistry (UFCH-W) OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.); Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) (UFCH-W) Impact factor: 6.337, year: 2016

  9. Quantum chemical determination of molecular geometries, interpretation of FT-IR, FT-Raman spectra and charge transfer properties for N-(2-cyanoethyl)-N-methylaniline.

    Science.gov (United States)

    Revathi, B; Nataraj, A; Balachandran, V

    2014-04-24

    FT-Raman and FT-IR spectra were recorded for N-(2-cyanoethyl)-N-methylaniline sample in solid state. The equilibrium geometries, harmonic vibrational frequencies, infrared and Raman scattering activities were computed using DFT method. Results obtained at this level of theory were used for a detailed interpretation of the infrared and Raman spectra, based on the potential energy distribution (PED) of the normal modes. Molecular parameters such as bond length, and bond angle were calculated with the same method. The intra-molecular charge transfer was calculated by means of natural bond orbital analysis (NBO). Hyperconjugative interaction energy was more during the π-π(*) transition. Energy gap of the molecule was found using HOMO and LUMO calculation, hence the less band gap, which seems to be more stable. Atomic charges of various atoms of title molecule and other thermo-dynamical parameters were calculated using same levels of calculation. The correlation equations between heat capacity, entropy, Gibb's free energies changes with temperatures were fitted by quadratic formula. UV-VIS spectral analyses of title molecule 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 were performed. The calculated frontier orbital energies, absorption wavelengths (λ), oscillator strengths (f) and excitation energies (E) for gas phase in different solvent are also illustrated. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

  10. Infrared and Raman scattering spectra of layered structured Ga3InSe4 crystals

    Science.gov (United States)

    Isik, M.; Gasanly, N. M.; Korkmaz, F.

    2013-03-01

    The infrared reflectivity and transmittance and Raman scattering in Ga3InSe4 layered crystals were investigated in the frequency ranges of 100-400, 400-4000 and 25-500 cm-1. The refractive and absorption indices, the frequencies of transverse and longitudinal optical modes, high- and low-frequency dielectric constants were obtained from the analysis of the IR reflectivity spectra. The bands observed in IR transmittance spectra were interpreted in terms of two-phonon absorption processes.

  11. 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 as...

  12. Surface enhanced Raman spectra of the organic nonlinear optic ...

    Indian Academy of Sciences (India)

    Wintec

    Institute of Chemistry, University of Opole, Olesksa 48 45-052 Opole, Poland. 1. Present Address: Department of ... The surface geometry of methyl 3-(4-methoxy phenyl)prop-2-enoate molecule was studied by analysis of the SERS spectra .... Harmonic vibrational wave numbers were calculated using analytic second de-.

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

    DEFF Research Database (Denmark)

    Sigurdsson, Sigurdur

    2003-01-01

    melanoma. The neural network classifier visualization showed that frequency bands, previously identified by visual inspection of Raman spectra by medical experts, were considered important for classification. Moreover, frequency band not previously used for skin lesion classification were identified....... 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...... brugt til diagnosering af hudkræft. Disse vigtige frekvensbånd stammer fra forskel i molekyle struktur i lipider og proteiner. Selv om temaet for denne afhandling er hudkræft diagnosering fra Raman spektra, kan dimensions reduceringen og det neurale netværk bruges til andre mønster genkendelses...

  14. Resonance Raman Spectra of the Transient Cl2 and Br2 Radical Anions

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter; Jensen, Niels-Henrik; Sillesen, Alfred Hegaard

    1984-01-01

    The resonance Raman spectra of the short-lived radical anions ClImage 2− and BrImage − in aqueous solution are reported. The observed wavenumbers of 279 cm−1 for ClImage − and 177 cm−1 for BrImage − are about 10% higher than those published for the corresponding species isolated in solid argon ma...

  15. Raman Spectra and Dynamics of Thiocyanate Ion in Poly(Vinyl Alcohol)-KSCN Films

    Science.gov (United States)

    Gafurov, M. M.; Rabadanov, K. Sh.; Shabanov, N. S.; Tretinnikov, O. N.; Amirov, A. M.; Gadjimagomedov, S. Kh.

    2017-11-01

    Raman spectra of poly(vinyl alcohol)-potassium-thiocyanate films are studied. Parameters of vibrational and orientational relaxation of thiocyanate ion in the polymer matrix are determined. The character and rate of vibrational dephasing become identical to SCN- vibrations in aqueous solution at salt concentrations ≥0.3 M.

  16. Raman spectra of titanium dioxide (anatase, rutile) with identified oxygen isotopes (16, 17, 18)

    Czech Academy of Sciences Publication Activity Database

    Frank, Otakar; Zukalová, Markéta; Lásková, Barbora; Kürti, J.; Koltai, J.; Kavan, Ladislav

    2012-01-01

    Roč. 14, č. 42 (2012), s. 14567-14572 ISSN 1463-9076 R&D Projects: GA AV ČR IAA400400804; GA AV ČR KAN200100801 Institutional support: RVO:61388955 Keywords : Raman spectra * TiO2 * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 3.829, year: 2012

  17. A Raman spectroscopy study on the effects of intermolecular hydrogen bonding on water molecules absorbed by borosilicate glass surface

    Science.gov (United States)

    Li, Fabing; Li, Zhanlong; Wang, Ying; Wang, Shenghan; Wang, Xiaojun; Sun, Chenglin; Men, Zhiwei

    2018-05-01

    The structural forms of water/deuterated water molecules located on the surface of borosilicate capillaries have been first investigated in this study on the basis of the Raman spectral data obtained at different temperatures and under atmospheric pressure for molecules in bulk and also for molecules absorbed by borosilicate glass surface. The strongest two fundamental bands locating at 3063 cm-1 (2438 cm-1) in the recorded Raman spectra are assigned here to the Osbnd H (Osbnd D) bond stretching vibrations and they are compared with the corresponding bands observed at 3124 cm-1 (2325 cm-1) in the Raman spectrum of ice Ih. Our spectroscopic observations have indicated that the structure of water and deuterated water molecules on borosilicate surface is similar to that of ice Ih (hexagonal phase of ice). These observations have also indicated that water molecules locate on the borosilicate surface so as to construct a bilayer structure and that strong and weak intermolecular hydrogen bonds are formed between water/deuterated molecules and silanol groups on borosilicate surface. In accordance with these findings, water and deuterated water molecules at the interface of capillary have a higher melting temperature.

  18. A Raman spectroscopy study on the effects of intermolecular hydrogen bonding on water molecules absorbed by borosilicate glass surface.

    Science.gov (United States)

    Li, Fabing; Li, Zhanlong; Wang, Ying; Wang, Shenghan; Wang, Xiaojun; Sun, Chenglin; Men, Zhiwei

    2018-05-05

    The structural forms of water/deuterated water molecules located on the surface of borosilicate capillaries have been first investigated in this study on the basis of the Raman spectral data obtained at different temperatures and under atmospheric pressure for molecules in bulk and also for molecules absorbed by borosilicate glass surface. The strongest two fundamental bands locating at 3063cm -1 (2438cm -1 ) in the recorded Raman spectra are assigned here to the OH (OD) bond stretching vibrations and they are compared with the corresponding bands observed at 3124cm -1 (2325cm -1 ) in the Raman spectrum of ice Ih. Our spectroscopic observations have indicated that the structure of water and deuterated water molecules on borosilicate surface is similar to that of ice Ih (hexagonal phase of ice). These observations have also indicated that water molecules locate on the borosilicate surface so as to construct a bilayer structure and that strong and weak intermolecular hydrogen bonds are formed between water/deuterated molecules and silanol groups on borosilicate surface. In accordance with these findings, water and deuterated water molecules at the interface of capillary have a higher melting temperature. Copyright © 2018. Published by Elsevier B.V.

  19. Studies of the Raman Spectra of Cyclic and Acyclic Molecules: Combination and Prediction Spectrum Methods

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Taijin; Assary, Rajeev S.; Marshall, Christopher L.; Gosztola, David J.; Curtiss, Larry A.; Stair, Peter C.

    2012-04-02

    A combination of Raman spectroscopy and density functional methods was employed to investigate the spectral features of selected molecules: furfural, 5-hydroxymethyl furfural (HMF), methanol, acetone, acetic acid, and levulinic acid. The computed spectra and measured spectra are in excellent agreement, consistent with previous studies. Using the combination and prediction spectrum method (CPSM), we were able to predict the important spectral features of two platform chemicals, HMF and levulinic acid.The results have shown that CPSM is a useful alternative method for predicting vibrational spectra of complex molecules in the biomass transformation process.

  20. Studies of the Raman spectra of cyclic and acyclic molecules: Combination and prediction spectrum methods

    Science.gov (United States)

    Kim, Taejin; Assary, Rajeev S.; Marshall, Christopher L.; Gosztola, David J.; Curtiss, Larry A.; Stair, Peter C.

    2012-04-01

    A combination of Raman spectroscopy and density functional methods was employed to investigate the spectral features of selected molecules: furfural, 5-hydroxymethyl furfural (HMF), methanol, acetone, acetic acid, and levulinic acid. The computed spectra and measured spectra are in excellent agreement, consistent with previous studies. Using the combination and prediction spectrum method (CPSM), we were able to predict the important spectral features of two platform chemicals, HMF and levulinic acid. The results have shown that CPSM is a useful alternative method for predicting vibrational spectra of complex molecules in the biomass transformation process.

  1. [Raman spectra of endospores of Bacillus subtilis by alkali stress].

    Science.gov (United States)

    Dong, Rong; Lu, Ming-qian; Li, Feng; Shi, Gui-yu; Huang, Shu-shi

    2013-09-01

    To research the lethal mechanism of spores stressed by alkali, laser tweezers Raman spectroscopy (LTRS) combined with principal components analysis (PCA) was used to study the physiological process of single spore with alkali stress. The results showed that both spores and germinated spores had tolerance with alkali in a certain range, but the ability of spores was obviously lower than that of spores due to the release of their Ca2+ -DPA which plays a key role in spores resistance as well as spores resistance to many stresses; A small amount of Ca2+ -DPA of spores was observed to release after alkali stress, however, the behavior of release was different with the normal Ca2+ -DPA release behavior induced by L-alanine; The data before and after alkali stress of the spores and g. spores with PCA reflected that alkali mainly injured the membrane of spores, and alkali could be easily enter into the inner structure of spores to damage the structure of protein backbone and injure the nucleic acid of spores. We show that the alkali could result in the small amount of Ca2+ -DPA released by destroying the member channel of spores.

  2. Resonance Raman spectra of wurtzite and zincblende CdSe nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Anne Myers, E-mail: amkelley@ucmerced.edu [Chemistry and Chemical Biology, School of Natural Sciences, University of California, 5200 North Lake Road, Merced, CA 95343 (United States); Dai, Quanqin; Jiang, Zhong-jie; Baker, Joshua A.; Kelley, David F. [Chemistry and Chemical Biology, School of Natural Sciences, University of California, 5200 North Lake Road, Merced, CA 95343 (United States)

    2013-08-30

    Highlights: ► Very similar resonance Raman spectra of wurtzite and zincblende CdSe nanocrystals. ► First absolute resonance Raman cross-sections reported for CdSe nanocrystals. ► LO overtones suggest slightly stronger electron–phonon coupling in wurtzite form. - Abstract: Resonance Raman spectra and absolute differential Raman cross-sections have been measured for CdSe nanocrystals in both the wurtzite and zincblende crystal forms at four excitation wavelengths from 457.9 to 514.5 nm. The frequency and bandshape of the longitudinal optical (LO) phonon fundamental is essentially identical for both crystal forms at each excitation wavelength. The LO phonon overtone to fundamental intensity ratio appears to be slightly higher for the wurtzite form, which may suggest slightly stronger exciton–phonon coupling from the Fröhlich mechanism in the wurtzite form. The LO fundamental Raman cross-sections are very similar for both crystal forms at each excitation wavelength.

  3. 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.; van den Ham, Dirk M.W.; van den Ham, D.M.W.; Briels, Willem J.; Feil, D.; 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

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

    Science.gov (United States)

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

    2013-02-15

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

  5. Wavelet data analysis of micro-Raman spectra for follow-up monitoring in oral pathologies

    Science.gov (United States)

    Camerlingo, C.; Zenone, F.; Perna, G.; Capozzi, V.; Cirillo, N.; Gaeta, G. M.; Lepore, M.

    2008-02-01

    A wavelet multi-component decomposition algorithm has been used for data analysis of micro-Raman spectra from human biological samples. In particular, measurements have been performed on some samples of oral tissue and blood serum from patients affected by pemphigus vulgaris at different stages. Pemphigus is a chronic, autoimmune, blistering disease of the skin and mucous membranes with a potentially fatal outcome. The disease is characterized histologically by intradermal blisters and immunopathologically by the finding of tissue bound and circulating immunoglobulin G (IgG) antibody directed against the cell surface of keratinocytes. More than 150 spectra were measured by means of a Raman confocal microspectrometer apparatus using the 632.8 nm line of a He-Ne laser source. A discrete wavelet transform decomposition method has been applied to the recorded Raman spectra in order to overcome related to low-level signals and the presence of noise and background components due to light scattering and fluorescence. The results indicate that appropriate data processing can contribute to enlarge the medical applications of micro-Raman spectroscopy.

  6. 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.

  7. Polarized Raman spectra of L-arginine hydrochloride monohydrated single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Faria, J.L.B. [Universidade Federal de Mato Grosso (UFMT), Cuiaba, MT (Brazil). Dept. de Fisica; Freire, P.T.C.; Goncalves, R.O.; Melo, F.E.A.; Mendes Filho, J., E-mail: tarso@fisica.ufc.b [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Dept. de Fisica; Lima, R.J.C.; Moreno, A.J.D. [Universidade Federal do Maranhao (UFMA), Imperatriz, MA (Brazil). Centro de Ciencias Sociais, Saude e Tecnologia

    2010-09-15

    Polarized Raman spectra of L-arginine hydrochloride monohydrated single crystal in nine different scattering geometries of the two irreducible representations of factor group C{sub 2} were studied at room temperature. The experimental wavenumber values are compared with those obtained from ab-initio calculation and the assignment of the Raman bands to the respective molecular vibrations is also given. Finally, a discussion related to a previously reported phase transition undergone by L-arginine hydrochloride monohydrated single crystal at low temperature is furnished. (author)

  8. Raman Spectra and Bulk Modulus of Nanodiamond in a Size Interval of 2-5 nm.

    Science.gov (United States)

    Popov, Mikhail; Churkin, Valentin; Kirichenko, Alexey; Denisov, Viktor; Ovsyannikov, Danila; Kulnitskiy, Boris; Perezhogin, Igor; Aksenenkov, Viktor; Blank, Vladimir

    2017-10-10

    Nanodiamond in a 2-5-nm size interval (which is typical for an appearance of quantum confinement effect) show Raman spectra composed of 3 bands at 1325, 1600, and 1500 cm -1 (at the 458-nm laser excitation) which shifts to 1630 cm -1 at the 257-nm laser excitation. Contrary to sp 2 -bonded carbon, relative intensities of the bands do not depend on the 458- and 257-nm excitation wavelengths, and a halfwidth and the intensity of the 1600 cm -1 band does not change visibly under pressure at least up to 50 GPa. Bulk modulus of the 2-5-nm nanodiamond determined from the high-pressure study is around 560 GPa. Studied 2-5-nm nanodiamond was purified from contamination layers and dispersed in Si or NaCl.

  9. Infrared spectra of hydrogen-bonded salicylic acid and its derivatives : Salicylic acid and acetylsalicylic acid

    Science.gov (United States)

    Wójcik, Marek J.

    1981-11-01

    Infrared spectra of hydrogen-bonded salicylic acid, O-deutero-salicylic acid and acetylsalicylic acid crystals have been studied experimentally and theoretically. Interpretation of these spectra was based on the Witkowski-Maréchal model. Semi-quantitative agreement between experimental and theoretical spectra can be achieved with the simplest form of this model, with values of interaction parameters transferable for equivalent intermolecular hydrogen bonds.

  10. Fluorescence and Raman spectra on surface of K9 glass by high fluence ultraviolet laser irradiation at 355 nm

    Science.gov (United States)

    Zhang, Zhen; Huang, Jin; Geng, Feng; Zhou, Xiaoyan; Feng, Shiquan; Ren, Dahua; Cheng, Xinlu; Jiang, Xiaodong; Wu, Weidong; Zheng, Wanguo; Tang, Yongjian

    2013-11-01

    In order to explore the damage mechanisms of K9 glass irradiated by high energy density ultraviolet laser, laser-induced fluorescence and Raman spectra were investigated. Compared the fluorescence spectra of damaged area, undamaged area and sub-damaged area, it can be conclude that the fluorescence spectrum of sub-damaged area is different from the structure of the other two areas. Especially, the main peak of the spectra at 415 nm reveals the unique characteristics of K9 glass. The structure at the sub-damaged area enhances intensity of the Raman scattering spectra. Three peaks of the spectra at about 500 nm and two characteristic peaks at about 550 nm exhibit the characterization of damaged area. A peak of the Raman scattering spectra at 350 nm which related to water can be observed. The relationship between intensity of Raman scattering and laser intensity at 355 nm is investigated by confocal Raman microscopy. At sub-damage area, signal of Raman scattering is rather high and decreased dramatically with respect to energy density. The major band at about 1470 cm-1 sharpened and moved to higher frequency with densification. These phenomena demonstrate that the structure of sub-damaged area has some characterization compared with the damaged area. The investigation of defect induced fluorescence and Raman spectra on surface of K9 glass is important to explore the damage mechanisms of optical materials irradiated by ultraviolet laser irradiation at 355 nm.

  11. [The application of piecewise direct standardization with SNV in calibration transfer of Raman spectra].

    Science.gov (United States)

    Huang, Cheng-wei; Dai, Lian-kui; Dong, Xue-feng

    2011-05-01

    To implement calibration transfer between Raman spectrometers, an improved piecewise direct standardization (PDS) is proposed in the present paper. Standard normal variate (SNV) is firstly introduced to reduce the influence of spectral background and intensity corresponding to the master spectrometer and the slave spectrometer; then PDS algorithm is used to eliminate the differences between Raman spectra for a specific sample. Moreover, a new quantitative criterion, called transfer error rate, is proposed to evaluate the performance of calibration model transfer. This improved PDS is applied to Raman spectral analysis of gasoline. The result shows that the proposed algorithm not only needs a small quantity of transfer samples, but also obtains high transfer accuracy and strong model robustness.

  12. 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

    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...... 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...

  13. Dispersive Fourier transformation for megahertz detection of coherent stokes and anti-stokes Raman spectra

    Science.gov (United States)

    Bohlin, Alexis; Patterson, Brian D.; Kliewer, Christopher J.

    2017-11-01

    In many fields of study, from coherent Raman microscopy on living cells to time-resolved coherent Raman spectroscopy of gas-phase turbulence and combustion reaction dynamics, the need for the capability to time-resolve fast dynamical and nonrepetitive processes has led to the continued development of high-speed coherent Raman methods and new high-repetition rate laser sources, such as pulse-burst laser systems. However, much less emphasis has been placed on our ability to detect shot to shot coherent Raman spectra at equivalently high scan rates, across the kilohertz to megahertz regime. This is beyond the capability of modern scientific charge coupled device (CCD) cameras, for instance, as would be employed with a Czerny-Turner type spectrograph. As an alternative detection strategy with megahertz spectral detection rate, we demonstrate dispersive Fourier transformation detection of pulsed (∼90 ps) coherent Raman signals in the time-domain. Instead of reading the frequency domain signal out using a spectrometer and CCD, the signal is transformed into a time-domain waveform through dispersive Fourier transformation in a long single-mode fiber and read-out with a fast sampling photodiode and oscilloscope. Molecular O- and S-branch rotational sideband spectra from both N2 and H2 were acquired employing this scheme, and the waveform is fitted to show highly quantitative agreement with a molecular model. The total detection time for the rotational spectrum was 20 ns, indicating an upper limit to the detection frequency of ∼50 MHz, significantly faster than any other reported spectrally-resolved coherent anti-Stokes Raman detection strategy to date.

  14. Determination of iron redox ratio in borosilicate glasses and melts from Raman spectra

    Energy Technology Data Exchange (ETDEWEB)

    Cochain, B. [SCDV-Laboratoire d' Etudes de Base sur les Verres, CEA Valrho, Centre de Marcoule, 30207 Bagnols-sur-ceze (France); Physique des Mineraux et des Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris Cedex05 (France); Neuville, D.R.; Richet, P. [Physique des Mineraux et des Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris Cedex05 (France); Henderson, G.S. [Dept of Geology, University of Toronto, 22 Russell Street, Toronto (Canada); Pinet, O. [SCDV-Laboratoire d' Etudes de Base sur les Verres, CEA Valrho, Centre de Marcoule, 30207 Bagnols-sur-ceze (France)

    2008-07-01

    A method is presented to determine the redox ratio of iron in borosilicate glasses and melts relevant to nuclear waste storage from an analysis of Raman spectra recorded at room or high temperature. The basis of this method is the strong variation of the spectral feature observed between 800 and 1200 cm{sup -1}, in which it is possible to assign a band to vibrational modes involving ferric iron in tetrahedral coordination whose intensity increases with iron content and iron oxidation. After baseline correction and normalization, fits to the Raman spectra made with Gaussian bands enable us to determine the proportion of ferric iron provided the redox ratio is known independently for at least two redox states for a given glass composition. This method is particularly useful for in situ determinations of the kinetics and mechanisms of redox reactions. (authors)

  15. Remote Raman spectra of benzene obtained from 217 meters using a single 532 nm laser pulse.

    Science.gov (United States)

    Chen, Teng; Madey, John M J; Price, Frank M; Sharma, Shiv K; Lienert, Barry

    2007-06-01

    This report describes a mobile Raman lidar system that has been developed for spectral measurements of samples located remotely at ranges of hundreds of meters. The performance of this system has been quantitatively verified in a lidar calibration experiment using a hard target of standardized reflectance. A new record in detection range was achieved for remote Raman systems using 532 nm laser excitation. Specifically, Raman spectra of liquid benzene were measured with an integration time corresponding to a single 532 nm laser pulse at a distance of 217 meters. The single-shot Raman spectra at 217 meters demonstrated high signal-to-noise ratio and good resolution sufficient for the unambiguous identification of the samples of interest. The transmitter consists of a 20 Hz Nd:YAG laser emitting at 532 nm and 1064 nm and a 178 mm telescope through the use of which allows the system to produce a focused beam at the target location. The receiver consists of a large custom telescope (609 mm aperture) and a Czerny-Turner monochromator equipped with two fast photomultiplier tubes.

  16. Prediction of Raman optical activity spectra of chiral 3-acetylcamphorato-cobalt complexes.

    Science.gov (United States)

    Luber, Sandra; Reiher, Markus

    2010-06-21

    We examine calculated vibrational Raman optical activity (ROA) spectra of octahedral cobalt complexes containing different combinations of acetylacetonato and 3-acetylcamphorato ligands. Starting from the Delta-tris(acetylacetonato)cobalt(III) complex, the ROA spectra of isomers generated by successive replacement of acetylacetonato ligands by chiral (+)- or (-)-3-acetylcamphorato ligands are investigated. In this way, it is possible to assess the influence of the degree of ligand substitution, ligand chirality, and geometrical isomerism on the ROA spectra. In addition, the effect of the Lambda-configuration is studied. It is found that the ROA spectra contain features that make it possible to identify each of the isomers, demonstrating the great sensitivity of ROA spectroscopy to the chiral nature of the various complexes.

  17. Infrared and Raman scattering spectra of layered structured Ga3InSe4 crystals

    International Nuclear Information System (INIS)

    Isik, M.; Gasanly, N.M.; Korkmaz, F.

    2013-01-01

    The infrared reflectivity and transmittance and Raman scattering in Ga 3 InSe 4 layered crystals were investigated in the frequency ranges of 100–400, 400–4000 and 25–500 cm −1 . The refractive and absorption indices, the frequencies of transverse and longitudinal optical modes, high- and low-frequency dielectric constants were obtained from the analysis of the IR reflectivity spectra. The bands observed in IR transmittance spectra were interpreted in terms of two-phonon absorption processes

  18. Time-dependent density functional methods for Raman spectra in open-shell systems.

    Science.gov (United States)

    Aquino, Fredy W; Schatz, George C

    2014-01-16

    We present an implementation of a time-dependent density functional theory (TD-DFT) linear response module in NWChem for unrestricted DFT calculations and apply it to the calculation of resonant Raman spectra in open-shell molecular systems using the short-time approximation. The new source code was validated and applied to simulate Raman spectra on several doublet organic radicals (e.g., benzyl, benzosemiquinone, TMPD, trans-stilbene anion and cation, and methyl viologen) and the metal complex copper phthalocyanine. We also introduce a divide-and-conquer approach for the evaluation of polarizabilities in relatively large systems (e.g., copper phthalocyanine). The implemented tool gives comparisons with experiment that are similar to what is commonly found for closed-shell systems, with good agreement for most features except for small frequency shifts, and occasionally large deviations for some modes that depend on the molecular system studied, experimental conditions not being accounted in the modeling such as solvation effects and extra solvent-based peaks, and approximations in the underlying theory. The approximations used in the quantum chemical modeling include (i) choice of exchange-correlation functional and basis set; (ii) harmonic approximation used in the frequency analysis to determine vibrational normal modes; and (iii) short-time approximation (omission of nuclear motion effects) used in calculating resonant Raman spectra.

  19. Ultraviolet Raman spectroscopy of catalysts: Adsorption and coke formation in zeolites and vibrational spectra of supported metal oxides

    Science.gov (United States)

    Chua, Yek Tann

    2001-10-01

    The primary goal of this dissertation is to study the physicochemical and catalytic properties of zeolites and supported metal oxide catalysts using UV Raman spectroscopy. In order to reduce the thermal degradation and possible photodecomposition of adsorbates by UV radiation, we have developed a novel fluidized bed method for measuring the UV Raman spectra of catalysts and adsorbates. The UV Raman spectra of various organic compounds adsorbed in zeolites H-USY and H-ZSM-5 are recorded. When measurements are performed on stationary and spinning samples, the Raman spectra show the presence of coke, a typical end product of heat and photochemistry. In contrast, the Raman peaks of the unreacted adsorbates dominate the spectra measured using the fluidized bed method. These results indicate that the fluidized bed technique is a good method for measuring UV Raman spectra of catalysts and adsorbates. The formation of coke in the methanol-to-gasoline conversion over zeolite H-ZSM-5 causes deactivation of the catalyst. To gain insight into the formation of coke, we have studied this reaction using UV Raman spectroscopy. The Raman spectral changes suggest coke is produced from conjugated olefins via cyclopentadiene intermediates. Aromatic compounds in gasoline may also be produced from cyclopentadienes. The adsorbate-induced structural changes of zeolites may alter the molecular sieving characteristics of these materials which ultimately affect their performance as catalysts and adsorbents. We have quantified the adsorbate-induced structural changes of zeolite H-RHO using UV Raman spectroscopy. The Raman spectra of the zeolite after the adsorption of water, methanol or acetonitrile are consistent with an increase in the average T-O-T angle of the zeolite of 5-8°. The adsorption of ammonia, on the other hand, decreases the average T-O-T angle by 5°. Because of certain advantages of UV Raman spectroscopy over visible Raman spectroscopy, recently there is a strong interest in

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-03-21

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

  1. 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.

  2. Spectroscopic properties of neuroleptics: IR and Raman spectra of Risperidone (Risperdal) and of its mono- and di-protonated forms

    Science.gov (United States)

    Alparone, Andrea

    2011-10-01

    Structures and IR and Raman spectra of Risperidone in its neutral, mono- and di-protonated forms were calculated in gas phase by DFT-B3LYP/6-31G* level. Mono-protonation occurs at the nitrogen atom of the piperidine ring, while nitrogen atom of the pyrimidine ring is the preferred site for the second protonation. The lowest-energy structure of the mono-protonated Risperidone is characterized by formation of a strong seven-membered O(pyrimidine ring)⋯ +H-N(piperidine ring) intramolecular hydrogen-bonded cycle. In the high-energy spectral region (3500-2500 cm -1), the bands of the N-H + stretches and the changes in wavenumbers and IR intensities of the C-H stretches near to the piperidine nitrogen atom (Bohlmann effect) are potentially useful to discriminate conformations and protonation states. Di-protonated structures can be identified by the presence of an isolated absorption peak located in the low-energy IR region (660-690 cm -1), attributed to the out-of-plane N-H +(pyrimidine ring) bending deformation. The most intense Raman band of neutral Risperidone placed at ca. 1500 cm -1, assigned to C dbnd C(pyrimidine ring) stretch + C dbnd N(pyrimidine ring) stretch, can be a useful vibrational marker to distinguish the neutral from the protonated forms.

  3. 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.

  4. Infrared and Raman spectra and theoretical calculations for benzocyclobutane in its electronic ground state

    Science.gov (United States)

    Ocola, Esther J.; Shin, Hee Won; Laane, Jaan

    2015-02-01

    The infrared and Raman spectra of vapor-phase and liquid-phase benzocyclobutane (BCB) have been recorded and assigned. The structure of the molecule was calculated using the MP2/cc-pVTZ basis set and the vibrational frequencies and spectral intensities were calculated using the B3LYP/cc-pVTZ level of theory. The agreement between experimental and calculated spectra is excellent. In order to allow comparisons with related molecules, ab initio and DFT calculations were also carried out for indan (IND), tetralin (TET), 1,4-benzodioxan (14BZD), 1,3-benzodioxan (13BZD) and 1,4-dihydronaphthalene (14DHN). The ring-puckering, ring-twisting, and ring-flapping vibrations were of particular interest as these reflect the rigidity of the bicyclic ring system. The infrared spectra of BCB show very nice examples of vapor-phase band types and combination bands.

  5. Principal component analysis of Raman spectra for TiO2 nanoparticle characterization

    Science.gov (United States)

    Ilie, Alina Georgiana; Scarisoareanu, Monica; Morjan, Ion; Dutu, Elena; Badiceanu, Maria; Mihailescu, Ion

    2017-09-01

    The Raman spectra of anatase/rutile mixed phases of Sn doped TiO2 nanoparticles and undoped TiO2 nanoparticles, synthesised by laser pyrolysis, with nanocrystallite dimensions varying from 8 to 28 nm, was simultaneously processed with a self-written software that applies Principal Component Analysis (PCA) on the measured spectrum to verify the possibility of objective auto-characterization of nanoparticles from their vibrational modes. The photo-excited process of Raman scattering is very sensible to the material characteristics, especially in the case of nanomaterials, where more properties become relevant for the vibrational behaviour. We used PCA, a statistical procedure that performs eigenvalue decomposition of descriptive data covariance, to automatically analyse the sample's measured Raman spectrum, and to interfere the correlation between nanoparticle dimensions, tin and carbon concentration, and their Principal Component values (PCs). This type of application can allow an approximation of the crystallite size, or tin concentration, only by measuring the Raman spectrum of the sample. The study of loadings of the principal components provides information of the way the vibrational modes are affected by the nanoparticle features and the spectral area relevant for the classification.

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

    Science.gov (United States)

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

    2015-03-01

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

  7. Polytypism in n-fatty acids and low-frequency Raman spectra: Stearic acid B form

    Science.gov (United States)

    Kobayashi, Masamichi; Kobayashi, Tohru; Itoh, Yuzo; Sato, Kiyotaka

    1984-03-01

    Single crystals of single-layered (mon) and double-layered (orth II) polytypes of stearic acid B form were obtained and their structures were investigated by the x-ray diffraction and vibrational spectroscopic methods. Two polytypes exhibited quite different Raman spectra in the frequency range from 65 to 2 cm-1. The Raman bands appeared as singlets in mon, while they split into doublets with different polarization in orth II through the interlamellar interactions between two successive layers contained in the unit cell. The frequencies of the phonon modes in orth II were found to be lower than the corresponding ones in mon, indicating that orth II (or mon) was the high-temperature (low-temperature) stable form.

  8. Highly reproducible surface-enhanced Raman spectra on semiconductor SnO2 octahedral nanoparticles.

    Science.gov (United States)

    Jiang, Li; Yin, Penggang; You, Tingting; Wang, Hua; Lang, Xiufeng; Guo, Lin; Yang, Shihe

    2012-12-07

    Highly reproducible surface-enhanced Raman scattering (SERS) spectra are obtained on the surface of SnO(2) octahedral nanoparticles. The spot-to-spot SERS signals show a relative standard deviation (RSD) consistently below 20 % in the intensity of the main Raman peaks of 4-mercaptobenzoic acid (4-MBA) and 4-nitrobenzenethiol (4-NBT), indicating good spatial uniformity and reproducibility. The SERS signals are believed to mainly originate from a charge-transfer (CT) mechanism. Time-dependent density functional theory (TD-DFT) is used to simulate the SERS spectrum and interpret the chemical enhancement mechanism in the experiment. The research extends the application of SERS and also establishes a new uniform SERS substrate. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. FTIR and Raman spectra of ion irradiated and annealed 4H-SiC

    International Nuclear Information System (INIS)

    Zhou Lihong; Yang Titao; Yao Cunfeng; Chinese Academy of Sciences, Beijing

    2007-01-01

    The 4H-SiC specimens were implanted with 110keV C-ions and then irradiated with 230MeV Pb-ions and subsequently annealed at different temperatures in vacuum. The samples were investigated after each annealing stage by using FTIR and Raman spectroscopy. The obtained FTIR spectra showed several interference fringes in the range from 960 cm -1 to 1450 cm -1 . The intensity of fringes decreases with the increase of annealing temperature, and an abrupt decrease of the fringe intensity was found for annealing above 900 degree C, indicating that there was a significant recovery of the irradiation-induced damage in the crystal for annealing at high temperatures. The Raman spectroscopy showed that after annealing at 1200 degree C for 30 min the amorphous layer was recovered and the precipitation of carbon atoms in graphite occurred. (authors)

  10. "Parallel factor analysis of multi-excitation ultraviolet resonance Raman spectra for protein secondary structure determination".

    Science.gov (United States)

    Oshokoya, Olayinka O; JiJi, Renee D

    2015-09-10

    Protein secondary structural analysis is important for understanding the relationship between protein structure and function, or more importantly how changes in structure relate to loss of function. The structurally sensitive protein vibrational modes (amide I, II, III and S) in deep-ultraviolet resonance Raman (DUVRR) spectra resulting from the backbone C-O and N-H vibrations make DUVRR a potentially powerful tool for studying secondary structure changes. Experimental studies reveal that the position and intensity of the four amide modes in DUVRR spectra of proteins are largely correlated with the varying fractions of α-helix, β-sheet and disordered structural content of proteins. Employing multivariate calibration methods and DUVRR spectra of globular proteins with varying structural compositions, the secondary structure of a protein with unknown structure can be predicted. A disadvantage of multivariate calibration methods is the requirement of known concentration or spectral profiles. Second-order curve resolution methods, such as parallel factor analysis (PARAFAC), do not have such a requirement due to the "second-order advantage." An exceptional feature of DUVRR spectroscopy is that DUVRR spectra are linearly dependent on both excitation wavelength and secondary structure composition. Thus, higher order data can be created by combining protein DUVRR spectra of several proteins collected at multiple excitation wavelengths to give multi-excitation ultraviolet resonance Raman data (ME-UVRR). PARAFAC has been used to analyze ME-UVRR data of nine proteins to resolve the pure spectral, excitation and compositional profiles. A three factor model with non-negativity constraints produced three unique factors that were correlated with the relative abundance of helical, β-sheet and poly-proline II dihedral angles. This is the first empirical evidence that the typically resolved "disordered" spectrum represents the better defined poly-proline II type structure

  11. Hydrogen bonding of sulfur ligands in blue copper and iron-sulfur proteins: detection by resonance raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mino, Y.; Loehr, T.M.; Wada, K.; Matsubara, H.; Sanders-Loehr, J.

    1987-12-15

    The resonance Raman spectrum of the blue copper protein azurin from Alcaligenes denitrificans exhibits nine vibrational modes between 330 and 460 cm/sup -1/, seven of which shift 0.4-3.0 cm/sup -1/ to lower energy after incubation of the protein in D/sub 2/O. These deuterium-dependent shifts have been previously ascribed to exchangeable protons on imidazole ligands or to exchangeable protons on amide groups which are hydrogen bonded to the cysteine thiolate ligands (a feature common to all blue copper proteins of known structure). In order to distinguish between these two possibilities, a systematic investigation of Fe/sub 2/S/sub 2/(Cys)/sub 4/-containing proteins was undertaken. Extensive hydrogen bonding between sulfur ligands and the polypeptide backbone had been observed in the crystal structure of ferredoxin from Spirulina platensis. The resonance Raman spectrum of this protein is typical of a chloroplast-type ferredoxin and exhibits deuterium-dependent shifts of -0.3 to -0.5 cm/sup -1/ in the Fe-S modes at 283, 367, and 394 cm/sup -1/ and -0.6 to -0.8 cm/sup -1/ in the Fe-S modes at 328 and 341 cm/sup -1/. Considerably greater deuterium sensitivity is observed in the Raman spectra of spinach ferredoxin and bovine adrenodoxin, particularly for the symmetric stretching vibration of the Fe/sub 2/S/sub 2/ moiety at approx. 390 cm/sup -1/. This feature decreases of 9.8 and 1.1 cm/sup -1/, respectively, for the two oxidized proteins in D/sub 2/O and by 1.8 cm/sup -1/ for reduced adrenodoxin in D/sub 2/O. These results suggest that the bridging sulfido groups may be more extensively hydrogen bonded in spinach ferredoxin and adrenodoxin than in S. platensis ferredoxin, with a further increase in hydrogen-bond strength in the reduced form of adrenodoxin.

  12. Spectra and structure of gallium compounds. Part X. Infrared and Raman spectra, vibrational assignment, and normal coordinate calculations for trimethylaminegallium trichloride

    Science.gov (United States)

    Durig, J. R.; Chatterjee, K. K.

    The far IR (450-480 cm-1) and Raman (3200-3230 cm-1) spectra of (CH3)3 NGaCl3 have been recorded in the solid state and interpreted in detail on the basis of C3 molecular symmetry. A modified valence force field model is used to calculate the frequencies and potential energy distribution of the adduct. The calculated force constants of the adduct are compared with those previously reported for the free Lewis acid and the free Lewis base moieties, and the observed differences ascribed to geometrical changes of the uncomplexed species on adduct formation and explained on the basis of the VSEPR model and non-bond interactions. Extensive coupling is observed between the GaN stretching mode and the NC3 symmetric stretching and the NC3 symmetric deformational modes. Strong coupling interaction is also found between the GaCl3 antisymmetric stretch and the NC3 antisymmetric deformation. The calculated value of 2.50 mdyn Å-1 for the GaN stretching force constant in (CH3)3NGaCl3 is larger than any of those previously determined in complexes such as (CH3)3NGaH3 (2.43 mdyn Å-1), (CH3)3NGa(CH3)3 (1.61 mdyn Å-1), and H3NGa(CH3)3 (1.08 mdyn Å-1). The observed variations in the magnitudes of the stretching force constants of the donor-acceptor dative bond is found to be consistent with the estimated relative stabilities of this series of adducts.

  13. Raman spectra of Pm2O3, PmF3, PmCl3, PmBr3 and PmI3

    International Nuclear Information System (INIS)

    Wilmarth, W.R.; Peterson, J.R.

    1988-01-01

    Raman spectral data are presented for the sesquioxide and the trihalides (F, Cl, Br and I) of promethium. The Raman spectra of these lanthanide compounds are reported for the first time and are compared with those of the homologous lanthanide compounds. Tentative symmetry assignments have been made for the observed Raman-active bands based on factor group analysis of their respective crystal structures and comparisons with the assigned Raman spectra of other lanthanide compounds. The characteristic band patterns of the Raman phonon spectra have been found to be very useful in determining the crystal structure of the respective promethium compounds. (author)

  14. Multivariate statistical analysis of Raman spectra to distinguish normal, tumor, lymph nodes and mastitis in mouse mammary tissues

    Science.gov (United States)

    Dai, H.; Thakur, J. S.; Serhatkulu, G. K.; Pandya, A. K.; Auner, G. W.; Naik, R.; Freeman, D. C.; Naik, V. M.; Cao, A.; Klein, M. D.; Rabah, R.

    2006-03-01

    Raman spectra ( > 680) of normal mammary gland, malignant mammary gland tumors, and lymph node tissues from mice injected with 4T1 tumor cells have been recorded using 785 nm excitation laser. The state of the tissues was confirmed by standard pathological tests. The multivariate statistical analysis methods (principle component analysis and discriminant functional analysis) have been used to categorize the Raman spectra. The statistical algorithms based on the Raman spectral peak heights, clearly separated tissues into six distinct classes, including mastitis, which is clearly separated from normal and tumor. This study suggests that the Raman spectroscopy can possibly perform a real-time analysis of the human mammary tissues for the detection of cancer.

  15. The Raman and SERS spectra of indigo and indigo-Ag2complex: DFT calculation and comparison with experiment.

    Science.gov (United States)

    Ricci, Marilena; Lofrumento, Cristiana; Becucci, Maurizio; Castellucci, Emilio M

    2018-01-05

    Using time-dependent density functional theory in conjunction with B3LYP functional and LANL2DZ/6-31+g(d,p) basis sets, static and pre-resonance Raman spectra of the indigo-Ag 2 complex have been calculated. Structure optimization, excitation energies and pre-resonance Raman spectra of the indigo molecule have been obtained at the same level of theory. The available experimental Raman spectra at 1064, 785 and 514nm and the SERS spectra at 785 and 514nm have been well reproduced by the calculation. Experimental SERS spectra are confronted with the calculated pre-resonance Raman spectra obtained for the indigo-Ag 2 complex. The Raman activities calculated under the infinite lifetime approximation show a strong dependence upon the proximity to the energy and the oscillator strength of the excitation electronic transition. The comparison of the integrated EFs for indigo and indigo-Ag 2 calculated Raman spectra, gave some hints as to the enhancement mechanisms acting for the different excitation wavelengths. Whereas for excitation at a wavelength corresponding to 785nm, the enhancement mechanism for the Raman spectrum of the metal complex seems the chemical one, the strong increment (ten times) of the integrated EF of the Raman spectra of the complex in the case of 514nm excitation, suggests the onset of other enhancement mechanisms. Assuming that intra-cluster transitions with high oscillator strength can be thought of as to mimic surface plasmons excitations, we suggest the onset of the electromagnetic mechanisms (EM) as the origin of the Raman spectrum enhancement. Nevertheless, other enhancement effects cannot be ruled out, as a new molecular transition gains strength in the proximity of the excitation wavelength, as a consequence of the symmetry lowering of the molecule in the complex. A large variation across vibrational modes, by a factor of at least 10 4 , was found for the EFs. This large variation in the EFs can indicate that B-term Herzberg-Teller scattering

  16. Application of micro Raman spectroscopy to industrial FC membranes

    International Nuclear Information System (INIS)

    Chikvaidze, G; Gabrusenoks, J; Kleperis, J; Vaivars, G

    2007-01-01

    Raman spectra of as-received and protonated membranes (Nafion NRE-212, Fumapem F-14100 and Fumasep FAA) were measured with He-Cd and Ar laser. For the first time the Raman and IR spectra are reported of Fumasep membranes. Most of peaks in vibration spectra active in Raman and IR of membranes are interpreted with C-F, C-S, C-O-C, SO 3 , C-C bonds. The vibration region connected with protons and H-O bond in both types of membranes is found in Raman and IR spectra

  17. FT-Raman spectra of cellulose and lignocellulose materials : “self-absorption” phenomenon and its implications for quantitative work

    Science.gov (United States)

    Umesh Agarwal; Nancy Kawai

    2003-01-01

    The phenomenon of “self-absorption” was found to exist in the FT-Raman spectra of cellulose and thermomechanical pulp (TMP), but not in the spectrum of milled wood lignin. For cellulose and TMP, the effect was responsible for reducing the intensity of the Raman bands in the C-H stretch region. Several factors including sampling position, sample thickness, and moisture...

  18. 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

  19. IR and Raman spectra of LaH(SeO3)2 and FeH(SeO3)2

    International Nuclear Information System (INIS)

    Ratheesh, R.; Suresh, G.; Nayar, V.U.; Morris, R.E.

    1995-01-01

    The infrared and Raman spectra of LaH(SeO 3 ) 2 and FeH(SeO 3 ) 2 crystals are recorded and analysed. Bands confirm the coexistence of HSeO 3 - and SeO 3 2- ions in both LaH(SeO 3 ) 2 and FeH(SeO 3 ) 2 crystals. The Se-OH stretching vibrations are observed to be at lower wavenumbers in LaH(SeO 3 ) 2 than that in the iron compound in agreement with the short O-O distance in the former. Observed bands indicate that the SeO 3 2- ions are more angularly distorted in FeH(SeO 3 ) 2 crystal. ABC bands, characteristic of strong hydrogen bonded systems are observed in the infrared spectra of both the crystals. (author). 15 refs., 2 figs., 1 tab

  20. Second-order Raman spectra of LiHxD1-x crystals

    International Nuclear Information System (INIS)

    Plekhanov, V.G.

    1994-01-01

    High-resolution Raman spectra of LiH x D 1-x cubic crystals were measured for the first time in a wide concentration range (0≤x≤1) at room temperature. The results agree well with data on inelastic neutron scattering and direct calculations of the lattice dynamics for LiH and LiD crystals. This allows one to assign the observed spectral features to the phonon excitations in X-, W-, L-, and K-points of the Brillouin zone. Spectra of LiD exhibit the high-frequency maximum with a pronounced doubled structure. This fact and the dependence of the maximum intensity on the excitation laser frequency provide clear evidence that the maximum is due to excitation of LO(Γ)-phonons in pure or mixed crystals. In the x approx-lt 0.4 range, the LO-phonons manifest themselves in the spectra of both pure LiD and mixed LiH x D 1-x crystals, which demonstrates for the first time their two-mode character in this concentration range. This conclusion is in contradiction with predictions of the coherent potential model. In this paper, causes of this conflict are briefly discussed. 36 refs., 5 figs., 2 tabs

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

    Science.gov (United States)

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

    2015-04-10

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

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

    Science.gov (United States)

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

    2018-01-01

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

  3. 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.

  4. Raman spectra of TiO2 thin films deposited electrochemically and by spray pyrolysis

    International Nuclear Information System (INIS)

    Shishiyanu, S.; Vartic, V.; Shishiyanu, T.; Stratan, Gh.; Rusu, E.; Zarrelli, M.; Giordano, M.

    2013-01-01

    In this paper we present our experimental results concerning the fabrication of TiO 2 thin films by spray pyrolysis and electrochemical deposition method onto different substrates - Corning glass, Si and optical fibers. The surface morphology of the TiO 2 thin films have been investigated by Atomic Force Microscopy. Raman shift spectra measurements have been done for the optical characterization of the fabricated titania thin films. The post-growth rapid photothermal processing (RPP) at temperatures of 100-800 degrees Celsius for 1-3 min have been applied. Our experimental results prove that by the application of post-growth RPP is possible to essentially improve the crystallinity of the deposited TiO 2 films. (authors)

  5. Use of a Fabry Perot Interferometer to Isolate Pure Rotational Raman Spectra of Diatomic Molecules

    Science.gov (United States)

    Arshinov, Yuri; Bobrovnikov, Sergey

    1999-07-01

    We propose to use a Fabry Perot interferometer (FPI) as a comb frequency filter to isolate pure rotational Raman spectra (PRRS) of nitrogen molecules. In making the FPI s free spectral range equal to the spectral spacing between the lines of nitrogen PRRS, which are practically equidistant, one obtains a device with a comb transmission function with the same period. However, to match the FPI transmission comb completely with the comb of nitrogen PRRS lines one should tune the wavelength of the radiation used to excite the PRRS of nitrogen exactly to the position of any minimum in the FPI transmission comb. Thus to achieve this task for the case of nitrogen PRRS one must take the FPI s free spectral range f 4 B N 2 and the wavelength of the exciting radiation such that (1 exc ) 4 B N 2 ( k 1 2 ), where B N 2 is the rotational constant of the nitrogen molecule and k is an arbitrary integer number. In this case all (odd and even) pure rotational Raman lines of nitrogen will pass through the FPI while the line of exciting radiation is being suppressed. Additionally, a FPI cuts out the spectrally continuous sky background light from the spectral gaps between the PRRS lines.

  6. Quantitative analysis of sugar composition in honey using 532-nm excitation Raman and Raman optical activity spectra

    Czech Academy of Sciences Publication Activity Database

    Šugar, Jan; Bouř, Petr

    2016-01-01

    Roč. 47, č. 11 (2016), s. 1298-1303 ISSN 0377-0486 R&D Projects: GA ČR GA15-09072S Institutional support: RVO:61388963 Keywords : honey * sugar mixtures * spectral decompositions * Raman spectroscopy * Raman optical activity Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.969, year: 2016

  7. Matrix isolation infrared spectra of O-H···π Hydrogen bonded ...

    Indian Academy of Sciences (India)

    Matrix isolation infrared spectra of O-H···π Hydrogen bonded complexes of Acetic acid and Trifluoroacetic acid with Benzene. PUJARINI BANERJEE, INDRANI BHATTACHARYA and TAPAS CHAKRABORTY. ∗. Department of Physical Chemistry, Indian Association for the Cultivation of Science, Kolkata 700 032, India.

  8. Preliminary investigations on the effects of ageing and cooking on the Raman spectra of porcine longissimus dorsi.

    Science.gov (United States)

    Beattie, J Renwick; Bell, Steven E J; Borggaard, Claus; Moss, Bruce W

    2008-12-01

    The influence of ageing and cooking on the Raman spectrum of porcine longissimus dorsi was investigated. The rich information contained in the Raman spectrum was highlighted, with numerous changes attributed to changes in the environment and conformations of the myofibrillar proteins. Predictions equations for shear force and cooking loss were developed from the Raman spectra of both raw and cooked pork. Good correlations and standard errors of prediction were obtained for both WB shear force and cooking loss, with the raw and the cooked samples showing almost identical results R(2)=0.77, root mean standard error of prediction (RMSEP)% of mean=12% for shear force; R(2)=0.71, RMSEP% of mean=10% for cooking loss. The Raman spectra were also able to predict the extent of cooking that occurred within the pork (R(2)(val)=0.94, RMSEP% of range=5.5%). Raman spectroscopy has considerable potential as a method for non-destructive and rapid determination of pork quality parameters such as tenderness. Raman spectroscopy may provide a means of determining changes during cooking and the extent to which foods have been cooked.

  9. Temperature dependence of low-frequency polarized Raman scattering spectra in TlInS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Paucar, Raul; Wakita, Kazuki [Electronics and Computer Engineering, Chiba Institute of Technology, Chiba (Japan); Shim, YongGu; Mimura, Kojiro [Graduate School of Engineering, Osaka Prefecture University, Osaka (Japan); Alekperov, Oktay; Mamedov, Nazim [Institute of Physics, Azerbaijan National Academy of Sciences, Baku (Azerbaijan)

    2017-06-15

    In this work, we examined phase transitions in the layered ternary thallium chalcogenide TlInS{sub 2} by studying the temperature dependence of polarized Raman spectra with the aid of the Raman confocal microscope system. The Raman spectra were measured over the temperature range of 77-320 K (which includes the range of successive phase transitions) in the low-frequency region of 35-180 cm{sup -1}. The optical phonons that showed strong temperature dependence were identified as interlayer vibrations related to phase transitions, while the phonons that showed weak temperature dependence were identified as intralayer vibrations. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. An Investigation on Micro-Raman Spectra and Wavelet Data Analysis for Pemphigus Vulgaris Follow-up Monitoring.

    Directory of Open Access Journals (Sweden)

    Maria Lepore

    2008-06-01

    Full Text Available A wavelet multi-component decomposition algorithm has been used for data analysis of micro-Raman spectra of blood serum samples from patients affected by pemphigus vulgaris at different stages. Pemphigus is a chronic, autoimmune, blistering disease of the skin and mucous membranes with a potentially fatal outcome. Spectra were measured by means of a Raman confocal microspectrometer apparatus using the 632.8 nm line of a He-Ne laser source. A discrete wavelet transform decomposition method has been applied to the recorded Raman spectra in order to overcome problems related to low-level signals and the presence of noise and background components due to light scattering and fluorescence. This numerical data treatment can automatically extract quantitative information from the Raman spectra and makes more reliable the data comparison. Even if an exhaustive investigation has not been done in this work, the feasibility of the follow-up monitoring of pemphigus vulgaris pathology has been clearly proved with useful implications for the clinical applications.

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

    NARCIS (Netherlands)

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

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

  12. Infrared and Raman spectra of (η 6-C 6H 6- nX n)Cr(CO) 3 complexes where X = Me ( n = 0-6) or OMe ( n = 0-2). A study of metal—ligand interactions

    Science.gov (United States)

    Armstrong, R. S.; Aroney, M. J.; Barnes, C. M.; Nugent, K. W.

    1994-07-01

    A systematic study is reported of the infrared and Raman spectra of methyl and methoxy substituted benzene chromium tricarbonyl complexes (η 6-C 6H 6- nX n)Cr(CO) 3 where X = Me ( n = 0-6) or OMe ( n = 0-2). Bands have been assigned and intensities calculated for a number of vibrational modes. Trends in the wavenumbers and band intensities of the arenemetal, metalcarbonyl and carbonyl bonds are examined to gain an insight into metal—ligand interactions and intramolecular electron rearrangements with progressive substitution on the arene. The results are discussed with regard σ-, π- and δ-contributions to arenemetal bonding and of σ- and π-components in metal-carbonyl and carbonyl bonding. The intensities are related to the polarities and polarizabilities of individual bonds within the molecules, and variations in these bond electronic properties with arene substitution are examined.

  13. PCA-MLP SVM distinction of salivary Raman spectra of dengue fever infection.

    Science.gov (United States)

    Radzol, A R M; Lee, Khuan Y; Mansor, W; Wong, P S; Looi, I

    2017-07-01

    Dengue fever (DF) is a disease of major concern caused by flavivirus infection. Delayed diagnosis leads to severe stages, which could be deadly. Of recent, non-structural protein (NS1) has been acknowledged as a biomarker, alternative to immunoglobulins for early detection of dengue in blood. Further, non-invasive detection of NS1 in saliva makes the approach more appealing. However, since its concentration in saliva is less than blood, a sensitive and specific technique, Surface Enhanced Raman Spectroscopy (SERS), is employed. Our work here intends to define an optimal PCA-SVM (Principal Component Analysis-Support Vector Machine) with Multilayer Layer Perceptron (MLP) kernel model to distinct between positive and negative NS1 infected samples from salivary SERS spectra, which, to the best of our knowledge, has never been explored. Salivary samples of DF positive and negative subjects were collected, pre-processed and analyzed. PCA and SVM classifier were then used to differentiate the SERS analyzed spectra. Since performance of the model depends on the PCA criterion and MLP parameters, both are examined in tandem. Its performance is also compared to our previous works on simulated NS1 salivary samples. It is found that the best PCA-SVM (MLP) model can be defined by 95 PCs from CPV criterion with P1 and P2 values of 0.01 and -0.2 respectively. A classification performance of [76.88%, 85.92%, 67.83%] is achieved.

  14. Raman Optical Activity Spectra from Density Functional Perturbation Theory and Density-Functional-Theory-Based Molecular Dynamics.

    Science.gov (United States)

    Luber, Sandra

    2017-03-14

    We describe the calculation of Raman optical activity (ROA) tensors from density functional perturbation theory, which has been implemented into the CP2K software package. Using the mixed Gaussian and plane waves method, ROA spectra are evaluated in the double-harmonic approximation. Moreover, an approach for the calculation of ROA spectra by means of density functional theory-based molecular dynamics is derived and used to obtain an ROA spectrum via time correlation functions, which paves the way for the calculation of ROA spectra taking into account anharmonicities and dynamic effects at ambient conditions.

  15. Evolution mechanism of mesoporous silicon nanopillars grown by metal-assisted chemical etching and nanosphere lithography: correlation of Raman spectra and red photoluminescence

    Science.gov (United States)

    Karadan, Prajith; John, Siju; Anappara, Aji A.; Narayana, Chandrabhas; Barshilia, Harish C.

    2016-07-01

    We have fabricated highly ordered, vertically aligned, high aspect ratio silicon nanopillars (SiNPLs) of diameter ~80 nm by combining metal-assisted chemical etching and nanosphere lithography. The evolution of surface morphology of porous silicon nanopillars has been explained, and the presence of mesoporous structures was detected on the top of silicon nanopillars using field emission scanning electron microscopy. The mesoporosity of the SiNPLs is confirmed by Brunauer-Emmett-Teller measurements. The peak shift and the splitting of optical phonon modes into LO and TO modes in the micro-Raman spectra of mesoporous SiNPLs manifest the presence of 2-3 nm porous Si nanocrystallites ( P-SiNCs) on the top of SiNPLs and the size of crystallites was calculated using bond polarizability model for spherical phonon confinement. The origin of red luminescence is explained using quantum confinement (QC) and QC luminescent center models for the P-SiNCs, which is correlated with the micro-Raman spectra. Finally, we confirmed the origin of the red luminescence is from the P-SiNCs formed on surface of SiNPLs, highly desired for LED devices by suitably tailoring the substrate.

  16. Effects of the voids filling on the lattice vibrations for the CoSb3-based thermoelectric materials-Raman scattering spectra and theoretical study

    International Nuclear Information System (INIS)

    Lu Pengxian; Shen Zigang; Hu Xing

    2010-01-01

    The unfilled CoSb 3 and the voids filled skutterudites (La, Ce and La 0.5 Ce 0.5 ) Fe 3 CoSb 12 powders were synthesized via a hydrothermal route and the effects of the La and Ce filling in the voids on the Raman scattering spectra were investigated. The results suggest that the phonon vibration frequencies of the filled skutterudites in the lower frequency range shift down significantly, while the others in the higher frequency range shift up slightly as compared with the unfilled CoSb 3 . The calculated phonon frequencies for the (La, Ce and La 0.5 Ce 0.5 ) Fe 3 CoSb 12 indicate that all the frequencies shift down, but the frequency shifting down in the lower frequency range is more remarkable than that in the higher frequency range. By comparing the electron density differences of the unfilled CoSb 3 and the voids filled (La, Ce and La 0.5 Ce 0.5 ) Fe 3 CoSb 12 , the frequency shifting phenomena observed in the Raman scattering spectra may be attributed to the complex bonding behaviors between the La or Ce atoms with the parent Co and Sb atoms.

  17. Extracting Optical Fiber Background from Surface-Enhanced Raman Spectroscopy Spectra Based on Bi-Objective Optimization Modeling.

    Science.gov (United States)

    Huang, Jie; Shi, Tielin; Tang, Zirong; Zhu, Wei; Liao, Guanglan; Li, Xiaoping; Gong, Bo; Zhou, Tengyuan

    2017-08-01

    We propose a bi-objective optimization model for extracting optical fiber background from the measured surface-enhanced Raman spectroscopy (SERS) spectrum of the target sample in the application of fiber optic SERS. The model is built using curve fitting to resolve the SERS spectrum into several individual bands, and simultaneously matching some resolved bands with the measured background spectrum. The Pearson correlation coefficient is selected as the similarity index and its maximum value is pursued during the spectral matching process. An algorithm is proposed, programmed, and demonstrated successfully in extracting optical fiber background or fluorescence background from the measured SERS spectra of rhodamine 6G (R6G) and crystal violet (CV). The proposed model not only can be applied to remove optical fiber background or fluorescence background for SERS spectra, but also can be transferred to conventional Raman spectra recorded using fiber optic instrumentation.

  18. Feature driven classification of Raman spectra for real-time spectral brain tumour diagnosis using sound.

    Science.gov (United States)

    Stables, Ryan; Clemens, Graeme; Butler, Holly J; Ashton, Katherine M; Brodbelt, Andrew; Dawson, Timothy P; Fullwood, Leanne M; Jenkinson, Michael D; Baker, Matthew J

    2016-12-19

    Spectroscopic diagnostics have been shown to be an effective tool for the analysis and discrimination of disease states from human tissue. Furthermore, Raman spectroscopic probes are of particular interest as they allow for in vivo spectroscopic diagnostics, for tasks such as the identification of tumour margins during surgery. In this study, we investigate a feature-driven approach to the classification of metastatic brain cancer, glioblastoma (GB) and non-cancer from tissue samples, and we provide a real-time feedback method for endoscopic diagnostics using sound. To do this, we first evaluate the sensitivity and specificity of three classifiers (SVM, KNN and LDA), when trained with both sub-band spectral features and principal components taken directly from Raman spectra. We demonstrate that the feature extraction approach provides an increase in classification accuracy of 26.25% for SVM and 25% for KNN. We then discuss the molecular assignment of the most salient sub-bands in the dataset. The most salient sub-band features are mapped to parameters of a frequency modulation (FM) synthesizer in order to generate audio clips from each tissue sample. Based on the properties of the sub-band features, the synthesizer was able to maintain similar sound timbres within the disease classes and provide different timbres between disease classes. This was reinforced via listening tests, in which participants were able to discriminate between classes with mean classification accuracy of 71.1%. Providing intuitive feedback via sound frees the surgeons' visual attention to remain on the patient, allowing for greater control over diagnostic and surgical tools during surgery, and thus promoting clinical translation of spectroscopic diagnostics.

  19. A combined experimental and theoretical studies on FT-IR, FT-Raman and UV-vis spectra of 2-chloro-3-quinolinecarboxaldehyde.

    Science.gov (United States)

    Prasad, M V S; Udaya Sri, N; Veeraiah, V

    2015-09-05

    In the present study, the FT-IR and FT-Raman spectra of 2-chloro-3-quinolinecarboxaldehyde (2Cl3QC) have been recorded in the region 4000-400 and 3500-50 cm(-1), respectively. The fundamental modes of vibrational frequencies of 2Cl3QC are assigned. Theoretical information on the optimized geometry, harmonic vibrational frequencies, infrared and Raman intensities were obtained by means of density functional theory (DFT) gradient calculations with complete relaxation in the potential energy surface using 6-31G(d,p) basis set. The vibrational frequencies which were determined experimentally from the spectral data are compared with those obtained theoretically from DFT calculations. A close agreement was achieved between the observed and calculated frequencies by refinement of the scale factors. The infrared and Raman spectra were also predicted from the calculated intensities. Thermodynamic properties like entropy, heat capacity, zero point energy, have been calculated for the molecule. The predicted first hyperpolarizability also shows that the molecule might have a reasonably good non-linear optical (NLO) behavior. The calculated HOMO-LUMO energy gap reveals that charge transfer occurs within the molecule. Stability of the molecule arising from hyper conjugative interactions, charge delocalization have been analyzed using natural bond orbitals (NBO) analysis. The results show that charge in electron density (ED) in the π(∗) antibonding orbitals and E((2)) energies confirms the occurrence of ICT (intra-molecular charge transfer) within the molecule. UV-visible spectrum of the title molecule has also been calculated using TD-DFT/CAM-B3LYP/6-31G(d,p) method. The calculated energy and oscillator strength almost exactly reproduces reported experimental data. Copyright © 2015 Elsevier B.V. All rights reserved.

  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. 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...... Ionic Liquid, To be submitted for J. Phys. Chem. A (2009)....

  2. Raman spectra of impact zircons in the Jarva-varaka layered massif (the Monchegorsk ore region, the Kola Peninsula

    Directory of Open Access Journals (Sweden)

    Kaulina T. V.

    2017-03-01

    Full Text Available Zircon crystals from granophyre norites of the Jarva-varaka massif of the Monchegorsk ore region (the Kola Peninsula have been studied by means of back-scattered electron (BSE imaging and Raman spectroscopy. The Jarva-varaka massif according to geological and geochemical data has been compared with the Sudbury structure, for which an impact origin is assumed. Zircon study is stipulated by zircon ability to keep signs of shock metamorphism even under granulite-facies conditions, thus it can be used for identification of ancient impact structures. BSE images reveal complicated internal texture – darker central domains (cores and light rims without texture. Mineral inclusions in zircon are represented by sillimanite and plagioclase which indicates that the studied zircon grains were inherited from the host aluminous gneisses. Zircon crystals show variation of Raman spectra from the core of crystals with typical zircon Raman pattern to complete absence of spectral bands in the marginal parts and rims. Mineral inclusions in zircon rims also have no Raman spectra. Such patterns may be associated with the transformation of crystalline zircon (and mineral inclusions in it to diaplectic glass under the influence of shock metamorphism, core domains were screened by rims and thus preserved their structure. The received data suggest the participation of the meteorite impact in the formation of the Jarva-varaka massif that requires further investigation.

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

    Czech Academy of Sciences Publication Activity Database

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

    2014-01-01

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

  4. Infrared and Raman scattering spectra of layered structured Ga{sub 3}InSe{sub 4} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Isik, M., E-mail: misik@atilim.edu.tr [Department of Electrical and Electronics Engineering, Atilim University, 06836 Ankara (Turkey); Gasanly, N.M. [Department of Physics, Middle East Technical University, 06800 Ankara (Turkey); Korkmaz, F. [Department of Electrical and Electronics Engineering, Atilim University, 06836 Ankara (Turkey)

    2013-03-01

    The infrared reflectivity and transmittance and Raman scattering in Ga{sub 3}InSe{sub 4} layered crystals were investigated in the frequency ranges of 100–400, 400–4000 and 25–500 cm{sup −1}. The refractive and absorption indices, the frequencies of transverse and longitudinal optical modes, high- and low-frequency dielectric constants were obtained from the analysis of the IR reflectivity spectra. The bands observed in IR transmittance spectra were interpreted in terms of two-phonon absorption processes.

  5. Influence of ageing on Raman spectra and the conductivity of monolayer graphene samples irradiated by heavy and light ions

    Energy Technology Data Exchange (ETDEWEB)

    Butenko, A.; Zion, E.; Richter, V.; Sharoni, A. [Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 52900 (Israel); Kaganovskii, Yu.; Wolfson, L.; Kogan, E.; Kaveh, M.; Shlimak, I. [Department of Physics, Jack and Pearl Resnick Institute, Bar-Ilan University, Ramat Gan 52900 (Israel)

    2016-07-28

    The influence of long-term ageing (about one year) on the Raman scattering (RS) spectra and the temperature dependence of conductivity has been studied in two series of monolayer graphene samples irradiated by different doses of C{sup +} and Xe{sup +} ions. It is shown that the main result of ageing consists of changes in the intensity and position of D- and G- and 2D-lines in RS spectra and in an increase of the conductivity. The observed effects are explained in terms of an increase of the radius of the “activated” area around structural defects.

  6. Raman spectra of p-type transparent semiconducting Cr{sub 2}O{sub 3}:Mg

    Energy Technology Data Exchange (ETDEWEB)

    Fleischer, Karsten, E-mail: fleisck@tcd.ie; Caffrey, David; Farrell, Leo; Norton, Emma; Mullarkey, Daragh; Arca, Elisabetta; Shvets, Igor V.

    2015-11-02

    We present an analysis of the Raman spectra of p-type transparent conducting Cr{sub 2}O{sub 3}:Mg grown by various techniques including spray pyrolysis, pulsed laser deposition, molecular beam epitaxy and reactive magnetron sputtering. The best performing films show a distinct broad range Raman signature related to defect-induced vibrational modes not seen in stoichiometric, undoped material. Our comparative study demonstrates that Raman spectroscopy can quantify unwanted dopant clustering in the material at high Mg concentrations, while also being sensitive to the Mg incorporation site. By correlating the Raman signature to the electrical properties of the films, growth processes can be optimised to give the best conducting films and the local defect structure for effective p-type doping can be studied. - Highlights: • Mg doping in Cr{sub 2}O{sub 3} can lead to dopant clustering in MgCr{sub 2}O{sub 4} phase. • Post-annealing in oxygen can dissolve these clusters improving doping. • High oxygen pressures during growth can prevent dopant clustering. • Raman spectroscopy is a powerful tool to assist growth optimization in p-type oxides.

  7. 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

    2014-11-11

    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. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Hydrogen bond dynamics and water structure in glucose-water solutions by depolarized Rayleigh scattering and low-frequency Raman spectroscopy

    Science.gov (United States)

    Paolantoni, Marco; Sassi, Paola; Morresi, Assunta; Santini, Sergio

    2007-07-01

    The effect of glucose on the relaxation process of water at picosecond time scales has been investigated by depolarized Rayleigh scattering (DRS) experiments. The process is assigned to the fast hydrogen bonding dynamics of the water network. In DRS spectra this contribution can be safely separated from the slower relaxation process due to the sugar. The detected relaxation time is studied at different glucose concentrations and modeled considering bulk and hydrating water contributions. As a result, it is found that in diluted conditions the hydrogen bond lifetime of proximal water molecules becomes about three times slower than that of the bulk. The effect of the sugar on the hydrogen bond water structure is investigated by analyzing the low-frequency Raman (LFR) spectrum sensitive to intermolecular modes. The addition of glucose strongly reduces the intensity of the band at 170cm-1 assigned to a collective stretching mode of water molecules arranged in cooperative tetrahedral domains. These findings indicate that proximal water molecules partially lose the tetrahedral ordering typical of the bulk leading to the formation of high density environments around the sugar. Thus the glucose imposes a new local order among water molecules localized in its hydration shell in which the hydrogen bond breaking dynamics is sensitively retarded. This work provides new experimental evidences that support recent molecular dynamics simulation and thermodynamics results.

  9. Proton dynamics in the strong chelate hydrogen bond of crystalline picolinic acid N-oxide. A new computational approach and infrared, raman and INS study.

    Science.gov (United States)

    Stare, Jernej; Panek, Jarosław; Eckert, Juergen; Grdadolnik, Joze; Mavri, Janez; Hadzi, Dusan

    2008-02-21

    Infrared, Raman and INS spectra of picolinic acid N-oxide (PANO) were recorded and examined for the location of the hydronic modes, particularly O-H stretching and COH bending. PANO is representative of strong chelate hydrogen bonds (H-bonds) with its short O...O distance (2.425 A). H-bonding is possibly well-characterized by diffraction, NMR and NQR data and calculated potential energy functions. The analysis of the spectra is assisted by DFT frequency calculations both in the gas phase and in the solid state. The Car-Parrinello quantum mechanical solid-state method is also used for the proton dynamics simulation; it shows the hydron to be located about 99% of time in the energy minimum near the carboxylic oxygen; jumps to the N-O acceptor are rare. The infrared spectrum excels by an extended absorption (Zundel's continuum) interrupted by numerous Evans transmissions. The model proton potential functions on which the theories of continuum formation are based do not correspond to the experimental and computed characteristics of the hydrogen bond in PANO, therefore a novel approach has been developed; it is based on crystal dynamics driven hydronium potential fluctuation. The envelope of one hundred 0 --> 1 OH stretching transitions generated by molecular dynamics simulation exhibits a maximum at 1400 cm-1 and a minor hump at approximately 1600 cm-1. These positions square well with ones predicted for the COH bending and OH stretching frequencies derived from various one- and two-dimensional model potentials. The coincidences with experimental features have to be considered with caution because the CPMD transition envelope is based solely on the OH stretching coordinate while the observed infrared bands correspond to heavily mixed modes as was previously shown by the normal coordinate analysis of the IR spectrum of argon matrix isolated PANO, the present CPMD frequency calculation and the empirical analysis of spectra. The experimental infrared spectra show some

  10. Profiling of liquid crystal displays with Raman spectroscopy: preprocessing of spectra

    NARCIS (Netherlands)

    Stanimirovic, Olja; Boelens, Hans F. M.; Mank, Arjan J. G.; Hoefsloot, Huub C. J.; Smilde, Age K.

    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

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

    NARCIS (Netherlands)

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

    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

  12. The electron–phonon coupling of fundamental, overtone, and combination modes and its effects on the resonance Raman spectra

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuo [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); College of Physics, Jilin University, Changchun 130012 (China); Li, Zhanlong; Wang, Shenghan; Gao, Shuqin [College of Physics, Jilin University, Changchun 130012 (China); Sun, Chenglin, E-mail: chenglin@jlu.edu.cn [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); College of Physics, Jilin University, Changchun 130012 (China); Li, Zuowei [College of Physics, Jilin University, Changchun 130012 (China)

    2015-12-15

    Highlights: • The Huang–Rhys factors and electron–phonon coupling constants are calculated. • The changes of overtone mode are larger than those of fundamental mode. • The variation pattern of electron–phonon coupling well interprets the changes of spectra. - Abstract: External field plays a very important role in the interaction between the π-electron transition and atomic vibration of polyenes. It has significant effects on both the Huang–Rhys factor and the electron–phonon coupling. In this paper, the visible absorption and resonance Raman spectra of all-trans-β-carotene are measured in the 345–295 K temperature range and it is found that the changes of the 0–1 and 0–2 vibration bands of the absorption spectra with the temperature lead to the different electron–phonon coupling of fundamental, overtone, and combination modes. The electron-phonon coupling constants of all the modes are calculated and analyzed under different temperatures. The variation law of the electron–phonon coupling with the temperature well interprets the changes of the resonance Raman spectra, such as the shift, intensity and line width of the overtone and combination modes, which are all greater than those of the fundamental modes.

  13. Monochannel versus multichannel detection in the acquisition of the micro-Raman spectra of high-Tc superconductors

    International Nuclear Information System (INIS)

    Schroeder, T.D.; Etz, E.S.; Pereles, S.F.

    1989-01-01

    Raman spectroscopy has become a widely used tool for the characterization of the new high-T c superconductors. Most reported work has come from the study of bulk samples, mainly the lanthanum- and yttrium-based copper oxide systems. Micro-Raman spectroscopy extends these investigations into the microscopic domain for spatially resolved crystal structure and phase identification, the examination of compositional homogeneity, especially in regard to oxygen stoichiometry. Results are correlated with methods of synthesis, sample processing and heat treatment, and with the observed electrical and magnetic properties. Difficulties in the Raman measurements arise from the fact that these solids have low scattering intensities, are opaque and optically absorbing and therefore subject to potential laser-induced modification. In this work on the microstructural characterization of the superconducting yttrium-barium-copper-oxygen (Y-Ba-Cu-O) system, the authors have employed two types of Raman microprobes to examine the relative merits of spectral acquisition by single-channel, PMT with photon counting, detection versus detection by multichannel analyzer with intensified diode array. They have obtained the room-temperature spectra of several types of samples (i.e., polycrystalline ceramic powders, sintered pellets, single-crystal material, and thin films) of composition YBa 2 Cu 3 O 7 - x (for 0≤x≤1) in the two different microprobes with 514.5 nm excitation

  14. Digital dewaxing of Raman signals: discrimination between nevi and melanoma spectra obtained from paraffin-embedded skin biopsies.

    Science.gov (United States)

    Tfayli, Ali; Gobinet, Cyril; Vrabie, Valeriu; Huez, Regis; Manfait, Michel; Piot, Olivier

    2009-05-01

    Malignant melanoma (MM) is the most severe tumor affecting the skin and accounts for three quarters of all skin cancer deaths. Raman spectroscopy is a promising nondestructive tool that has been increasingly used for characterization of the molecular features of cancerous tissues. Different multivariate statistical analysis techniques are used in order to extract relevant information that can be considered as functional spectroscopic descriptors of a particular pathology. Paraffin embedding (waxing) is a highly efficient process used to conserve biopsies in tumor banks for several years. However, the use of non-dewaxed formalin-fixed paraffin-embedded tissues for Raman spectroscopic investigations remains very restricted, limiting the development of the technique as a routine analytical tool for biomedical purposes. This is due to the highly intense signal of paraffin, which masks important vibrations of the biological tissues. In addition to being time consuming and chemical intensive, chemical dewaxing methods are not efficient and they leave traces of the paraffin in tissues, which affects the Raman signal. In the present study, we use independent component analysis (ICA) on Raman spectral images collected on melanoma and nevus samples. The sources obtained from these images are then used to eliminate, using non-negativity constrained least squares (NCLS), the paraffin contribution from each individual spectrum of the spectral images of nevi and melanomas. Corrected spectra of both types of lesion are then compared and classified into dendrograms using hierarchical cluster analysis (HCA).

  15. 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

  16. FT-IR, Raman and DFT studies on the vibrational spectra of 2,2-bis ...

    African Journals Online (AJOL)

    propane (baep) were examined both experimentally and theoretically including FT-IR and Raman spectroscopic methods. Among the possible structural configurations, 30 of them were handled in the framework of this study. The structural ...

  17. Raman spectra, electrochemical redox potentials and intramolucular reorganization due to ionization and excitation of benzodifuranone chromophore

    Czech Academy of Sciences Publication Activity Database

    Luňák, S. Jr.; Frumarová, Božena; Mikysek, T.; Vyňuchal, J.

    2013-01-01

    Roč. 570, 10 May (2013), s. 50-55 ISSN 0009-2614 Institutional support: RVO:61389013 Keywords : benzodifuranone * DFT calculations * Raman spectroscopy Subject RIV: CA - Inorganic Chemistry Impact factor: 1.991, year: 2013

  18. Molecules-in-molecules fragment-based method for the calculation of chiroptical spectra of large molecules: Vibrational circular dichroism and Raman optical activity spectra of alanine polypeptides.

    Science.gov (United States)

    Jose, K V Jovan; Raghavachari, Krishnan

    2016-12-01

    The molecules-in-molecules (MIM) fragment-based method has recently been adapted to evaluate the chiroptical (vibrational circular dichroism [VCD] and Raman optical activity [ROA]) spectra of large molecules such as peptides. In the MIM-VCD and MIM-ROA methods, the relevant higher energy derivatives of the parent molecule are assembled from the corresponding derivatives of smaller fragment subsystems. In addition, the missing long-range interfragment interactions are accounted at a computationally less expensive level of theory (MIM2). In this work we employed the MIM-VCD and MIM-ROA fragment-based methods to explore the evolution of the chiroptical spectroscopic characteristics of 3 10 -helix, α-helix, β-hairpin, γ-turn, and β-extended conformers of gas phase polyalanine (chain length n = 6-14). The different conformers of polyalanine show distinctive features in the MIM chiroptical spectra and the associated spectral intensities increase with evolution of system size. For a better understanding the site-specific effects on the vibrational spectra, isotopic substitutions were also performed employing the MIM method. An increasing redshift with the number of isotopically labeled 13 C=O functional groups in the peptide molecule was seen. For larger polypeptides, we implemented the two-step-MIM model to circumvent the high computational expense associated with the evaluation of chiroptical spectra at a high level of theory using large basis sets. The chiroptical spectra of α-(alanine) 20 polypeptide obtained using the two-step-MIM model, including continuum solvation effects, show good agreement with the full calculations and experiment. This benchmark study suggests that the MIM-fragment approach can assist in predicting and interpreting chiroptical spectra of large polypeptides. © 2016 Wiley Periodicals, Inc.

  19. Raman spectra of MgSiO3 . 10% Al2O3-perovskite at various pressures and temperatures

    International Nuclear Information System (INIS)

    Liu Lingun; Irifune, T.

    1995-01-01

    Variations of Raman spectra of MgSiO 3 . 10% Al 2 O 3 -perovskite were investigated up to about 270 kbar at room temperature and in the range 108-425 K at atmospheric pressure. Like MgSiO 3 -perovskite, the Raman frequencies of MgSiO 3 . 10% Al 2 O 3 -perovskite increase nonlinearly with increasing pressure and decrease linearly with increasing temperature within the experimental uncertainties and the range investigated. A comparison of these data with those of MgSiO 3 -perovskite suggests that MgSiO 3 . 10% Al 2 O 3 -perovskite is slightly more compressible than MgSiO 3 -perovskite, and that the volume thermal expansion for MgSiO 3 . 10% Al 2 O 3 -perovskite is also slightly greater than that for MgSiO 3 -perovskite. (orig.)

  20. raman

    Indian Academy of Sciences (India)

    also had the devoted and loyal assistance of Asutosh Dey, known to everyone in the Association as Ashu Babu. Raman soon ...... Even after reaching the hotel, the stream of photographers and news- paper reporters continued to show us their ...... My affection, loyalty and respect for him were something extraordinary and I ...

  1. Spectra and structure of gallium compounds. Part IX . Infrared and Raman spectra of trimethylphosphinegallium trichloride and normal coordinate calculations of gallium trichloride and the adduct

    Science.gov (United States)

    Durig, J. R.; Chatterjee, K. K.

    1982-05-01

    The infrared (3200-50 cm -1)and the Raman (3200-30 cm -1) spectra of (CH 3) 3PGaCI 3 have been recorded for the solid state. The spectra are interpreted on the basis of an effective C3v molecular symmetry for the crystalline state and a complete vibrational assignment except for the torsional modes is presented. The frequencies and potential energy distribution for GaCl 3 and those of the adduct have been calculated utilizing a modified valence force field model. A comparison of the calculated potential constants for the adduct with those of the free Lewis acid and base is made and the differences are shown to be consistent with structural changes upon adduct formation and explained in terms of the VSEPR model. Extensive coupling is observed between the GaP stretching mode and the GaCI 3 and the PC 3 stretching and symmetric deformational modes. Various degrees of coupling are also observed between other skeletal modes of vibration, including coupling between the PC 3 and GaCI 3 rocking motions. The value of 2.01 mdyn Å -1 for the GaP stretching force constant is the same as that previously determined for the same constant for (CH 3) 3PGaH 3. Several weak bands, observed in the low frequency region of the infrared and Raman spectra of crystalline (CH 3) 3PGaCl 3, are characterized as lattice modes arising from intermolecular librations. These results are compared to the similar quantities in some corresponding molecules.

  2. Theory of the low frequency mechanical modes and Raman spectra of the M13 bacteriophage capsid with atomic detail

    International Nuclear Information System (INIS)

    Dykeman, Eric C; Sankey, Otto F

    2009-01-01

    We present a theoretical study of the low frequency vibrational modes of the M13 bacteriophage using a fully atomistic model. Using ideas from electronic structure theory, the few lowest vibrational modes of the M13 bacteriophage are determined using classical harmonic analysis. The relative Raman intensity is estimated for each of the mechanical modes using a bond polarizability model. Comparison of the atomic mechanical modes calculated here with modes derived from elastic continuum theory shows that a much richer spectrum emerges from an atomistic picture.

  3. Vibrational assignments for the Raman and the phosphorescence spectra of 9,10-anthraquinone and 9,10-anthraquinone-d81

    International Nuclear Information System (INIS)

    Lehmann, K.K.; Smolarek, J.; Khalil, O.S.; Goodman, L.

    1979-01-01

    The Raman spectra of 9,10-anthraquinone (AQ) and 9,10-anthraquinone-d/sub 8/ are examined. Raman band assignments are made from this data and from a published normal coordinate analysis. The Raman spectra of AQ at 5K is reported and vibrational assignments for the phosphorescence spectra of AQ in n-hexane at 4.2 K are reexamined in light of new 3 B 1 /sub g/ → 1 A/sub g/ phosphorescence data. Contrary to previous work from this laboratory, it is concluded that although higher order vibronic interactions may be operative between the two closely spaced 3 A/sub u/- 3 B 1 /sub g/ electronic states, these interactions are not manifested in the phosphorescence spectra of AQ in n-hexane at 4.2 K

  4. 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.

  5. Identifying the structure of 4-chlorophenyl isocyanide adsorbed on Au(111) and Pt(111) surfaces by first-principles simulations of Raman spectra.

    Science.gov (United States)

    Hu, Wei; Duan, Sai; Zhang, Yujin; Ren, Hao; Jiang, Jun; Luo, Yi

    2017-12-13

    Surface Raman spectroscopy has become one of the most powerful analytical tools for interfacial structures. However, theoretical modeling for the Raman spectra of molecular adsorbate on metallic surfaces is a long-standing challenge because accurate descriptions of the electronic structure for both the metallic substrates and adsorbates are required. Here we present a quasi-analytical method for high-precision surface Raman spectra at the first principle level. Using this method, we correlate both geometrical and electronic structures of a single 4-chlorophenyl isocyanide (CPI) molecule adsorbed on a Au(111) or Pt(111) surface with its Raman spectra. The "finger-print" frequency shift of the CN stretching mode reveals the in situ configuration of CPI is vertical adsorption on the top site of the Au(111) surface, but a bent configuration when it adsorbs on the hollow site of the Pt(111) surface. Electronic structure calculations reveal that a π-back donation mechanism often causes a red shift to the Raman response of CN stretching mode. In contrast, σ donation as well as a wall effect introduces a blue shift to the CN stretching mode. A clear relationship for the dependence of Raman spectra on the surface electronic and geometrical information is built up, which largely benefits the understanding of chemical and physical changes during the adsorption. Our results highlight that high-precision theoretical simulations are essential for identifying in situ geometrical and electronic surface structures.

  6. Low-frequency Raman spectra of sub- and supercritical CO2: qualitative analysis of the diffusion coefficient behavior.

    Science.gov (United States)

    Idrissi, A; Longelin, S; Damay, P; Leclercq, F

    2005-09-01

    We report the results of the low-frequency Raman experiments on CO(2) which were carried out in a wide density range, along the liquid-gas coexistence curve in a temperature range of 293-303 K, and on the critical isochore of 94.4 cm(3) mol(-1) in a temperature range of 304-315 K. In our approach, the qualitative behavior of the diffusion coefficient D is predicted, assuming the following: first, that the low-frequency Raman spectra can be interpreted in terms of the translation rotation motions; second, that the random force could be replaced by the total force to calculate the friction coefficient; and finally, that the Einstein frequency is associated with the position of the maximum of the low-frequency Raman spectrum. The results show that the diffusion coefficient increases along the coexistence curve, and its values are almost constant on the critical isochore. The predicted values reproduce qualitatively those obtained by other techniques. The values of D were also calculated by molecular-dynamics simulation and they qualitatively reproduce the behavior of D.

  7. Raman Spectra of ZrS2 and ZrSe2 from Bulk to Atomically Thin Layers

    Directory of Open Access Journals (Sweden)

    Samuel Mañas-Valero

    2016-09-01

    Full Text Available In the race towards two-dimensional electronic and optoelectronic devices, semiconducting transition metal dichalcogenides (TMDCs from group VIB have been intensively studied in recent years due to the indirect to direct band-gap transition from bulk to the monolayer. However, new materials still need to be explored. For example, semiconducting TMDCs from group IVB have been predicted to have larger mobilities than their counterparts from group VIB in the monolayer limit. In this work we report the mechanical exfoliation of ZrX2 (X = S, Se from bulk down to the monolayer and we study the dimensionality dependence of the Raman spectra in ambient conditions. We observe Raman signal from bulk to few layers and no shift in the peak positions is found when decreasing the dimensionality. While a Raman signal can be observed from bulk to a bilayer for ZrS2, we could only detect signal down to five layers for flakes of ZrSe2. These results show the possibility of obtaining atomically thin layers of ZrX2 by mechanical exfoliation and represent one of the first steps towards the investigation of the properties of these materials, still unexplored in the two-dimensional limit.

  8. Thermal expansion, anharmonicity and temperature-dependent Raman spectra of single- and few-layer MoSe₂ and WSe₂.

    Science.gov (United States)

    Late, Dattatray J; Shirodkar, Sharmila N; Waghmare, Umesh V; Dravid, Vinayak P; Rao, C N R

    2014-06-06

    We report the temperature-dependent Raman spectra of single- and few-layer MoSe2 and WSe2 in the range 77-700 K. We observed linear variation in the peak positions and widths of the bands arising from contributions of anharmonicity and thermal expansion. After characterization using atomic force microscopy and high-resolution transmission electron microscopy, the temperature coefficients of the Raman modes were determined. Interestingly, the temperature coefficient of the A(2)(2u) mode is larger than that of the A(1g) mode, the latter being much smaller than the corresponding temperature coefficients of the same mode in single-layer MoS2 and of the G band of graphene. The temperature coefficients of the two modes in single-layer MoSe2 are larger than those of the same modes in single-layer WSe2. We have estimated thermal expansion coefficients and temperature dependence of the vibrational frequencies of MoS2 and MoSe2 within a quasi-harmonic approximation, with inputs from first-principles calculations based on density functional theory. We show that the contrasting temperature dependence of the Raman-active mode A(1g) in MoS2 and MoSe2 arises essentially from the difference in their strain-phonon coupling. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Czech Academy of Sciences Publication Activity Database

    Lopes, P.C.; Moreira, J.A.; Almeida, A.; Esteves, A.; Gregora, Ivan; Ledinský, Martin; Lopes, J.C.; Henrique, R.; Oliveira, A.

    2011-01-01

    Roč. 16, č. 12 (2011), 127001/1-127001/12 ISSN 1083-3668 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10100521 Keywords : biomedical optics * Raman spectroscopy * deconvolution * data processing Subject RIV: BH - Optics , Masers, Lasers Impact factor: 3.157, year: 2011

  10. Superconductive B-doped nanocrystalline diamond thin films: Electrical transport and Raman spectra

    Czech Academy of Sciences Publication Activity Database

    Nesládek, M.; Tromson, D.; Mer, Ch.; Bergonzo, P.; Hubík, Pavel; Mareš, Jiří J.

    2006-01-01

    Roč. 88, č. 23 (2006), 232111/1-232111/3 ISSN 0003-6951 R&D Projects: GA ČR(CZ) GA202/06/0040 Institutional research plan: CEZ:AV0Z10100521 Keywords : nanocrystalline diamond * superconductivity * magnetoresistance * Raman spectroscopy * Fano resonance Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.977, year: 2006

  11. FTIR, FT-RAMAN, NMR, spectra, normal co-ordinate analysis, NBO, NLO and DFT calculation of N,N-diethyl-4-methylpiperazine-1-carboxamide molecule.

    Science.gov (United States)

    Muthu, S; Elamurugu Porchelvi, E

    2013-11-01

    The Fourier Transform Infrared (FT-IR) and FT-Raman of N,N-diethyl-4-methylpiperazine-1-carboxamide (NND4MC) have been recorded and analyzed. The structure of the compound was optimized and the structural characteristics were determined by density functional theory (DFT) using B3LYP method with 6-31G(d,p) and 6-311G(d,p) basis sets. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The theoretically predicted FT-IR and FT-Raman spectra of the title molecule have been constructed. The detailed interpretation of the vibrational spectra has been carried out with aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that electron density (ED) in the σ(*) and π(*) antibonding orbitals and second order delocalization energies (E2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. The electronic dipole moment (μD) and the first hyperpolarizability (βtot) values of the investigated molecule were computed using Density Functional Theory (DFT/B3LYP) with 6-31G(d,p) and 6-311G(d,p) basis sets. The calculated results also show that the NND4MC molecule may have microscopy nonlinear optical (NLO) behavior with non zero values. Mulliken atomic charges of NND4MC were calculated. The (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. The UV-Vis spectrum of the compound was recorded. The theoretical electronic absorption spectra have been calculated by using CIS, TD-DFT methods. A study on the electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MEP) were also performed. Copyright © 2013 Elsevier B

  12. Influence of the shaking time on the forensic analysis of FTIR and Raman spectra of spray paints.

    Science.gov (United States)

    Muehlethaler, Cyril; Massonnet, Geneviève; Buzzini, Patrick

    2014-04-01

    In order to decide if replicated measurements of a trace fall within the intra-variability expected for reference paint samples, a forensic scientist has to understand and integrate all reasonable sources of variation. The origins of such variation in spectra can be various, but mainly include differences in components distribution (homogeneity of spraying) or differences originating from the manufacturing process (production batches). Instrumental variation can also be problematic for non-successive measurements. Infrared and Raman spectra were collected to study the homogeneity of the paint distribution after shaking a spray can for times of 0, 1, 2, 3, 4 and 5min. The results confirm that differences arise in both the spectroscopic techniques used in this study. Mainly, this survey shows that the problematic of shaking is particularly important when the pigment content can be detected from spray paint samples within the infrared domain. In these situations, the signal from the pigment might produce strong absorptions that vary with shaking time, leading to differences in relative intensities with respect to those attributed to the binder. For Raman spectroscopy, it has been shown that a gradient of pigment concentration is observable in some samples depending on the shaking time. The proportion of the signal due to the pigment increases with shaking times from 0 to 1min and diminishes afterwards, to finally reach stabilization around 3min of shaking. Not all samples are affected by these differences and it should always be evaluated on a case-by-case basis. From a statistical point-of-view, principal component analyses of the replicates show that the spectra are reproducible after 3min of shaking. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  13. Characterization of sp3bond content of carbon films deposited by high power gas injection magnetron sputtering method by UV and VIS Raman spectroscopy.

    Science.gov (United States)

    Zdunek, Krzysztof; Chodun, Rafał; Wicher, Bartosz; Nowakowska-Langier, Katarzyna; Okrasa, Sebastian

    2018-04-05

    This paper presents the results of investigations of carbon films deposited by a modified version of the magnetron sputtering method - HiPGIMS (High Power Gas Injection Magnetron Sputtering). In this experiment, the magnetron system with inversely polarized electrodes (sputtered cathode at ground potential and positively biased, spatially separated anode) was used. This arrangement allowed us to conduct the experiment using voltages ranging from 1 to 2kV and a power supply system equipped with 25/50μF capacitor battery. Carbon films were investigated by VIS/UV Raman spectroscopy. Sp 3 /sp 2 bonding ratio was evaluated basing the elementary components of registered spectra. Our investigation showed that sp 3 bond content increases with discharge power but up to specific value only. In extreme conditions of generating plasma impulses, we detected a reversed relation of the sp 3 /sp 2 ratio. In our opinion, a energy of plasma pulse favors nucleation of a sp 3 phase because of a relatively higher ionization state but in extreme cases the influence of energy is reversed. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. Characterization of sp3 bond content of carbon films deposited by high power gas injection magnetron sputtering method by UV and VIS Raman spectroscopy

    Science.gov (United States)

    Zdunek, Krzysztof; Chodun, Rafał; Wicher, Bartosz; Nowakowska-Langier, Katarzyna; Okrasa, Sebastian

    2018-04-01

    This paper presents the results of investigations of carbon films deposited by a modified version of the magnetron sputtering method - HiPGIMS (High Power Gas Injection Magnetron Sputtering). In this experiment, the magnetron system with inversely polarized electrodes (sputtered cathode at ground potential and positively biased, spatially separated anode) was used. This arrangement allowed us to conduct the experiment using voltages ranging from 1 to 2 kV and a power supply system equipped with 25/50 μF capacitor battery. Carbon films were investigated by VIS/UV Raman spectroscopy. Sp3/sp2 bonding ratio was evaluated basing the elementary components of registered spectra. Our investigation showed that sp3 bond content increases with discharge power but up to specific value only. In extreme conditions of generating plasma impulses, we detected a reversed relation of the sp3/sp2 ratio. In our opinion, a energy of plasma pulse favors nucleation of a sp3 phase because of a relatively higher ionization state but in extreme cases the influence of energy is reversed.

  15. Ab initio modeling of fused silica, crystal quartz, and water Raman spectra

    Czech Academy of Sciences Publication Activity Database

    Dračínský, Martin; Benda, Ladislav; Bouř, Petr

    2011-01-01

    Roč. 512, č. 13 (2011), s. 54-59 ISSN 0009-2614 R&D Projects: GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033 Grant - others:GA MŠk(CZ) 2B08021 Program:2B Institutional research plan: CEZ:AV0Z40550506 Keywords : fused silica * Raman spectroscopy * Car -Parrinello molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.337, year: 2011

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

    International Nuclear Information System (INIS)

    Salyulev, A.B.; Zakir'yanova, I.D.

    2008-01-01

    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 PCl 5 vapors in molten TbCl 3 . 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 [ru

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

    Indian Academy of Sciences (India)

    1–4] on substituted biomolecules. These molecules do not occur freely in natural bi- ological metabolism. The understanding of the vibrational spectra of free molecules might be helpful in understanding specific biological processes and in the ...

  18. Side Chain and Flexibility Contributions to the Raman Optical Activity Spectra of a Model Cyclic Hexapeptide

    Czech Academy of Sciences Publication Activity Database

    Hudecová, J.; Kapitán, Josef; Baumruk, V.; Hammer, R. P.; Keiderling, T. A.; Bouř, Petr

    2010-01-01

    Roč. 114, č. 28 (2010), s. 7642-7651 ISSN 1089-5639 R&D Projects: GA ČR GA203/06/0420; GA ČR GA202/07/0732; GA AV ČR IAA400550702 Grant - others:GA UK(CZ) 126310 Institutional research plan: CEZ:AV0Z40550506 Keywords : Raman optical activity * ab initio * side chain * flexibility * peptide Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.732, year: 2010

  19. 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.

  20. Zn(II)-concentration dependent Raman spectra in the dithizone complex on gold nanoparticle surfaces in environmental water samples

    Science.gov (United States)

    Ly, Nguyen Hoang; Joo, Sang-Woo

    2015-11-01

    After the formation of dithizone with metal ion complexes, a selective Raman detection method for the Zn2+ ions in aqueous solutions was developed by observing the intensity change of the ring mode peaks at ∼1585 cm-1 on gold nanoparticles (AuNPs). At high concentrations of Zn2+ ions, the conformation of the dithizone complex may have different orientations on AuNPs to yield the spectral changes at ca. ∼510 and ∼1585 cm-1. The concentration dependent spectra changes indicated that a detection limit would be in the submicromolar region of Zn2+ ions. The other ions of Mg2+, K+, Fe3+, Hg2+, Co2+, Fe2+, Pb2+, Cu2+, Ni2+, Cr3+, NH4+, Cd2+, Na+, Ca2+, and Mn2+ at micromolar concentrations of 1 μM did not produce such spectral changes. The detection limit based on the Raman band intensities was estimated to be as low as 500 nM of Zn2+ ion in aqueous solutions. The three real samples of tap, river, and seawater were tested under the interference of the commonly existing interfering ions. Despite the presence of highly concentrated Na, Ca, Mg, and K, our interfacial spectroscopic methodology of Zn2+ determination could be applied in the environmental water samples.

  1. Infrared and Raman Spectroscopic Study of Carbon-Cobalt Composites

    Directory of Open Access Journals (Sweden)

    André Tembre

    2011-01-01

    Full Text Available Analysis of carbon-cobalt thin films using infrared spectroscopy has shown existence of carbon-cobalt stretching mode and great porosity. The Raman spectroscopy and high-resolution transmission electron microscopy have been used in order to investigate the microstructure of the films. These films exhibit complex Raman spectra suggesting the presence of amorphous and crystallized phases. The different fractions of phases and the correlation between the atomic bond structures and the Raman features depend on the cobalt content.

  2. Infrared and Raman Spectroscopic Study of Carbon-Cobalt Composites

    OpenAIRE

    André Tembre; Jacques Hénocque; Martial Clin

    2011-01-01

    Analysis of carbon-cobalt thin films using infrared spectroscopy has shown existence of carbon-cobalt stretching mode and great porosity. The Raman spectroscopy and high-resolution transmission electron microscopy have been used in order to investigate the microstructure of the films. These films exhibit complex Raman spectra suggesting the presence of amorphous and crystallized phases. The different fractions of phases and the correlation between the atomic bond structures and the Raman feat...

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

    Science.gov (United States)

    Muehlethaler, Cyril; Massonnet, Genevieve; Esseiva, Pierre

    2011-06-15

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

  4. 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...... and that the models used must take this into account. Hence, the use of statistical methods to interpret and understand the infrared and Raman spectra and images from biological tissues, cells, parts of cells, fluids, and even whole organism should change accordingly. As the species, conformers and structures...... of biomolecules are very sensitive to their environment and aggregation state, the combined use of infrared and Raman spectroscopy and imaging and theoretical simulations are clearly fields, which can benefit from their joint and mutual development....

  5. Raman spectra of a Lower Cambrian ctenophore embryo from southwestern Shaanxi, China

    Science.gov (United States)

    Chen, Jun-Yuan; Schopf, J. William; Bottjer, David J.; Zhang, Chen-Yu; Kudryavtsev, Anatoliy B.; Tripathi, Abhishek B.; Wang, Xiu-Qiang; Yang, Yong-Hua; Gao, Xiang; Yang, Ying

    2007-01-01

    The Early Cambrian (≈540 million years old) Meishucun fossil assemblage of Ningqiang County (Shaanxi Province), China, contains the oldest complex skeletonized organisms known in the geological record. We here report the finding in this assemblage of an exquisitely preserved late-stage embryo of a ctenophore (“comb jelly”), its fine structure documented by confocal laser scanning microscopy and shown by Raman spectroscopy to be composed of carbonaceous kerogen permineralized in apatite. In its spheroidal morphology, the presence of eight comb rows and the absence of tentacles, this embryo resembles an adult ctenophore (Maotianoascus octonarius) known from the immediately younger Chengjiang fauna of Yunnan, China. The oldest ctenophore and the only embryonic comb jelly known from the fossil record, this exceptionally well preserved specimen provides important clues about the early evolution of the phylum Ctenophora and of metazoans in general. PMID:17404242

  6. Raman spectra of amorphous silicon thin films deposited by glow discharge

    International Nuclear Information System (INIS)

    Bustarret, E.; Alvarez, F.; Brenzikofer, R.; Vilche Pena, A.; Chambouleyron, I.

    1983-01-01

    The local disorder present in films of a-Si:H and a-Si sub(x) N 1 - sub(x):H has been studied through first order Raman spectroscopy, using the 5145A line of an Argon laser in a backscattering geometry at room temperature. This allowed us to compare thin films deposited in two different reactors where the capacitively coupled glow-discharge was produced either in a 'cross field' or a 'parallel field' geometry. Gaseous mixtures of SiH 4 , N 2 , He and Ar have been used in both cases. The systematic variation of the preparation parameters leads to a whole class of 'alloys' including partially micro-crystallized films. (Author) [pt

  7. 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 4000-400cm(-1) and 4000-10cm(-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 (1)H and (13)C 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 〈β〉, 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Signature of the hydrogen-bonded environment of liquid water in X-ray emission spectra from first-principles calculations

    Science.gov (United States)

    Shen, Huaze; Chen, Mohan; Sun, Zhaoru; Xu, Limei; Wang, Enge; Wu, Xifan

    2018-02-01

    Based on ab initio molecular dynamics simulations and density functional theory, we performed a systematic theoretical study to elucidate the correlation between the H-bonded environment and Xray emission spectra of liquid water. The spectra generated from excited water molecules embedded in an intact H-bonded environment yield broader spectral peaks and a larger spectral range than the spectra generated from water molecules in a broken H-bonded environment. Such differences are caused by the local electronic structures on the excited water molecules within the core-hole lifetime that evolve differently through the rearrangement of neighboring water molecules in different H-bonded environments.

  9. Establishing the link between fibril formation and Raman optical activity spectra of insulin

    Czech Academy of Sciences Publication Activity Database

    Kessler, Jiří; Yamamoto, S.; Bouř, Petr

    2017-01-01

    Roč. 19, č. 21 (2017), s. 13614-13621 ISSN 1463-9076 R&D Projects: GA ČR(CZ) GA16-05935S; GA ČR GA15-09072S Grant - others:COST(XE) CA15214 Institutional support: RVO:61388963 Keywords : molecular dynamics clusters * absolute configuration * vibrational spectra Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.123, year: 2016

  10. Structure, Raman spectra and defect chemistry modelling of conductive pyrochlore oxides

    DEFF Research Database (Denmark)

    Poulsen, F.W.; Glerup, M.; Holtappels, P.

    2000-01-01

    Mixed ionic-electronic conducting pyrochlore structure oxides, with Pr and Gd on the A site and Zr, Mn, Ce, Sn, In, Mo, and Ti on the B site, were characterised by X-ray powder diffraction and Raman spectroscopy. Mn and In have a solubility around x = 0.1-0.2 in Pr2Zr2-xMnxO7 and Pr2Sn2-xInxO7......-O(x) and V-O on the O site, interstitial oxygens O-i", and delocalised electrons and electron holes. Four mass action law expressions govern such a model. The defect model can rationalise why home-valent doping, i.e. substitution of Zr(4+) by Ce(4+), can lead to an increase in ionic conductivity....... The calculated Brouwer diagram for Pr2Zr1.6Ce0.4O7+/-delta is shown. This composition has a transition from mixed ionic p-type to presumably pure ionic conduction around pO(2) = 10(-7.5) atm. At pO(2)

  11. [Raman spectra study on radiation damage in EC9706 cells by 60Cogamma-rays].

    Science.gov (United States)

    Qi, Jian; Guo, Zheng-Yuan; Zhang, Guang-Shui; Wu, Dian-Yong; Tang, Wei-Yue

    2009-07-01

    Raman spectrum was used to study the structure and content of protein, nucleic acid and fat, while EC9706 cells irradiated by 60Co gamma-ray were cultivated for 24 h. The results showed that for spectrum intensity and frequency deviation, there were big differences between each exposure group and control group. For the 1 244 cm(-1) peak of amide III, beta folder changed to disordered conformations in the middle dose (4, 5Gy) groups. The 1 341 cm(-1) peak of v (the indole ring of Trp) was red-shifted in every dose group. There was a 2-3 cm(-1) red shift at the 782 cm(-1) peak in the big dose groups (7, 8Gy). It was showed that the non-hydrogenation of v(s)(PO2-) was strengthened due to big dose gamma-rays radiation. There was a 4 cm(-1) blue shift at the 1 446 cm(-1) peak of delta (CH2, CH3). It maybe resulted from 60Co gamma-rays' damage to the film of EC9706 cells. The preferable dose of 60Co gamma-rays may be found by analyzing the variety of the above-mentioned peaks in some dose groups.

  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

    system of staggered (approximate D3d symmetry), in analogy with the linear Al-O-Al geometry of the analogous [Al2OF6]2- ion, found previously. The calculations included determination of the vibrational harmonic normal modes and the infrared and Raman spectra, (vibrational band wavenumbers and intensities......), without any empiric adjustments of the harmonic force constants, using constants directly predicted from the Gaussian 03W program. Previously obtained IR absorption and Raman scattering spectra of melts are assigned, by comparing to the ab initio quantum mechanical vibrational analysis results....... It is concluded that the small oxide content commonly found in basic and neutral tetrachloroaluminate melts, most probably consist of [Al4O2Cl10]2- ions and the vibrational spectra are given....

  13. Raman and photoluminescence spectra of ZnTe/CdSe and ZnTe/CdTe tetrapod shaped nano-hetero structures

    Science.gov (United States)

    Fiore, Angela; Morello, Giovanni; Scremin, Barbara Federica

    2018-01-01

    In the present paper we report the Raman and photoluminescence characterization of two nano-hetero-structures of II-VI semiconductors, tetrapod shaped. The examined samples were constituted of a ZnTe core and either CdSe or CdTe arms. The main contributions to the Raman spectra were assigned to phonons from the arms of the structures, but the weak contribution from the ZnTe core was identified from the separate measurement of spectra of the seeds used for growing the arms. The simultaneously acquired photoluminescence spectra allowed identifying an intense band characteristic of a Type II band alignment at 920 nm for the ZnTe/CdSe nanostructures.

  14. CCSD(T) Study of Dimethyl-Ether Infrared and Raman Spectra

    Science.gov (United States)

    Villa, Mauro; Senent, Maria L.; Doménguez-Gómez, R.; Carvajal, Miguel

    2011-11-01

    CCSD(T) state-of-the-art ab initio calculations are used to determine a vibrationally corrected three-dimensional potential energy surface of dimethyl-ether depending on the two methyl torsions and the COC bending angle. The surface is employed to obtain variationally the lowest vibrational energies that can be populated at very low temperatures. The interactions between the bending and the torsional coordinates are responsible for the displacements of the torsional overtone bands and several combination bands. The effect of these interactions on the potential parameters is analyzed. Second order perturbation theory is used as a help for the understanding of many spectroscopic parameters and to obtain anharmonic fundamentals for the 3N - 9 neglected modes as well as the rotational parameters. To evaluate the surface accuracy and to verify previous assignments, the calculated vibrational levels are compared with experimental data corresponding to the most abundant isotopologue. The surface has been empirically adjusted for understanding the origin of small divergences between ab initio calculations and experimental data. Our calculations confirm previous assignments and show the importance of including the COC bending degree of freedom for computing with a higher accuracy the excited torsional term values through the Fermi interaction. Besides, this work shows a possible lack of accuracy of some available experimental transition frequencies and proposes a new assignment for a transition line. As an example, the transition 100-120 has been computed at 445.93 cm(-1), which is consistent with the observed transition frequency in the Raman spectrum at 450.5 cm(-1).

  15. Allergic reactions in red tattoos: Raman spectroscopy for 'fingerprint' detection of chemical risk spectra in tattooed skin and culprit tattoo inks.

    Science.gov (United States)

    Hutton Carlsen, K; Køcks, M; Sepehri, M; Serup, J

    2016-11-01

    The aim of this study was to assess the feasibility of Raman spectroscopy as a screening technique for chemical characterisation of tattoo pigments in pathologic reacting tattoos and tattoo ink stock products to depict unsafe pigments and metabolites of pigments. Twelve dermatome shave biopsies from allergic reactions in red tattoos were analysed with Raman spectroscopy (A 785-nm 300 mW diode laser). These were referenced to samples of 10 different standard tattoo ink stock products, three of these identified as the culprit inks used by the tattooist and thus by history the source of the allergy. Three primary aromatic amine (PAA) laboratory standards (aniline, o-anisidine and 3,3'-dichlorobenzidine) were also studied. Application of Raman spectroscopy to the shave biopsies was technically feasible. In addition, all ten inks and the three PAA standards could be discriminated. 10/12 shave biopsies provided clear fingerprint Raman signals which differed significantly from background skin, and Raman spectra from 8/12 biopsies perfectly matched spectra from the three culprit ink products. The spectrum of one red ink (a low cost product named 'Tattoo', claimed to originate from Taiwan, no other info on label) was identified in 5/12 biopsies. Strong indications of the inks 'Bright Red' and 'Crimson Red' were seen in three biopsies. The three PAA's could not be unambiguously identified. This study, although on a small-scale, demonstrated Raman spectroscopy to be feasible for chemical analysis of red pigments in allergic reactions. Raman spectroscopy has a major potential for fingerprint screening of problematic tattoo pigments in situ in skin, ex vivo in skin biopsies and in tattoo ink stock products, thus, to eliminate unsafe ink products from markets. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  16. Determination by vibrational spectra of the strength and the bond length of atoms U and O in uranyl complexes

    International Nuclear Information System (INIS)

    Rodriguez S, A.; Martinez Q, E.

    1996-01-01

    The vibrational spectra of different uranyl compounds were studied. The wave number was related to the harmonic oscillator model and to the mathematical expression of Badger as modified by Jones, to determine the strength and the bond length of atoms U and O in UO 2 2+ . A mathematical simplification develop by us is proposed and its results compared with values obtained by other methods. (Author)

  17. 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)

    2016-02-11

    the fingerprint region 400-1400 cm−1 R. L. Aggarwal,a L. W. Farrar, S. Di Cecca, and T. H. Jeys MIT Lincoln Laboratory, Lexington, MA 02420-9108, USA...sulfide (H2S), phos- gene (COCl2), and sulfur dioxide (SO2) toxic gases have been measured in the fingerprint region 400-1400 cm−1. A relatively compact...important for the detection of these gases using Raman spectroscopy in the fingerprint region 400-1400 cm−1. Raman spectra and cross sections are

  18. Time-Resolved Absorption and Resonance Raman Spectra of the lowest Excited Triplet State of All-Trans-1,3,5-Heptatriene

    DEFF Research Database (Denmark)

    Langkilde, Frans; Wilbrandt, Robert Walter; Jensen, Niels-Henrik

    1984-01-01

    The lowest excited triplet state of all-trans-1,3,5-heptatriene has been studied by time-resolved absorption and resonance Raman spectroscopy. The difference absorption spectrum of the triplet state has a maximum around 315 nm, and the triplet state decays by first-order kinetics with k = (3.4 ± 0.......3) × 106 s−1. Time-resolved resonance Raman spectra of the heptatriene triplet excited at 317.5 nm showed bands at 1574, 1298, 1275, 1252, 1209, and 1132 cm−1....

  19. Effects of strong inter-hydrogen bond dynamical couplings in the polarized IR spectra of adipic acid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Flakus, Henryk T., E-mail: flakus@ich.us.edu.pl [Institute of Chemistry, University of Silesia, 9 Szkolna Street, Pl-40-006 Katowice (Poland); Tyl, Aleksandra; Jablonska, Magdalena [Institute of Chemistry, University of Silesia, 9 Szkolna Street, Pl-40-006 Katowice (Poland)

    2009-10-16

    This paper presents the results of the re-investigation of polarized IR spectra of adipic acid and of its d{sub 2}, d{sub 8} and d{sub 10} deuterium derivative crystals. The spectra were measured at 77 K by a transmission method using polarized light for two different crystalline faces. Theoretical analysis concerned linear dichroic effects and H/D isotopic effects observed in the spectra of the hydrogen and deuterium bonds in adipic acid crystals at the frequency ranges of the {nu}{sub O-H} and the {nu}{sub O-D} bands. The two-branch fine structure pattern of the {nu}{sub O-H} and {nu}{sub O-D} bands and the basic linear dichroic effects characterizing them were ascribed to the vibronic mechanism of vibrational dipole selection rule breaking for IR transitions in centrosymmetric hydrogen bond dimers. It was proved that for isotopically diluted crystalline samples of adipic acid, a non-random distribution of protons and deuterons occurs in the dimers (H/D isotopic 'self-organization' effect). This effect results from the dynamical co-operative interactions involving the dimeric hydrogen bonds.

  20. Effects of strong inter-hydrogen bond dynamical couplings in the polarized IR spectra of adipic acid crystals

    Science.gov (United States)

    Flakus, Henryk T.; Tyl, Aleksandra; Jablońska, Magdalena

    2009-10-01

    This paper presents the results of the re-investigation of polarized IR spectra of adipic acid and of its d2, d8 and d10 deuterium derivative crystals. The spectra were measured at 77 K by a transmission method using polarized light for two different crystalline faces. Theoretical analysis concerned linear dichroic effects and H/D isotopic effects observed in the spectra of the hydrogen and deuterium bonds in adipic acid crystals at the frequency ranges of the νO-H and the νO-D bands. The two-branch fine structure pattern of the νO-H and νO-D bands and the basic linear dichroic effects characterizing them were ascribed to the vibronic mechanism of vibrational dipole selection rule breaking for IR transitions in centrosymmetric hydrogen bond dimers. It was proved that for isotopically diluted crystalline samples of adipic acid, a non-random distribution of protons and deuterons occurs in the dimers (H/D isotopic " self-organization" effect). This effect results from the dynamical co-operative interactions involving the dimeric hydrogen bonds.

  1. State-by-state investigation of destructive interference in resonance Raman spectra of neutral tyrosine and the tyrosinate anion with the simplified sum-over-states approach.

    Science.gov (United States)

    Cabalo, Jerry B; Saikin, Semion K; Emmons, Erik D; Rappoport, Dmitrij; Aspuru-Guzik, Alán

    2014-10-16

    UV resonance Raman scattering is uniquely sensitive to the molecular electronic structure as well as intermolecular interactions. To better understand the relationship between electronic structure and resonance Raman cross section, we carried out combined experimental and theoretical studies of neutral tyrosine and the tyrosinate anion. We studied the Raman cross sections of four vibrational modes as a function of excitation wavelength, and we analyzed them in terms of the contributions of the individual electronic states as well as of the Albrecht A and B terms. Our model, which is based on time-dependent density functional theory (TDDFT), reproduced the experimental resonance Raman spectra and Raman excitation profiles for both studied molecules with good agreement. We found that for the studied modes, the contributions of Albrecht's B terms in the Raman cross sections were important across the frequency range spanning the L(a,b) and B(a,b) electronic excitations in tyrosine and the tyrosinate anion. Furthermore, we demonstrated that interference with high-energy states had a significant impact and could not be neglected even when in resonance with a lower-energy state. The symmetry of the vibrational modes served as an indicator of the dominance of the A or B mechanisms. Excitation profiles calculated with a damping constant estimated from line widths of the electronic absorption bands had the best consistency with experimental results.

  2. [Characteristics of Raman spectra of minerals in the veins of Wenchuan earthquake fault zone].

    Science.gov (United States)

    Xie, Chao; Zhou, Ben-gang; Liu, Lei; Zhou, Xiao-cheng; Yi, Li; Chen, Zhi; Cui, Yue-ju; Li, Jing; Chen, Zheng-wei; Du, Jian-guo

    2015-01-01

    Quartz in the veins at the Shenxigou section of Wenchuan earthquake fault zone was investigated by micro-Raman spectroscopic measurement, and the distribution of compressive stress in the fault zone was estimated by the frequency shifts of the 464 cm-1 vibrational mode of quartz grains in the veins. It was showed that the 464 cm-1 peak arising from the quartz grains in the veins near the fault plane shifts by 3. 29 cm-1 , and the corresponding compressive stress is 368. 63 MPa, which is significantly lower than the stress accumulation on both sides due to multi-stage events. Stress accumulation increased with moving away from the fault plane in the footwall with the offset of the 464 cm-1 peak arising from the quartz grains in the veins increasing, which can reach 494. 77 MPa at a distance of 21 m with a high offset of 4. 40 cm-1 of the 464 cm-1 peak. The compressive stress gets the maximum value of 519.87 MPa at a distance of 10 m from the fault plane in the hanging wall with the offset of the 464 cm-1 peak arising from the quartz grains in the veins being 4. 62 cm-1, followed by a sudden drop in stress accumulation, and it drops to 359. 59 MPa at a distance of 17 m. Because of moving away from the foult plane at the edge of the foult zone, the stress drops to 359. 59 MPa with a small value of 464 cm-1 peak offset 3. 21 cm-1 at a distance of 27 m from the fault plane in the hanging wall due to the little effect by the fault activity. Therefore, the stress of Wenchuan earthquake fault zone is partially released, but the rest of the stress distribution is uneven, and there is also a high stress accumulation in somewhere in the fault zone, which reflects that the mechanical properties of the rocks in the fault zone have a characteristic of unevenness in space.

  3. A pseudo-Voigt component model for high-resolution recovery of constituent spectra in Raman spectroscopy

    DEFF Research Database (Denmark)

    Alstrøm, Tommy Sonne; Schmidt, Mikkel Nørgaard; Rindzevicius, Tomas

    2017-01-01

    Raman spectroscopy is a well-known analytical technique for identifying and analyzing chemical species. Since Raman scattering is a weak effect, surface-enhanced Raman spectroscopy (SERS) is often employed to amplify the signal. SERS signal surface mapping is a common method for detecting trace a...

  4. Optimization of classification and regression analysis of four monoclonal antibodies from Raman spectra using collaborative machine learning approach.

    Science.gov (United States)

    Le, Laetitia Minh Maï; Kégl, Balázs; Gramfort, Alexandre; Marini, Camille; Nguyen, David; Cherti, Mehdi; Tfaili, Sana; Tfayli, Ali; Baillet-Guffroy, Arlette; Prognon, Patrice; Chaminade, Pierre; Caudron, Eric

    2018-07-01

    The use of monoclonal antibodies (mAbs) constitutes one of the most important strategies to treat patients suffering from cancers such as hematological malignancies and solid tumors. These antibodies are prescribed by the physician and prepared by hospital pharmacists. An analytical control enables the quality of the preparations to be ensured. The aim of this study was to explore the development of a rapid analytical method for quality control. The method used four mAbs (Infliximab, Bevacizumab, Rituximab and Ramucirumab) at various concentrations and was based on recording Raman data and coupling them to a traditional chemometric and machine learning approach for data analysis. Compared to conventional linear approach, prediction errors are reduced with a data-driven approach using statistical machine learning methods. In the latter, preprocessing and predictive models are jointly optimized. An additional original aspect of the work involved on submitting the problem to a collaborative data challenge platform called Rapid Analytics and Model Prototyping (RAMP). This allowed using solutions from about 300 data scientists in collaborative work. Using machine learning, the prediction of the four mAbs samples was considerably improved. The best predictive model showed a combined error of 2.4% versus 14.6% using linear approach. The concentration and classification errors were 5.8% and 0.7%, only three spectra were misclassified over the 429 spectra of the test set. This large improvement obtained with machine learning techniques was uniform for all molecules but maximal for Bevacizumab with an 88.3% reduction on combined errors (2.1% versus 17.9%). Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Vibrational analysis using FT-IR, FT-Raman spectra and HF-DFT methods and NBO, NLO, NMR, HOMO-LUMO, UV and electronic transitions studies on 2,2,4-trimethyl pentane.

    Science.gov (United States)

    Suvitha, A; Periandy, S; Govindarajan, M; Gayathri, P

    2015-03-05

    In this work, the vibrational spectral analysis was carried out by using Raman and infrared spectroscopy in the range 100-4000cm(-1)and 50-4000cm(-1), respectively, for 2,2,4-Trimethyl Pentane, TMP (C8H18) molecule. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and geometrical parameter calculations based on Hartree Fock (HF) and density functional theory (DFT) method with 6-311++G(d,p) basis set. The scaled B3LYP/6-311++G(d,p) results shows the best agreement with the experimental values over the other method. The calculated HOMO and LUMO energies shows that charge transfer within the molecule. The physical reactions of single bond hydrocarbon TMP were investigated. The results of the calculations were applied to simulate spectra of the title compound, which shows the excellent agreement with observed spectra. Besides, Mulliken atomic charges, UV, frontier molecular orbital (FMO), MEP, NLO activity, Natural Bond-Orbital (NBO) analysis, NMR and thermodynamic properties of title molecule were also performed. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. 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.

  7. The infrared, Raman, NMR and UV spectra, ab initio calculations and spectral assignments of 2-amino-4-chloro-6-methoxypyrimidine.

    Science.gov (United States)

    Cinar, Z; Karabacak, M; Cinar, M; Kurt, M; Chinna Babu, P; Sundaraganesan, N

    2013-12-01

    The 2-amino-4-chloro-6-methoxypyrimidine abbreviated as ACMP have been investigated by both the experimental and theoretical methods; through this work we provide the essential fact about the structural and vibrational insights. The optimized molecular structure, atomic charges, vibrational frequencies and ultraviolet spectral interpretation of ACMP have been studied by performing DFT/B3LYP/6-311++G(df,pd) level of theory. The FT-IR, FT-Raman spectra were recorded in the region 4000-400 cm(-1) and 4000-50 cm(-1) respectively. The UV absorption spectrum of the compound that dissolved in ethanol and water solution were recorded in the range of 200-400 nm. The scaled wavenumbers are compared with the experimental values. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. Based on the UV spectrum and TD-DFT calculations, the electronic structure and the assignments of the absorption bands were carried out. The (1)H, (13)C and DEPT 135 nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated using with the Gauge Including Atomic Orbital (GIAO) method and compared with experimental results. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. 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

  9. Surface-enhanced Raman scattering spectra of adsorbates on Cu₂O nanospheres: charge-transfer and electromagnetic enhancement.

    Science.gov (United States)

    Jiang, Li; You, Tingting; Yin, Penggang; Shang, Yang; Zhang, Dongfeng; Guo, Lin; Yang, Shihe

    2013-04-07

    Surface-enhanced Raman scattering (SERS) spectra of 4-mercaptobenzoic acid (4-MBA) have been investigated on the surface of Cu2O nanospheres. The SERS signals were believed to originate from the static chemical enhancement, resonant chemical enhancement and electromagnetic enhancement. The coupling between the adsorbates and the semiconductor, evidenced by the shift in absorption spectrum of modified Cu2O and the enhancement of non-totally symmetric modes of the 4-MBA and 4-mercaptopyridine (4-MPY) molecules, were invoked to explain the experimental results. Furthermore, simulations were employed to investigate the nature of the enhancement mechanisms operative between the molecules and the semiconductor. Density functional theory (DFT) calculations suggested a charge transfer (CT) transition process between the molecules and the Cu2O nanospheres. Three-dimensional finite-difference time domain (3D-FDTD) simulations were conducted to map out the electromagnetic field around the Cu2O nanospheres. The experimental and simulation results have revealed the promise of the Cu2O nanospheres as a good SERS substrate and the prospect of using the SERS substrate as a valuable tool for in situ investigation and assay of the adsorption behavior on semiconductor surfaces.

  10. Vibrational spectra, molecular structure, natural bond orbital, first order hyperpolarizability, thermodynamic analysis and normal coordinate analysis of Salicylaldehyde p-methylphenylthiosemicarbazone by density functional method

    Science.gov (United States)

    Porchelvi, E. Elamurugu; Muthu, S.

    2015-01-01

    The thiosemicarbazone compound, Salicylaldehyde p-methylphenylthiosemicarbazone (abbreviated as SMPTSC) was synthesized and characterized by FTIR, FT-Raman and UV. Density functional (DFT) calculations have been carried out for the title compound by performing DFT level of theory using B3LYP/6-31++G(d,p) basis set. The molecular geometry and vibrational frequencies were calculated and compared with the experimental data. The detailed interpretation of the vibrational spectra has been carried out with aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology. The electronic dipole moment (μD) and the first hyperpolarizability (βtot) values of the investigated molecule were computed using density functional theory (DFT/B3LYP) with 6-311++G(d,p) basis set. The stability and charge delocalization of the molecule was studied by natural bond orbital (NBO) analysis. Thearomaticities of the phenyl rings were studied using the standard harmonic oscillator model of aromaticity (HOMA) index. Mulliken population analysis on atomic charges is also calculated. The molecule orbital contributions are studied by density of energy states (DOSs).

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

    Czech Academy of Sciences Publication Activity Database

    Sato, H.; Dybal, Jiří; Murakami, R.; Noda, I.; Ozaki, Y.

    744-747, - (2005), s. 35-46 ISSN 0022-2860 R&D Projects: GA AV ČR IAA4050208 Keywords : infrared and Raman spectroscopy * quantum chemical calculation * C-H...O hydrogen bonding Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.440, year: 2005

  12. 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 (13)C 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. 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.

  14. Anhamonic finite temperature effects on the Raman and Infrared spectra to determine the crystal structure phase III of solid molecular hydrogen

    OpenAIRE

    Singh, Ranber; Azadi, Sam; Kühne, Thomas D.

    2013-01-01

    We present theoretical calculations of the Raman and IR spectra, as well as electronic properties at zero and finite temperature to elucidate the crystal structure of phase III of solid molecular hydrogen. We find that anharmonic finite temperature are particularly important and qualitatively influences the main conclusions. While P6$_3$/m is the most likely candidate for phase III at the nuclear ground state, at finite temperature the C2/c structure appears to be more suitable.

  15. The IR spectra, hydrogen bonding and conformations of aliphatic and aromatic epoxy carbamates

    Science.gov (United States)

    Furer, V. L.

    1999-12-01

    The IR spectra of hexamethylene-bis (methyl) glycidyl carbamate, toluene-2,4-bis (methyl) glycidyl carbamate in the crystalline state and in the melt were studied. The absorption curves for the most stable molecular conformations were compared with experimental IR spectra. The IR spectra of toluene-2,4-bis (methyl) glycidyl carbamate and methyl- N-methyl carbamate clusters were calculated. The spectral features of the different molecular structures were revealed. The results obtained can be used for the analysis of the chemical and physical transformations in polyurethanes.

  16. Composition and Structure of Microalgae Indicated in Raman and Hyperspectral Spectra and Scanning Electron Microscopy: from Cyanobacteria to Isolates from Coal-bed Methane Water Ponds

    Science.gov (United States)

    Zhou, X.; Zhou, Z.; Apple, M. E.; Spangler, L.

    2017-12-01

    Microalgae can be used for many potential applications for human's benefits. These potential applications included biofuel production from microalgae, biofiltering to cleaning water, chemical extraction as nutrients, etc. However, exploration for such applications is still in the early stages. For instance, many species and strains of microalgae have been investigated for their lipid content and growing conditions for efficient productions of lipids, but no specific species have yet been chosen as a fuel source for commercial production because of the huge biodiversity and subsequently a wide range of species that can potentially be exploited for biodiesel production, the great variability between species in their fuel precursor producing capabilities. Numerous coal-bed methane water ponds were established in the world as a consequence of coal-bed methane production from deep coal seams. Microalgae were isolated from such ponds and potentially these ponds can be used as venues for algal production. In this study, we characterized chemical composition and structure of the Cyanobacteria Anabaena cylindrica (UTEX # 1611) and isolates from coal-bed methane ponds Nannochloropsis gaditana and PW95 using Laser Raman Spectroscopy (LRS), hyperspectral spectra, and Scanning Electron Microscope (SEM). The objective is to seek bio-indicators for potential applications of these microalgae species. For instance, indicator of rich content lips shows the great potential for biofuel production. Fig.1 shows an example of the Raman spectra of the three species in desiccated form. The spectral peaks were isolated and the corresponding composition was identified. The insert at the right hand of the Raman spectrum of each species is the micrograph of the cell morphology under a microscope. The Raman spectra of cells in aquatic solutions were also obtained and compared with the desiccated form. The hyperspectral reflectances of the three species show quite different characteristics and

  17. New Raman method for aqueous solutions: xi-function dispersion evidence for strong F(-)-water H-bonds in aqueous CsF and KF solutions.

    Science.gov (United States)

    Walrafen, George E

    2005-08-15

    The Raman xi-function dispersion method recently elucidated for the strong H-bond breaker, ClO4-, in water [G. E. Walrafen, J. Chem. Phys. 122, 094510 (2005)] is extended to the strongly H-bond forming ion, F-. Measuring the xi function is analogous to measuring DeltaG from the thermodynamic activity of the water, aH2O, as the stoichiometric mol fraction of the water in the solution decreases due to addition of an electrolyte or nonelectrolyte. xi is the derivative of the OH-stretching part of the Gibbs free energy with respect to the water mol fraction; xiomega identical with-RT[ partial differential ln(Iomega/IREF) partial differentialX2](T,P). I is the Raman intensity at omega (omega=Raman shift in cm-1); IREF, that at an arbitrary reference omega; and, X2 is the water mol fraction (X1=CsF or KF mol fraction). ln(Iomega/IREF) was found to be linear in X2 for the complete range of OH-stretching omega's, with correlation coefficients as large as 0.999 96. Linearity of ln(Iomega/IREF) versus X2 is an experimental fact for all omega's throughout the spontaneous Raman OH-stretching contour; this fact cannot be negated by relative contributions of ultrafast/fast, homogeneous/inhomogeneous processes which may underlie this linearity. Linearity in ln(Iomega/IREF) versus 1T, or in ln(Iomega/IREF) versus P, was also observed for the Raman H-bond energy DeltaE and pair volume DeltaV dispersions, respectively. A low-frequency maximum (MAX) and a high-frequency minimum (MIN) were observed in the xi function dispersion curve. Deltaxi=xiMIN-xiMAX values of -7000+/-800-cal/mol H2O for CsF, and the experimentally equal Deltaxi=-6400+/-1000-cal/mol H2O for KF, were obtained. These Deltaxi's are opposite in sign but have nearly the same absolute magnitude as the Deltaxi value for NaClO4 in water; Deltaxi=+8050+/-100-cal/mol H2O. A positive Deltaxi corresponds to a water-water H-bond breaker; a negative Deltaxi to a H-bond former; specifically, a F--water H-bond former, in the

  18. Shell morphology and Raman spectra of epitaxial Ge-SixGe1-x and Si-SixGe1-x core-shell nanowires

    Science.gov (United States)

    Wen, Feng; Dillen, David C.; Kim, Kyounghwan; Tutuc, Emanuel

    2017-06-01

    We investigate the shell morphology and Raman spectra of epitaxial Ge-SixGe1-x and Si-SixGe1-x core-shell nanowire heterostructures grown using a combination of a vapor-liquid-solid (VLS) growth mechanism for the core, followed by in-situ epitaxial shell growth using ultra-high vacuum chemical vapor deposition. Cross-sectional transmission electron microscopy reveals that the VLS growth yields cylindrical Ge, and Si nanowire cores grown along the ⟨111⟩, and ⟨110⟩ or ⟨112⟩ directions, respectively. A hexagonal cross-sectional morphology is observed for Ge-SixGe1-x core-shell nanowires terminated by six {112} facets. Two distinct morphologies are observed for Si-SixGe1-x core-shell nanowires that are either terminated by four {111} and two {100} planes associated with the ⟨110⟩ growth direction or four {113} and two {111} planes associated with the ⟨112⟩ growth direction. We show that the Raman spectra of Si- SixGe1-x are correlated with the shell morphology thanks to epitaxial growth-induced strain, with the core Si-Si mode showing a larger red shift in ⟨112⟩ core-shell nanowires compared to their ⟨110⟩ counterparts. We compare the Si-Si Raman mode value with calculations based on a continuum elasticity model coupled with the lattice dynamic theory.

  19. Surface-enhanced Raman scattering spectra revealing the inter-cultivar differences for Chinese ornamental Flos Chrysanthemum: a new promising method for plant taxonomy

    Directory of Open Access Journals (Sweden)

    Heng Zhang

    2017-10-01

    Full Text Available Abstract Background Flos Chrysanthemi, as a part of Chinese culture for a long history, is valuable for not only environmental decoration but also the medicine and food additive. Due to their voluminously various breeds and extensive distributions worldwide, it is burdensome to make recognition and classification among numerous cultivars with conventional methods which still rest on the level of morphologic observation and description. As a fingerprint spectrum for parsing molecular information, surface-enhanced Raman scattering (SERS could be a suitable candidate technique to characterize and distinguish the inter-cultivar differences at molecular level. Results SERS spectra were used to analyze the inter-cultivar differences among 26 cultivars of Chinese ornamental Flos Chrysanthemum. The characteristic peaks distribution patterns were abstracted from SERS spectra and varied from cultivars to cultivars. For the bands distributed in the pattern map, the similarities in general showed their commonality while in the finer scales, the deviations and especially the particular bands owned by few cultivars revealed their individualities. Since the Raman peaks could characterize specific chemical components, those diversity of patterns could indicate the inter-cultivar differences at the chemical level in fact. Conclusion In this paper, SERS technique is feasible for distinguishing the inter-cultivar differences among Flos Chrysanthemum. The Raman spectral library was built with SERS characteristic peak distribution patterns. A new method was proposed for Flos Chrysanthemum recognition and taxonomy.

  20. H-bonding vs non-H-bonding in 100% pyrene methacrylate comb polymers: self-assembly probed by time-resolved emission spectra and temperature dependent fluorescence.

    Science.gov (United States)

    Kaushlendra, K; Asha, S K

    2014-05-08

    The differences in self-organization behavior in novel 100% pyrene labeled comb methacrylate polymers probed as a function of their varied origins of excimer formation are presented. The different structural variations in the polymers included the presence or absence of hydrogen bonding interactions in the form of urethane linkages, short or long alkyl spacer segments separating the pyrene units from the polymer backbone and linear versus kinked urethane linkage. The effect of variable concentration and temperature on the chemical shift of the NH proton of the urethane linkage was probed using (1)H NMR experiments conducted at temperatures varying from 25 to 70 °C at two different concentrations (2.5 and 25 mmol) in DMSO-d6 as solvent. The photophysical properties of the polymers in dilute DMF solutions were investigated by steady state emission, fluorescence decay studies, time-resolved emission spectra (TRES), and variable temperature emission studies. It was observed that the polymer poly(PBH) having a non-hydrogen-bondable ester linkage in the pendant chains formed an excimer completely via a static mechanism and the ground state aggregate species were not broken even at higher temperatures. The polymer poly(PIC) having a short hydrogen-bondable urethane linkage formed an excimer via a static as well as dynamic mechanism. The other hydrogen-bondable urethane methacrylate polymers having a linear linker poly(PHH) and kinked linker (PIHP) formed excimer mostly via a dynamic mechanism with a very small contribution from the static route. The TRES studies carried out for the polymers provided significant insight into the excimer formation mechanism in these polymers. The variable temperature fluorescence studies highlighted the differences in the H-bonded vs non-H-bonded polymer as a function of their excimer recovery upon cooling.

  1. Carbon Nanotubes' Effect on Mitochondrial Oxygen Flux Dynamics: Polarography Experimental Study and Machine Learning Models using Star Graph Trace Invariants of Raman Spectra.

    Science.gov (United States)

    González-Durruthy, Michael; Monserrat, Jose M; Rasulev, Bakhtiyor; Casañola-Martín, Gerardo M; Barreiro Sorrivas, José María; Paraíso-Medina, Sergio; Maojo, Víctor; González-Díaz, Humberto; Pazos, Alejandro; Munteanu, Cristian R

    2017-11-11

    This study presents the impact of carbon nanotubes (CNTs) on mitochondrial oxygen mass flux ( J m ) under three experimental conditions. New experimental results and a new methodology are reported for the first time and they are based on CNT Raman spectra star graph transform (spectral moments) and perturbation theory. The experimental measures of J m showed that no tested CNT family can inhibit the oxygen consumption profiles of mitochondria. The best model for the prediction of J m for other CNTs was provided by random forest using eight features, obtaining test R-squared ( R ²) of 0.863 and test root-mean-square error (RMSE) of 0.0461. The results demonstrate the capability of encoding CNT information into spectral moments of the Raman star graphs (SG) transform with a potential applicability as predictive tools in nanotechnology and material risk assessments.

  2. Carbon Nanotubes’ Effect on Mitochondrial Oxygen Flux Dynamics: Polarography Experimental Study and Machine Learning Models using Star Graph Trace Invariants of Raman Spectra

    Directory of Open Access Journals (Sweden)

    Michael González-Durruthy

    2017-11-01

    Full Text Available This study presents the impact of carbon nanotubes (CNTs on mitochondrial oxygen mass flux (Jm under three experimental conditions. New experimental results and a new methodology are reported for the first time and they are based on CNT Raman spectra star graph transform (spectral moments and perturbation theory. The experimental measures of Jm showed that no tested CNT family can inhibit the oxygen consumption profiles of mitochondria. The best model for the prediction of Jm for other CNTs was provided by random forest using eight features, obtaining test R-squared (R2 of 0.863 and test root-mean-square error (RMSE of 0.0461. The results demonstrate the capability of encoding CNT information into spectral moments of the Raman star graphs (SG transform with a potential applicability as predictive tools in nanotechnology and material risk assessments.

  3. Effects of Zn doping on crystal structure, Raman spectra and superconductivity of SmBa2Cu3O7−δ systems

    International Nuclear Information System (INIS)

    Xue, Renzhong; Dai, Haiyang; Chen, Zhenping; Li, Tao; Xue, Yuncai

    2013-01-01

    Highlights: ► Zn ions affect significantly the lattice parameter of the SmBa 2 Cu 3−x Zn x O 7−δ (SBCZO) ceramic. ► Raman spectra of SBCZO samples obviously change with increasing Zn doping content. ► The superconducting transition temperature decreases with increasing Zn content. ► Induced lattice disorder and local magnetic moment in CuO 2 planes are related to suppression of T c . -- Abstract: Polycrystalline SmBa 2 Cu 3−x Zn x O 7−δ (SBCZO) (x = 0.0–0.4) samples are prepared by the usual solid-state reaction technique. The effects of Zn doping on the structure, the grain morphology, Raman spectra and electronic transport properties of SBCZO systems have been investigated. The orthorhombic structure of the samples does not change remarkably. The samples become denser and grain boundary becomes unclear with the increase of Zn content. Raman spectra exhibit different features with increasing Zn content which shows that Zn ions act as strong scattering centers to the charge carriers in the CuO 2 planes, enhance the disorder of the CuO 2 planes and increase oxygen depletion in Cu-O chains. The measurements of the resistivity show that the superconducting transition temperature T c decreases rapidly and the superconducting transition width increases gradually with increasing Zn contents. Furthermore, the changes of the samples’ normal state resistivity from metallic to semi-conducting behavior show the increase of heterogeneities with increasing Zn content which causes inter-grain or intra-grain disorders. All the results suggest that lattice disorder in the CuO 2 planes, the oxygen content change in Cu-O chains and local weak superconductivity regions due to the substitution of Zn for Cu are related to the suppression of T c in the SBCZO systems

  4. 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.

  5. 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...... gaseous free states without any assumed symmetry. The calculations on the monomeric [TMGH]+ ion and the dimeric ion pair converged to give geometries near the established crystal structure of the [TMGH]Cl salt. This salt is known to contain dimeric ion pairs of the kind [TMGH]ClCl[TMGH](Fig.1...... that dimeric molecular ion pairs with four N-H+…Cl- hydrogen bonds seem to exist also in the solutions, and probably are responsible for the relatively high solubility of the “salt” in ethanol. The “salt” can be easily sublimed at about 200-230 oC. The Raman spectrum of the vapor at 225 ºC has a characteristic...

  6. 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

  7. 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

    2015-05-05

    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. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Chemometric evaluation of temperature-dependent surface-enhanced Raman spectra of riboflavin: What is the best multivariate approach to describe the effect of temperature?

    Science.gov (United States)

    Kokaislová, Alžběta; Kalhousová, Milena; Gráfová, Michaela; Matějka, Pavel

    2014-10-01

    Riboflavin is an essential nutrient involved in energetic metabolism. It is used as a pharmacologically active substance in treatment of several diseases. From analytical point of view, riboflavin can be used as an active part of sensors for substances with affinity to riboflavin molecules. In biological environment, metal substrates coated with riboflavin are exposed to temperatures that are different from room temperature. Hence, it is important to describe the influence of temperature on adsorbed molecules of riboflavin, especially on orientation of molecules towards the metal surface and on stability of adsorbed molecular layer. Surface-enhanced Raman scattering (SERS) spectroscopy is a useful tool for investigation of architecture of molecular layers adsorbed on metal surfaces because the spectral features in SERS spectra change with varying orientation of molecules towards the metal surface, as well as with changes in mutual interactions among adsorbed molecules. In this study, riboflavin was adsorbed on electrochemically prepared massive silver substrates that were exposed to temperature changes according to four different temperature programs. Raman spectra measured at different temperatures were compared considering positions of spectral bands, their intensities, bandwidths and variability of all these parameters. It was found out that increase of substrate temperature up to 50 °C does not lead to any observable decomposition of riboflavin molecules, but the changes of band intensity ratios within individual spectra are apparent. To distinguish sources of variability beside changes in band intensities and widths, Principal Component Analysis (PCA) was applied. Discriminant Analysis (DA) was used to explore if the SERS spectra can be separated according to temperature. The results of Partial Least Squares (PLS) regression demonstrate the possibility to predict the sample temperature using SERS spectral features. Results of all performed experiments and

  9. Fermi energy dependence of the G-band resonance Raman spectra of single-wall carbon nanotubes

    Czech Academy of Sciences Publication Activity Database

    Park, J. S.; Sasaki, K.; Saito, R.; Izumida, W.; Kalbáč, Martin; Farhat, H.; Dresselhaus, G.; Dresselhaus, M. S.

    2009-01-01

    Roč. 80, č. 8 (2009), 081402-1-081402-4 ISSN 1098-0121 R&D Projects: GA MŠk LC510; GA MŠk ME09060 Institutional research plan: CEZ:AV0Z40400503 Keywords : Fermi energy dependence * Raman spectroscopy * single waled carbon nanotubes Subject RIV: CG - Electrochemistry Impact factor: 3.475, year: 2009

  10. Structure refinement, infrared and Raman spectra of KDyP.sub.4./sub.O.sub.12./sub..

    Czech Academy of Sciences Publication Activity Database

    Horchani, K.; Ferid, M.; Gacon, J. C.; Lecocq, S.; Trabelsi-Ayedi, M.; Gregora, Ivan

    2002-01-01

    Roč. 37, - (2002), s. 1259-1267 ISSN 0025-5408 Institutional research plan: CEZ:AV0Z1010914 Keywords : crystal structure * x-ray diffraction * infrared spectroscopy * Raman spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.892, year: 2002

  11. Structure refinement, infrared and Raman spectra of KDyP.sub.4./sub.O.sub.12./sub..

    Czech Academy of Sciences Publication Activity Database

    Horchani, K.; Ferid, M.; Gacon, J.C.; Lecocq, S.; Trabelsi-Ayedi, M.; Gregora, Ivan

    2002-01-01

    Roč. 37, - (2002), s. 1259-1267 ISSN 0025-5408 Institutional research plan: CEZ:AV0Z1010914 Keywords : crystal structure * X-ray diffraction * infrared spectroscopy * Raman spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.892, year: 2002

  12. Ionic conductivity and Raman spectra of Na--Li, K--Li, and K--Sn β-Al2O3

    International Nuclear Information System (INIS)

    Kaneda, T.; Bates, J.B.; Wang, J.C.; Engstrom, H.

    1979-01-01

    The ionic conductivity and Raman spectra of Na, Na--Li, K, K--Li, and K--Sn β-Al 2 O 3 were measured in order to understand the mechanisms of mixed-ion conduction. It was observed that at 300 0 K, for example, the conductivity of a crystal with composition Na 0 . 82 Li 0 . 18 β-Al 2 O 3 was about one-fifth that of pure Na cyrstals, while the conductivity of K 0 . 80 Li 0 . 20 β-Al 2 O 3 was more than three orders of magnitude lower than that of pure K compounds. The results of a model calculation indicated that the Li + ions are the main carrier species in the Na--Li and K--Li mixed compounds. Features observed in the Raman spectra were attributed to paired- and single-ion vibrations. It is concluded that the K + ions which contribute to a band at 69 cm -1 in K β-Al 2 O 3 are the effective carriers for conduction

  13. Hydrogen bonding of tyrosine B10 to heme-bound oxygen in Ascaris hemoglobin. Direct evidence from UV resonance Raman spectroscopy.

    Science.gov (United States)

    Huang, S; Huang, J; Kloek, A P; Goldberg, D E; Friedman, J M

    1996-01-12

    The hemoglobin from Ascaris suum, a parasitic nematode, has a spontaneous dissociation rate for the dioxygen ligand that is 3 orders of magnitude less than for mammalian myoglobins or hemoglobins. In this hemoglobin, the distal histidine is replaced with a glutamine which is capable of forming a stabilizing hydrogen bond to the bound dioxygen. A single hydrogen bond from a glutamine is, under typical circumstances, not sufficient to account for the low off rate for oxygen. Several studies point to a second hydrogen bond to the heme-bound dioxygen originating from tyrosine B10 as the source of this unusual reactivity. In this study ultraviolet (UV) resonance Raman spectroscopy is used to directly observe the formation of this hydrogen bond upon oxygen binding. The study reveals that both oxygen and carbon monoxide induce similar conformational changes in the globin upon binding to the heme; however, in the case of oxygen, a strong hydrogen bond involving a tyrosine is also observed. Similar studies on the QE7L mutant of this Hb suggest that the glutamine plays a role in stabilizing a rigid tertiary structure associated with the distal heme pocket. This conformation maintains the tyrosine in an orientation conducive to hydrogen bond formation with a heme-bound dioxygen ligand.

  14. Large Variations of the Raman Signal in the Spectra of Twisted Bilayer Graphene on a BN Substrate.

    Science.gov (United States)

    Kalbac, Martin; Frank, Otakar; Kong, Jing; Sanchez-Yamagishi, Javier; Watanabe, Kenji; Taniguchi, Takashi; Jarillo-Herrero, Pablo; Dresselhaus, Mildred S

    2012-03-15

    We report an unusual enhancement of the Raman signal of the G mode in a twisted graphene bilayer (2-LG) on a hexagonal single-crystalline boron nitride substrate. We used an isotopically engineered 2-LG, where the top layer was composed of (13)C atoms and the bottom layer of (12)C atoms. Consequently, it was possible by Raman spectroscopy to distinguish between the enhancement coming from the top and bottom layers. The enhancement of the G mode was, however, found to be similar for the top and bottom layers, and this enhancement effect was observed only at certain locations on the substrate. The experiment with two different laser excitation energies showed that the location of the enhanced spots is dependent on the laser excitation energy. Therefore our results suggest that the enhancement comes from new states in the electronic structure, which are a consequence of a local specific rotation of the grains in graphene layers.

  15. L-Alanyl-L-alanine Conformational Changes Induced by pH As Monitored by the Raman Optical Activity Spectra

    Czech Academy of Sciences Publication Activity Database

    Šebek, Jiří; Kapitán, Josef; Šebestík, Jaroslav; Baumruk, V.; Bouř, Petr

    2009-01-01

    Roč. 113, č. 27 (2009), s. 7760-7768 ISSN 1089-5639 R&D Projects: GA ČR GA202/07/0732; GA ČR GA203/07/1517; GA AV ČR IAA400550702 Institutional research plan: CEZ:AV0Z40550506 Keywords : Raman optical activity * peptides * conformation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.899, year: 2009

  16. 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.}

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

    International Nuclear Information System (INIS)

    Salyulev, A.B.; Vovkotrub, Eh.G.; Strekalovskij, V.N.

    2008-01-01

    Raman spectroscopy was used to reveal the formation of novel complexes involving [Zr 2 Cl 9 ] - and [Hf 2 Cl 9 ] - anions in molten mixtures of ZrCl 4 and HfCl 4 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 ZrCl 4 or HfCl 4 [ru

  18. Raman spectra and DFT calculations for botryococcene and methylsqualene hydrocarbons from the B race of the green microalga Botryococcus braunii

    Science.gov (United States)

    Tatli, Mehmet; Chun, Hye Jin; Camp, Charles H.; Li, Jingting; Cicerone, Marcus T.; Shih, Wei-Chuan; Laane, Jaan; Devarenne, Timothy P.

    2017-11-01

    Botryococcus braunii, a green colonial microalga, is a prodigious producer of liquid hydrocarbon oils that can be used as renewable feedstocks for producing combustion engine fuels. The B race of B. braunii mainly produces the triterpene hydrocarbons known as botryococcenes, which have over twenty known structures. Minor hydrocarbons in the B race include the triterpene methylsqualenes. Here we report an examination of the molecular structure for ten botryococcenes and five methylsqualenes using Raman spectroscopy and density functional theory (DFT) calculations in an effort to distinguish between these structurally similar molecules by spectroscopic approaches. The DFT calculations show that these molecules have between 243 and 271 vibrational frequencies. A comparison of the experimental Raman spectroscopy and DFT calculations indicates several spectral regions such as those for ν(Cdbnd C) stretching, CH2/CH3 bending, and ring bending can be used to distinguish between these molecules. In an extension of this analysis, a broadband coherent anti-Stokes Raman spectroscopy (BCARS) analysis was used to clearly distinguish between several botryococcenes isomers.

  19. Plasmon-less surface enhanced Raman spectra induced by self-organized networks of silica nanoparticles produced by femtosecond lasers.

    Science.gov (United States)

    Bellouard, Yves; Block, Erica; Squier, Jeff; Gobet, Jean

    2017-05-01

    Raman spectroscopy is the workhorse for label-free analysis of molecules. It relies on the inelastic scattering of incoming monochromatic light impinging molecules of interest. This effect leads to a very weak emission of light spectrum that provides a signature of the molecules being observed. Considerable efforts have been made over the last decades, in particular with the development of Surface Enhanced Raman Spectroscopy (SERS), to enhance the intensity of the emitted signal so that ultimately, traces of molecules can be detected. Here, we show that dense self-organized networks of quasi-monodisperse nanoparticles redepositing during femtosecond laser ablation of trenches in fused silica can lead to a significant field enhancement effect, enabling the Raman detection of a single-molecule layer deposited on the surface (so called monolayer). Unlike previously reported for SERS experiments, here, there is no metal layer promoting plasmonics effects causing localized field enhancement. The method for producing SERS substrates is therefore quite straightforward and low cost.

  20. 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...

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

    Science.gov (United States)

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

    2017-12-01

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

  2. Fourier-transform Raman spectroscopic study of human hair

    Science.gov (United States)

    Akhtar, W.; Edwards, H. G. M.; Farwell, D. W.; Nutbrown, M.

    1997-07-01

    Fourier-transform Raman microscopic spectra of normal, untreated and bleached hair fibres are presented. Vibrational assignments are made and differences are ascribed to the production of cysteic acid from cysteine. Changes in conformation associated with the disulphide bond in the keratotic component are noted from the ν(CSSC) vibrational modes at wave numbers near 500 cm -1. Raman spectra of hair root ends have also been investigated with a diminution in cysteine content being observed. Application of the technique to the biomedical investigation of healthy and diseased hair is proposed.

  3. Thermal characteristics, Raman spectra, optical and structural properties of TiO2-Bi2O3-B2O3-TeO2 glasses

    Science.gov (United States)

    Gupta, Nupur; Khanna, Atul; Gonzàlez, Fernando; Iordanova, Reni

    2017-05-01

    Tellurite and borotellurite glasses containing Bi2O3 and TiO2 were prepared and structure-property correlations were carried out by density measurements, X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Raman and UV-visible spectroscopy. Titanium tellurite glasses require high melt-cooling rates and were fabricated by splat quenching. On adding B2O3, the glass forming ability (GFA) enhances, and glasses could be synthesized at lower quenching rates. The density of glasses shows a direct correlation with molecular mass of the constituents. UV-visible studies were used to determine the optical band gap and refractive index. Raman studies found that the co-ordination number of tellurium ions with oxygen (NTe-O) decreases with the increase in B2O3 as well as Bi2O3 content while, TiO2 produce only a small decrease in NTe-O, which explains the lower GFA of titanium tellurite glasses that do not contain Bi2O3 and B2O3. DSC studies show that the glass transition temperature (Tg) increases with B2O3 and TiO2 concentrations and that Tg correlates well with bond enthalpy of the metal oxides.

  4. Quantum well effect in bulk PbI(2) crystals revealed by the anisotropy of photoluminescence and Raman spectra.

    Science.gov (United States)

    Baltog, I; Baibarac, M; Lefrant, S

    2009-01-14

    On subjecting a bulk 2H-PbI(2) crystal to vacuum annealing at 500 K followed by a sudden cooling at liquid nitrogen temperature stacking faults are generated that separate distinct layers of nanometric thickness in which different numbers of I-Pb-I atomic layers are bundled together. Such structures, containing two, three, four, five etc I-Pb-I atomic layers, behave as quantum wells of different widths. The signature of such a transformation is given by a shift towards higher energies of the fundamental absorption edge, which is experimentally revealed by specific anisotropies in the photoluminescence and Raman spectra. The quantum confining effect is made visible by specific variations of a wide extra-excitonic band (G) at 2.06 eV that originates in the radiative recombination of carriers (electrons and holes), trapped on the surface defects. The excitation spectrum of the G band, with p polarized exciting light, reveals a fine structure comprised of narrow bands at 2.75, 2.64, 2.59 and 2.56 eV, which are associated with the PbI(2) quantum wells formed from two, three, four and five I-Pb-I atomic layers of 0.7 nm thickness. Regardless of the polarization state of the laser exciting light of 514.5 nm (2.41 eV), which is close to the band gap energy of PbI(2) (2.52 eV), the Raman scattering on bulk as-grown PbI(2) crystals has the character of a resonant process. For p polarized exciting light, the Raman scattering process on vacuum annealed PbI(2) becomes non-resonant. This originates from the quantum well structures generated inside the crystal, whose band gap energies are higher than the energy of the exciting light.

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

    Science.gov (United States)

    Arjunan, V; Mohan, S

    2009-03-01

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

  6. Raman scattering spectra, magnetic and ferroelectric properties of BiFeO3-CoFe2O4 nanocomposite thin films structure

    Science.gov (United States)

    Tyagi, Mintu; Kumari, Mukesh; Chatterjee, Ratnamala; Sharma, Puneet

    2014-09-01

    Multiferroic (1-x)BiFeO3(BFO)-xCoFe2O4(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 (Ms 40.3 emu/cm3, Mr 12.9 emu/cm3, Hc 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.

  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%.

  8. Resonance Raman detection of iron-ligand vibrations in cyano(pyridine)(octaethylporphinato)iron(III): Effects of pyridine basicity on the Fe-CN bond strength

    International Nuclear Information System (INIS)

    Uno, Tadayuki; Hatano, Keiichiro; Nishimura, Yoshifumi; Arata, Yoji

    1988-01-01

    The influence of axial ligand basicity on the bonding of iron(III) in cyano adducts of octaethylporphyrin has been studied by resonance Raman spectroscopy. In a six-coordinate ferric low-spin complex, cyano(pyridine)(octaethylporphinato)iron(III), Fe(OEP)(CN)(py), Raman lines at 449 and 191 cm -1 were assigned to the ν(Fe-CN) and ν(Fe-py) stretching modes, respectively. When pyridine was displaced with its derivatives, py-X, where X = 4-cyano, 3-acetyl, 3-methyl, 4-methyl, 3,4-dimethyl, and 4-dimethylamino, the ν(Fe-CN) stretching frequency was found to decrease in the complex with a high pyridine basicity. It was concluded that the stronger the trans pyridine basicity, the weaker the iron-carbon (cyanide) bond. A clear frequency shift was observed in the ν 4 model, though most of the porphyrin vibrations were insensitive to the ligand substitution. The frequency of the ν 4 mode, which is the C a -N(pyrrole) breathing vibration of the porphyrin skeleton, was found to increase with an increase in pyridine basicity. This is contrary to what was found in ferrous low-spin hemes as CO complexes. The ν 4 shift in the CN complexes was explained in terms of forward π donation; donation of electrons from the porphyrin π orbital to the d π vacancy of the low-spin iron(III) weakened the C a -N(pyrrole) bonds and hence decreased the ν 4 frequency. 32 references, 8 figures

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-07-25

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

  10. Pre-resonance enhancement of exceptional intensity in Aggregation-Induced Raman Optical Activity (AIROA) spectra of lutein derivatives

    Science.gov (United States)

    Zajac, G.; Lasota, J.; Dudek, M.; Kaczor, A.; Baranska, M.

    2017-02-01

    Recently reported new phenomenon of Aggregation-Induced Raman Optical Activity is demonstrated here for the first time in the pre-resonance conditions for lutein diacetate and 3‧-epi-lutein supramolecular self-assembles. We demonstrate that minor alterations in the lutein structure (e.g. acetylation of hydroxyl groups or different configuration at one of the chiral center) can lead to definitely different spectral profiles and optical properties due to formation of aggregates of different structure and type. Lutein forms only H-aggregates, lutein diacetate only J-aggregates, while 3‧-epi-lutein can occur in both forms simultaneously. Variety of aggregates' structures is so large that not only the type of aggregation is different, but also their chirality. It is remarkable that even in the pre-resonance conditions, aggregation of lutein derivatives can lead to the intense ROA signal, and moreover, 3‧-epi-lutein demonstrated the highest resonance ROA CID ratio that has ever been reported.

  11. The conformational stability, solvation and the assignments of the experimental infrared, Raman, 1H and 13C NMR spectra of the local anesthetic drug lidocaine

    Science.gov (United States)

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

    2015-05-01

    The structure, vibrational and 1H and 13C NMR spectra of the local anesthetic drug lidocaine were investigated by the B3LYP/6-311G∗∗ calculations. The molecule was predicted to have the non-planar cis (NCCN ∼ 0°) structures being about 2-6 kcal/mol lower in energy than the corresponding trans (NCCN ∼ 180°) forms. The calculated NCCN (9.6°) and CNCC (-132.2°) torsional angles were in a good qualitative agreement with the reported X-ray angles (3.1 and 13.0°, -102.67 and -77.9°, respectively, for H-bonded dimers). The Gibbs energy of solution of lidocaine in formamide, water, dimethylsulfoxide, acetonitrile, methanol, ethanol and chloroform solutions was estimated at the B3LYP level. The predicted affinity of lidocaine toward the alcohols, acetonitrile and chloroform solutions was in excellent agreement with the reported experimental solubility of the drug in organic solvents. The analysis of the observed vibrational spectra is consistent with the presence of lidocaine in only one conformation at room temperature. The 1H and 13C NMR spectra of lidocaine were interpreted by experimental and DFT calculated chemical shifts of the drug. The RMSD between experimental and theoretical 1H and 13C chemical shifts for lidocaine is 0.47 and 8.26 ppm, respectively.

  12. Natural amber, copal resin and colophony investigated by UV-VIS, infrared and Raman spectrum

    Science.gov (United States)

    Rao, ZhiFan; Dong, Kun; Yang, XiaoYun; Lin, JinChang; Cui, XiaoYing; Zhou, RongFeng; Deng, Qing

    2013-08-01

    Natural amber, copal resin and colophony are have investigated by UV-VIS, infrared and Raman spectrum. In order to distinguish the natural amber, copal resin and colophony, we have successfully used the nondestructive examination (NDE) technology. The results show that UV-VIS could not distinguish these compositions. The infrared spectra can distinguish them, but the technology may destroy the specimen. The Raman spectra show three characteristic peaks of vibration near position 932 cm-1 and position 1179 cm-1 of copal resin, which confirm the existence of terpenes compounds in it. In the Raman spectra of colophony, the vibration characteristic peak at position 1589 cm-1, caused by the conjugate double bond of internal unsaturated resin acid, is the basis of the characteristic difference between colophony and natural amber. The advantages of the distinguished technology by Raman spectroscopy are convenient and nondestructive examination for natural amber, copal resin and colophony.

  13. Structures of Ge15Sb x Se85- x chalcogenide glasses affect their Raman gain performance

    Science.gov (United States)

    Peng, Xuefeng; Dai, Shixun; Xu, Dong; Xu, Hang; Li, Xing; Lin, Changgui; Zhang, Peiqing; Xu, Tiefeng

    2017-10-01

    A series of Ge15Sb x Se85- x ( x = 5, 10, 15, 20, 25, and 30 mol%) chalcogenide glasses were prepared by traditional melt-quenching method. The refractive indexes, infrared transmissions, and spontaneous Raman spectra of the glass samples were measured. Based on the spontaneous Raman scattering theory and considering the measured Raman spectral data, we calculated the Raman gain coefficients of the chalcogenide glasses. The effect of Sb on the structures and Raman gain coefficients of the glass samples was then systematically investigated to understand the role of chemical composition in glass structure and Raman gain coefficient. In the Ge15Sb x Se85- x glasses, the number of heteropolar Ge-Se, Sb-Se bonds increased, whereas that of homopolar Se-Se bonds decreased at increased Sb concentration. The Raman gain coefficients increased until it reached a maximum value (290 × 10-13 m/W at Ge15Sb20Se65) and then decreased when the Sb concentration further increased. These results showed that the Raman gain coefficients of Ge-Sb-Se chalcogenide glasses without poisonous elements were over 300 times of that of commonly fused silica and closely correlated with the structures of the glasses, suggesting that the Raman gain coefficient can be adjusted by modifying the structures of the glasses. This work provides a new possibility for environment-friendly Raman fiber laser and amplifier materials.

  14. 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.

  15. Specific behavior of the p-aminothiophenol--silver sol system in their Ultra-Violet-Visible (UV-Visible) and Surface Enhanced Raman (SERS) spectra.

    Science.gov (United States)

    Firkala, Tamás; Tálas, Emília; Mihály, Judith; Imre, Tímea; Kristyán, Sándor

    2013-11-15

    The UV-Visible and Surface Enhanced Raman Spectroscopy (SERS) behavior of silver sol (a typical SERS agent) were studied in the presence of different bifunctional thiols such as p-aminothiophenol, p-mercaptobenzoic acid, p-nitrothiophenol, p-aminothiophenol hydrochloride, and 2-mercaptoethylamine hydrochloride in diluted aqueous solution. Our results confirm that the p-aminothiophenol induced aggregation of citrate stabilized silver colloid originates from its electrostatic nature, as well as the azo-bridge formation cannot be the reason of the observed time dependent UV-Visible spectra. Based on our parallel SERS and electrospray ionization mass spectrometry measurements, we have concluded that certain amount of oxidized form of the probe molecule has to be present for the so-called b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Our findings seem to support the idea that the azo-bridge formation is responsible for the b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. FT-IR, FT-Raman, UV/Vis spectra and fluorescence imaging studies on 2-(bromoacetyl)benzo(b)furan by ab initio DFT calculations.

    Science.gov (United States)

    Veeraiah, A

    2015-08-05

    The vibrational and electronic properties of 2-(bromoacetyl)benzo(b)furan have been studied in the ground state using experimental techniques (FT-IR, FT-Raman and UV) and density functional theory (DFT) employing B3LYP exchange correlation with the 6-31G(d,p) basis set. The theoretically calculated optimized parameters, vibrational frequencies etc., were compared with the experimental values, which yield good agreement between the observed and calculated values. The complete assignments of fundamental modes were performed on the basis of the potential energy distribution (PED). UV-visible spectrum of the compound was recorded in the region 300-600 nm and compared with the theoretical spectrum obtained from SAC-CI calculations. A good agreement is observed between the experimental and theoretical spectra. Fluorescence microscopic imaging studies proved that the compound can be used as one of the potential light sources in the yellow region with suitable excitation. Further, the predicted electronic transitions between the MOs 47→64, 52→62, 56→65, 56→72, 56→77 of the compound show a strong line at 569.8 nm. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. 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.

  18. Demonstration of Z-d(5BrCGAT5BrCG) and B-d(CGCGATCGCG) form crystal structures in DNA-cobalt hexammine complexes by Kr 647.1 nm excitation of Raman spectra.

    Science.gov (United States)

    Benevides, J M; Wang, A H; Thomas, G J

    1993-03-25

    Cobalt hexammine [Co(NH3)6(3+)] is an efficient DNA complexing agent which significantly perturbs nucleic acid secondary structure. We have employed red excitation (647.1 nm) from a krypton laser to obtain Raman spectra of the highly colored complexes formed between cobalt hexammine and crystals of the DNA oligomers, d(5BrCGAT5BrCG) and d(CGCGATCGCG), both of which incorporate out-of-alternation pyrimidine/purine sequences. The Co(NH3)6(3+) complex of d(5BrCGAT5BrCG) exhibits a typical Z-form Raman signature, similar to that reported previously for the alternating d(CGCGCG) sequence. Comparison of the Raman bands of d(5BrCGAT5BrCG) with those of other oligonucleotide and polynucleotide structures suggests that C3'-endo/syn and C3'-endo/anti thymidines may exhibit distinctive nucleoside conformation markers, and tentative assignments are proposed. The Raman markers for C2'-endo/anti adenosine in this Z-DNA are consistent with those reported previously for B-DNA crystals containing C2'-endo/anti dA. Raman bands of the cobalt hexammine complex of d(CGCGATCGCG) are those of B-DNA, but with significant differences from the previously characterized B-DNA dodecamer, d(CGCAAATTTGCG). The observed differences suggest an unusual deoxyguanosine conformer, possibly related to a previously characterized structural intermediate in the B-->Z transition. The present results show that crystallization of d(CGCGATCGCG) in the presence of cobalt hexammine is not alone sufficient to induce the left-handed Z-DNA conformation. This investigation represents the first application of off-resonance Raman spectroscopy for characterization of highly chromophoric DNA and illustrates the feasibility of the Raman method for investigating other structurally perturbed states of DNA-cobalt hexammine complexes.

  19. Degree of Conversion of Self-etch Adhesives: In Situ Micro-Raman Analysis.

    Science.gov (United States)

    Navarra, C O; Cadenaro, M; Frassetto, A; Fontanive, L; Di Lenarda, R; Breschi, L

    2016-01-01

    Degree of conversion (DC) affects the physicochemical properties of dental adhesives. The aim of this study was to measure the DC within the hybrid layer of four one-step self-etch adhesives using Raman microspectroscopy. The hypothesis tested was that there was no difference among the tested adhesives. The selected one-step self-etch adhesives (Clearfil S 3 Bond Plus, I-BOND, G-BOND, and Adper Easy Bond) were applied on human dentin disks and polymerized in accordance with the manufacturers' instructions. Specimens were transversally cut to expose the bonded interfaces to the micro-Raman beam, and Raman spectra were collected along the dentin/adhesive interface. Measurements were performed at 1-μm intervals. The relative intensities of bands associated with the C=C bond (at 1640 cm -1 ) and an internal stable peak (1610 cm -1 ) were determined to calculate the degree of conversion within the hybrid layer. Data were statistically analyzed with Kolmogorov-Smirnov and Bartlett tests and Kruskal-Wallis and Mann-Whitney U-tests. The DC ranked as follows: G-BOND (93%±6%) ≥ Adper Easy Bond (92%±6%) ≥ I-BOND (89%±7%) > Clearfil S3 Bond Plus (80%±14%) (pself-etch adhesives showed a clinically acceptable DC that was material dependent.

  20. State-by-State Investigation of Destructive Interference in Resonance Raman Spectra of Neutral Tyrosine and the Tyrosinate Anion with the Simplified Sum-over-States Approach

    OpenAIRE

    Cabalo, Jerry B.; Saikin, Semion K.; Emmons, Erik D.; Rappoport, Dmitrij; Aspuru-Guzik, Alan

    2014-01-01

    UV resonance Raman scattering is uniquely sensitive to the molecular electronic structure as well as intermolecular interactions. To better understand the relationship between electronic structure and resonance Raman cross section, we carried out combined experimental and theoretical studies of neutral tyrosine and the tyrosinate anion. We studied the Raman cross sections of four vibrational modes as a function of excitation wavelength, and we analyzed them in terms of the contributions of th...

  1. Raman spectroscopy an intensity approach

    CERN Document Server

    Guozhen, Wu

    2017-01-01

    This book summarizes the highlights of our work on the bond polarizability approach to the intensity analysis. The topics covered include surface enhanced Raman scattering, Raman excited virtual states and Raman optical activity (ROA). The first chapter briefly introduces the Raman effect in a succinct but clear way. Chapter 2 deals with the normal mode analysis. This is a basic tool for our work. Chapter 3 introduces our proposed algorithm for the Raman intensity analysis. Chapter 4 heavily introduces the physical picture of Raman virtual states. Chapter 5 offers details so that the readers can have a comprehensive idea of Raman virtual states. Chapter 6 demonstrates how this bond polarizability algorithm is extended to ROA intensity analysis. Chapters 7 and 8 offer details on ROA, showing many findings on ROA mechanism that were not known or neglected before. Chapter 9 introduces our proposed classical treatment on ROA which, as combined with the results from the bond polarizability analysis, leads to a com...

  2. 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.

  3. 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.

  4. 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.

  5. Supramolecular structures for determination and identification of the bond lengths in novel uranyl complexes from their infrared spectra

    Science.gov (United States)

    El-Sonbati, A. Z.; Diab, M. A.; Morgan, Sh. M.; Seyam, H. A.

    2018-02-01

    Novel dioxouranium (VI) heterochelates with neutral bidentate compounds (Ln) have been synthesized. The ligands and the heterochelates [UO2(Ln)2(O2NO)2] were confirmed and characterized by elemental analysis, 1H NMR, UV.-Vis, IR, mass spectroscopy, X-ray diffraction and thermogravimetric analysis (TGA). IR spectral data suggest that the molecules of the Schiff base are coordinated to the central uranium atom (ON donor). The nitrato groups are coordinated as bidentate ligands. The thermodynamic parameters were calculated using Coats-Redfern and Horowitz-Metzger methods. The ligands (Ln) and their complexes (1-3) showed the υ3 frequency of UO22+ has been shown to be an excellent molecular probe for studying the coordinating power of the ligands. The values of υ3 of the prepared complexes containing UO22+ were successfully used to calculate the force constant, FUO (1n 10-8N/Å) and the bond length RUO (Å) of the Usbnd O bond. A strategy based upon both theoretical and experimental investigations has been adopted. The theoretical aspects are described in terms of the well-known theory of 5d-4f transitions. Wilson's, matrix method, Badger's formula, and Jones and El-Sonbati equations were used to calculate the Usbnd O bond distances from the values of the stretching and interaction force constants. The most probable correlation between Usbnd O force constant to Usbnd O bond distance were satisfactorily discussed in term of Badger's rule and the equations suggested by Jones and El-Sonbati. The effect of Hammett's constant is also discussed.

  6. 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...

  7. Theoretical, ab initio and DFT, study of the structure and vibrational analysis of Raman, IR and INS spectra of (CH{sub 3}){sub 3}SiNCO

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Liencres, M.P. [Department of Physical and Analytical Chemistry, University of Jaen, 23071 Jaen (Spain)], E-mail: liencres@ujaen.es; Navarro, A. [Department of Physical and Analytical Chemistry, University of Jaen, 23071 Jaen (Spain); Ben Altabef, A. [Instituto de Quimica Fisica, Facultad de Bioquimica, Quimica y Farmacia, Universidad Nacional de Tucuman, San Lorenzo 456, 4000 S.M. de Tucuman (Argentina); Lopez-Gonzalez, J.J. [Department of Physical and Analytical Chemistry, University of Jaen, 23071 Jaen (Spain); Fernandez-Gomez, M. [Department of Physical and Analytical Chemistry, University of Jaen, 23071 Jaen (Spain); Kearley, G.J. [Department of Radiation, Radionuclides and Reactors, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)

    2006-11-08

    The molecular geometry for trimethylsilylisocyanate ((CH{sub 3}){sub 3}SiNCO) has been calculated at MP2 and DFT/B3LYP and DFT/B3PW91 methods, and using the 6-31G*, 6-311G**, 6-311++G**, cc-pVDZ and cc-pVTZ basis sets. The equilibrium structure of the molecule, linear or bent as concerns the -SiNCO moiety, was found to rely on the method employed. The potential energy surface of -SiNC bending has been investigated by quantum mechanical ab initio calculations at MPn (n = 2-4) and QCISD(T) levels of theory with the cc-pVTZ basis set. This large amplitude bending motion (the {upsilon} {sub 24} mode) was determined to be very anharmonic, with a low barrier to linearity of the SiNCO skeleton of {approx}4-25 cm{sup -1}. New vapour and liquid IR, liquid Raman spectra and, for first time, INS spectrum have been recorded, and a complete vibrational assignment has been performed. INS data have allowed to assign two modes at 674 cm{sup -1} and 141 cm{sup -1} which, so far, have been considered as silent, i.e. A{sub 2}, since previous authors have used a frame of C {sub 3v} symmetry for this system. The intermolecular interactions show to have little effect on the torsional region (below 250 cm{sup -1} in INS spectrum) and the isolated-molecule approximation works well in that region. A normal coordinate analysis has been carried out by scaling the force fields calculated at MP2/6-311++G** and B3LYP/cc-pVDZ levels of theory using the scaled quantum mechanical force field (SQMFF) methodology. In order to get the best possible agreement between calculated and observed vibrational wavenumbers, the scale factors were refined by least squares yielding a final r.m.s. of {approx}7 cm{sup -1}.

  8. Exposure to 1.8 GHz electromagnetic fields affects morphology, DNA-related Raman spectra and mitochondrial functions in human lympho-monocytes.

    Science.gov (United States)

    Lasalvia, M; Scrima, R; Perna, G; Piccoli, C; Capitanio, N; Biagi, P F; Schiavulli, L; Ligonzo, T; Centra, M; Casamassima, G; Ermini, A; Capozzi, V

    2018-01-01

    Blood is a fluid connective tissue of human body, where it plays vital functions for the nutrition, defense and well-being of the organism. When circulating in peripheral districts, it is exposed to some physical stresses coming from outside the human body, as electromagnetic fields (EMFs) which can cross the skin. Such fields may interact with biomolecules possibly inducing non thermal-mediated biological effects at the cellular level. In this study, the occurrence of biochemical/biological modifications in human peripheral blood lympho-monocytes exposed in a reverberation chamber for times ranging from 1 to 20 h to EMFs at 1.8 GHz frequency and 200 V/m electric field strength was investigated. Morphological analysis of adherent cells unveiled, in some of these, appearance of an enlarged and deformed shape after EMFs exposure. Raman spectra of the nuclear compartment of cells exposed to EMFs revealed the onset of biochemical modifications, mainly consisting in the reduction of the DNA backbone-linked vibrational modes. Respirometric measurements of mitochondrial activity in intact lympho-monocytes resulted in increase of the resting oxygen consumption rate after 20 h of exposure, which was coupled to a significant increase of the FoF1-ATP synthase-related oxygen consumption. Notably, at lower time-intervals of EMFs exposure (i.e. 5 and 12 h) a large increase of the proton leak-related respiration was observed which, however, recovered at control levels after 20 h exposure. Confocal microscopy analysis of the mitochondrial membrane potential supported the respiratory activities whereas no significant variations in the mitochondrial mass/morphology was observed in EMFs-exposed lympho-monocytes. Finally, altered redox homeostasis was shown in EMFs-exposed lympho-monocytes, which progressed differently in nucleated cellular subsets. This results suggest the occurrence of adaptive mechanisms put in action, likely via redox signaling, to compensate for early impairments

  9. 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

  10. Whole-molecule calculation of log p based on molar volume, hydrogen bonds, and simulated 13C NMR spectra.

    Science.gov (United States)

    Schnackenberg, Laura K; Beger, Richard D

    2005-01-01

    The prediction of Log P is usually accomplished using either substructure or whole-molecule approaches. However, these methods are complicated, and previous whole-molecule approaches have not been successful for the prediction of Log P in very complex molecules. The observed chemical shifts in nuclear magnetic resonance (NMR) spectroscopy are related to the electrostatics at the nucleus, which are influenced by solute-solvent interactions. The different solvation effects on a molecule by either water or methanol have a strong effect on the NMR chemical shift value. Therefore, the chemical shift values observed in an aqueous and organic solvent should correlate to Log P. This paper develops a rapid, objective model of Log P based on molar volume, hydrogen bonds, and differences in calculated 13C NMR chemical shifts for a diverse set of compounds. A partial least squares (PLS) model of Log P built on the sum of carbon chemical shift differences in water and methanol, molar volume, number of hydrogen bond donors and acceptors in 162 diverse compounds gave an r2 value of 0.88. The average r2 for 10 training models of Log P made from 90% of the data was 0.87+/-0.01. The average q2 for 10 leave-10%-out cross-validation test sets was 0.87+/-0.05.

  11. Raman Spectra of Crystalline Double Calcium Orthovanadates Ca10M(VO4)7 (M = Li, K, Na) and Their Interpretation Based on Deconvolution Into Voigt Profilesparagraph>Please check captured article title, if appropriate.paragraph>-->

    Science.gov (United States)

    Khodasevich, I. A.; Voitikov, S. V.; Orlovich, V. A.; Kosmyna, M. B.; Shekhovtsov, A. N.

    2016-09-01

    Unpolarized spontaneous Raman spectra of crystalline double calcium orthovanadates Ca10M(VO4)7 (M = Li, K, Na) in the range 150-1600 cm-1 were measured. Two vibrational bands with full-width at half-maximum (FWHM) of 37-50 cm-1 were found in the regions 150-500 and 700-1000 cm-1. The band shapes were approximated well by deconvolution into Voigt profiles. The band at 700-1000 cm-1 was stronger and deconvoluted into eight Voigt profiles. The frequencies of two strong lines were ~848 and ~862 cm-1 for Ca10Li(VO4)7; ~850 and ~866 cm-1 for Ca10Na(VO4)7; and ~844 and ~866 cm-1 for Ca10K(VO4)7. The Lorentzian width parameters of these lines in the Voigt profiles were ~5 times greater than those of the Gaussian width parameters. The FWHM of the Voigt profiles were ~18-42 cm-1. The two strongest lines had widths of 21-25 cm-1. The vibrational band at 300-500 cm-1 was ~5-6 times weaker than that at 700-1000 cm-1 and was deconvoluted into four lines with widths of 25-40 cm-1. The large FWHM of the Raman lines indicated that the crystal structures were disordered. These crystals could be of interest for Raman conversion of pico- and femtosecond laser pulses because of the intense vibrations with large FWHM in the Raman spectra.

  12. 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 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.

  13. Double and Triple Si-H-M Bridge Bonds: Matrix Infrared Spectra and Theoretical Calculations for Reaction Products of Silane with Ti, Zr, and Hf Atoms.

    Science.gov (United States)

    Xu, Bing; Shi, Peipei; Huang, Tengfei; Wang, Xuefeng; Andrews, Lester

    2017-05-25

    Infrared spectra of matrix isolated dibridged Si(μ-H) 2 MH 2 and tribridged Si(μ-H) 3 MH molecules (M = Zr and Hf) were observed following the laser-ablated metal atom reactions with SiH 4 during condensation in excess argon and neon, but only the latter species was observed with titanium. Assignments of the major vibrational modes, which included terminal MH, MH 2 and hydrogen bridge Si-H-M stretching modes, were confirmed by the appropriate SiD 4 isotopic shifts and density functional vibrational frequency calculations (B3LYP and BPW91). The Si-H-M hydrogen bridge bond is calculated as weak covalent interaction and compared with the C-H···M agostic interaction in terms of electron localization function (ELF) analysis and noncovalent interaction index (NCI) calculations. Furthermore, the different products of Ti, Zr, and Hf reactions with SiH 4 are discussed in detail.

  14. Demonstration of Z-d(5BrCGAT5BrCG) and B-d(CGCGATCGCG) form crystal structures in DNA-cobalt hexammine complexes by Kr 647.1 nm excitation of Raman spectra.

    OpenAIRE

    Benevides, J M; Wang, A H; Thomas, G J

    1993-01-01

    Cobalt hexammine [Co(NH3)6(3+)] is an efficient DNA complexing agent which significantly perturbs nucleic acid secondary structure. We have employed red excitation (647.1 nm) from a krypton laser to obtain Raman spectra of the highly colored complexes formed between cobalt hexammine and crystals of the DNA oligomers, d(5BrCGAT5BrCG) and d(CGCGATCGCG), both of which incorporate out-of-alternation pyrimidine/purine sequences. The Co(NH3)6(3+) complex of d(5BrCGAT5BrCG) exhibits a typical Z-form...

  15. Splitting rules for the electronic spectra of two-dimensional Fibonacci-class quasicrystals with one kind of atom and two bond lengths

    Science.gov (United States)

    Yang, Xiangbo; Xing, Da

    2002-04-01

    On the basis of the substitution rules for a one-dimensional Fibonacci-class chain, we construct two-dimensional Fibonacci-class quasicrystals with one kind of atom and two bond lengths. In the framework of the single-electron tight-binding nearest-interaction transfer model, we study the splitting rules of the electronic energy spectra for two-dimensional Fibonacci-class quasicrystals by means of a decomposition-decimation method based on a renormalization-group technique, and we also calculate the electronic energy spectra numerically. It is found that there exist only three kinds of clusters-n×n, n×(n+1), and (n+1)×(n+1)-for all classes of two-dimensional quasilattices, and that the electronic energy bands split as Ym-n-l. The general formula of the number for energy levels is obtained. We discover that there is a kind of so-called Fibonacci-class-number set for the parameters used to describe the energy-level number, and we obtain the set formulas. The experienced formula are sought out. The analytical results are confirmed by numerical simulations.

  16. 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.

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

    Science.gov (United States)

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

    2018-01-01

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

  18. On the Raman and infrared vibrational spectra of the ɛ and ζ phases of oxygen. Systematic DFT studies with localized basis sets

    Science.gov (United States)

    Ochoa-Calle, A. J.; Zicovich-Wilson, C. M.; Ramírez-Solís, A.

    2015-10-01

    We address the pressure evolution of the Raman and infrared vibrational modes of the ɛ and ζ phases of oxygen. We use DFT with various GGA and hybrid functionals with localized atomic basis sets. The frequency evolution of the OV, MIR, FIR, L1 and L2 modes is in good agreement with experimental data. The better performance of all methods at pressures >30 GPa is related to the decreasing multireference character of the (O2)4 unit cell wavefunction. Hybrid functionals predict the ɛ-ζ phase transition by the appearance of red-shifted L1 and L2 Raman modes in the transition pressure region.

  19. 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.

  20. Optical band gap and Raman spectra in AxB0.2-x(TeO2)0.8 glasses

    Czech Academy of Sciences Publication Activity Database

    Ožďanová, J.; Tichá, H.; Tichý, Ladislav

    2010-01-01

    Roč. 12, č. 5 (2010), s. 1024-1029 ISSN 1454-4164 Institutional research plan: CEZ:AV0Z40500505 Keywords : telluride glasses * optical band gap * Raman scattering Subject RIV: CA - Inorganic Chemistry Impact factor: 0.412, year: 2010 http://joam.inoe.ro/index.php?option=magazine&op=view&idu=2453&catid=50

  1. 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. ...

  2. 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)

    2015-11-24

    fingerprint region 400...ammonia (NH3), chlorine (Cl2), hydrogen sulfide (H2S), phosgene (COCl2), and sulfur dioxide (SO2) toxic gases have been measured in the fingerprint ...in the fingerprint region 400‐ 1400 cm‐1. Raman cross sections of a number of gases (CH4, C2H6, C3H8, C6H6, CO, CO2, F2, HBr, HCl, HF, H2, H2O,

  3. Surface-Enhanced Raman Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    near-ultraviolet range of electromagnetic spectra. The shift in energy in Raman effect gives information about the ... Raman spectroscopy is commonly used in chemistry, since vibrational information is very specific for the ... in polarizability is compatible with preservation of the center of symmetry. Thus, in a centrosymmetric ...

  4. NBO, HOMO-LUMO, UV, NLO, NMR and vibrational analysis of veratrole using FT-IR, FT-Raman, FT-NMR spectra and HF-DFT computational methods.

    Science.gov (United States)

    Suvitha, A; Periandy, S; Gayathri, P

    2015-03-05

    This work deals with FT-IR, FT-Raman and FT-NMR spectral analysis and NBO, NLO, HOMO-LUMO and electronic transitions studies on veratrole. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands were interpreted with the aid of structure optimizations and geometrical parameter calculations based on Hartree-Fock (HF) and density functional theory (DFT) method with 6-311++G(d, p) basis set. A study on the electronic properties, such as HOMO and LUMO energies were performed by time independent DFT approach. In addition, molecular electrostatic potential (MEP), Natural Bond-Orbital (NBO) analysis and thermodynamic properties were performed. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by gauge independent atomic orbital (GIAO) method and compared with experimental chemical shift. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. In situ Raman spectra of the discharge products of calcium and lithium-anoded thionyl chloride cells — sulphur dioxide generation in oxyhalide systems

    Science.gov (United States)

    Hagan, W. P.; Sargeant, D. G.

    A cell has been constructed that allows a calcium or lithium-anoded oxyhalide cell of conventional composition to be analysed for catholyte-soluble discharge products using laser Raman spectroscopy. Both cells showed the presence of sulphur dioxide solvated by thionyl chloride. Species of the type M(SOCl 2)(SO 2) n+ (AlCl 4) n- could only be detected in cells having calcium or lithium anodes with LiAlCl 4 as the supporting electrolyte in thionyl chloride. Vapour pressure measurements of discharging cells confirmed that Ca(AlCl 4) 2 was less likely to form a complex with sulphur dioxide than the analogous lithium salt.

  6. Determination of the conjugated linoleic acids in cow's milk fat by Fourier transform Raman spectroscopy.

    Science.gov (United States)

    Meurens, Marc; Baeten, Vincent; Yan, Shou He; Mignolet, Eric; Larondelle, Yvan

    2005-07-27

    The collective term "conjugated linoleic acid" or "CLA" generally refers to a mixture of conjugated positional and geometric isomers of linoleic (cis-9,cis-12-octodecadienoic) acid. In nature, these isomers are mainly formed in the rumen by biohydrogenation of polyunsaturated fatty acids. This study concerns a first trial of CLA determination in cow's milk fat by Raman spectroscopy. The spectra of pure cis-9-oleic, cis-9,cis-12-linoleic, cis-9,trans-11-linoleic, and trans-10,cis-12-linoleic acids have been examined in comparison with the spectra of selected milk-fat samples containing between 0 and 3% of CLA. The trial of CLA determination by Raman spectroscopy on cow milk fat has reached its objective with the two following results. First, the examination of the Raman spectra allows to identify three specific Raman signals of the chemical bonds associated to the cis,trans conjugated C=C in the rumenic and trans-10,cis-12-octodecadienoic acids at 1652, 1438, and 3006 cm(-1). Second, the calibration of Raman spectrometer for the CLA determination has indicated that these three specific signals suit very well for the accurate and reliable measurement of CLA concentration in milk fat. To our knowledge, the present study is the first successful attempt to determine the CLA content of milk fat by a spectrophotometric method.

  7. Lattice dynamics and Raman scattering by phonons of GaAs/AlAs(001) superlattices.

    Science.gov (United States)

    Berdekas, D; Ves, S

    2009-07-08

    The lattice dynamics of (GaAs)(n)/(AlAs)(n)(001) superlattices (SLs), n = 1,2, with perfect and disordered (non-perfect) interfaces is studied in detail. The SLs with disordered interfaces are approached by primitive cells, much larger in volume than that of the perfect SL primitive cell. The dynamical matrices of the SLs have been constructed from a combination of the dynamical matrices corresponding to the bulk crystalline constituents, while the interionic forces are calculated by using a ten-parameter valence overlap shell model (VOSM). Furthermore, we calculate the Raman spectra, for both perfect and disordered superlattices by using an eight-parameter bond polarizability model (BPM). Our theoretical results are in very good agreement with the available experimental spectra. Finally, our results clearly demonstrate that intermixing of Ga and Al cations, even to a very small extent, can induce Raman activity, which although not expected in the spectra of perfect superlattices, is actually observed experimentally.

  8. 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.

  9. 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.

  10. Temperature-dependent Raman spectra and electrical properties of 0.69Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.31PbTiO{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Bijun [Changzhou University, School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou (China); Liu, Xing [Changzhou University, School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou (China); Chinese Academy of Sciences, Key Laboratory of Inorganic Function Material and Device, Shanghai (China); Li, Xiaobing; Zhao, Xiangyong; Luo, Haosu [Chinese Academy of Sciences, Key Laboratory of Inorganic Function Material and Device, Shanghai (China); Ding, Jianning [Changzhou University, School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou (China); Jiangsu University, School of Material Science and Engineering, Zhenjiang (China)

    2016-09-15

    The temperature-dependent Raman spectra and electrical properties of the 0.69Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.31PbTiO{sub 3} (0.69PMN-0.31PT) single crystals were investigated. Based on the group theory, the poled 0.69PMN-0.31PT single crystals belong to the monoclinic crystal system, which was confirmed by the room-temperature Raman spectra. The 0.69PMN-0.31PT single crystals experience successive structural phase transitions, i.e., a monoclinic-tetragonal (FE{sub M}-FE{sub T}) phase transition at T{sub M-T} and a tetragonal-cubic (FE{sub T}-P{sub C}) phase transition at T{sub m} determined by the dielectric measurement. Due to the enhancement of long-range order, their FE{sub M}-FE{sub T} phase transition becomes more obvious after the poling process. The wavenumbers and line widths of the 271, 502, 575, 795 cm{sup -1} Raman modes, and the intensity ratios of I{sub 271cm}{sup {sub -}{sub 1}}/I{sub 795cm}{sup {sub -}{sub 1}} and I{sub 502cm}{sup {sub -}{sub 1}}/I{sub 575cm}{sup {sub -}{sub 1}} exhibit obvious anomalies around T{sub M-T} and T{sub m}, which are closely related to the FE{sub M}-FE{sub T} and FE{sub T}-P{sub C} phase transitions. The temperature and electric field (E)-induced phase transitions are observed in the unipolar strain-E (S-E) curves. The converse piezoelectric constant (d{sub 33}), maximum strain value (S{sub max}%) and longitudinal electrostrictive coefficient (Q) increase considerably around the ferroelectric phase transition temperature T{sub M-T}. (orig.)

  11. Vibrational spectra and molecular conformation of taurine and its related compounds

    Science.gov (United States)

    Ohno, Keiichi; Mandai, Yoshitaka; Matsuura, Hiroatsu

    1992-04-01

    IR and Raman spectra have been measured for taurine (2-aminoethanesulfonic acid) and its sodium salt in the solid state and Raman spectra for aqueous solutions of taurine with different pH values. Normal coordinate treatment has been carried out. The analysis of the spectra has indicated that, in the solid state, the molecule of taurine takes the gauche form while that of the sodium salt takes the trans form, and that the trans and gauche forms coexist in both acidic and basic aqueous solutions. The CS stretching bands for the gauche and trans forms were observed at 742 cm -1 and 803 cm -1 respectively. These bands were applied to a conformational analysis of other compounds containing a taurine skeleton; sodium taurocholate takes the gauche conformation about the bond axis NCCS.

  12. Effect of a continuum current in Raman spectra of two magnons in Bi2Sr2Ca1Cu1Cu2O8+Δ

    International Nuclear Information System (INIS)

    Massa, N.E.; Etchegoin, P.G.; Fainstein, C.

    1990-01-01

    It is a known fact, that high temperature superconducting oxides show antiferromagnetic order of the CuO 2 plains as their main characteristic. This allows the use of techniques, which are common to Raman spectroscopy, for the detection of inelastic scattering of magnon pairs represented by a wide band centered around 2500 cm -1 . This communication presents the results of preliminary measurements of such excitations in Bi-2212 tablets which are nominally pure, semiconducting, and doped with Fe under a DC current at temperatures lower than T c . Under these circumstances we find an increase in the full width half maximum of the approximately symmetrical band of two magnons in the tablet and a significantly higher intensity on the high frequency side. These measurements suggest that the carriers involved in the direct current might affect the exchange interaction by means of an electro-magnon interaction. (Author). 5 refs., 2 figs

  13. Polarized Raman spectroscopic characterization of normal and oral cancer blood plasma

    Science.gov (United States)

    Pachaiappan, Rekha; Prakasarao, Aruna; Singaravelu, Ganesan

    2017-02-01

    In India oral cancer ranks the top due to the habitual usage of tobacco in its various forms and remains the major burden. Hence priority is given for early diagnosis as it is the better solution for cure or to improve the survival rate. For the past three decades, optical spectroscopic techniques have shown its capacity in the discrimination of normal and malignant samples. Many research works have conventional Raman in the effective detection of cancer using the variations in bond vibrations of the molecules. However in addition polarized Raman provides the orientation and symmetry of biomolecules. If so can polarized Raman be the better choice than the conventional Raman in the detection of cancer? The present study aimed to found the answer for the above query. The conventional and polarized Raman spectra were acquired for the same set of blood plasma samples of normal subjects and oral malignant (OSCC) patients. Thus, obtained Raman spectral data were compared using linear discriminant analysis coupled with artificial neural network (LDA-ANN). The depolarization ratio of biomolecules such as antioxidant, amino acid, protein and nucleic acid bases present in blood plasma was proven to be the best attributes in the categorization of the groups. The polarized Raman results were promising in discriminating oral cancer blood plasma from that of normal blood plasma with improved efficiency. The results will be discussed in detail.

  14. Insights into Protein Structure and Dynamics by Ultraviolet and Visible Resonance Raman Spectroscopy.

    Science.gov (United States)

    López-Peña, Ignacio; Leigh, Brian S; Schlamadinger, Diana E; Kim, Judy E

    2015-08-11

    Raman spectroscopy is a form of vibrational spectroscopy based on inelastic scattering of light. In resonance Raman spectroscopy, the wavelength of the incident light falls within an absorption band of a chromophore, and this overlap of excitation and absorption energy greatly enhances the Raman scattering efficiency of the absorbing species. The ability to probe vibrational spectra of select chromophores within a complex mixture of molecules makes resonance Raman spectroscopy an excellent tool for studies of biomolecules. In this Current Topic, we discuss the type of molecular insights obtained from steady-state and time-resolved resonance Raman studies of a prototypical photoactive protein, rhodopsin. We also review recent efforts in ultraviolet resonance Raman investigations of soluble and membrane-associated biomolecules, including integral membrane proteins and antimicrobial peptides. These examples illustrate that resonance Raman is a sensitive, selective, and practical method for studying the structures of biological molecules, and the molecular bonding, geometry, and environments of protein cofactors, the backbone, and side chains.

  15. Vibrational spectra of solid HNFX (C6H8F8N8O4): Experiments and theory

    Science.gov (United States)

    Nicol, Malcolm; Gobin, Cedric; Kim, Eunja

    2007-03-01

    Assignment of the vibrational spectra of molecular solids such as HNFX is very complex. We have made a combined experimental and modeling study of the vibrational spectra of solid HNFX. Crystalline HFNX consists of unit cell with 9 HNFX molecules in Ci symmetry. Vibrational modes were calculated by using the PCFF force field method and were directly compared to measured IR and Raman spectra. A complimentary calculation for molecular HNFX allows us to identify the intramolecular motions measured in experiments. Intermolecular motion by F--H bonds between HNFX molecules will be discussed in this talk.

  16. FT-IR and FT-Raman spectra, thermo dynamical behavior, HOMO and LUMO, UV, NLO properties, computed frequency estimation analysis and electronic structure calculations on α-bromotoluene.

    Science.gov (United States)

    Govindarajan, M; Periandy, S; Carthigayen, K

    2012-11-01

    In this work, the vibrational spectral analysis was carried out by using Raman and infrared spectroscopy in the range 100-4,000 cm(-1) and 50-4,000 cm(-1), respectively, for the title molecules. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on Hartee Fock (HF) and density functional theory (DFT) method and different basis sets combination. The complete vibrational assignments of wavenumbers were made on the basis of potential energy distribution (PED). The scaled B3LYP/6-311++G(d,p) results show the best agreement with the experimental values over the other methods. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The influences of bromine atom and methyl group on the geometry of benzene and its normal modes of vibrations have also been discussed. The results of the calculations were applied to simulated spectra of the title compounds, which show excellent agreement with observed spectra. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. 2D-COS of in situ μ-Raman and in situ IR spectra for structure evolution characterisation of NEP-deposited cobalt oxide catalyst during n-nonane combustion.

    Science.gov (United States)

    Chlebda, Damian K; Jodłowski, Przemysław J; Jędrzejczyk, Roman J; Łojewska, Joanna

    2017-11-05

    New catalytic systems are still in development to meet the challenge of regulations concerning the emission of volatile organic compounds (VOCs). This is because such compounds have a significant impact on air quality and some of them are toxic to the environment and human beings. The catalytic combustion process of VOCs over non-noble metal catalysts is of great interest to researchers. The high conversion parameters and cost effective preparation makes them a valuable alternative to monoliths and noble metal catalysts. In this study, the cobalt catalyst was prepared by non-equilibrium plasma deposition of organic precursor on calcined kanthal steel. Thus prepared, cobalt oxide based microstructural short-channel reactors were tested for n-nonane combustion and the catalyst surfaces were examined by in situ μ-Raman spectroscopy and in situ infrared spectroscopy. The spectra collected at various temperatures were used in generalised two-dimensional correlation analysis to establish the sequential order of spectral intensity changes and correlate the simultaneous changes in bands selectively coupled by different interaction mechanisms. The 2D synchronous and asynchronous contour maps were proved to be a valuable extension to the standard analysis of the temperature dependent 1D spectra. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. 2D-COS of in situ μ-Raman and in situ IR spectra for structure evolution characterisation of NEP-deposited cobalt oxide catalyst during n-nonane combustion

    Science.gov (United States)

    Chlebda, Damian K.; Jodłowski, Przemysław J.; Jędrzejczyk, Roman J.; Łojewska, Joanna

    2017-11-01

    New catalytic systems are still in development to meet the challenge of regulations concerning the emission of volatile organic compounds (VOCs). This is because such compounds have a significant impact on air quality and some of them are toxic to the environment and human beings. The catalytic combustion process of VOCs over non-noble metal catalysts is of great interest to researchers. The high conversion parameters and cost effective preparation makes them a valuable alternative to monoliths and noble metal catalysts. In this study, the cobalt catalyst was prepared by non-equilibrium plasma deposition of organic precursor on calcined kanthal steel. Thus prepared, cobalt oxide based microstructural short-channel reactors were tested for n-nonane combustion and the catalyst surfaces were examined by in situ μ-Raman spectroscopy and in situ infrared spectroscopy. The spectra collected at various temperatures were used in generalised two-dimensional correlation analysis to establish the sequential order of spectral intensity changes and correlate the simultaneous changes in bands selectively coupled by different interaction mechanisms. The 2D synchronous and asynchronous contour maps were proved to be a valuable extension to the standard analysis of the temperature dependent 1D spectra.

  19. 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.

  20. FT-IR and FT-Raman spectra, molecular structure and first-order molecular hyperpolarizabilities of a potential antihistaminic drug, cyproheptadine HCl

    Science.gov (United States)

    Sagdinc, Seda G.; Erdas, Dilek; Gunduz, Ilknur; Sahinturk, Ayse Erbay

    2015-01-01

    Cyproheptadine hydrochloride (CYP HCl) {4-(5H-dibenzo[a,d]-cyclohepten-5-ylidene)-1-methylpiperidine hydrochloride} is a first-generation antihistamine with additional anticholinergic, antiserotonergic, and local-anesthetic properties. The geometry optimization, Mulliken atomic charges and wavenumber and intensity of the vibrational bands of all of the possible modes of CYP HCl have been calculated using ab initio Hartree-Fock (HF) and density functional theory (DFT) employing the B3LYP functional with the 6-311G(d,p) basis set. We have compared the calculated IR and Raman wavenumbers with experimental data. Quantum-chemical calculations of the geometrical structure, energies, and molecular electrostatic potential and NBO analysis of CYP HCl have been performed using the B3LYP/6-311G(d,p) method. The electric dipole moment (μ), static polarizability (α) and the first hyperpolarizability (β) values of the title compound have been computed using HF and DFT methods. The study reveals that the antihistaminic pharmacological property of CYP HCl has a large β value and, hence, may in general have potential applications in the development of non-linear optical materials. The experimental and calculated results for CYP HCl have also been compared with those for mianserin HCl.

  1. Raman spectroscopy

    Science.gov (United States)

    Raman spectroscopy has gained increased use and importance in recent years for accurate and precise detection of physical and chemical properties of food materials, due to the greater specificity and sensitivity of Raman techniques over other analytical techniques. This book chapter presents Raman s...

  2. 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.

  3. Industrial applications of Raman spectroscopy

    Science.gov (United States)

    Grasselli, J. G.; Walder, F.; Petty, C.; Kemeny, G.

    1993-03-01

    In the last two decades, Raman spectroscopy has matured as an important method for the study of molecules and complex molecular systems. This is evident from the number of fine texts and the many review articles which have been published describing theory and applications of Raman spectroscopy over a very broad range of subjects (1-10). Raman spectroscopy is the essential partner to infrared spectroscopy for a complete vibrational analysis of a molecule in structure determinations. From the understanding developed on small molecules, theory was extended to interpret the spectra of larger systems such as polymers, biological molecules, and ordered condensed phases. The contribution of Raman spectroscopy to these areas has been significant. It was the development of commercial lasers in the 1960s which spurred the renewed interest in the Raman technique. But applications were still limited for highly fluorescing or intensely colored systems. In 1986, a breakthrough paper by Hirschfeld and Chase (11) described the use of near-infrared laser excitation and a commercial interferometer-based FT-IR spectrometer to record FT-Raman spectra. Significant advantages included the inherent multiplex, throughput and data processing features of the FT interferometers and the use of a ND:YAG laser (1.064 μm) which dramatically decreased problems with sample fluorescence and decomposition. A deluge of papers describing applications of FT-Raman spectroscopy can be found in the Journal of Raman Spectroscopy, Spectrochimica Acta (special issues 40A ad 47A), and Applied Spectroscopy since then.

  4. Transcutaneous Raman Spectroscopy of Murine Bone In Vivo

    OpenAIRE

    Schulmerich, Matthew V.; Cole, Jacqueline H.; Kreider, Jaclynn M.; Esmonde-White, Francis; Dooley, Kathryn A.; Goldstein, Steven A.; Morris, Michael D.

    2009-01-01

    Raman spectroscopy can provide valuable information about bone tissue composition in studies of bone development, biomechanics, and health. In order to study the Raman spectra of bone in vivo, instrumentation that enhances the recovery of subsurface spectra must be developed and validated. Five fiber-optic probe configurations were considered for transcutaneous bone Raman spectroscopy of small animals. Measurements were obtained from the tibia of sacrificed mice, and the bone Raman signal was...

  5. 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.

    nucleobases is perceived. The results obtained for the three ILs families outlined, Imidazolium-, Phosphonium- and Ammonium-based ILs, show that the ILs containing a carbonyl group in the anion present higher dissolution capabilities. This is due to the establishment of hydrogen bonds between uracil and IL...... 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...... 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...

  6. Temperature dependent polymorphism of pyrazinamide: An in situ Raman and DFT study

    Science.gov (United States)

    Sharma, Poornima; Nandi, Rajib; Gangopadhyay, Debraj; Singh, Anurag; Singh, Ranjan K.

    2018-02-01

    The α and γ polymorphs of drug pyrazinamide have been detected with the help of temperature dependent Raman spectroscopic technique. Pyrazinamide is a very useful drug used for the treatment of tuberculosis (TB) and plays a significant role in destroying the dormant tubercle bacilli which are not destroyed by other common TB drugs. Temperature dependent Raman spectra suggest polymorphic phase change from α → γ form of pyrazinamide between 145 and 146 °C. In situ Raman spectra of pyrazinamide between 145 and 146 °C show the conversion of α → γ form by the shift in Cdbnd O stretching vibration accompanied by several other changes. The phase change is characterized by the breaking of two linear Nsbnd H ⋯ O type hydrogen bonds associated with Cdbnd O stretching vibration in α dimer and formation of one linear Nsbnd H ⋯ N type hydrogen bond along with a weak intramolecular Csbnd H ⋯ O type hydrogen bond in the γ dimer.

  7. Quantitative Infrared Absorption Spectra and Vibrational Assignments of Crotonaldehyde and Methyl Vinyl Ketone Using Gas-Phase Mid-Infrared, Far-Infrared, and Liquid Raman Spectra: s-cis vs s-trans Composition Confirmed via Temperature Studies and ab Initio Methods

    Energy Technology Data Exchange (ETDEWEB)

    Lindenmaier, Rodica; Williams, Stephen D.; Sams, Robert L.; Johnson, Timothy J.

    2016-12-16

    Methyl vinyl ketone (MVK) and crotonaldehyde are chemical isomers; both are also important species in tropospheric chemistry. We report quantitative vapor-phase infrared spectra of crotonaldehyde and MVK vapors over the 540-6500 cm-1 range. Vibrational assignments of all fundamental modes are made for both molecules based on far- and mid-infrared vapor-phase spectra, liquid Raman spectra, along with density functional theory and ab initio MP2 and high energy-accuracy compound theoretical models (W1BD). Theoretical results indicate that at room temperature the crotonaldehyde equilibrium mixture is approximately 97% s-trans and only 3% s-cis conformer. Nearly all observed bands are thus associated with the s-trans conformer, but a few appear to be uniquely associated the s-cis conformer, notably ν16c at 730.90 cm-1, which displays a substantial intensity increase with temperature (62% upon going from 5 to 50 oC). The intensity of the corresponding mode of the s-trans conformer decreases with temperature. Under the same conditions, the MVK equilibrium mixture is approximately 69% s-trans conformer and 31% s-cis. W1BD calculations indicate that for MVK this is one of those (rare) cases where there are comparable populations of both conformers, ~doubling the number of observed bands and exacerbating the vibrational assignments. We uniquely assign the bands associated with both the MVK s-cis conformer as well as those of the s-trans, thus completing the vibrational analyses of both conformers from the same set of experimental spectra. Integrated band intensities are reported for both molecules along with global warming potential values. Using the quantitative IR data, potential bands for atmospheric monitoring are also discussed.

  8. A Fast and Cost-Effective Detection of Melamine by Surface Enhanced Raman Spectroscopy Using a Novel Hydrogen Bonding-Assisted Supramolecular Matrix and Gold-Coated Magnetic Nanoparticles

    Directory of Open Access Journals (Sweden)

    Jing Neng

    2017-05-01

    Full Text Available A fast and cost-effective melamine detection approach has been developed based on surface enhanced Raman spectroscopy (SERS using a novel hydrogen bonding-assisted supramolecular matrix. The detection utilizes Fe3O4/Au magnetic nanoparticles coated with 5-aminoorotic acid (AOA as a SERS active substrate (Fe3O4/Au–AOA, and Rhodamine B (RhB conjugated AOA as a Raman reporter (AOA–RhB. Upon mixing the reagents with melamine, a supramolecular complex [Fe3O4/Au–AOA•••melamine•••AOA–RhB] was formed due to the strong multiple hydrogen bonding interactions between AOA and melamine. The complex was separated and concentrated to a pellet by an external magnet and used as a supramolecular matrix for the melamine detection. Laser excitation of the complex pellet produced a strong SERS signal diagnostic for RhB. The logarithmic intensity of the characteristic RhB peaks was found to be proportional to the concentration of melamine with a limit of detection of 2.5 µg/mL and a detection linearity range of 2.5~15.0 µg/mL in milk. As Fe3O4 nanoparticles and AOA are thousands of times less expensive than the monoclonal antibody used in a traditional sandwich immunoassay, the current assay drastically cut down the cost of melamine detection. The current approach affords promise as a biosensor platform that cuts down sample pre-treatment steps and measurement expense.

  9. Raman measurements of phase transitions in dense solid hydrogen and deuterium to 325 GPa.

    Science.gov (United States)

    Zha, Chang-sheng; Cohen, R E; Mao, Ho-kwang; Hemley, Russell J

    2014-04-01

    Raman spectroscopy of dense hydrogen and deuterium performed to 325 GPa at 300 K reveals previously unidentified transitions. Detailed analysis of the spectra from multiple experimental runs, together with comparison with previous infrared and Raman measurements, provides information on structural modifications of hydrogen as a function of density through the I-III-IV transition sequence, beginning near 200 GPa at 300 K. The data suggest that the transition sequence at these temperatures proceeds by formation of disordered stacking of molecular and distorted layers. Weaker spectral changes are observed at 250, 285, and 300 GPa, that are characterized by discontinuities in pressure shifts of Raman frequencies, and changes in intensities and linewidths. The results indicate changes in structure and bonding, molecular orientational order, and electronic structure of dense hydrogen at these conditions. The data suggest the existence of new phases, either variations of phase IV, or altogether new structures.

  10. Raman scattering investigation of the water-bridge phenomenon: Some preliminary results

    Directory of Open Access Journals (Sweden)

    Francesco Aliotta

    2010-09-01

    Full Text Available A floating water-bridge is formed if a high-voltage direct current is applied between two beakers filled of chemically pure water. Raman spectra of the OH-stretching region have been obtained at ambient condition of temperature and pressure. These preliminary results seem to indicate that the hydrogen-bond structure is only slightly modified by the presence of the electric field applied to form the floating water-bridge in agreement with recent neutron scattering investigation. In fact, the polarized Raman spectrum of the pure water and of the water-bridge is almost superimposable. We are planning to carry out further spectroscopic analysis, at different thermodynamic conditions, for better understanding the role played by the hydrogen-bond in driving the formation of the floating water-bridge.

  11. Resonance Raman Optical Activity and Surface Enhanced Resonance Raman Optical Activity analysis of Cytochrome C

    DEFF Research Database (Denmark)

    Johannessen, Christian; Abdali, Salim; White, Peter C.

    2007-01-01

    High quality Resonance Raman (RR) and resonance Raman Optical Activity (ROA) spectra of cytochrome c were obtained in order to perform full assignment of spectral features of the resonance ROA spectrum. The resonance ROA spectrum of cytochrome c revealed a distinct spectral signature pattern due...... Enhanced Raman Spectroscopy (ChERS) spectra of the protein were successfully obtained at very low concentration (as low as 1 µM). The assignment of spectral features was based on the information obtained from the RR and resonance ROA spectra. Excellent agreement between RR and SERRS spectra is reported...

  12. Raman spectrum analysis on the solid-liquid boundary layer of BGO crystal growth

    International Nuclear Information System (INIS)

    Zhang Xia; Yin Shaotang; Wan Songming; Zhang Qingli; You Jinglin; Chen Hui; Zhao Sijie

    2007-01-01

    We study the Raman spectra of Bi 4 Ge 3 O 12 crystal at different temperatures, as well as its melt. The structure characters of the single crystal, melt and growth solid-liquid boundary layer of BGO are investigated by their high-temperature Raman spectra for the first time. The rule of structure change of BGO crystal with increasing temperature is analysed. The results show that there exists [GeO 4 ] polyhedral structure and Bi ion independently in BGO melt. The bridge bonds Bi-O-Bi and Bi-O-Ge appear in the crystal and at the boundary layer, but disappear in the melt. The structure of the growth solid-liquid boundary layer is similar to that of BGO crystal. In the melt, the long-range order structure of the crystal disappears. The thickness of the growth solid-liquid boundary layer of BGO crystal is about 50 μm. (authors)

  13. 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.

  14. The IR spectra and hydrogen bonding of toluene-2,6-bis(methyl) and 4,4'-diphenylmethane-bis(methyl) carbamates

    Science.gov (United States)

    Furer, V. L.

    2000-03-01

    The IR spectroscopy has been used to study models of polyurethanes containing different hard segments. The spectra of toluene-2,6-bis(methyl) and 4,4'-diphenylmethane-bis(methyl) carbamates at different temperatures were studied. The absorption curves of the free and associated carbamate molecules were compared with experimental IR spectra. The characteristic features of toluene-2,6-bis(methyl) carbamate and methyl- N-methyl carbamate clusters were revealed. The IR spectra for the two most stable toluene-2,6-bis(methyl) carbamate conformations were compared. The origin of the multiplet structure of bands in the experimental IR spectra of polyurethanes was discussed. The results obtained can be used for the analysis of the chemical and physical transformations in urethanes and polyurethanes.

  15. Infrared and Raman spectroscopy: principles and spectral interpretation

    National Research Council Canada - National Science Library

    Larkin, Peter

    2011-01-01

    .... The book reviews basic principles, instrumentation, sampling methods, quantitative analysis, origin of group frequencies and qualitative interpretation using generalized Infrared (IR) and Raman spectra...

  16. 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...

  17. High-temperature Raman study of L-alanine, L-threonine and taurine crystals related to thermal decomposition

    International Nuclear Information System (INIS)

    Cavaignac, A.L.O.; Lima, R.J.C.; Façanha Filho, P.F.; Moreno, A.J.D.; Freire, P.T.C.

    2016-01-01

    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.

  18. 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.

  19. Raman Spectroscopy.

    Science.gov (United States)

    Gerrard, Donald L.

    1984-01-01

    Reviews literature on Raman spectroscopy from late 1981 to late 1983. Topic areas include: instrumentation and sampling; liquids and solutions; gases and matrix isolation; biological molecules; polymers; high-temperature and high-pressure studies; Raman microscopy; thin films and surfaces; resonance-enhanced and surface-enhanced spectroscopy; and…

  20. Crystal structures and vibrational spectra of biuret co-crystals with cyanuric and glutaric acids, discussion of hydrogen bonding involving carbonyl groups

    Czech Academy of Sciences Publication Activity Database

    Matulková, I.; Mathauserová, J.; Císařová, I.; Němec, I.; Fábry, Jan

    2016-01-01

    Roč. 231, č. 5 (2016), s. 291-300 ISSN 2194-4946 R&D Projects: GA ČR GA14-05506S Institutional support: RVO:68378271 Keywords : biuret * crystal structure analysis * hydrogen bonding * vibrational spectroscopy * X-ray diffraction Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.179, year: 2016

  1. FT-IR, RAMAN AND DFT STUDIES ON THE VIBRATIONAL ...

    African Journals Online (AJOL)

    Bis(aminoethoxy)propane, IR spectra, Raman spectra, Molecular structure, DFT. INTRODUCTION. Ketal based linkages have recently been investigated for the development of novel acid- cleavable polymers those are formulated into the ...

  2. INFRARED AND RAMAN SPECTROSCOPIC STUDY OF ION ...

    African Journals Online (AJOL)

    Infrared and Raman spectroscopy techniques have been used to study the ionic interactions of strontium(II) and barium(II) with thiocyanate ion in liquid ammonia. A number of bands were observed in both n (CN) and n (CS) regions of infrared and Raman spectra and these were assigned to 1:1 contact ion pair, ...

  3. PULSED MULTICHANNEL RAMAN SPECTROMETRY OF TRANSIENT STATES

    OpenAIRE

    Buntinx, G.; Bridoux, M.; Deffontaine, A.; Poizat, O.

    1987-01-01

    Spontaneous Raman spectroscopy is a nonperturbing diagnostic tool that provides detailed structural information about molecules through the vibrational-line positions and intensities. Because of many specific properties, pulsed Raman spectroscopy can provide valuable information in situations in which ultrarapid recording of the vibrational spectra is of crucial importance.

  4. 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....

  5. Spectroscopic (FT-IR, FT-Raman, UV and NMR) investigation, conformational stability, NLO properties, HOMO-LUMO and NBO analysis of hydroxyquinoline derivatives by density functional theory calculations.

    Science.gov (United States)

    Prabavathi, N; Nilufer, A; Krishnakumar, V

    2013-10-01

    The FTIR and FT-Raman spectra of 2-hydroxyquinoline and its derivatives have been recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The optimized geometry, frequency and intensity of the vibrational bands of these compounds were obtained by the density functional theory using 6-311++G(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 were 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. (1)H and (13)C NMR spectra were recorded and its corresponding nuclear magnetic resonance chemical shifts of the molecule were also calculated using the gauge independent atomic orbital (GIAO) method. UV-visible spectrum of the compound was recorded and the electronic properties HOMO and LUMO energies were measured by time-dependent (TD-DFT) approach. Molecular stability and bond strength were investigated by applying the natural bond orbital analysis (NBO). The calculated HOMO and LUMO energies show that charge transfer occurs in the molecules. In addition, the non-linear optical properties were discussed from the dipole moment values and excitation wavelength in the UV-visible region. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. NIR-FT-Raman spectroscopic studies of hexammine and pentammine chromium(III) complexes

    Science.gov (United States)

    Chen, Yuying; Christensen, Daniel H.; Sørensen, Georg O.; Nielsen, Ole Faurskov; Jacobsen, Claus J. H.; Hyldtoft, Jens

    1994-03-01

    The NIR-FT-Raman spectra are presented for the hexammine [Cr(NH 3) 6]X 3 (where X = Br -, NO -3), pentamminechloro [Cr(NH 3) 5Cl]X 2 (where X = Cl -, ClO -4), and pentammineaqua [Cr(NH 3) 5(H 2O)]X 3 (where X = ClO -4, CF 3SO -3) chromium(III) complexes. The NIR-FT-Raman spectra, with an excitation wavelength of 1064 nm, were obtained at room temperature without problems from the strongly colored samples, which often cause problems with excitation by lasers in the visible region. All the Raman frequencies observed from the complexes have been assigned to the skeleton vibrational region from 100 to 600 cm -1. The symmetry and the general valence force constants for the bonds chromium(III)nitrogen, chromium(III)oxygen and chromium(III)chloro have been obtained. The nature of the metalligand bond between chromium(III) ammine complexes has been compared with recent results obtained for similar cobalt(III) ammine complexes.

  7. Pulsed cathodoluminescence and Raman spectra of MoS{sub 2} and WS{sub 2} nanocrystals and their combination MoS{sub 2}/WS{sub 2} produced by self-propagating high-temperature synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Bozheyev, Farabi, E-mail: farabi.bozheyev@gmail.com [Institute of High Technology Physics, National Research Tomsk Polytechnic University, 30 Lenin Ave., 634050 Tomsk (Russian Federation); National Nanolaboratory, al-Farabi Kazakh National University, 71 al-Farabi Ave., 050000 Almaty (Kazakhstan); Nazarbayev University Research and Innovation System, 53 Kabanbay Batyr St., 010000 Astana (Kazakhstan); Valiev, Damir [Institute of High Technology Physics, National Research Tomsk Polytechnic University, 30 Lenin Ave., 634050 Tomsk (Russian Federation); Nemkayeva, Renata [National Nanolaboratory, al-Farabi Kazakh National University, 71 al-Farabi Ave., 050000 Almaty (Kazakhstan)

    2016-02-29

    Molybdenum and tungsten disulfide nanoplates were produced by self-propagating high-temperature synthesis in argon atmosphere. This method provides an easy way to produce MoS{sub 2} and WS{sub 2} from nanoplates up to single- and several layers. The Raman peak intensities corresponding to in-plane E{sup 1}{sub 2g} and out-of-plane A{sub 1g} vibration modes and their shifts strongly depend on the thicknesses of the MoS{sub 2} and WS{sub 2} platelets indicating size-dependent scaling laws and properties. An electron beam irradiation of MoS{sub 2} and WS{sub 2} powders leads to an occurrence of pulsed cathodoluminescence (PCL) spectra at 575 nm (2.15 eV) and 550 nm (2.25 eV) characteristic to their intrinsic band gaps. For the combination of MoS{sub 2} and WS{sub 2} nanopowders, a PCL shoulder at 430 nm (2.88 eV) was observed, which is explained by the radiative electron-hole recombination at the MoS{sub 2}/WS{sub 2} grain boundaries. The luminescence decay kinetics of the MoS{sub 2}/WS{sub 2} nanoplates appears to be slower than for individual MoS{sub 2} and WS{sub 2} platelets due to a spatial separation of electrons and holes at MoS{sub 2}/WS{sub 2} junction resulting in extension of recombination time.

  8. Operando Raman Micro Spectroscopy of Polymer Electrolyte Fuel Cells

    Science.gov (United States)

    2016-01-16

    exchange site local symmetry. © The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons...Operando Raman spectroscopy.—All operando Raman spectra were acquired using a WITec Inc. (Ulm, Germany) Confocal Raman Microscope ( CRM 200). A 488

  9. Measurement of benzenethiol adsorption to nanostructured Pt, Pd, and PtPd films using Raman spectroelectrochemistry.

    Science.gov (United States)

    Pomfret, Michael B; Pietron, Jeremy J; Owrutsky, Jeffrey C

    2010-05-04

    Raman spectroscopy and electrochemical methods were used to study the behavior of the model adsorbate benzenethiol (BT) on nanostructured Pt, Pd, and PtPd electrodes as a function of applied potential. Benzenethiol adsorbs out of ethanolic solutions as the corresponding thiolate, and voltammetric stripping data reveal that BT is oxidatively removed from all of the nanostructured metals upon repeated oxidative and reductive cycling. Oxidative stripping potentials for BT increase in the order Pt < PtPd < Pd, indicating that BT adsorbs most strongly to nanoscale Pd. Yet, BT Raman scattering intensities, measured in situ over time scales of minutes to hours, are most persistent on the film of nanostructured Pt. Raman spectra indicate that adsorbed BT desorbs from nanoscale Pt at oxidizing potentials via cleavage of the Pt-S bond. In contrast, on nanoscale Pd and PtPd, BT is irreversibly lost due to cleavage of BT C-S bonds at oxidizing potentials, which leaves adsorbed sulfur oxides on Pd and PtPd films and effects the desulfurization of BT. While Pd and PtPd films are less sulfur-resistant than Pt films, palladium oxides, which form at higher potentials than Pt oxides, oxidatively desulfurize BT. In situ spectroelectrochemical Raman spectroscopy provides real-time, chemically specific information that complements the cyclic voltammetric data. The combination of these techniques affords a powerful and convenient method for guiding the development of sulfur-tolerant PEMFC catalysts.

  10. A review of Raman spectroscopy advances with an emphasis on clinical translation challenges in oncology

    Science.gov (United States)

    Jermyn, Michael; Desroches, Joannie; Aubertin, Kelly; St-Arnaud, Karl; Madore, Wendy-Julie; De Montigny, Etienne; Guiot, Marie-Christine; Trudel, Dominique; Wilson, Brian C.; Petrecca, Kevin; Leblond, Frederic

    2016-12-01

    There is an urgent need for improved techniques for disease detection. Optical spectroscopy and imaging technologies have potential for non- or minimally-invasive use in a wide range of clinical applications. The focus here, in vivo Raman spectroscopy (RS), measures inelastic light scattering based on interaction with the vibrational and rotational modes of common molecular bonds in cells and tissue. The Raman ‘signature’ can be used to assess physiological status and can also be altered by disease. This information can supplement existing diagnostic (e.g. radiological imaging) techniques for disease screening and diagnosis, in interventional guidance for identifying disease margins, and in monitoring treatment responses. Using fiberoptic-based light delivery and collection, RS is most easily performed on accessible tissue surfaces, either on the skin, in hollow organs or intra-operatively. The strength of RS lies in the high biochemical information content of the spectra, that characteristically show an array of very narrow peaks associated with specific chemical bonds. This results in high sensitivity and specificity, for example to distinguish malignant or premalignant from normal tissues. A critical issue is that the Raman signal is often very weak, limiting clinical use to point-by-point measurements. However, non-linear techniques using pulsed-laser sources have been developed to enable in vivo Raman imaging. Changes in Raman spectra with disease are often subtle and spectrally distributed, requiring full spectral scanning, together with the use of tissue classification algorithms that must be trained on large numbers of independent measurements. Recent advances in instrumentation and spectral analysis have substantially improved the clinical feasibility of RS, so that it is now being investigated with increased success in a wide range of cancer types and locations, as well as for non-oncological conditions. This review covers recent advances and

  11. Raman spectroscopy of femtosecond multipulse irradiation of vitreous silica: Experiment and simulation

    Science.gov (United States)

    Shcheblanov, N. S.; Povarnitsyn, M. E.; Mishchik, K. N.; Tanguy, A.

    2018-02-01

    We report an experimental and numerical study of femtosecond multipulse laser-induced densification in vitreous silica (v -SiO2 ) and its signature in Raman spectra. We compare the experimental findings to the recently developed molecular dynamics (MD) approach accounting for bond breaking due to laser irradiation, together with a dynamical matrix approach and bond polarizability model based on first-principles calculations for the estimation of Raman spectra. We observe two stages of the laser-induced densification and Raman spectrum evolution: growth during several hundreds of pulses followed by further saturation. At the medium range, the network connectivity change in v -SiO2 is expressed in reduction of the major ring fractions leading to more compacted structure. With the help of the Sen and Thorpe model, we also study the short-range order transformation and derive the interbonding Si-O-Si angle change from the Raman measurements. Experimental findings are in excellent agreement with our MD simulations and hence support a bond-breaking mechanism of laser-induced densification. Thus, our modeling explains well the laser-induced changes both in the short-range order caused by the appearance of Si coordination defects and medium-range order connected to evolution of the ring distribution. Finally, our findings disclose similarities between sheared, permanently densified, and laser-induced glass and suggest interesting future experiments in order to clarify the impact of the thermomechanical history on glasses under shear, cold and hot compression, and laser-induced densification.

  12. Oral pathology diagnosis by means of micro-Raman spectroscopy on biopsies and blood serum

    Science.gov (United States)

    Zenone, F.; Lepore, M.; Perna, G.; Carmone, P.; Delfino, I.; Gaeta, G. M.; Capozzi, V.

    2007-02-01

    Pemphigus vulgaris is a chronic, autoimmune, blistering disease of the skin and mucous membranes with a potentially fatal outcome. In this case micro-Raman spectroscopy (μ-RS) can provide a powerful tool for a not invasive analysis of biological tissue for biopsy and in vivo investigation. Based on the evaluation of molecular vibration frequencies, the μ-RS is able to detect the main molecular bonds of protein constituents, as the C-H and C-C ones. Changes in frequency or in the relative intensity of the vibration modes revealed by μ-RS can be related to changes of chemical bond and of protein structure induced by pathology. Quantitative information on the intensity variation of specific Raman lines can be extracted by Partial Least Square (PLS) analysis. μ-RS was performed on some samples of oral tissue and blood serum from informed patients affected by pemphigus vulgaris (an oral pathology) at different pathology stages. The spectra were measured by means of a Raman confocal microspectrometer apparatus using the 633 nm line of a He- Ne laser source. The main protein bonds are clearly detectable in the considered samples giving important information on the integrity and on the state of tissue and blood serum components (lipids and proteins), and consequently on the occurrence of pathology.

  13. Raman spectroscopy of white wines.

    Science.gov (United States)

    Martin, Coralie; Bruneel, Jean-Luc; Guyon, François; Médina, Bernard; Jourdes, Michael; Teissedre, Pierre-Louis; Guillaume, François

    2015-08-15

    The feasibility of exploiting Raman scattering to analyze white wines has been investigated using 3 different wavelengths of the incoming laser radiation in the near-UV (325 nm), visible (532 nm) and near infrared (785 nm). To help in the interpretation of the Raman spectra, the absorption properties in the UV-visible range of two wine samples as well as their laser induced fluorescence have also been investigated. Thanks to the strong intensity enhancement of the Raman scattered light due to electronic resonance with 325 nm laser excitation, hydroxycinnamic acids may be detected and analyzed selectively. Fructose and glucose may also be easily detected below ca. 1000 cm(-1). This feasibility study demonstrates the potential of the Raman spectroscopic technique for the analysis of white wines. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. 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

    In this work, Raman spectra in the 900-1,800 cm(-1) wavenumber region of in vivo and ex vivo breast tissues of both healthy mice (normal) and mice with induced mammary gland tumors (abnormal) were measured. In the case of the in vivo tissues, the Raman spectra were collected for both transcutaneo...

  15. Surface-enhanced Raman spectroscopy of DNA bases

    NARCIS (Netherlands)

    Otto, Cornelis; van den Tweel, T.J.J.; de Mul, F.F.M.; Greve, Jan

    1986-01-01

    A Raman microprobe has been used to measure the surface-enhanced Raman spectra of adenine, guanine, cytosine and thymine. Comparison of the SERS spectrum with solution spectra shows that some line positions are not influenced by the adsorption process while others show large shifts. In the SERS

  16. Electronic structure and vibrational spectra of cis-diammine(orotato)platinum(II), a potential cisplatin analogue: DFT and experimental study

    Science.gov (United States)

    Wysokiński, Rafał; Hernik, Katarzyna; Szostak, Roman; Michalska, Danuta

    2007-03-01

    Orotic acid (vitamin B 13) is a key intermediate in biosynthesis of the pyrimidine nucleotides in living organisms, moreover, it may serve as the biological carrier for some metal ions. cis-Diammine(orotato)platinum(II), cis-[Pt(C 5H 2N 2O 4)(NH 3) 2] can be considered as a new potential cisplatin analogue. The FT-Raman and FT-IR spectra of the title complex are reported, for the first time. The molecular structure, vibrational frequencies, and the theoretical infrared and Raman intensities have been calculated by the density functional mPW1PW91 method. The detailed vibrational assignment has been made on the basis of the calculated potential energy distribution. The theoretically predicted IR and Raman spectra show very good agreement with experiment. Natural bond orbital (NBO) analyses were performed for cisplatin, carboplatin and the title complex. The results provided new data on the nature of platinum-ligand bonding in these compounds. Strong intramolecular hydrogen bond between the orotate ligand and the coordinated ammonia group stabilizes the structure of the platinum(II) complex. Thus, it is suggested that the orotate ligand in the title complex is more inert to the substitution reactions than the chloride ligands in cisplatin.

  17. Electronic structure and vibrational spectra of cis-diammine(orotato)platinum(II), a potential cisplatin analogue: DFT and experimental study

    International Nuclear Information System (INIS)

    Wysokinski, Rafal; Hernik, Katarzyna; Szostak, Roman; Michalska, Danuta

    2007-01-01

    Orotic acid (vitamin B 13 ) is a key intermediate in biosynthesis of the pyrimidine nucleotides in living organisms, moreover, it may serve as the biological carrier for some metal ions. cis-Diammine(orotato)platinum(II), cis-[Pt(C 5 H 2 N 2 O 4 )(NH 3 ) 2 ] can be considered as a new potential cisplatin analogue. The FT-Raman and FT-IR spectra of the title complex are reported, for the first time. The molecular structure, vibrational frequencies, and the theoretical infrared and Raman intensities have been calculated by the density functional mPW1PW91 method. The detailed vibrational assignment has been made on the basis of the calculated potential energy distribution. The theoretically predicted IR and Raman spectra show very good agreement with experiment. Natural bond orbital (NBO) analyses were performed for cisplatin, carboplatin and the title complex. The results provided new data on the nature of platinum-ligand bonding in these compounds. Strong intramolecular hydrogen bond between the orotate ligand and the coordinated ammonia group stabilizes the structure of the platinum(II) complex. Thus, it is suggested that the orotate ligand in the title complex is more inert to the substitution reactions than the chloride ligands in cisplatin

  18. Electronic structure and vibrational spectra of cis-diammine(orotato)platinum(II), a potential cisplatin analogue: DFT and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Wysokinski, Rafal; Hernik, Katarzyna [Faculty of Chemistry, Wroclaw University of Technology, Smoluchowskiego 23, 50-370 Wroclaw (Poland); Szostak, Roman [Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14, 50-383 Wroclaw (Poland); Michalska, Danuta [Faculty of Chemistry, Wroclaw University of Technology, Smoluchowskiego 23, 50-370 Wroclaw (Poland)], E-mail: danuta.michalska@pwr.wroc.pl

    2007-03-06

    Orotic acid (vitamin B{sub 13}) is a key intermediate in biosynthesis of the pyrimidine nucleotides in living organisms, moreover, it may serve as the biological carrier for some metal ions. cis-Diammine(orotato)platinum(II), cis-[Pt(C{sub 5}H{sub 2}N{sub 2}O{sub 4})(NH{sub 3}){sub 2}] can be considered as a new potential cisplatin analogue. The FT-Raman and FT-IR spectra of the title complex are reported, for the first time. The molecular structure, vibrational frequencies, and the theoretical infrared and Raman intensities have been calculated by the density functional mPW1PW91 method. The detailed vibrational assignment has been made on the basis of the calculated potential energy distribution. The theoretically predicted IR and Raman spectra show very good agreement with experiment. Natural bond orbital (NBO) analyses were performed for cisplatin, carboplatin and the title complex. The results provided new data on the nature of platinum-ligand bonding in these compounds. Strong intramolecular hydrogen bond between the orotate ligand and the coordinated ammonia group stabilizes the structure of the platinum(II) complex. Thus, it is suggested that the orotate ligand in the title complex is more inert to the substitution reactions than the chloride ligands in cisplatin.

  19. "Long-distance" H/D isotopic self-organization phenomena in scope of the infrared spectra of hydrogen-bonded terephthalic and phthalic acid crystals.

    Science.gov (United States)

    Flakus, Henryk T; Hachuła, Barbara; Hołaj-Krzak, Jakub T; Al-Agel, Faisal A; Rekik, Najeh

    2017-02-15

    This paper deals with the experimental and theoretical studies of abnormal properties of terephthalic acid (TAC) and phthalic acid (PAC) crystals manifested in the H/D isotopic exchange. The widely utilized deuteration routine appeared to be insufficiently effective in the case of the h 6 -TAC isotopomer. In the case of the d 4 -TAC derivative the isotopic exchange process occurred noticeably more effectively. In contrast, both isotopomers of PAC, h 6 and d 4 , appeared much more susceptible for deuteration. A theoretical model was elaborated describing "long-distance" dynamical co-operative interactions involving hydrogen bonds in TAC and PAC crystals. The model assumes extremely strong dynamical co-operative interactions of hydrogen bonds from the adjacent (COOH) 2 cycles. This leads to an additional stabilization of h 6 -TAC molecular chains. The interaction energies affect the chemical equilibrium of the H/D isotopic exchange. The model predicts a differentiated influence of the H and D atoms linked to the aromatic rings on to the process. In this approach the totally-symmetric CH bond stretching vibrations and the proton stretching totally symmetric vibrations couple with the π-electronic motions. It was also shown that identical hydrogen isotope atoms, H or D, in whole TAC molecules, noticeably enlarge the energy of the dynamical co-operative interactions in the crystals, in contrast to the case of different hydrogen isotopes present in the carboxyl groups and linked to the aromatic rings. The "long-distance" dynamical co-operative interactions in PAC crystals were found of a minor importance due to the electronic properties of PAC molecules. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Resonance Raman study on indoleamine 2,3-dioxygenase: Control of reactivity by substrate-binding

    Energy Technology Data Exchange (ETDEWEB)

    Yanagisawa, Sachiko; Hara, Masayuki [Graduate School of Life Science and Picobiology Institute, University of Hyogo, Koto 3-2-1, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan); Sugimoto, Hiroshi; Shiro, Yoshitsugu [Biometal Science Laboratory, RIKEN SPring-8 Center, Harima Institute, Koto 1-1-1, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Ogura, Takashi, E-mail: ogura@sci.u-hyogo.ac.jp [Graduate School of Life Science and Picobiology Institute, University of Hyogo, Koto 3-2-1, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan)

    2013-06-20

    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{sup −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.

  1. Molecular Dynamics and Spectra. II. Diatomic Raman.

    Science.gov (United States)

    1981-02-01

    in, /he C’omputer .Simi/e-awn of ondeImed Mc’dha, edited by 1). (eperely (National Resource f~or Computation in C’hemisry. Berke- ley , 1980)) p. 13. 21...Quantum Mec /tanocs, 10 o1 , luondamnewals ( W. A. Benjamiin . Nes% )i fork. 1966) pp. 66-74. 256-264. 56. K. F. I loldy, L. C. Kiot/. and K. R. Wilson...Sets (Academic Press, New York. 1959) 61 J . A. Koni ngstein . hitroductfioo fo the Thecory of the( Rainan lei (I) Reidel, Do)1rdi cclhi. 1972) 62 It

  2. Surface-enhanced Raman spectra on graphene

    Czech Academy of Sciences Publication Activity Database

    Ek Weis, Johan; Vejpravová, Jana; Verhagen, Timotheus; Melníková Komínková, Zuzana; da Costa, Sara; Kalbáč, Martin

    2018-01-01

    Roč. 49, č. 1 (2018), s. 168-173 ISSN 0377-0486 R&D Projects: GA MŠk LL1301; GA ČR(CZ) GA15-01953S; GA MŠk(CZ) LM2015073 Grant - others:GA MŠk(CZ) CZ.02.1.01/0.0/0.0/16_013/0001821 Institutional support: RVO:61388955 ; RVO:68378271 Keywords : charge transfer * graphene * graphene-plasmon interaction Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 2.969, year: 2016

  3. Surface-enhanced Raman spectra on graphene

    Czech Academy of Sciences Publication Activity Database

    Ek Weis, Johan; Vejpravová, Jana; Verhagen, Timotheus; Melníková Komínková, Zuzana; da Costa, Sara; Kalbáč, Martin

    2018-01-01

    Roč. 49, č. 1 (2018), s. 168-173 ISSN 0377-0486 R&D Projects: GA MŠk LL1301; GA ČR(CZ) GA15-01953S; GA MŠk(CZ) LM2015073 Grant - others:GA MŠk(CZ) CZ.02.1.01/0.0/0.0/16_013/0001821 Institutional support: RVO:61388955 ; RVO:68378271 Keywords : charge transfer * graphene * graphene -plasmon interaction Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 2.969, year: 2016

  4. Determining milk isolated and conjugated trans-unsaturated fatty acids using fourier transform Raman spectroscopy.

    Science.gov (United States)

    Stefanov, Ivan; Baeten, Vincent; Abbas, Ouissam; Colman, Ellen; Vlaeminck, Bruno; De Baets, Bernard; Fievez, Veerle

    2011-12-28

    The feasibility of Raman spectroscopy in combination with partial least-squares (PLS) regression for the determination of individual or grouped trans-monounsaturated fatty acids (trans-MUFA) and conjugated linoleic acids (CLA) in milk fat is demonstrated using spectra obtained at two temperature conditions: room temperature and after freezing at -80 °C. The PLS results displayed capability for direct semiroutine quantification of several individual CLA (cis-9,trans-11 and trans-10,cis-12 C18:2) and trans-MUFA (trans-4-15 C18:1) in minor concentrations (below 1.0 g/100 g of milk fat). Calibration models were based on reference data cross-correlation or determined by specific scattering signals in the Raman spectra. Distinct bands for trans-MUFA (1674 cm(-1)) and CLA (1653 cm(-1)) from the trans isolated and cis,trans conjugated C ═ C bonds were identified, as well as original evidence for the temperature effect (new bands, peak shifts, and higher intensities) on the Raman spectra of fatty acid methyl ester and triacylglyceride standards, are supplied.

  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 active components of skin cancer.

    Science.gov (United States)

    Feng, Xu; Moy, Austin J; Nguyen, Hieu T M; Zhang, Jason; Fox, Matthew C; Sebastian, Katherine R; Reichenberg, Jason S; Markey, Mia K; Tunnell, James W

    2017-06-01

    Raman spectroscopy (RS) has shown great potential in noninvasive cancer screening. Statistically based algorithms, such as principal component analysis, are commonly employed to provide tissue classification; however, they are difficult to relate to the chemical and morphological basis of the spectroscopic features and underlying disease. As a result, we propose the first Raman biophysical model applied to in vivo skin cancer screening data. We expand upon previous models by utilizing in situ skin constituents as the building blocks, and validate the model using previous clinical screening data collected from a Raman optical fiber probe. We built an 830nm confocal Raman microscope integrated with a confocal laser-scanning microscope. Raman imaging was performed on skin sections spanning various disease states, and multivariate curve resolution (MCR) analysis was used to resolve the Raman spectra of individual in situ skin constituents. The basis spectra of the most relevant skin constituents were combined linearly to fit in vivo human skin spectra. Our results suggest collagen, elastin, keratin, cell nucleus, triolein, ceramide, melanin and water are the most important model components. We make available for download (see supplemental information) a database of Raman spectra for these eight components for others to use as a reference. Our model reveals the biochemical and structural makeup of normal, nonmelanoma and melanoma skin cancers, and precancers and paves the way for future development of this approach to noninvasive skin cancer diagnosis.

  7. Raman scattering of Cisplatin near silver nanoparticles

    Science.gov (United States)

    Mirsaleh-Kohan, Nasrin; Duplanty, Michael; Torres, Marjorie; Moazzezi, Mojtaba; Rostovtsev, Yuri V.

    2018-03-01

    The Raman scattering of Cisplatin (the first generation of anticancer drugs) has been studied. In the presence of silver nanoparticles, strong modifications of Raman spectra have been observed. The Raman frequencies have been shifted and the line profiles are broadened. We develop a theoretical model to explain the observed features of the Raman scattering. The model takes into account self-consistently the interaction of molecules with surface plasmonic waves excited in the silver nanoparticles, and it provides a qualitative agreement with the observed Raman spectra. We have demonstrated that the using silver nanoparticles can increase sensitivity of the technique, and potentially it has a broader range of applications to both spectroscopy and microscopy.

  8. 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...

  9. 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.

  10. Infrared and Raman Study of the Recluse Spider Silk

    Science.gov (United States)

    Wang, S. L.; Wang, Qijue; Xing, Zhen; Schniepp, H. C.; Qazilbash, M. M.

    Spider silk exhibits remarkable mechanical properties, such as high tensile strength and toughness. We want to gain insight into the composition and structure of spider silk to discover the origin of these properties. We are especially interested in the organization of the crystalline beta sheets that are expected to contribute to the high strength of the silk from the recluse spider, Loxosceles laeta. The recluse spider produces a silk that has a unique geometry amongst arachnids. We measure the silk's optical properties, particularly the infrared-active and Raman-active vibrations. Broadband infrared transmission spectra were collected in the spectral range between 600 cm-1 and 4000 cm-1, with light polarized parallel and perpendicular to the long axis of the silk. Raman micro-spectroscopy was performed in the spectral range 500 cm-1 and 4000 cm- 1 with a 514 nm laser. The infrared and Raman vibrational modes are fit with Lorentzian and pseudo-Voigt functions. The vibrational modes are assigned to specific structures and electronic bonds in the silk. This work was supported by NASA/ Virginia Space Grant Consortium.

  11. Implementation of Deep Ultraviolet Raman Spectroscopy

    DEFF Research Database (Denmark)

    Liu, Chuan

    are located in the visible range, e.g. for petroleum product analysis. Deep Ultraviolet Raman spectroscopy applied to this research field was claimed to be able to solve the problem. Chapter 5 is devoted to gasoline analysis by the use of the DUV Raman spectroscopy. Firstly, some sampling difficulties...... (absorption, condensation) are described. We have found a way to solve the problems, and our solution, using a special designed gas gap cell to obtain measurements of extraordinary high quality, are presented. The DUV Raman spectra of gasoline were excited by three different wavelengths, 257.3, 244.0 and 229...... spectra of the gasoline samples. It is virtually unimportant what the rest of the sample consisted of. The most intense characteristic band is located at 1381 cm-1. The Raman spectra of home-made artificial gasoline mixtures - with gradually increasing Naphthalene contents - can be used to determine...

  12. 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.

  13. Use of Raman spectroscopy in the analysis of nickel allergy

    Science.gov (United States)

    Alda, Javier; Castillo-Martinez, Claudio; Valdes-Rodriguez, Rodrigo; Hernández-Blanco, Diana; Moncada, Benjamin; González, Francisco J.

    2013-06-01

    Raman spectra of the skin of subjects with nickel allergy are analyzed and compared to the spectra of healthy subjects to detect possible biochemical differences in the structure of the skin that could help diagnose metal allergies in a noninvasive manner. Results show differences between the two groups of Raman spectra. These spectral differences can be classified using principal component analysis. Based on these findings, a novel computational technique to make a fast evaluation and classification of the Raman spectra of the skin is presented and proposed as a noninvasive technique for the detection of nickel allergy.

  14. On the intermolecular vibrational coupling, hydrogen bonding, and librational freedom of water in the hydration shell of mono- and bivalent anions.

    Science.gov (United States)

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

    2014-10-28

    The hydration energy of an ion largely resides within the first few layers of water molecules in its hydration shell. Hence, it is important to understand the transformation of water properties, such as hydrogen-bonding, intermolecular vibrational coupling, and librational freedom in the hydration shell of ions. We investigated these properties in the hydration shell of mono- (Cl(-) and I(-)) and bivalent (SO4(2-) and CO3(2-)) anions by using Raman multivariate curve resolution (Raman-MCR) spectroscopy in the OH stretch, HOH bend, and [bend+librational] combination bands of water. Raman-MCR of aqueous Na-salt (NaCl, NaI, Na2SO4, and Na2CO3) solutions provides ion-correlated spectra (IC-spectrum) which predominantly bear the vibrational characteristics of water in the hydration shell of respective anions. Comparison of these IC-spectra with the Raman spectrum of bulk water in different spectral regions reveals that the water is vibrationally decoupled with its neighbors in the hydration shell. Hydrogen-bond strength and librational freedom also vary with the nature of anion: hydrogen-bond strength, for example, decreases as CO3(2-) > SO4(2-) > bulk water ≈ Cl(-) > I(-); and the librational freedom increases as CO3(2-) ≈ SO4(2-) water water in the hydration shell of anions.

  15. Resonance Raman study of benzyl radical

    DEFF Research Database (Denmark)

    Langkilde, F.W.; Bajdor, K.; Wilbrandt, R.

    1992-01-01

    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...

  16. Upgrade of an old Raman Spectrometer

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Berg, Rolf W.; Stenby, Erling Halfdan

    2004-01-01

    Improvement of a conventional Jeol Raman spectrometer with a single channel photo multiplier detector is described. New optical components (fibres, mirror, lens and CCD detector) have been chosen to design a high quality and easy-to-use instrument. Tests have shown that with this modified...... spectrometer Raman spectra can be acquired of a quality comparable to the spectra obtained previously, but the time needed to obtain a spectrum is markedly reduced. Selected test spectra and a simple calibration procedure to obtain the wavenumber values from the band CCD pixel position are presented....

  17. Variability in automated assignment of NOESY spectra and three-dimensional structure determination: A test case on three small disulfide-bonded proteins

    Energy Technology Data Exchange (ETDEWEB)

    Savarin, Philippe; Zinn-Justin, Sophie; Gilquin, Bernard [CEA-Saclay, Departement d' Ingenierie et d' Etudes des Proteines (Bat. 152) (France)

    2001-01-15

    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, {kappa}-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, {kappa}-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, {kappa}-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.

  18. Investigation of the Brill transition in nylon 6,6 by Raman, THz-Raman, and two-dimensional correlation spectroscopy

    Science.gov (United States)

    Bertoldo Menezes, D.; Reyer, A.; Musso, M.

    2018-02-01

    The Brill transition is a phase transition process in polyamides related with structural changes between the hydrogen bonds of the lateral functional groups (Cdbnd O) and (Nsbnd H). In this study, we have used the potential of Raman spectroscopy for exploring this phase transition in polyamide 6,6 (nylon 6,6), due to the sensitivity of this spectroscopic technique to small intermolecular changes affecting vibrational properties of relevant functional groups. During a step by step heating and cooling process of the sample we collected Raman spectra allowing us from two-dimensional Raman correlation spectroscopy to identify which spectral regions suffered the largest influence during the Brill transition, and from Terahertz Stokes and anti-Stokes Raman spectroscopy to obtain complementary information, e.g. on the temperature of the sample. This allowed us to grasp signatures of the Brill transition from peak parameters of vibrational modes associated with (Csbnd C) skeletal stretches and (CNH) bending, and to verify the Brill transition temperature at around 160 °C, as well as the reversibility of this phase transition.

  19. 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.

  20. Understanding of local structure-function relationships of zeolites used in industry through polarized raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, O. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Lascola, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Fessler, K. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Achey, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hunter, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-09-26

    The overall objective of this project is to optics procurement and instrumental setup completed in Robert Lascola’s laboratory. An Ondax THz-Raman probe was installed in order to obtain Raman terahertz spectra of commercially available Zeolites.

  1. Interfacing capillary electrophoresis and surface-enhanced resonance Raman spectroscopy for the determination of dye compounds

    NARCIS (Netherlands)

    Arraez Roman, D.; Efremov, E.V.; Ariese, F.; Segura Carretero, A.; Gooijer, C.

    2005-01-01

    The at-line coupling of capillary electrophoresis (CE) and surface-enhanced resonance Raman spectroscopy (SERRS) was optimized for the separation and subsequent spectroscopic identification of charged analytes (dye compounds). Raman spectra were recorded following deposition of the electropherogram

  2. Gem and mineral identification using GL Gem Raman and comparison with other portable instruments

    Science.gov (United States)

    Culka, Adam; Hyršl, Jaroslav; Jehlička, Jan

    2016-11-01

    Several mainly silicate minerals in their gemstone varieties have been analysed by the Gem Raman portable system by Gemlab R&T, Vancouver, Canada, in order to ascertain the general performance of this relatively non-expensive tool developed exactly for the purpose of gemstone identification. The Raman spectra of gemstones acquired by this system have been subsequently critically compared with the data obtained by several other portable or handheld Raman instruments. The Raman spectra acquired with the Gem Raman instrument were typically of lesser quality when compared with the spectra taken by other instruments. Characteristic features such as steep baseline probably due to the fluorescence of the minerals, Raman bands much broader and therefore less resolved closely located Raman bands, and generally greater shifts of the band positions from the reference values were encountered. Some gemstone groups such as rubies did not provide useful Raman spectra at all. Nevertheless, general identification of gemstones was possible for a selection of gemstones.

  3. Investigation of glutathione-derived electrostatic and hydrogen-bonding interactions and their role in defining Grx5 [2Fe-2S] cluster optical spectra and transfer chemistry.

    Science.gov (United States)

    Sen, Sambuddha; Bonfio, Claudia; Mansy, Sheref S; Cowan, J A

    2018-03-01

    Human glutaredoxin 5 (Grx5) is one of the core components of the Isc (iron-sulfur cluster) assembly and trafficking machinery, and serves as an intermediary cluster carrier, putatively delivering cluster from the Isu scaffold protein to target proteins. The tripeptide glutathione is intimately involved in this role, providing cysteinyl coordination to the iron center of the Grx5-bound [2Fe-2S] cluster. Grx5 has a well-defined glutathione-binding pocket with protein amino acid residues providing many ionic and hydrogen binding contacts to the bound glutathione. In this report, we investigated the importance of these interactions in cluster chirality and exchange reactivity by systematically perturbing the crucial contacts by use of natural and non-natural amino acid substitutions to disrupt the binding contacts from both the protein and glutathione. Native Grx5 could be reconstituted with all of the glutathione analogs used, as well as other thiol ligands, such as DTT or L-cysteine, by in vitro chemical reconstitution, and the holo proteins were found to transfer [2Fe-2S] cluster to apo ferredoxin 1 at comparable rates. However, the circular dichroism spectra of these derivatives displayed prominent differences that reflect perturbations in local cluster chirality. These studies provided a detailed molecular understanding of glutathione-protein interactions in holo Grx5 that define both cluster spectroscopy and exchange chemistry.

  4. Raman scattering and luminescence of high-Tc superconducting oxides

    International Nuclear Information System (INIS)

    Eremenko, V.V.; Gnezdilov, V.P.; Fomin, V.I.; Fugol', I.Ya.; Samovarov, V.N.

    1989-01-01

    Raman and luminescence spectra of high-T c superconducting oxides are summarized, mainly YBa 2 Cu 3 O 7-σ and partly La 2-x Ba x CuO 4-σ . In raman spectra we succeeded to distinguish electron scattering to define the energy gap Δ in the superconducting state. The luminescence spectra are due to the emission of oxygen and interaction with conduction electrons. 70 refs.; 13 figs

  5. Raman, surface-enhanced Raman, and density functional theory characterization of (diphenylphosphoryl)(pyridin-2-, -3-, and -4-yl)methanol.

    Science.gov (United States)

    Proniewicz, Edyta; Pięta, Ewa; Zborowski, Krzysztof; Kudelski, Andrzej; Boduszek, Bogdan; Olszewski, Tomasz K; Kim, Younkyoo; Proniewicz, Leonard M

    2014-07-31

    This work presents near-infrared Raman spectroscopy (FT-RS) and surface-enhanced Raman scattering (SERS) studies of three pyridine-α-hydroxymethyl biphenyl phosphine oxide isomers: (diphenylphosphoryl)(pyridin-2-yl)methanol (α-Py), (diphenylphosphoryl)(pyridin-3-yl)methanol (β-Py), and (diphenylphosphoryl)(pyridin-4-yl)methanol (γ-Py) adsorbed onto colloidal and roughened in oxidation-reduction cycles silver surfaces. The molecular geometries in the equilibrium state and vibrational frequencies were calculated by density functional theory (DFT) at the B3LYP 6-311G(df,p) level of theory. The results imply that the most stable structure of the investigated molecules is a dimer created by two intermolecular hydrogen bonds between the H atom of the α-hydroxyl group (in up (HOU) or down (HOD) stereo bonds position) and the O atom of tertiary phosphine oxide (═O) of the two monomers. Comparison the FT-RS spectra with the respective SERS spectra allowed us to predict the orientation of the hydroxyphosphonate derivatives of pyridine that depends upon both the position of the substituent relative to the ring N atom (in α-, β-, and γ-position, respectively) and the type of silver substrate.

  6. Raman Chandrasekar

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education. Raman Chandrasekar. Articles written in Resonance – Journal of Science Education. Volume 13 Issue 5 May 2008 pp 430-439 General Article. How Children Learn to Use Language - An Overview of R. Narasimhan's Ideas on Child Language Acquisition.

  7. CV Raman

    Indian Academy of Sciences (India)

    style, philosophy and motivations. We thus have here an authoritative biography of the most .... What motivated Raman to do the extraordinary things he did against all odds? What was the secret of his success? ... to Professor S. Chandrasekhar for permission to quote some of his statements. I am very indebted to Prof.

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

    Science.gov (United States)

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

    1999-05-01

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

  9. Theory of Graphene Raman Scattering.

    Science.gov (United States)

    Heller, Eric J; Yang, Yuan; Kocia, Lucas; Chen, Wei; Fang, Shiang; Borunda, Mario; Kaxiras, Efthimios

    2016-02-23

    Raman scattering plays a key role in unraveling the quantum dynamics of graphene, perhaps the most promising material of recent times. It is crucial to correctly interpret the meaning of the spectra. It is therefore very surprising that the widely accepted understanding of Raman scattering, i.e., Kramers-Heisenberg-Dirac theory, has never been applied to graphene. Doing so here, a remarkable mechanism we term"transition sliding" is uncovered, explaining the uncommon brightness of overtones in graphene. Graphene's dispersive and fixed Raman bands, missing bands, defect density and laser frequency dependence of band intensities, widths of overtone bands, Stokes, anti-Stokes anomalies, and other known properties emerge simply and directly.

  10. Structural refinement, photoluminescence and Raman spectroscopy of wurtzite Mn-doped Zn O pellets

    Energy Technology Data Exchange (ETDEWEB)

    Marquina, J.; Martin, J.; Luengo, J.; Vera, F.; Roa, L. [Centro de Estudios Avanzados en Optica, Universidad de los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Gonzalez, J. [Centro de Estudios de Semiconductores, Universidad de los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Rodriguez, F.; Renero L, C.; Valiente, R. [Malta-Consolider Team, CITIMAC, Facultad de Ciencias, Universidad de Cantabria, Santander 69005 (Spain); Delgado, G. E., E-mail: marquinajesus@gmail.com [Laboratorio de Cristalografia, Facultad de Ciencias, Universidad de los Andes, Merida 5101 (Venezuela, Bolivarian Republic of)

    2017-11-01

    We report the results of the Rietveld refinement, photoluminescence and Raman spectroscopy of Mn-doped Zn O ceramic pellets. Rietveld refinement shows that samples crystallize in the wurtzite structure and for the Mn-doped sample indicated that the Mn atoms substitute the Zn tetrahedral crystallographic sites in the Zn O host lattice. The emission and absorption spectra of Mn-doped Zn O have been investigated in the visible-UV region and the data have been interpreted in terms of the wurtzite Zn O electronic structure. Two broad bands, one due to superposition between donor bound excitons (DX) and free excitons (FX) and other due free-to bond excitonic recombination (FB) dominates the low-temperature photoluminescence spectra of Mn-doped Zn O bulk. In the Raman spectrum, an extra mode at ∼520 cm{sup -1} has been observed in agreement with earlier works, and it is an indicator for the incorporation of Mn{sup +2} ions into the Zn O host matrix since it is not is observed in Zn O pristine. Rietveld refinement of the X-ray diffraction patterns, energy-dispersive X-ray spectroscopy (EDS) technique, and Raman spectroscopies were performed to study these effects. (Author)

  11. Semiconductor-driven ?turn-off? surface-enhanced Raman scattering spectroscopy: application in selective determination of chromium(vi) in water? ?Electronic supplementary information (ESI) available: Detailed Benesi?Hildebrand plot, IR spectra, Raman assignments, and experiment optimization. See DOI: 10.1039/c4sc02618g Click here for additional data file.

    OpenAIRE

    Ji, Wei; Wang, Yue; Tanabe, Ichiro; Han, Xiaoxia; Zhao, Bing; Ozaki, Yukihiro

    2014-01-01

    Semiconductor materials have been successfully used as surface-enhanced Raman scattering (SERS)-active substrates, providing SERS technology with a high flexibility for application in a diverse range of fields. Here, we employ a dye-sensitized semiconductor system combined with semiconductor-enhanced Raman spectroscopy to detect metal ions, using an approach based on the ?turn-off? SERS strategy that takes advantage of the intrinsic capacity of the semiconductor to catalyze the degradation of...

  12. Raman and TEM characterization of high fluence C implanted nanometric Si on insulator

    Energy Technology Data Exchange (ETDEWEB)

    Reis, R.M.S. dos [Instituto de Fisica, UFRGS, C.P. 15051, 91501-970, Porto Alegre, RS (Brazil); Maltez, R.L., E-mail: maltez@if.ufrgs.br [Instituto de Fisica, UFRGS, C.P. 15051, 91501-970, Porto Alegre, RS (Brazil); Moreira, E.C.; Dias, Y.P. [Universidade Federal do Pampa - UNIPAMPA, Campus Bage, 96400-970, Bage, RS (Brazil); Boudinov, H. [Instituto de Fisica, UFRGS, C.P. 15051, 91501-970, Porto Alegre, RS (Brazil)

    2012-07-15

    In this work we present Raman and transmission electron microscopy (TEM) characterization of high fluence C implanted nanometric silicon on insulator. The analyzed samples were 35 and 60 nm top layers of Si, which were entirely converted into SiC layers by 2.3 Multiplication-Sign 10{sup 17} cm{sup -2} and 4.0 Multiplication-Sign 10{sup 17} cm{sup -2} carbon implantations. We report the behavior of C-C signal from Raman spectra for such overall Si to SiC conversions before and after 1250 Degree-Sign C annealing. A remarkable effect is observed in the region of C signal (1100-1700 cm{sup -1}), where fitting with Lorentzian curves reveals that there are different types of C-C bonds. Raman spectroscopy in this region was then employed to relatively characterize the SiC structural quality. TEM measurements support our Raman interpretation by direct structural evaluation of the formed SiC layers.

  13. Detection of biologically active diterpenoic acids by Raman Spectroscopy

    DEFF Research Database (Denmark)

    Talian, Ivan; Orinak, Andrej; Efremov, Evtim V.

    2010-01-01

    is not suitable for their unambiguous identification, especially not in solution. We attempted to increase the sensitivity by applying UV-resonance Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) techniques. The UV-Raman spectra of the three compounds in ethanol/water 50 : 50 showed only very......Three poorly detectable, biologically active diterpenoic acids, kaurenoic, abietic, and gibberellic acid, were studied by using different modes of Raman spectroscopy. Because of their structural similarities, in the absence of strongly polarizable groups, conventional Raman spectroscopy...

  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. Solvatochromism of 9,10-phenanthrenequinone: An electronic and resonance Raman spectroscopic study

    Science.gov (United States)

    Ravi Kumar, Venkatraman; Rajkumar, Nagappan; Umapathy, Siva

    2015-01-01

    Solvent effects play a vital role in various chemical, physical, and biological processes. To gain a fundamental understanding of the solute-solvent interactions and their implications on the energy level re-ordering and structure, UV-VIS absorption, resonance Raman spectroscopic, and density functional theory calculation studies on 9,10-phenanthrenequinone (PQ) in different solvents of diverse solvent polarity has been carried out. The solvatochromic analysis of the absorption spectra of PQ in protic dipolar solvents suggests that the longest (1n-π1*; S1 state) and the shorter (1π-π1*; S2 state) wavelength band undergoes a hypsochromic and bathochromic shift due to intermolecular hydrogen bond weakening and strengthening, respectively. It also indicates that hydrogen bonding plays a major role in the differential solvation of the S2 state relative to the ground state. Raman excitation profiles of PQ (400-1800 cm-1) in various solvents followed their corresponding absorption spectra therefore the enhancements on resonant excitation are from single-state rather than mixed states. The hyperchromism of the longer wavelength band is attributed to intensity borrowing from the nearby allowed electronic transition through vibronic coupling. Computational calculation with C2ν symmetry constraint on the S2 state resulted in an imaginary frequency along the low-frequency out-of-plane torsional modes involving the C=O site and therefore, we hypothesize that this mode could be involved in the vibronic coupling.

  16. Solvatochromism of 9,10-phenanthrenequinone: an electronic and resonance Raman spectroscopic study.

    Science.gov (United States)

    Ravi Kumar, Venkatraman; Rajkumar, Nagappan; Umapathy, Siva

    2015-01-14

    Solvent effects play a vital role in various chemical, physical, and biological processes. To gain a fundamental understanding of the solute-solvent interactions and their implications on the energy level re-ordering and structure, UV-VIS absorption, resonance Raman spectroscopic, and density functional theory calculation studies on 9,10-phenanthrenequinone (PQ) in different solvents of diverse solvent polarity has been carried out. The solvatochromic analysis of the absorption spectra of PQ in protic dipolar solvents suggests that the longest (1n-π(1)*; S1 state) and the shorter (1π-π(1)*; S2 state) wavelength band undergoes a hypsochromic and bathochromic shift due to intermolecular hydrogen bond weakening and strengthening, respectively. It also indicates that hydrogen bonding plays a major role in the differential solvation of the S2 state relative to the ground state. Raman excitation profiles of PQ (400-1800 cm(-1)) in various solvents followed their corresponding absorption spectra therefore the enhancements on resonant excitation are from single-state rather than mixed states. The hyperchromism of the longer wavelength band is attributed to intensity borrowing from the nearby allowed electronic transition through vibronic coupling. Computational calculation with C2ν symmetry constraint on the S2 state resulted in an imaginary frequency along the low-frequency out-of-plane torsional modes involving the C=O site and therefore, we hypothesize that this mode could be involved in the vibronic coupling.

  17. Raman and surface-enhanced Raman spectroscopy of amino acids and nucleotide bases for target bacterial vibrational mode identification

    Science.gov (United States)

    Guicheteau, Jason; Argue, Leanne; Hyre, Aaron; Jacobson, Michele; Christesen, Steven D.

    2006-05-01

    Raman and surface-enhanced Raman spectroscopy (SERS) studies of bacteria have reported a wide range of vibrational mode assignments associated with biological material. We present Raman and SER spectra of the amino acids phenylalanine, tyrosine, tryptophan, glutamine, cysteine, alanine, proline, methionine, asparagine, threonine, valine, glycine, serine, leucine, isoleucine, aspartic acid and glutamic acid and the nucleic acid bases adenosine, guanosine, thymidine, and uridine to better characterize biological vibrational mode assignments for bacterial target identification. We also report spectra of the bacteria Bacillus globigii, Pantoea agglomerans, and Yersinia rhodei along with band assignments determined from the reference spectra obtained.

  18. 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.

  19. Structural investigations of transition metal (II) tetracyanonickelate complexes of 3-chloropyridine using Fourier transform-infrared and laser Raman spectroscopy

    Science.gov (United States)

    Akyüz, Sevim; Akyüz, Tanil; Eric, J.; Davies, D.

    1992-01-01

    The FT-IR and laser-Raman spectra of five new complexes of the formula ML 2Ni(CN) 4 (where MMn, Fe, Ni, Zn or Cd; L3-chloropyridine) are reported. The complexes are shown to have a structure consisting of two dimensional polymeric layers formed with Ni(CN) 4 ions bridged by ML 2 cations. For a given series of isomorphous complexes, the effects of metal ligand bond formation on the ligand vibrational modes are examined and the metal-sensitivity sequence of the ligand frequencies is found to be Mn≈Cd

  20. Semiconductor-driven “turn-off” surface-enhanced Raman scattering spectroscopy: application in selective determination of chromium(vi) in water† †Electronic supplementary information (ESI) available: Detailed Benesi–Hildebrand plot, IR spectra, Raman assignments, and experiment optimization. See DOI: 10.1039/c4sc02618g Click here for additional data file.

    Science.gov (United States)

    Ji, Wei; Wang, Yue; Tanabe, Ichiro; Han, Xiaoxia

    2015-01-01

    Semiconductor materials have been successfully used as surface-enhanced Raman scattering (SERS)-active substrates, providing SERS technology with a high flexibility for application in a diverse range of fields. Here, we employ a dye-sensitized semiconductor system combined with semiconductor-enhanced Raman spectroscopy to detect metal ions, using an approach based on the “turn-off” SERS strategy that takes advantage of the intrinsic capacity of the semiconductor to catalyze the degradation of a Raman probe. Alizarin red S (ARS)-sensitized colloidal TiO2 nanoparticles (NPs) were selected as an example to show how semiconductor-enhanced Raman spectroscopy enables the determination of Cr(vi) in water. Firstly, we explored the SERS mechanism of ARS–TiO2 complexes and found that the strong electronic coupling between ARS and colloidal TiO2 NPs gives rise to the formation of a ligand-to-metal charge-transfer (LMCT) transition, providing a new electronic transition pathway for the Raman process. Secondly, colloidal TiO2 nanoparticles were used as active sites to induce the self-degradation of the Raman probe adsorbed on their surfaces in the presence of Cr(vi). Our data demonstrate the potential of ARS–TiO2 complexes as a SERS-active sensing platform for Cr(vi) in an aqueous solution. Remarkably, the method proposed in this contribution is relatively simple, without requiring complex pretreatment and complicated instruments, but provides high sensitivity and excellent selectivity in a high-throughput fashion. Finally, the ARS–TiO2 complexes are successfully applied to the detection of Cr(vi) in environmental samples. Thus, the present work provides a facile method for the detection of Cr(vi) in aqueous solutions and a viable application for semiconductor-enhanced Raman spectroscopy based on the chemical enhancement they contribute. PMID:28694937

  1. Raman spectroscopy for the in-line polymer-drug quantification and solid state characterization during a pharmaceutical hot-melt extrusion process.

    Science.gov (United States)

    Saerens, L; Dierickx, L; Lenain, B; Vervaet, C; Remon, J P; De Beer, T

    2011-01-01

    The aim of this study was to evaluate the suitability of Raman spectroscopy as a Process Analytical Technology (PAT) tool for the in-line determination of the active pharmaceutical ingredient (API) concentration and the polymer-drug solid state during a pharmaceutical hot-melt extrusion process. For in-line API quantification, different metoprolol tartrate (MPT)--Eudragit® RL PO mixtures, containing 10%, 20%, 30% and 40% MPT, respectively, were extruded and monitored in-line in the die using Raman spectroscopy. A PLS model, regressing the MPT concentrations versus the in-line collected Raman spectra, was developed and validated, allowing real-time API concentration determination. The correlation between the predicted and real MPT concentrations of the validation samples is acceptable (R(2)=0.997). The predictive performance of the calibration model is rated by the root mean square error of prediction (RMSEP), which is 0.59%. Two different polymer-drug mixtures were prepared to evaluate the suitability of Raman spectroscopy for in-line polymer-drug solid state characterization. Mixture 1 contained 90% Eudragit® RS PO and 10% MPT and was extruded at 140°C, hence producing a solid solution. Mixture 2 contained 60% Eudragit® RS PO and 40% MPT and was extruded at 105°C, producing a solid dispersion. The Raman spectra collected during these extrusion processes provided two main observations. First, the MPT Raman peaks in the solid solution broadened compared to the corresponding solid dispersion peaks, indicating the presence of amorphous MPT. Second, peak shifts appeared in the spectra of the solid dispersion and solid solution compared to the physical mixtures, suggesting interactions between Eudragit® RS PO and MPT, most likely hydrogen bonds. These shifts were larger in the spectra of the solid solution. DSC analysis confirmed these Raman solid state observations and the interactions seen in the spectra. Raman spectroscopy is a potential PAT-tool for in

  2. In situ raman spectroelectrochemistry of electron transfer between glassy carbon and a chemisorbed nitroazobenzene monolayer.

    Science.gov (United States)

    Itoh, Takashi; McCreery, Richard L

    2002-09-11

    In situ Raman spectroscopy was used to monitor 4-nitroazobenzene (NAB) in an electrochemical cell, both as a free molecule and as a chemisorbed monolayer on a glassy carbon (GC) electrode surface. Reduction of free NAB exhibited two well-defined voltammetric couples in acetonitrile, and the accompanying spectral changes supported a mechanism involving two successive 1-e(-) transfers. Raman spectra of NAB chemisorbed to GC via diazonium ion reduction were obtained in acetonitrile with a high-sensitivity, line-focused CCD spectrometer. The chemisorbed NAB spectra were quite different from the free NAB spectra, and were sufficiently strong to monitor as a function of applied potential. In the potential range of +400 to -800 mV vs Ag/Ag(+), the intensity of the Raman bands associated with the phenyl-NO(2) moiety varied, implying an electronic interaction between the pi system of the graphitic substrate and the chemisorbed NAB molecules. Negative of -800 mV, a 1-e(-) voltammetric reduction peak was observed, which was reversible on the positive voltage scan. This peak was accompanied by significant spectral changes, particularly the loss of the N=N and NO(2) stretches. The spectra are consistent with formation of a quinoid structure containing a C=C double bond between the NAB and the graphitic surface. The electron transfer and spectral changes occurred over a wider potential range than expected for a conventional Nernstian equilibrium, but did not appear to be broadened by slow electron-transfer kinetics. The results imply a significant perturbation of electron transfer between the GC and the monolayer, caused by strong electronic coupling between the graphitic pi system and the NAB orbitals. Rather than a discrete electron transfer to a free molecule, the electron transfer to chemisorbed NAB is more gradual, and is presumably driven by the electric field at the electrode/solution interface.

  3. 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

    2010-02-03

    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.

  4. Application of Raman spectroscopy to forensic fibre cases.

    Science.gov (United States)

    Lepot, L; De Wael, K; Gason, F; Gilbert, B

    2008-09-01

    Five forensic fibre cases in which Raman spectroscopy proved to be a good complementary method for microspectrophotometry (MSP) are described. Absorption spectra in the visible range are indeed sometimes characteristic ofa certain dye but this one can be subsequently identified unambiguously by Raman spectroscopy using a spectral library. In other cases the comparison of Raman spectra of reference fibres and suspect fibres led to an improvement of the discrimination power. The Raman measurements have been performed directly on mounted fibres and the spectra showed only little interference from the mounting resin and glass. Raman spectroscopy is therefore a powerful method that can be applied in routine fibre analysis following optical microscopy and MSP measurements.

  5. 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

  6. Study of vibrational spectra of beta-LiYb(WO4)2

    International Nuclear Information System (INIS)

    Kondratov, O.I.; Efremov, V.A.; Petrov, K.I.; Fomichev, V.V.

    1978-01-01

    The Raman and infrared absorption spectra (up to 30 cm -1 ) of β-Li Yb(WO 4 ) 29 and a spectrum of an isotope-substituted, with respect to lithium, sample have been measured. Frequencies and shapes of normal vibration of two non-equivalent crystal directions have been calculated in a polymer approximation. The system of force constants has been determined. The frequency branches of the vibrations have been calculated when a phase vector changes from S=1 to 100 and atoms displacements. The calculation results have shown that a considerable contribution to the vibrations of end W-O bonds (the region of 900-930 cm -1 ) is made by the coordinates of the n-O bonds (where M is Li or Yb) elongation and by deformation of the WOM and OMO angles

  7. Raman spectroscopy of graphene on different substrates and ...

    Indian Academy of Sciences (India)

    We show the evolution of Raman spectra with a number of graphene layers on different substrates, SiO2/Si and conducting indium tin oxide (ITO) plate. The mode peak position and the intensity ratio of and 2 bands depend on the preparation of sample for the same number of graphene layers. The 2 Raman band ...

  8. Confocal direct imaging Raman microscope: design and applications in biology

    NARCIS (Netherlands)

    Sijtsema, N.M.; Wouters, Siddi D.; de Grauw, Cees J.; de Grauw, C.J.; Otto, Cornelis; Greve, Jan

    1998-01-01

    A confocal direct imaging Raman microscope (CDIRM) based on two synchronized scanning mirrors, a monochromator, and two charge-coupled device (CCD) cameras has been developed. With this system it is possible to make both Raman spectra of a small measurement volume and images of a larger sample area

  9. Dynamics of allostery in hemoglobin: roles of the penultimate tyrosine H bonds.

    Science.gov (United States)

    Kneipp, Janina; Balakrishnan, Gurusamy; Chen, Ruopian; Shen, Tong-Jian; Sahu, Sarata C; Ho, Nancy T; Giovannelli, Janel L; Simplaceanu, Virgil; Ho, Chien; Spiro, Thomas G

    2006-02-17

    The tyrosine residues adjacent to the C termini of the hemoglobin (Hb) subunits, alphaY140 and betaY145, are expected to play important structural roles, because the C termini are the loci of T-state quaternary salt-bridges, and because the tyrosine side-chains bridge the H and F helices via H bonds to the alphaV93 and betaV98 carbonyl groups. These roles have been investigated via measurements of oxygen binding, (1)H NMR spectra, resonance Raman (RR) spectra, and time-resolved resonance Raman (TR(3)) spectra on site mutants in which the Hcdots, three dots, centeredF H bonds are eliminated by replacing the tyrosine residues with phenylalanine. The TR(3) spectra confirm the hypothesis, based on TR(3) studies of wild-type Hb, that the Hcdots, three dots, centeredF H bonds break and then re-form during the sub-microsecond phase of the R-T quaternary transition. The TR(3) spectra support the inference from other mutational studies that the alphabeta dimers act as single dynamic units in this early phase, motions of the E and F helices being coupled tightly across the dimer interface. Formation of T quaternary contacts occurs at about the same rate in the mutants as in HbA. However, these contacts are weakened substantially by the Y/F substitutions. Equilibrium perturbations are apparent also, especially for the alpha-subunits, in which relaxation of the Fe-His bond, strengthening of the Acdots, three dots, centeredE interhelical H bond, and weakening of the "switch" quaternary contact in deoxyHb are all apparent. Structural effects are less marked for the beta-chain Y/F replacement, but the Bohr effect is reduced by 25%, indicating that the salt-bridge and H bond interactions of the adjacent C terminus are loosened. The alpha-chain replacement reduces the Bohr effect much more, consistent with the global perturbations detected by the structure probes.

  10. Structural, intramolecular hydrogen bonding and vibrational studies ...

    Indian Academy of Sciences (India)

    The harmonic oscillator model of aromaticity (HOMA) index elucidated the impact of hydrogen bond- ing in the ring. Intramolecular hydrogen bonding energy has been calculated from topological study. The low wavenumber vibrational modes obtained from experimental FT-Raman spectrum also supported the presence.

  11. Infrared absorption and Raman scattering spectroscopic studies of condensed ions

    International Nuclear Information System (INIS)

    Dao, N.Q.; Knidiri, M.

    1975-01-01

    Infrared and Raman spectra of the complex K 5 (UO 2 ) 2 F 9 were recorded in the region 4000 to 80 cm -1 . Factor group analysis was used to classify the internal vibrations of the binuclear ion (UO 2 ) 2 F 9 5- . Infrared and Raman spectra were assigned and splitting of the internal modes of the (UO 2 ) 2 F 9 5- anion interpreted. (author)

  12. In situ Raman spectroelectrochemistry of azobenzene monolayers on glassy carbon.

    Science.gov (United States)

    Itoh, Takashi; McCreery, Richard L

    2007-05-01

    In situ Raman spectra of chemisorbed azobenzene (AB) monolayers on glassy carbon (GC) electrodes were observed under potentiostatic conditions in acetonitrile (ACN) with tetrabutyl-ammonium tetrafluoroborate (TBA-BF4). The Raman intensities of these spectra were high below -1000 mV, and this is attributed to the change in absorbance of AB on GC. In this paper, we describe chemisorbed AB molecules on GC electrode surfaces under potentiostatic conditions.

  13. Defects in individual semiconducting single wall carbon nanotubes: Raman spectroscopic and in situ Raman spectroelectrochemical study.

    Science.gov (United States)

    Kalbac, Martin; Hsieh, Ya-Ping; Farhat, Hootan; Kavan, Ladislav; Hofmann, Mario; Kong, Jing; Dresselhaus, Mildred S

    2010-11-10

    Raman spectroscopy and in situ Raman spectroelectrochemistry have been used to study the influence of defects on the Raman spectra of semiconducting individual single-walled carbon nanotubes (SWCNTs). The defects were created intentionally on part of an originally defect-free individual semiconducting nanotube, which allowed us to analyze how defects influence this particular nanotube. The formation of defects was followed by Raman spectroscopy that showed D band intensity coming from the defective part and no D band intensity coming from the original part of the same nanotube. It is shown that the presence of defects also reduces the intensity of the symmetry-allowed Raman features. Furthermore, the changes to the Raman resonance window upon the introduction of defects are analyzed. It is demonstrated that defects lead to both a broadening of the Raman resonance profile and a decrease in the maximum intensity of the resonance profile. The in situ Raman spectroelectrochemical data show a doping dependence of the Raman features taken from the defective part of the tested SWCNT.

  14. Characterization of Water Solubility in n-Octacosane Using Raman Spectroscopy.

    Science.gov (United States)

    Giraudet, Cédric; Papavasileiou, Konstantinos D; Rausch, Michael H; Chen, Jiaqi; Kalantar, Ahmad; van der Laan, Gerard P; Economou, Ioannis G; Fröba, Andreas P

    2017-11-30

    In this study, we demonstrate the ability of polarization-difference Raman spectroscopy (PDRS) to detect dissolved free water molecules in a n-octacosane (n-C 28 H 58 ) liquid-rich phase, and thus to determine its solubility, at temperatures and pressures relevant to the Fischer-Tropsch synthesis. Our results for the pure alkane reveal thermal decomposition above a temperature of 500 K as well as an increase of gauche conformers of the alkane chains with an increase in temperature. For binary homogeneous mixtures, raw spectra obtained from two different polarization scattering geometries did not show a relevant signal in the OH stretching frequency range. In contrast, isotropic spectra obtained from the PDRS technique reveal a narrow and tiny peak associated with the dangling OH bonds. Over the complete range of temperatures and pressures, no signature of hydrogen-bonded water molecules was observed in the isotropic Raman scattering intensities. A thorough investigation covering a large range of temperatures and pressures using PDRS signals showed that the higher the fraction of gauche conformers of hydrocarbon, the higher the solubility of water. The proportion of gauche and trans conformers was found to be water-concentration-independent, and the intensity of the OH-dangling peak increased linearly with increasing the vapor partial pressure of water. Therefore, we established a relation between a relevant intensity ratio and the concentration of water obtained from SAFT calculations. Contrary to the results from relevant literature, the calibration factor was found to be temperature-independent between 424 and 572 K. The isotropic Raman scattering intensities are corrected in order to provide a better representation of the vibrational density of states. The influence of correction of the isotropic scattering intensities on the solubility measurements as well as on the analysis of the molecular arrangement is discussed.

  15. BETA SPECTRA. I. Negatrons spectra

    International Nuclear Information System (INIS)

    Grau Malonda, A.; Garcia-Torano, E.

    1978-01-01

    Using the Fermi theory of beta decay, the beta spectra for 62 negatrons emitters have been computed introducing a correction factor for unique forbidden transitions. These spectra are plotted vs. energy, once normal i sed, and tabulated with the related Fermi functions. The average and median energies are calculated. (Author)

  16. Coherent Raman scattering: Applications in imaging and sensing

    Science.gov (United States)

    Cui, Meng

    In this thesis, I discuss the theory, implementation and applications of coherent Raman scattering to imaging and sensing. A time domain interferometric method has been developed to collect high resolution shot-noise-limited Raman spectra over the Raman fingerprint regime and completely remove the electronic background signal in coherent Raman scattering. Compared with other existing coherent Raman microscopy methods, this time domain approach is proved to be simpler and more robust in rejecting background signal. We apply this method to image polymers and biological samples and demonstrate that the same setup can be used to collect two photon fluorescence and self phase modulation signals. A signal to noise ratio analysis is performed to show that this time domain method has a comparable signal to noise ratio to spectral domain methods, which we confirm experimentally. The coherent Raman method is also compared with spontaneous Raman scattering. The conditions under which coherent methods provide signal enhancement are discussed and experiments are performed to compare coherent Raman scattering with spontaneous Raman scattering under typical biological imaging conditions. A critical power, above which coherent Raman scattering is more sensitive than spontaneous Raman scattering, is experimentally determined to be ˜1mW in samples of high molecule concentration with a 75MHz laser system. This finding is contrary to claims that coherent methods provide many orders of magnitude enhancement under comparable conditions. In addition to the far field applications, I also discuss the combination of our time domain coherent Raman method with near field enhancement to explore the possibility of sensing and near field imaging. We report the first direct time-resolved coherent Raman measurement performed on a nanostructured substrate for molecule sensing. The preliminary results demonstrate that sub 20 fs pulses can be used to obtain coherent Raman spectra from a small number

  17. Vibrational spectroscopic (FTIR and FT-Raman), first-order hyperpolarizablity, HOMO, LUMO, NBO, Mulliken charge analyses of 2-ethylimidazole based on Hartree-Fock and DFT calculations.

    Science.gov (United States)

    Arivazhagan, M; Manivel, S; Jeyavijayan, S; Meenakshi, R

    2015-01-05

    The FTIR and FT-Raman spectra of 2-ethylimidazole (2EIDZ) have been recorded in the region 4000-400 cm(-1) and 3500-50 cm(-1), respectively. Utilizing the observed FTIR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compound were carried out. The optimized molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, were calculated by ab initio Hartree-Fock (HF) and density functional theory (DFT/B3LYP) methods with 6-311++G(d,p) basis set. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. A detailed interpretation of the infrared and Raman spectra of 2EIDZ is also reported based on total energy distribution (TED). The values of the total dipole moment (μ) and the first-order hyperpolarizability (β) of the compound were computed. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. Besides, HOMO and LUMO analysis, Mulliken's charge analysis and several thermodynamic properties have been calculated. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2017-07-01

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

  19. Emerging Dental Applications of Raman Spectroscopy

    Science.gov (United States)

    Choo-Smith, Lin-P'ing; Hewko, Mark; Sowa, Michael G.

    Until recently, the application of Raman spectroscopy to investigate dental tissues has primarily focused on using microspectroscopy to characterize dentin and enamel structures as well as to understand the adhesive interface of various resin and bonding agents used in restorative procedures. With the advent of improved laser, imaging/mapping and fibre optic technologies, the applications have expanded to investigate various biomedical problems ranging from oral cancer, bacterial identification and early dental caries detection. The overall aim of these applications is to develop Raman spectroscopy into a tool for use in the dental clinic. This chapter presents the recent dental applications of Raman spectroscopy as well as discusses the potential, strengths and limitations of the technology in comparison with alternative techniques. In addition, a discussion and rationale about combining Raman spectroscopy with other optical techniques will be included.

  20. 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.

  1. Raman spectrometer with microprobe capability

    Science.gov (United States)

    Boyd, J. T.; Jackson, H. E.

    1986-01-01

    This report describes the results of this equipment grant funded as a part of the Department of Defense (DOD) University Research Instrumentation Program. This grant funded the purchase of a Raman spectrometer with microprobe capability having resolution of 1.0 micron. This report describes the equipment selecting decision, the configuration of the instrument selected, and some experimental results. The experimental results include Raman spectra used in characterization of laser recrystallized silicon and ion implanted regions in semi-insulating GaAs. The Raman microprobe can be used to characterize the effects of substrate temperature, beam power density and shape, beam scan speed and direction, deposition rate, substrate seeding, and polysilicon encapsulation schemes both near and away from grain boundaries. The frequency shift and the peak width of the Raman scattering from the triply degenerate zone center phonon in Si allow determination of the strain in the grains of laser recrystallized polysilicon. Reducing these strains will allow us to achieve large single grains of device quality.

  2. Infrared spectra of U.S. automobile original finishes (post - 1989). VIII: In situ identification of bismuth vanadate using extended range FT-IR spectroscopy, Raman spectroscopy, and X-ray fluorescence spectrometry.

    Science.gov (United States)

    Suzuki, Edward M

    2014-03-01

    Chrome Yellow (PbCrO4 ·xPbSO4 ) was a common pigment in U.S. automobile OEM finishes for more than three decades, but in the early 1990s its use was discontinued. One of its main replacements was Bismuth Vanadate (BiVO4 ·nBi2 MoO6 , n = 0-2), which was commercially introduced in 1985, as this inorganic pigment also produces a very bright hue and has excellent outdoor durability. This paper describes the in situ identification of Bismuth Vanadate in automotive finishes using FT-IR and dispersive Raman spectroscopy and XRF spectrometry. Some differentiation of commercial formulations of this pigment is possible based on far-infrared absorptions, Raman data, and elemental analysis. The spectral differences arise from the presence or absence of molybdenum, the use of two crystal polymorphs of BiVO4 , and differences in pigment stabilizers. Bismuth Vanadate is usually not used alone, and it is typically found with Isoindoline Yellow, hydrous ferric oxide, rutile, Isoindolinone Yellow 3R, or various combinations of these. © 2013 American Academy of Forensic Sciences.

  3. Surface-enhanced Raman spectroscopy of urine by an ingenious near-infrared Raman spectrometer

    Science.gov (United States)

    Feng, Shangyuan; Chen, Weiwei; Li, Yongzeng; Chen, Guannan; Huang, Zufang; Liao, Xiaohua; Xie, Zhiming; Chen, Rong

    2007-11-01

    This paper demonstrates the potential of an elaborately devised near-infrared Raman system in analysis of urine. 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 aggregation of the colloidal silver particles. We have reported the surface-enhanced Raman (SERS) spectra of urine, and studied the silver solution enhanced effects on the urine Raman scattering. The Raman bands of human's urine was assigned to certain molecule vibrations. We have found that different donators have dissimilar SERS of urine in different physiological condition. Comparatively few studies have explored the ability of Raman spectroscopy for the analysis of urine acid. In the present report, we investigated the ability of surface enhanced Raman spectroscopy to measure uric acid in the human urine. The results suggested that the present Raman system holds considerable promise for practical use. Practical applications such as the quantitative medical examination of urine metabolites may also be feasible in the near future.

  4. UV Raman spectroscopy of H2-air flames excited with a narrowband KrF laser

    Science.gov (United States)

    Shirley, John A.

    1990-01-01

    Raman spectra of H2 and H2O in flames excited by a narrowband KrF excimer laser are reported. Observations are made over a porous-plug, flat-flame burner reacting H2 in air, fuel-rich with nitrogen dilution to control the temperature, and with an H2 diffusion flame. Measurements made from UV Raman spectra show good agreement with measurements made by other means, both for gas temperature and relative major species concentrations. Laser-induced fluorescence interferences arising from OH and O2 are observed in emission near the Raman spectra. These interferences do not preclude Raman measurements, however.

  5. Raman spectroscopy in high temperature chemistry

    International Nuclear Information System (INIS)

    Drake, M.C.; Rosenblatt, G.M.

    1979-01-01

    Raman spectroscopy (largely because of advances in laser and detector technology) is assuming a rapidly expanding role in many areas of research. This paper reviews the contribution of Raman spectroscopy in high temperature chemistry including molecular spectroscopy on static systems and gas diagnostic measurements on reactive systems. An important aspect of high temperature chemistry has been the identification and study of the new, and often unusual, gaseous molecules which form at high temperatures. Particularly important is the investigation of vibrational-rotational energy levels and electronic states which determine thermodynamic properties and describe chemical bonding. Some advantages and disadvantages of high temperature Raman spectrosocpy for molecular studies on static systems are compared: (1) Raman vs infrared; (2) gas-phase vs condensed in matries; and (3) atmospheric pressure Raman vs low pressure techniques, including mass spectroscopy, matrix isolation, and molecular beams. Raman studies on molecular properties of gases, melts, and surfaces are presented with emphasis on work not covered in previous reviews of high temperature and matrix isolation Raman spectroscopy

  6. 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 nucleic...

  7. 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

  8. Intramolecular hydrogen bonding in 5-nitrosalicylaldehyde: IR spectrum and quantum chemical calculations

    Science.gov (United States)

    Moosavi-Tekyeh, Zainab; Taherian, Fatemeh; Tayyari, Sayyed Faramarz

    2016-05-01

    The structural parameters, and vibrational frequencies of 5-nitrosalicylaldehyde (5NSA) were studied by the FT-IR and Raman spectra and the quantum chemical calculations carried out at the B3LYP/6-311++G(d,p) level of theory in order to investigate the intramolecular hydrogen bonding (IHB) present in its structure. The strength and nature of IHB in the optimized structure of 5NSA were studied in detail by means of the atoms in molecules (AIM) and the natural bond orbital (NBO) approaches. The results obtained were then compared with the corresponding data for its parent molecule, salicylaldehyde (SA). Comparisons made between the geometrical structures for 5NSA and SA, their OH/OD stretching and out-of-plane bending modes, their enthalpies for the hydrogen bond, and their AIM parameters demonstrated a stronger H-bonding in 5NSA compared with that in SA. The calculated binding enthalpy (ΔHbind) for 5NSA was -10.92 kcal mol-1. The observed νOH and γOH appeared at about 3120 cm-1 and 786 cm-1 respectively. The stretching frequency shift of H-bond formation was 426 cm-1 which is consistent with ΔHbind and the strength of H-bond in 5NSA. The delocalization energies and electron delocalization indices derived by the NBO and AIM approaches indicate that the resonance effects were responsible for the stronger IHB in 5NSA than in SA.

  9. Micro-structural study of the GeS2-In2S3-KCl glassy system by Raman scattering.

    Science.gov (United States)

    Haizheng, Tao; Xiujian, Zhao; Wei, Tong; Shun, Mao

    2006-07-01

    Room temperature Raman spectra of samples on three serials within the GeS(2)-In(2)S(3)-KCl glassy system have been investigated systematically. According to XRD patterns and Raman spectra of several pseudo-binary systems, the Cl atoms, which was added into the GeS(2)-In(2)S(3) glasses through KCl, was considered to be leading to the breaking of In-In bonds among the S(3)In-InS(3) ethane-like units and the forming of InS(4-x)Cl(x), InS(6-x)Cl(x) mixed polyhedra. Considering the effect of K(+) ions upon mixed anion units (InS(4-x)Cl(x) and InS(6-x)Cl(x)) and the corresponding micro-structural model, the Raman spectral evolution of the GeS(2)-In(2)S(3)-KCl glasses can be elucidated successfully. The microstructure of the GeS(2)-In(2)S(3)-KCl glasses was considered to be that the potassium atoms, which exist in the form of chlorine atoms as its nearest neighbor, are homogeneously dispersed in the glassy net formed by the micro-structural units such as InS(4), InS(6), InS(4-x)Cl(x), InS(6-x)Cl(x), GeS(4) polyhedra and S(3)In(Ge)-In(Ge)S(3) ethane-like units.

  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. 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.

  12. L-glutamine: Dynamical properties investigation by means of INS, IR, RAMAN, 1H NMR and DFT techniques

    International Nuclear Information System (INIS)

    Pawlukojć, A.; Hołderna-Natkaniec, K.; Bator, G.; Natkaniec, I.

    2014-01-01

    Graphical abstract: - Highlights: • The L-glutamine was investigated by INS, IR, Raman and 1 H NMR spectroscopy. • DFT calculations for the solids state model were performed. • The NH 3 + torsional vibration mode is observed in the INS spectra. • Activation energy for the NH 3 + 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 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 3 + group in hydrogen bonds are observed at 2400, 2618 and 2619 cm −1 , while the NH 3 + torsion vibration mode is observed at 441 cm −1 . The band at 2041 cm −1 is assigned to combinations of the NH 3 + bending symmetry vibration and the CO 2 - rocking vibration and can be used as an “indicator band” for the identification of the NH 3 + groups in amino acid. For the L-glutamine an activation energy needed for the NH 3 + 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. Molecular structure, vibrational spectroscopic (FT-IR, FT-Raman), UV and NBO analysis of 2-chlorobenzonitrile by density functional method.

    Science.gov (United States)

    Krishnan, Akhil R; Saleem, H; Subashchandrabose, S; Sundaraganesan, N; Sebastain, S

    2011-02-01

    In this work, we will report a combined experimental and theoretical study on molecular structure, vibrational spectra, NBO and UV spectral analysis of 2-chlorobenzonitrile (2-ClBN). The FT-IR solid phase (4000-400 cm(-1)), and FT-Raman spectra (3500-50 cm(-1)) of 2-ClBN was recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of 2-ClBN in the ground state have been calculated by using the density functional methods (BLYP, B3LYP) with 6-31G(d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the σ* and π* anti bonding orbitals and E2 energies confirms the occurrence of ICT (Intra molecular Charge Transfer) within the molecule. The UV spectrum was measured in ethanol solution. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) results complements with the experimental findings. The calculated HOMO and LUMO energies also confirm that charge transfer occurs within the molecule. Finally calculated results were applied to simulated Infrared and Raman spectra of the title compound which show good agreement with observed spectra. Copyright © 2010 Elsevier B.V. All rights reserved.

  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

    2016-01-15

    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. ((1))H and ((13))C 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. ((1))H and ((13))C 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Raman spectroscopic characterization of multiwall carbon nanotubes and of composites

    Directory of Open Access Journals (Sweden)

    L. Bokobza

    2012-07-01

    Full Text Available In this work Raman spectroscopy was used for extensive characterization of multiwall carbon nanotube (MWNTs and of MWCNTs/rubber composites. We have measured the Raman spectra of bundled and dispersed multiwall carbon nanotubes. All the Raman bands of the carbon nanotubes are seen to shift to higher wavenumbers upon debundling on account of less intertube interactions. Effects of laser irradiation were also investigated. Strong effects are observed by changing the wavelength of the laser excitation. On the other hand, at a given excitation wavelength, changes on the Raman bands are observed by changing the laser power density due to sample heating during the measurement procedure.

  16. Light absorption, electron paramagnetic resonance and resonance Raman characteristics of nitridochromium(V) protoporphyrin-IX and its reconstituted hemoproteins.

    Science.gov (United States)

    Hori, H; Tsubaki, M; Yu, N T; Yonetani, T

    1991-04-29

    A surprisingly stable complex of the photolyzed product of azidochromium(III)protoporphyrin-IX was prepared and examined by light absorption, electron paramagnetic resonance (EPR) and resonance Raman spectroscopies. The characteristic EPR spectrum for this complex was consistent with a nitridochromium(V)-porphyrin complex which was two oxidation equivalents above the resting Cr(III) complex. The Cr(V)-N stretching mode was observed at 1010 cm-1 by resonance Raman spectroscopy. A simple diatomic harmonic oscillation model gave a force constant of 6.7 mdyn/A for the Cr(V)-N bond, in the region characteristic for the metal-nitrogen triple bond. Nitridochromium(V) protoporphyrin-IX reconstituted myoglobin and cytochrome c peroxidase were prepared for the first time. The nitridochromium(V)-porphyrins in these apo-proteins were unstable in contrast with the protein-free chromium(V)porphyrin. Upon irradiation of the azide complexes of the chromium(III) protoporphyrin-IX reconstituted myoglobin and cytochrome c peroxidase with ultraviolet light aerobically at room temperature, the characteristic optical and EPR spectra for nitridochromium(V) derivatives were observed. The optical spectra of these photo-induced products were different from those of the nitridochromium(V) protoporphyrin-IX reconstituted hemoproteins. The electrochemical structures of the unusual metalloporphyrin seemed to be modulated by the heme surrounding amino acid residues.

  17. Micro-Raman scattering in ZnTe thin films

    International Nuclear Information System (INIS)

    Larramendi, E. M.; Gutierrez Z-B, K.; Hernandez, E.; Melo, O. de; Berth, G.; Wiedemeier, V.; Lischka, K; Schikora, D.; Woggon, U.

    2008-01-01

    In this work we present micro-raman measurements on ZnTe thin films grown by isothermal closed space sublimation on GaAs(001) substrates in helium and nitrogen atmospheres. Micro-raman spectra were recorded at room temperature using the backscattering geometry (illuminated spot: 3 μm2, 0.3 cm-1 of resolution and the line 532 nm of a DPSSL as power excitation). Up to four order LO-phonon replicas and no peak from TO phonon were observed in the micro-raman spectra as evidence of the epitaxial character and good quality of the films (the TO mode is forbidden according to the selection rules for backscattering along [001] of this heterostructure). The micro-raman spectra also revealed two features at low energy, which have been assigned incorrectly in recent works. We demonstrate that these raman peaks can be associated to the presence of few monolayers of crystalline tellurium or its oxides on the surface of the films. These features were not observed in micro-raman spectra of as grown ZnTe films terminated in a Zn surface. However, they were detected after a prolonged exposure of the samples to air. In addition, it is shown that this effect is accelerated under a high power laser excitation (laser annealing) as used in conventional micro-Raman measurement setups. Preliminary results that suggest the inclusion of nitrogen in ZnTe structure are also shown. (Full text)

  18. DFT-assisted spectroscopic characterization of pyrazosulfuron-ethyl: FT-Raman, FTIR and UV-vis studies of a sulfonyl urea herbicide

    Science.gov (United States)

    Monicka, J. Clemy; James, C.

    2014-10-01

    Raman and IR spectra of pyrazosulfuron-ethyl have been reported here, and it is shown that the spectra has been fully interpreted in terms of assigning normal modes to the various spectral features by using density functional theory calculations. The Raman bands observed for PY in solid phase are characteristic for the carbonyl group, Csbnd C, Csbnd H and Nsbnd H stretching and deformation vibrations. The dimer structure of PY was optimized, including the Nsbnd H…N and Csbnd H…O intermolecular interactions. Stability of the molecule arising from hyperconjugative interactions leading to its bioactivity and charge delocalization have been analyzed using natural bond orbital analysis. Spectral analysis reveals the substantial effect of non-bonding interaction, conjugation and induction effects in the molecule which in turn influences the bioactivity of the compound. Red shifting of (∼94 cm-1) Nsbnd H stretching band substantiates the presence of strong Nsbnd H…N intramolecular hydrogen bonding in the molecule. The aromatic behavior of pyrimidine and pyrazole ring has been calculated using the HOMA method.

  19. 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 C-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. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Optical nonlinearity and electric conductivity origin study on sucrose crystal by using IR, Raman, INS, NMR, and EPR spectroscopies.

    Science.gov (United States)

    Szostak, M Magdalena; Piela, Katarzyna; Hołderna-Natkaniec, Krystyna; Natkaniec, Ireneusz; Bidzińska, Ewa

    2014-08-18

    The supposed importance of hydrogen bonds toward the origin of second harmonic generation (SHG) and electric conductivity in crystalline sucrose was investigated by IR (4000-10cm(-1)), INS (2000-10cm(-1), at 35K), polarized Raman (3600-50cm(-1)) spectra, and (1)H NMR second moment line records in the temperature range 450-80K. The temperature dependence of NIR (7000-5500cm(-1)) polarized spectra gave information about -CH2 motions complementary to NMR results concerning -CH2OH group rearrangements. The EPR spectra were applied to study the generation of radical ions by exposure to NIR radiation. Density functional theory quantum chemical calculations were performed to reproduce the vibrational spectra in order to complete as far as possible the assignments of bands observed by us and in the literature in sucrose crystals, and to throw more light on the possible reasons of sucrose electric conductivity and optical nonlinearity by the knowledge of theoretical values of dipole moments, polarizabilities, first order hyperpolarizabilities of sucrose molecule and clusters as well as ionization energy and electron affinity. The proton transfer in one specific hydrogen bond parallel to the helical axis b is proposed to be the most important in SHG and conductivity origin. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Corrosion product characterisation by fibre optic raman spectroscopy

    International Nuclear Information System (INIS)

    Guzonas, D.A.; Rochefort, P.A.; Turner, C.W.

    1998-01-01

    Fibre optic Raman spectroscopy has been used to characterise secondary-side deposits removed from CANDU steam generators. The deposits examined were in the form of powders, millimetre-sized flakes, and deposits on the surfaces of pulled steam generator tubes. The compositions of the deposits obtained using Raman spectroscopy are similar to the compositions obtained using other ex-situ analytical techniques. A semi-quantitative estimate of amounts of the major components can be obtained from the spectra. It was noted that the signal-to-noise ratio of the Raman spectra decreased as the amount of magnetite in the deposit increased, as a result of absorption of the laser light by the magnetite. The conversion of magnetite to hematite by the laser beam was observed when high laser powers were used. The Raman spectra of larger flake samples clearly illustrate the inhomogeneous nature of the deposits. (author)

  2. Raman spectrometric studies of selected lanthanide tribromides and trichlorides

    International Nuclear Information System (INIS)

    Daniel, J.F.

    1988-03-01

    Laser Raman spectroscopy was used to identify the crystal structures of lanthanide and actinide compounds. The phonon Raman spectrum is characteristic of the particular crystal structure. GdCl 3 exhibits two crystal structures, the UCl 3 -type hexagonal and the PuBr 3 -type orthorhombic. In the literature it is reported that the low temperature form is orthorhombic; results of experiments here suggest that it is hexagonal. Interconversion between these two forms can be accomplished with temperature andor pressure. In the present work laser Raman spectrometry was used to monitor crystal structure changes in GdCl 3 as a function of temperature or pressure to determine the temperature or pressure at which the hexagonal-to-orthorhombic transformation occurs. Raman spectroscopy was also used to determine the symmetry assignments for the Raman-active bands of a single crystal. Raman spectra of polycrystalline NdBr 3 have been recorded at room temperature and pressure and at approximately 100/degree/K. In addition, polarized Raman spectra of a single crystal NdBr 3 have been measured. Based on these polarization measurements, symmetry assignments of eight Raman-active modes were made. These assignments are useful in interpreting the phonon Raman spectrum of any compound exhibiting the PuBr 3 -type orthorhombic structure. 24 figs., 5 tabs

  3. Tracking wave packet dynamics in photodissociation of liquid CH3I with time- and frequency-resolved impulsive stimulated Raman scattering

    Science.gov (United States)

    Wang, Yang; Song, Yun-fei; Liu, Wei-long; Liu, Yu-qiang; Duo, Li-ping; Jiang, Li-lin; Yang, Yan-qiang

    2015-07-01

    We demonstrate that broadband impulsive stimulated Raman scattering with transient grating experimental geometry is capable of recording vibrational spectra in time and frequency domains to reveal the dissociation mechanism of liquid CH3I. The repulsive 3Q0 potential energy surface is modified to a quasi-bound surface in the liquid CH3I due to the solvent cage, making the wave packets to get trapped. A small portion of the wave packet passes through the solvent cage, resulting in the Csbnd I bond breakage with the product I2. This work provides a first glimpse of immense potential of BB-ISRS in studying photodissociation dynamics in liquids.

  4. Structure and reactivity of thiazolium azo dyes: UV-visible, resonance Raman, NMR, and computational studies of the reaction mechanism in alkaline solution.

    Science.gov (United States)

    Abbott, Laurence C; Batchelor, Stephen N; Moore, John N

    2013-03-07

    UV-visible absorption, resonance Raman, and (1)H NMR spectroscopy, allied with density functional theory (DFT) calculations, have been used to study the structure, bonding, and alkaline hydrolysis mechanism of the cationic thiazloium azo dye, 2-[2-[4-(diethylamino)phenyl]diazenyl]-3-methyl-thiazolium (1a), along with a series of six related dyes with different 4-dialkylamino groups and/or other phenyl ring substituents (2a-c, 3a-c) and the related isothiazolium azo dye, 5-[2-[4-(dimethylamino)phenyl]diazenyl]-2-methyl-isothiazolium (4). These diazahemicyanine dyes are calculated to have a similar low-energy structure that is cis, trans at the (iso)thiazolium-azo group, and for which the calculated Raman spectra provide a good match with the experimental data; the calculations on these structures are used to assign and discuss the transitions giving rise to the experimental spectra, and to consider the bonding and its variation between the dyes. UV-visible, Raman, and NMR spectra recorded from minutes to several weeks after raising the pH of an aqueous solution of 1a to ca. 11.5 show that the dominant initial step in the reaction is loss of diethylamine to produce a quinonimine (ca. hours), with subsequent reactions occurring on longer time scales (ca. days to weeks); kinetic analyses give a rate constant of 2.6 × 10(-2) dm(3) mol(-1) s(-1) for reaction of 1a with OH(-). UV-visible spectra recorded on raising the pH of the other dyes in solution show similar changes that are attributed to the same general reaction mechanism, but with different rate constants for which the dependence on structure is discussed.

  5. Rydberg and π-π* transitions in film surfaces of various kinds of nylons studied by attenuated total reflection far-ultraviolet spectroscopy and quantum chemical calculations: peak shifts in the spectra and their relation to nylon structure and hydrogen bondings.

    Science.gov (United States)

    Morisawa, Yusuke; Yasunaga, Manaka; Sato, Harumi; Fukuda, Ryoichi; Ehara, Masahiro; Ozaki, Yukihiro

    2014-10-09

    Attenuated total reflection far-ultraviolet (ATR-FUV) spectra in the 145-260 nm region were measured for surfaces (thickness 50-200 nm) of various kinds of nylons in cast films to explore their electronic transitions in the FUV region. ATR-FUV spectra show two major bands near 150 and 200 nm in the surface condensed phase of nylons. Transmittance (Tr) spectra were also observed in particular for the analysis of valence excitations. Time-dependent density functional theory (TD-DFT/CAM-B3LYP) calculations were carried out using the model systems to provide the definitive assignments of their absorption spectra and to elucidate their peak shifts in several nylons, in particular, focusing on their crystal alignment structures and intermolecular hydrogen bondings. Two major bands of nylon films near 150 and 200 nm are characterized as σ-Rydberg 3p and π-π* transitions of nylons, respectively. These assignments are also coherent with those of liquid n-alkanes (n = 5-14) and liquid amides observed previously. The Rydberg transitions are delocalized over the hydrocarbon chains, while the π-π* transitions are relatively localized at the amide group. Differences in the peak positions and intensity were found in both ATR- and Tr-FUV spectra for different nylons. A red-shift of the π-π* amide band in the FUV spectra of nylon-6 and nylon-6/6 models in α-form is attributed to the crystal structure pattern and the intermolecular hydrogen bondings, which result in the different delocalization character of the π-π* transitions and transition dipole coupling.

  6. 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.

  7. Spectroscopic (FT-IR, FT-Raman, UV absorption, 1H and 13C NMR) and theoretical (in B3LYP/6-311++G** level) studies on alkali metal salts of caffeic acid.

    Science.gov (United States)

    Świsłocka, Renata

    2013-01-01

    The effect of some metals on the electronic system of benzoic and nicotinic acids has recently been investigated by IR, Raman and UV spectroscopy [1-3]. Benzoic and nicotinic acids are regarded model systems representing a wide group of aromatic ligands which are incorporated into enzymes. In this work the FT-IR (in solid state and in solution), FT-Raman, UV absorption and (1)H and (13)C NMR spectra of caffeic acid (3,4-dihydroxycinnamic acid) and its salts with lithium, sodium, potassium, rubidium and caesium were registered, assigned and analyzed. The effect of alkali metals on the electronic system of ligands was discussed. Studies of differences in the number and position of bands from the IR, Raman, UV absorption spectra and chemical shifts from NMR spectra allowed to conclude on the distribution of electronic charge in the molecules, the delocalization energy of π electrons and the reactivity of ligands in metal complexes. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G** basis set. Bond lengths, angles and dipole moments for the optimized structures of caffeic acid and lithium, sodium, potassium caffeinates were also calculated. The theoretical wavenumbers and intensities of IR spectra were obtained. The calculated parameters were compared to the experimental characteristics of investigated compounds. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Vibrational Spectra of Oxo-Centered Trinuclear Carboxylate Complexes

    Science.gov (United States)

    Chaisa-Ard, Nittayaporn

    1990-01-01

    Available from UMI in association with The British Library. The work presented in this thesis has been undertaken with an aim of studying vibrational spectroscopy of oxo -centered trinuclear carboxylate complexes. Resonance Raman spectra of the mixed-metal complex (Fe_2NiO(OOCCH_3 )_6(C_5H _5N)_3) (C _5H_5N) and of the complex (Fe_3O(OOCCH _3)_6(C_5 H_5N)_3) NO_3 have been recorded with different exciting lines. Mode assignments of these complexes have been made in conjunction with previously reported electronic diffuse reflectance spectra. For the (Fe_2 NiO(OOCCH_3)_6 (C_5H_5N) _3) (C_5H _5N) complex we found two components of the vibration nu_ {rm as}(Fe_2NiO) and we assigned the higher frequency as the A_1 component while the lower is the B_2 component. For the (Fe_3O(OOCCH _3)_6(C _5H_5N)_3 ) NO_3 complex we found that there is only a single band at 570 cm^{ -1} and it is visible only with the use of exciting lines below 15500 cm^{-1} . We assigned this band to nu_ {rm as}(Fe_3O), doubly degenerate (E^'). Infrared spectra of (Cr_3O(OOCCH _3)_6(H _2O)_3) Cl.6H _2O were carried out at room and low temperature and inelastic neutron scattering spectra at 20 K. INS spectra of the (Cr_3O(OOCCH _3)_6(H_2 O)_3) Cl.6H_2 O and three related complexes with the Fe _3^{III} and mixed-valence Fe_2^{III}Fe ^{II} cluster show a large number of well-resolved peaks throughout the frequency range of conventional vibrational spectroscopy, and the frequencies agree with IR and Raman measurements. As a result the mode assignments in this series of compounds can be reassessed. Synthesis and characterisation of the guanidinium salt of the mu_3-oxo hexapropionato trifluoro chromium(III) complex, (Cr_3O(OOCC _2H_5) _6F_3) (C(NH _2)_3) _2 have been done. Elemental analysis was satisfactory. Mode assignments were studied by spectroscopic methods, and the Cr-F stretching frequency was found. Finally, the structure determination was done by X-ray crystallography. The space group was found

  9. Temperature-dependent vibrational spectra and structure of liquid water from classical and quantum simulations with the MB-pol potential energy function

    Science.gov (United States)

    Reddy, Sandeep K.; Moberg, Daniel R.; Straight, Shelby C.; Paesani, Francesco

    2017-12-01

    The structure of liquid water as a function of temperature is investigated through the modeling of infrared and Raman spectra along with structural order parameters calculated from classical and quantum molecular dynamics simulations with the MB-pol many-body potential energy function. The magnitude of nuclear quantum effects is also monitored by comparing the vibrational spectra obtained from classical and centroid molecular dynamics, both in intensities and peak positions. The observed changes in spectral activities are shown to reflect changes in the underlying structure of the hydrogen-bond network and are found to be particularly sensitive to many-body effects in the representation of the electrostatic interactions. Overall, good agreement is found with the experimental spectra, which provides further evidence for the accuracy of MB-pol in predicting the properties of water.

  10. Degree of conversion of two-step etch-and-rinse adhesives: In situ micro-Raman analysis.

    Science.gov (United States)

    Navarra, Chiara Ottavia; Breschi, Lorenzo; Turco, Gianluca; Diolosà, Marina; Fontanive, Luca; Manzoli, Lucia; Di Lenarda, Roberto; Cadenaro, Milena

    2012-09-01

    DC of three commercial two-step etch-and-rinse adhesives across the dentine-adhesive interface was investigated using micro-Raman spectroscopy. The hypothesis tested was that no difference in DC would exist among the adhesives tested. Adper Scotchbond 1XT (3M ESPE), Prime&Bond NT (Dentsply DeTrey), and Ambar (FGM) were applied on human dentine disks (n=9). Composite increments of 2mm were then applied on the adhesive surface. Raman spectra were collected along the dentine-adhesive interface. The relative intensities of the peaks associated with the mineral (PO(4)(3-) at 960cm(-1)) and the adhesive (CC at 1640cm(-1); phenyl CC at 1610cm(-1)) were used to identify the adhesive within the hybrid layer and calculate its DC. Adper Scotchbond 1XT and Ambar showed similar DC (79±7% and 77±7%, respectively), while a lower DC was found for Prime&Bond NT (70±7%; pAmbar performed significantly better than Prime&Bond NT. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Standoff ultracompact micro-Raman sensor for planetary surface explorations.

    Science.gov (United States)

    Abedin, M Nurul; Bradley, Arthur T; Misra, Anupam K; Bai, Yingxin; Hines, Glenn D; Sharma, Shiv K

    2018-01-01

    We report the development of an innovative standoff ultracompact micro-Raman instrument that would solve some of the limitations of traditional micro-Raman systems to provide a superior instrument for future NASA missions. This active remote sensor system, based on a 532 nm laser and a miniature spectrometer, is capable of inspection and identification of minerals, organics, and biogenic materials within several centimeters (2-20 cm) at a high 10 μm resolution. The sensor system is based on inelastic (Raman) light scattering and laser-induced fluorescence. We report on micro-Raman spectroscopy development and demonstration of the standoff Raman measurements by acquiring Raman spectra in daylight at a 10 cm target distance with a small line-shaped laser spot size of 17.3 μm (width) by 5 mm (height).

  12. UV Resonant Raman Spectrometer with Multi-Line Laser Excitation

    Science.gov (United States)

    Lambert, James L.; Kohel, James M.; Kirby, James P.; Morookian, John Michael; Pelletier, Michael J.

    2013-01-01

    A Raman spectrometer employs two or more UV (ultraviolet) laser wavel engths to generate UV resonant Raman (UVRR) spectra in organic sampl es. Resonant Raman scattering results when the laser excitation is n ear an electronic transition of a molecule, and the enhancement of R aman signals can be several orders of magnitude. In addition, the Ra man cross-section is inversely proportional to the fourth power of t he wavelength, so the UV Raman emission is increased by another fact or of 16, or greater, over visible Raman emissions. The Raman-scatter ed light is collected using a high-resolution broadband spectrograph . Further suppression of the Rayleigh-scattered laser light is provi ded by custom UV notch filters.

  13. Lanthanum trilactate: Vibrational spectroscopic study - infrared/Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Švecová, M.; Novák, Vít; Bartůněk, V.; Člupek, M.

    2016-01-01

    Roč. 87, Nov (2016), s. 123-128 ISSN 0924-2031 Institutional support: RVO:61388963 Keywords : lanthanum trilactate * tris(2-hydroxypropanoato-O1,O2) * lanthanum tris[2-(hydroxy-kappa O)propanoato-kappa O] * Raman spectra * infrared spectra * DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.740, year: 2016

  14. Surface-enhanced Raman scattering of a Ag/oligo(phenyleneethynylene)/Ag sandwich.

    Science.gov (United States)

    Fletcher, Melissa; Alexson, D M; Prokes, Sharka; Glembocki, Orest; Vivoni, Alberto; Hosten, Charles

    2011-02-01

    α,ω-Dithiols are a useful class of compounds in molecular electronics because of their ability to easily adsorb to two metal surfaces, producing a molecular junction. We have prepared Ag nanosphere/oligo(phenyleneethynylene)/Ag sol (AgNS/OPE/Ag sol) and Ag nanowire/oligo(phenyleneethynylene)/Ag sol (AgNW/OPE/Ag sol) sandwiches to simulate the architecture of a molecular electronic device. This was achieved by self-assembly of OPE on the silver nanosurface, deprotection of the terminal sulfur, and deposition of Ag sol atop the monolayer. These sandwiches were then characterized by surface-enhanced Raman scattering (SERS) spectroscopy. The resulting spectra were compared to the bulk spectrum of the dimer and to the Ag nanosurface/OPE SERS spectra. The intensities of the SERS spectra in both systems exhibit a strong dependence on Ag deposition time and the results are also suggestive of intense interparticle coupling of the electromagnetic fields in both the AgNW/OPE/Ag and the AgNS/OPE/Ag systems. Three previously unobserved bands (1219, 1234, 2037 cm(-1)) arose in the SER spectra of the sandwiches and their presence is attributed to the strong enhancement of the electromagnetic field which is predicted from the COSMOL computational package. The 544 cm(-1) disulfide bond which is observed in the spectrum of solid OPE but is absent in the AgNS/OPE/Ag and AgNW/OPE/Ag spectra is indicative of chemisorption of OPE to the nanoparticles through oxidative dissociation of the disulfide bond. Copyright © 2010 Elsevier B.V. All rights reserved.

  15. Raman spectroscopic study of plasma-treated salmon DNA

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Geon Joon; Kim, Yong Hee; Choi, Eun Ha [Plasma Bioscience Research Center, Kwangwoon University, Seoul 139-701 (Korea, Republic of); Kwon, Young-Wan [Department of Chemistry, Korea University, Seoul 136-701 (Korea, Republic of)

    2013-01-14

    In this research, we studied the effect of plasma treatment on the optical/structural properties of the deoxyribonucleic acid (DNA) extracted from salmon sperm. DNA-cetyltrimethylammonium (CTMA) films were obtained by complexation of DNA with CTMA. Circular dichroism (CD) and Raman spectra indicated that DNA retained its double helical structure in the solid film. The Raman spectra exhibited several vibration modes corresponding to the nuclear bases and the deoxyribose-phosphate backbones of the DNA, as well as the alkylchains of CTMA. Dielectric-barrier-discharge (DBD) plasma treatment induced structural modification and damage to the DNA, as observed by changes in the ultraviolet-visible absorption, CD, and Raman spectra. The optical emission spectra of the DBD plasma confirmed that DNA modification was induced by plasma ions such as reactive oxygen species and reactive nitrogen species.

  16. ULTRAVIOLET RAMAN SPECTRAL SIGNATURE ACQUISITION: UV RAMAN SPECTRAL FINGERPRINTS.

    Energy Technology Data Exchange (ETDEWEB)

    SEDLACEK,III, A.J.FINFROCK,C.

    2002-09-01

    As a member of the science-support part of the ITT-lead LISA development program, BNL is tasked with the acquisition of UV Raman spectral fingerprints and associated scattering cross-sections for those chemicals-of-interest to the program's sponsor. In support of this role, the present report contains the first installment of UV Raman spectral fingerprint data on the initial subset of chemicals. Because of the unique nature associated with the acquisition of spectral fingerprints for use in spectral pattern matching algorithms (i.e., CLS, PLS, ANN) great care has been undertaken to maximize the signal-to-noise and to minimize unnecessary spectral subtractions, in an effort to provide the highest quality spectral fingerprints. This report is divided into 4 sections. The first is an Experimental section that outlines how the Raman spectra are performed. This is then followed by a section on Sample Handling. Following this, the spectral fingerprints are presented in the Results section where the data reduction process is outlined. Finally, a Photographs section is included.

  17. Raman Optical Activity of Biological Molecules

    Science.gov (United States)

    Blanch, Ewan W.; Barron, Laurence D.

    Now an incisive probe of biomolecular structure, Raman optical activity (ROA) measures a small difference in Raman scattering from chiral molecules in right- and left-circularly polarized light. As ROA spectra measure vibrational optical activity, they contain highly informative band structures sensitive to the secondary and tertiary structures of proteins, nucleic acids, viruses and carbohydrates as well as the absolute configurations of small molecules. In this review we present a survey of recent studies on biomolecular structure and dynamics using ROA and also a discussion of future applications of this powerful new technique in biomedical research.

  18. Raman microspectroscopy of optically trapped micro- and nanoobjects

    Science.gov (United States)

    Jonáš, Alexandr; Ježek, Jan; Šerý, Mojmír; Zemánek, Pavel

    2008-12-01

    We describe and characterize an experimental system for Raman microspectroscopy of micro- and nanoobjects optically trapped in aqueous suspensions with the use of a single-beam gradient optical trap (Raman tweezers). This system features two separate lasers providing light for the optical trapping and excitation of the Raman scattering spectra from the trapped specimen, respectively. Using independent laser beams for trapping and spectroscopy enables optimizing the parameters of both beams for their respective purposes. Moreover, it is possible to modulate the position of the trapped object relative to the Raman beam focus for maximizing the detected Raman signal and obtaining spatially resolved images of the trapped specimen. Using this experimental system, we have obtained Raman scattering spectra of individual optically confined micron and sub-micron sized polystyrene beads and baker's yeast cells. Sufficiently high signal-to-noise ratio of the spectra could be achieved using a few tens of milliwatts of the Raman beam power and detector integration times on the order of seconds.

  19. 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.

  20. Raman exfoliative cytology for oral precancer diagnosis

    Science.gov (United States)

    Sahu, Aditi; Gera, Poonam; Pai, Venkatesh; Dubey, Abhishek; Tyagi, Gunjan; Waghmare, Mandavi; Pagare, Sandeep; Mahimkar, Manoj; Murali Krishna, C.

    2017-11-01

    Oral premalignant lesions (OPLs) such as leukoplakia, erythroplakia, and oral submucous fibrosis, often precede oral cancer. Screening and management of these premalignant conditions can improve prognosis. Raman spectroscopy has previously demonstrated potential in the diagnosis of oral premalignant conditions (in vivo), detected viral infection, and identified cancer in both oral and cervical exfoliated cells (ex vivo). The potential of Raman exfoliative cytology (REC) in identifying premalignant conditions was investigated. Oral exfoliated samples were collected from healthy volunteers (n=20), healthy volunteers with tobacco habits (n=20), and oral premalignant conditions (n=27, OPL) using Cytobrush. Spectra were acquired using Raman microprobe. Spectral acquisition parameters were: λex: 785 nm, laser power: 40 mW, acquisition time: 15 s, and average: 3. Postspectral acquisition, cell pellet was subjected to Pap staining. Multivariate analysis was carried out using principal component analysis and principal component-linear discriminant analysis using both spectra- and patient-wise approaches in three- and two-group models. OPLs could be identified with ˜77% (spectra-wise) and ˜70% (patient-wise) sensitivity in the three-group model while with 86% (spectra-wise) and 83% (patient-wise) in the two-group model. Use of histopathologically confirmed premalignant cases and better sampling devices may help in development of improved standard models and also enhance the sensitivity of the method. Future longitudinal studies can help validate potential of REC in screening and monitoring high-risk populations and prognosis prediction of premalignant lesions.

  1. Use of low-frequency Raman spectroscopy and chemometrics for the quantification of crystallinity in amorphous griseofulvin tablets

    DEFF Research Database (Denmark)

    Mah, Pei T.; Fraser, Sara J.; Reish, Matthew E.

    2015-01-01

    drug is quantified using low-frequency Raman spectroscopy in concert with chemometrics for the first time. Importantly, these data are directly compared to simultaneously obtained mid-frequency Raman spectra, as well as to FT-Raman data, which is commonly used for such quantification. Griseofulvin...

  2. Analysis of phthalate ester content in poly(vinyl chloride) plastics by means of Fourier transform Raman spectroscopy

    DEFF Research Database (Denmark)

    Nørbygaard, Thomas; Berg, Rolf W.

    2004-01-01

    Fourier transform (FT) Raman spectroscopy is applied to a range of phthalate ester plasticizers in pure form as well as in poly(vinyl chloride) (PVC) samples. It is found that phthalate esters as a group can be identified by a set of six characteristic Raman bands. FT-Raman spectra of 22 phthalate...

  3. Comparison of UV and visible Raman spectroscopy of bulk metal molybdate and metal vanadate catalysts.

    Science.gov (United States)

    Tian, Hanjing; Wachs, Israel E; Briand, Laura E

    2005-12-15

    The visible (532 and 442 nm) and UV (325 nm) Raman spectra of bulk mixed metal oxides (metal molybdates and metal vanadates) were compared on the same spectrometer, for the first time, to allow examination of how varying the excitation energy from visible to UV affects the resulting Raman spectra. The quality of the Raman spectra was found to be a strong function of the absorption properties of the bulk mixed oxide. For bulk mixed metal oxides that absorb weakly in the visible and UV regions, both the visible and UV Raman spectra were of high quality and exhibit identical vibrational bands, but with slightly different relative intensities. For bulk mixed metal oxides that absorb strongly in the UV and visible regions and/or strongly in the UV and weakly in the visible regions, the visible Raman spectra are much richer in structural information and of higher resolution than the corresponding UV Raman spectra. This is a consequence of the strong UV absorption that significantly reduces the sampling volume and number of scatterers giving rise to the Raman signal. The shallower escape depth of UV Raman, however, was not sufficient to detect vibrations from the surface metal oxide species that are present on the outermost surface layer of these crystalline mixed metal oxide phases as previously suggested. It was also demonstrated that there is no sample damage by the more energetic UV excitation when very low laser powers and fast detectors are employed, thus avoiding the need of complicated fluidized bed sample arrangements sometimes used for UV Raman investigations. The current comparative Raman investigation carefully documents, for the first time, the advantages and disadvantages of applying different excitation energies in collecting Raman spectra of bulk mixed metal oxide materials.

  4. 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

  5. Molecular structure, spectroscopic (FTIR, FT-Raman, 13C and 1H NMR, UV), polarizability and first-order hyperpolarizability, HOMO-LUMO analysis of 2,4-difluoroacetophenone.

    Science.gov (United States)

    Jeyavijayan, S

    2015-02-05

    The FTIR and FT-Raman spectra of 2,4-difluoroacetophenone (DFAP) have been recorded in the regions 4000-400 cm(-1) and 3500-50 cm(-1), respectively. Utilizing the observed FTIR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compound were carried out. The optimum molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities, were calculated by density functional theory (DFT/B3LYP) method with 6-31+G(d,p) and 6-311++G(d,p) basis sets. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. A detailed interpretation of the infrared and Raman spectra of DFAP is also reported based on total energy distribution (TED). Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The MEP map shows the negative potential sites are on oxygen atom as well as the positive potential sites are around the hydrogen atoms. The UV-Vis spectral analysis of DFAP has also been done which confirms the charge transfer of DFAP. The chemical shifts of H atoms and C atoms were calculated using NMR analysis. Furthermore, the polarizability, the first hyperpolarizability and total dipole moment of the molecule have been calculated. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. NIR Raman spectroscopy in medicine and biology: results and aspects

    Science.gov (United States)

    Schrader, B.; Dippel, B.; Erb, I.; Keller, S.; Löchte, T.; Schulz, H.; Tatsch, E.; Wessel, S.

    1999-05-01

    Analyses of biomaterial by 'classical' Raman spectroscopy with excitation in the visible range has not been possible since the fluorescence of many essential constituents of all animal and plant cells and tissues overlays the Raman spectra completely. Fluorescence, however, is virtually avoided, when Raman spectra are excited with the Nd : YAG laser line at 1064 nm. Within seven dissertations we explored different fields of potential applications to medical diagnostics. Identification and qualification of tissues and cells is possible. Tumors show small but significant differences to normal tissues; in order to develop a reliable tool for tumor diagnostics more research is necessary, especially a collection of reference spectra in a data bank is needed. Raman spectra of biomineralization structures in teeth and bones show pathological tissues as well as the development of new mineralized structures. NIR Raman spectra of flowers, leaves, and fruit show, without special preparation, their constituents: alkaloids, the essential oils, natural dyes, flavors, spices and drugs. They allow application to taxonomy, optimizing plant breeding and control of food.

  7. The spectroscopic (FT-IR, FT-IR gas phase, FT-Raman and UV) and NBO analysis of 4-Hydroxypiperidine by density functional method.

    Science.gov (United States)

    Sebastian, S; Sundaraganesan, N

    2010-03-01

    In this work, we report a combined experimental and theoretical study on molecular structure, vibrational spectra, NBO and UV-spectral analysis of 4-Hydroxypiperidine (4-HP). The FT-IR solid phase (4000-400 cm(-1)), FT-IR gas phase (5000-400 cm(-1)) and FT-Raman spectra (3500-50 cm(-1)) of 4-HP was recorded. The molecular geometry, harmonic vibrational frequencies and bonding features of 4-HP in the ground-state have been calculated by using the density functional methods (BLYP, B3LYP) with 6-311G (d,p) as basis set. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the Scaled Quantum Mechanical Force Field Methodology (SQMFF). Stability of the molecule arising from hyperconjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The results show that charge in electron density (ED) in the sigma* antibonding orbitals and E (2) energies confirms the occurrence of ICT (Intra-molecular Charge Transfer) within the molecule. The UV spectrum was measured in ethanol solution. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) result complements the experimental findings. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Finally the calculation results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra. Copyright 2009 Elsevier B.V. All rights reserved.

  8. Surface-Enhanced Raman Scattering Nanoparticles as Optical Labels for Imaging Cell Surface Proteins

    Science.gov (United States)

    MacLaughlin, Christina M.

    Assaying the expression of cell surface proteins has widespread application for characterizing cell type, developmental stage, and monitoring disease transformation. Immunophenotyping is conducted by treating cells with labelled targeting moieties that have high affinity for relevant surface protein(s). The sensitivity and specificity of immunophenotyping is defined by the choice of contrast agent and therefore, the number of resolvable signals that can be used to simultaneously label cells. Narrow band width surface-enhanced Raman scattering (SERS) nanoparticles are proposed as optical labels for multiplexed immunophenotying. Two types of surface coatings were investigated to passivate the gold nanoparticles, incorporate SERS functionality, and to facilitate attachment of targeting antibodies. Thiolated poly(ethylene glycol) forms dative bonds with the gold surface and is compatible with multiple physisorbed Raman-active reporter molecules. Ternary lipid bilayers are used to encapsulate the gold nanoparticles particles, and incorporate three different classes of Raman reporters. TEM, UV-Visible absorbance spectroscopy, DLS, and electrophoretic light scattering were used characterize the particle coating. Colourimetric protein assay, and secondary antibody labelling were used to quantify the antibody conjugation. Three different in vitromodels were used to investigate the binding efficacy and specificity of SERS labels for their biomarker targets. Primary human CLL cells, LY10 B lymphoma, and A549 adenocarcinoma lines were targeted. Dark field imaging was used to visualize the colocalization of SERS labels with cells, and evidence of receptor clustering was obtained based on colour shifts of the particles' Rayleigh scattering. Widefield, and spatially-resolved Raman spectra were used to detect labels singly, and in combination from labelled cells. Fluorescence flow cytometry was used to test the particles' binding specificity, and SERS from labelled cells was also

  9. Surface-enhanced Raman spectroscopy of double-shell hollow nanoparticles: electromagnetic and chemical enhancements.

    Science.gov (United States)

    Mahmoud, Mahmoud A

    2013-05-28

    Enhancements of the Raman signal by the newly prepared gold-palladium and gold-platinum double-shell hollow nanoparticles were examined and compared with those using gold nanocages (AuNCs). The surface-enhanced Raman spectra (SERS) of thiophenol adsorbed on the surface of AuNCs assembled into a Langmuir-Blodgett monolayer were 10-fold stronger than AuNCs with an inner Pt or Pd shell. The chemical and electromagnetic enhancement mechanisms for these hollow nanoparticles were further proved by comparing the Raman enhancement of nitrothiophenol and nitrotoulene. Nitrothiophenol binds to the surface of the nanoparticles by covalent interaction, and Raman enhancement by both the two mechanisms is possible, while nitrotoulene does not form any chemical bond with the surface of the nanoparticles and hence no chemical enhancement is expected. Based on discrete dipole approximation (DDA) calculations and the experimental SERS results, AuNCs introduced a high electromagnetic enhancement, while the nanocages with inner Pt or Pd shell have a strong chemical enhancement. The optical measurements of the localized surface plasmon resonance (LSPR) of the nanocages with an outer Au shell and an inner Pt or Pd shell were found, experimentally and theoretically, to be broad compared with AuNCs. The possible reason could be due to the decrease of the coherence time of Au oscillated free electrons and fast damping of the plasmon energy. This agreed well with the fact that a Pt or Pd inner nanoshell decreases the electromagnetic field of the outer Au nanoshell while increasing the SERS chemical enhancement.

  10. Evidence of low intermolecular coupling in rubrene single crystals by Raman scattering

    International Nuclear Information System (INIS)

    Weinberg-Wolf, J R; McNeil, L E; Liu Shubin; Kloc, Christian

    2007-01-01

    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 π-electron overlap in this material

  11. Development of a multiplexing fingerprint and high wavenumber Raman spectroscopy technique for real-time in vivo tissue Raman measurements at endoscopy

    Science.gov (United States)

    Bergholt, Mads Sylvest; Zheng, Wei; Huang, Zhiwei

    2013-03-01

    We report on the development of a novel multiplexing Raman spectroscopy technique using a single laser light together with a volume phase holographic (VPH) grating that simultaneously acquires both fingerprint (FP) and high wavenumber (HW) tissue Raman spectra at endoscopy. We utilize a customized VPH dual-transmission grating, which disperses the incident Raman scattered light vertically onto two separate segments (i.e., -150 to 1950 cm-1 1750 to 3600 cm-1) of a charge-coupled device camera. We demonstrate that the multiplexing Raman technique can acquire high quality in vivo tissue Raman spectra ranging from 800 to 3600 cm-1 within 1.0 s with a spectral resolution of 3 to 6 cm-1 during clinical endoscopy. The rapid multiplexing Raman spectroscopy technique covering both FP and HW ranges developed in this work has potential for improving in vivo tissue diagnosis and characterization at endoscopy.

  12. Development of a multiplexing fingerprint and high wavenumber Raman spectroscopy technique for real-time in vivo tissue Raman measurements at endoscopy.

    Science.gov (United States)

    Bergholt, Mads Sylvest; Zheng, Wei; Huang, Zhiwei

    2013-03-01

    We report on the development of a novel multiplexing Raman spectroscopy technique using a single laser light together with a volume phase holographic (VPH) grating that simultaneously acquires both fingerprint (FP) and high wavenumber (HW) tissue Raman spectra at endoscopy. We utilize a customized VPH dual-transmission grating, which disperses the incident Raman scattered light vertically onto two separate segments (i.e., -150 to 1950  cm⁻¹; 1750 to 3600  cm⁻¹) of a charge-coupled device camera. We demonstrate that the multiplexing Raman technique can acquire high quality in vivo tissue Raman spectra ranging from 800 to 3600  cm⁻¹ within 1.0 s with a spectral resolution of 3 to 6  cm⁻¹ during clinical endoscopy. The rapid multiplexing Raman spectroscopy technique covering both FP and HW ranges developed in this work has potential for improving in vivo tissue diagnosis and characterization at endoscopy.

  13. Cyclic Organic Peroxides Characterization by Mass Spectrometry and Raman Microscopy

    Science.gov (United States)

    2011-04-01

    included d -ace- tone (99% isotope), acetone, cyclopentanone, hexamethylene tetraamine, benzoyl peroxide (98% w/w), and formaldehyde (CH O, 37% wt...absorption of the N-H stretching at 3336 cm in FTIR absorption and 3346 cm in Raman scattering [40], [41]. Urea has a strong carbonyl absorption in the range...demonstrate the presence of a carbonyl group. The corresponding Raman signal was observed about 1650–1770 cm . Characterization of the nitrogen-carbon bond

  14. Structure and property investigations of TDO in aqueous phase by density functional theory, UV absorption, and Raman spectroscopy.

    Science.gov (United States)

    Shao, Jianzhong; Liu, Xiaoyun; Chen, Pin; Wu, Qiuxia; Zheng, Xuming; Pei, Kemei

    2014-05-01

    Density functional theory, UV absorption, and Raman spectroscopy are used to investigate the structure and properties of TDO in aqueous solution. The equilibrium structures, UV absorption spectra, interaction energies, and Raman spectroscopy data of TDO, AIMSA, and 12 TDO or AIMSA clusters are calculated. Raman spectroscopy experiments are carried out by 488 and 208 nm laser excitation. The Raman spectra of TDO in solid and aqueous phases have been compared, and the most possible structure for TDO in aqueous phase was deduced from analysis of the DFT calculations for the examined models, the experimental UV absorption spectrum, and Raman spectra of TDO. The interaction energy results show that TDO's solubility in water is originated from the TDO-water cyclic oligomer. The calculated UV absorption and Raman spectra of the I2·2H2O-cyc cluster model agree with the experimental results of TDO in aqueous solution very well.

  15. Raman scattering of rare earth hexaborides

    International Nuclear Information System (INIS)

    Ogita, Norio; Hasegawa, Takumi; Udagawa, Masayuki; Iga, Fumitoshi; Kunii, Satoru

    2009-01-01

    Raman scattering spectra were measured for the rare-earth hexaborides RB 6 (R = Ce, Gd, or Dy). All Raman-active phonons due to B 6 vibrations were observed in the range 600 - 1400 cm -1 . Anomalous peaks were detected below 200 cm -1 , which correspond to vibrations of rare-earth ion excited by second-order Raman scattering process. The intensity and energy of the rare-earth mode decrease with decreasing temperature. This suggests that the rare-earth ion vibrates in a shallow and anharmonic potential due to the boron cage. Using the reported values of mean square displacement of rare-earth ion, we estimated the anharmonic contribution for the rare-earth vibrations.

  16. Diazonium-derived aryl films on gold nanoparticles: evidence for a carbon-gold covalent bond.

    Science.gov (United States)

    Laurentius, Lars; Stoyanov, Stanislav R; Gusarov, Sergey; Kovalenko, Andriy; Du, Rongbing; Lopinski, Gregory P; McDermott, Mark T

    2011-05-24

    Tailoring the surface chemistry of metallic nanoparticles is generally a key step for their use in a wide range of applications. There are few examples of organic films covalently bound to metal nanoparticles. We demonstrate here that aryl films are formed on gold nanoparticles from the spontaneous reduction of diazonium salts. The structure and the bonding of the film is probed with surface-enhanced Raman scattering (SERS). Extinction spectroscopy and SERS show that a nitrobenzene film forms on gold nanoparticles from the corresponding diazonium salt. Comparison of the SERS spectrum with spectra computed from density functional theory models reveals a band characteristic of a Au-C stretch. The observation of this stretch is direct evidence of a covalent bond. A similar band is observed in high-resolution electron energy loss spectra of nitrobenzene layers on planar gold. The bonding of these types of films through a covalent interaction on gold is consistent with their enhanced stability observed in other studies. These findings provide motivation for the use of diazonium-derived films on gold and other metals in applications where high stability and/or strong adsorbate-substrate coupling are required.

  17. 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 ...

  18. Polarized Raman spectroscopy of chemically vapour deposited diamond films

    International Nuclear Information System (INIS)

    Prawer, S.; Nugent, K.W.; Weiser, P.S.

    1994-01-01

    Polarized micro-Raman spectra of chemically vapour deposited diamond films are presented. It is shown that important parameters often extracted from the Raman spectra such as the ratio of the diamond to non-diamond component of the films and the estimation of the level of residual stress depend on the orientation of the diamond crystallites with respect to the polarization of the incident laser beam. The dependence originates from the fact that the Raman scattering from the non-diamond components in the films is almost completely depolarized whilst the scattering from the diamond components is strongly polarized. The results demonstrate the importance of taking polarization into account when attempting to use Raman spectroscopy in even a semi-quantitative fashion for the assessment of the purity, perfection and stress in CVD diamond films. 8 refs., 1 tab. 2 figs

  19. Dome C ultracarbonaceous Antarctic micrometeorites. Infrared and Raman fingerprints

    Science.gov (United States)

    Dartois, E.; Engrand, C.; Duprat, J.; Godard, M.; Charon, E.; Delauche, L.; Sandt, C.; Borondics, F.

    2018-01-01

    Context. UltraCarbonaceous Antarctic MicroMeteorites (UCAMMs) represent a small fraction of interplanetary dust particles reaching the Earth's surface and contain large amounts of an organic component not found elsewhere. They are most probably sampling a contribution from the outer regions of the solar system to the local interplanetary dust particle (IDP) flux. Aims: We characterize UCAMMs composition focusing on the organic matter, and compare the results to the insoluble organic matter (IOM) from primitive meteorites, IDPs, and the Earth. Methods: We acquired synchrotron infrared microspectroscopy (μFTIR) and μRaman spectra of eight UCAMMs from the Concordia/CSNSM collection, as well as N/C atomic ratios determined with an electron microprobe. Results: The spectra are dominated by an organic component with a low aliphatic CH versus aromatic C=C ratio, and a higher nitrogen fraction and lower oxygen fraction compared to carbonaceous chondrites and IDPs. The UCAMMs carbonyl absorption band is in agreement with a ketone or aldehyde functional group. Some of the IR and Raman spectra show a C≡N band corresponding to a nitrile. The absorption band profile from 1400 to 1100 cm-1 is compatible with the presence of C-N bondings in the carbonaceous network, and is spectrally different from that reported in meteorite IOM. We confirm that the silicate-to-carbon content in UCAMMs is well below that reported in IDPs and meteorites. Together with the high nitrogen abundance relative to carbon building the organic matter matrix, the most likely scenario for the formation of UCAMMs occurs via physicochemical mechanisms taking place in a cold nitrogen rich environment, like the surface of icy parent bodies in the outer solar system. The composition of UCAMMs provides an additional hint of the presence of a heliocentric positive gradient in the C/Si and N/C abundance ratios in the solar system protoplanetary disc evolution. Part of the equipment used in this work has been

  20. Transformation of multiwall carbon nanotubes to onions with layers cross-linked by sp3 bonds under high pressure and shear deformation

    Directory of Open Access Journals (Sweden)

    A. M. Pankov

    2017-08-01

    Full Text Available A pressure-induced phase transition of multiwall carbon nanotubes (MWNT to a new structure at room temperature is studied using a shear diamond anvil cell, X-ray photoelectron spectra (XPS, transmission electron microscope (TEM and Raman procedures. We observe a cardinal pressure-induced change in the nanoparticles shape from multi-shell tubes to multi-shell spheres. MWNT transforms to onions with layers cross-linked by sp3 bonds under the 45-65 GPa compressive stress combined with shear deformation at room temperature. TEM and XPS results show that about 40% of the carbon atoms in the new phase are sp3-bounded.

  1. Transformation of multiwall carbon nanotubes to onions with layers cross-linked by sp3 bonds under high pressure and shear deformation

    Science.gov (United States)

    Pankov, A. M.; Bredikhina, A. S.; Kulnitskiy, B. A.; Perezhogin, I. A.; Skryleva, E. A.; Parkhomenko, Yu. N.; Popov, M. Yu.; Blank, V. D.

    2017-08-01

    A pressure-induced phase transition of multiwall carbon nanotubes (MWNT) to a new structure at room temperature is studied using a shear diamond anvil cell, X-ray photoelectron spectra (XPS), transmission electron microscope (TEM) and Raman procedures. We observe a cardinal pressure-induced change in the nanoparticles shape from multi-shell tubes to multi-shell spheres. MWNT transforms to onions with layers cross-linked by sp3 bonds under the 45-65 GPa compressive stress combined with shear deformation at room temperature. TEM and XPS results show that about 40% of the carbon atoms in the new phase are sp3-bounded.

  2. [XPS and Raman spectral analysis of nitrogenated tetrahedral amorphous carbon (ta-C : N) films with different nitrogen content].

    Science.gov (United States)

    Chen, Wang-Shou; Zhu, Jia-Qi; Han, Jie-Cai; Tian, Gui; Tan, Man-Lin

    2009-01-01

    Nitrogenated tetrahedral amorphous carbon (ta-C : N) films were prepared on the polished C--Si substrates by introducing highly pure nitrogen gas into the cathode region and the depositing chamber synchronously using filtered cathodic vacuum arc (FCVA) technology. The nitrogen content in the films was controlled by changing the flow rate of nitrogen gas. The configuration of ta-C : N films was investigated by means of X-ray photoelectron spectroscopy (XPS) and visible Raman spectroscopy. It was shown that the nitrogen content in the films increased from 0.84 at% to 5.37 at% monotonously when the nitrogen flow rate was varied from 2 seem to 20 sccm. The peak position of C (1s) core level moved towards higher binding energy with the increase in nitrogen content. The shift of C (1s) peak position could be ascribed to the chemical bonding between carbon and nitrogen atoms even though more three-fold coordinated sp2 configuration as in graphite was formed when the films were doped with more nitrogen atoms. Additionally, the half width of C(1s) peak gradually was also broadened with increasing nitrogen content. In order to discover clearly the changing regularities of the microstructure of the films, the XPS C(1s) spectra and Raman spectra were deconvoluted using a Gaussian-Lorentzian mixed lineshape. It was shown that the tetrahedral hybridization component was still dominant even though the ratio of sp2/sp3 obtained from C(1s) spectra rose with the increase in nitrogen content. The Raman measurements demonstrated that the G peak position shifted towards higher frequency from 1,561 to 1,578 cm(-1) and the ratio of ID/IG also rose with the increase in nitrogen content. Both results indicated that the graphitizing tendency could occur with the increase in nitrogen content in the films.

  3. Evaluation of bone quality in osteoporosis model mice by Raman spectroscopy

    Science.gov (United States)

    Ishimaru, Yasumitsu; Oshima, Yusuke; Imai, Yuuki; Iimura, Tadahiro; Takanezawa, Sota; Hino, Kazunori; Miura, Hiromasa

    2017-04-01

    To evaluate the bone quality in the osteoporosis, we generated sciatic nerve resection (NX) mice as an osteoporosis model and analyzed by Raman spectroscopy. Raman spectra were measured in anterior cortical surface of the proximal tibia at 5 points in each bone. After that, the samples were fixed with 70% ethanol. We then performed DXA and μCT measurement. Raman peak intensity ratios were significantly different between NX and Control. Those changes in the Raman peak intensity ratios may reflect loss of bone quality in the osteoporosis model. Raman spectroscopy is a promising technique for measuring the bone quality and bone strength.

  4. Raman microprobe analysis during the direct laser writing of silicon microstructures

    International Nuclear Information System (INIS)

    Magnotta, F.; Herman, I.P.

    1986-01-01

    Raman microprobe techniques are used for the first time as a real-time probe during local direct laser writing and also as an in situ probe after writing. The Stokes--Raman emission observed during pyrolytic deposition of micron-dimension structures of silicon on germanium and vitreous carbon substrates is found to be weaker, more asymmetric, and to peak at a smaller Raman shift than the corresponding spectrum of the same structure similarly probed in situ after deposition. Results of detailed post-deposition Raman analysis of these silicon microstructures are presented and compared to the Raman spectra of oven-heated silicon. Potential applications of these techniques are discussed

  5. Fine Structure of the Low-Frequency Raman Phonon Bands of Single-Wall Carbon Nanotubes

    Science.gov (United States)

    Iliev, M. N.; Litvinchuk, A. P.; Arepalli, S.; Nikolaev, P.; Scott, C. D.

    1999-01-01

    The Raman spectra of singled-wall carbon nanotubes (SWNT) produced by laser and are process were studied between 5 and 500 kappa. The line width vs. temperature dependence of the low-frequency Raman bands between 150 and 200/ cm deviates from that expected for phonon decay through phonon-phonon scattering mechanism. The experimental results and their analysis provided convincing evidence that each of the low-frequency Raman lines is a superposition of several narrower Raman lines corresponding to tubes of nearly the same diameter. The application of Raman spectroscopy to probe the distribution of SWNT by both diameter and chirality is discussed.

  6. Normal coordinate analysis and vibrational spectroscopy (FT-IR and FT-Raman) studies of (2S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoic acid using ab initio HF and DFT method

    Science.gov (United States)

    Prabakaran, A.; Muthu, S.

    2012-12-01

    The FT-IR and FT-Raman spectra of (2S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoic acid (2ADMA) were recorded in the region 4000-400 cm-1 and 4000-100 cm-1, respectively. The geometrical structure, harmonic vibrational frequency, infrared intensity, Raman activities and bonding features of this compound was carried out by ab initio HF and DFT methods with 6-31G (d,p) basis set. The complete vibrational frequency assignments were made by normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). The electric dipole moment (μ) and the first-order hyperpolarizability (β0) values have been the computed quantum mechanically. The calculated HOMO and LUMO energies show that, the charge transfer occurs within the molecule. The charge delocalizations of these molecules have been analyzed using NBO analysis. The solvent effects have been calculated using TD-DFT in combination with the polarized continuum model (PCM), and the results are in good agreement with experimental measurements. The other molecular properties like Mulliken population analysis, electrostatic potential (ESP) and thermodynamic properties of the title compound at the different temperatures have been calculated. Finally, the calculation results were applied to simulate infrared and Raman spectra of the title compound which shows good agreement with observed spectra.

  7. Drop coating deposition Raman spectroscopy of proteinogenic amino acids compared with their solution and crystalline state

    Science.gov (United States)

    Pazderka, Tomáš; Kopecký, Vladimír

    2017-10-01

    The Raman spectra of 20 proteinogenic amino acids were recorded in the solution, glass phase (as drop coating deposition Raman (DCDR) samples) and crystalline forms in the wide spectral range of 200-3200 cm- 1. The most apparent spectral differences between the Raman spectra of the crystalline forms, glass phases and aqueous solutions of amino acids were briefly discussed and described in the frame of published works. The possible density dependencies of spectral bands were noted. In some cases, a strong influence of the sample density, as well as of the organization of the water envelope, was observed. The most apparent changes were observed for Ser and Thr. Nevertheless, for the majority of amino acids, the DCDR sample form is an intermediate between the solution and crystalline forms. In contrast, aromatic amino acids have only a small sensitivity to the form of the sample. Our reference set of Raman spectra is useful for revealing discrepancies between the SERS and solid/solution spectra of amino acids. We also found that some previously published Raman spectra of polycrystalline samples resemble glassy state rather than crystalline spectra. Therefore, this reference set of spectra will find application in every branch of Raman spectroscopy where the spectra of biomolecules are collected from coatings.

  8. Modern Trends in Imaging VI: Raman Scattering in Pathology

    Directory of Open Access Journals (Sweden)

    Zachary J. Smith

    2012-01-01

    Full Text Available Raman scattering is the inelastic scattering of light by chemical bonds, and can therefore show molecular specificity. It can be used both in pure spectroscopy mode, and in imaging mode. While many applications of Raman spectroscopy and imaging in the biomedical field have been so far demonstrated, the use of this technology for pathology applications is still in early stages. In this paper we review some of the most important recent developments in this field, including a description of relevant technologies, applications to molecular sensing, characterization of cells and tissues of interest, and disease detection via Raman scattering.

  9. Raman spectroscopic biochemical mapping of tissues

    Science.gov (United States)

    Stone, Nicholas; Hart Prieto, Maria C.; Kendall, Catherine A.; Shetty, Geeta; Barr, Hugh

    2006-02-01

    Advances in technologies have brought us closer to routine spectroscopic diagnosis of early malignant disease. However, there is still a poor understanding of the carcinogenesis process. For example it is not known whether many cancers follow a logical sequence from dysplasia, to carcinoma in situ, to invasion. Biochemical tissue changes, triggered by genetic mutations, precede morphological and structural changes. These can be probed using Raman or FTIR microspectroscopy and the spectra analysed for biochemical constituents. Local microscopic distribution of various constituents can then be visualised. Raman mapping has been performed on a number of tissues including oesophagus, breast, bladder and prostate. The biochemical constituents have been calculated at each point using basis spectra and least squares analysis. The residual of the least squares fit indicates any unfit spectral components. The biochemical distribution will be compared with the defined histopathological boundaries. The distribution of nucleic acids, glycogen, actin, collagen I, III, IV, lipids and others appear to follow expected patterns.

  10. Analysis of human hair by Raman microspectroscopy

    Science.gov (United States)

    Plascencia-Castro, A. S.; Cordova-Fraga, T.; Piña-Ruiz, A. L.; Hernández-Rayas, A.; Bernal, J. J.

    2017-04-01

    Raman microspectroscopy is an optical compound identification technique, which is widely used nowadays for different field applications. A crucial part of this technique is the focus given to the sample in the microscope because it depends on which part of the sample it will analyze. In this work, the effects of irradiating a natural hair samples, obtained from women aged 18 to 55, with a monochromatic light of the Raman spectrometer in two different focus is presented. Two different spectra were obtained with a peak in common. Depending on the information wanted, how the sample is focused plays a crucial role, either way the spectra is information-rich and may be used for biomedical applications.

  11. 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.

  12. Communication: The highest frequency hydrogen bond vibration and an experimental value for the dissociation energy of formic acid dimer

    DEFF Research Database (Denmark)

    Kollipost, F.; Larsen, René Wugt; Domanskaya, A.V.

    2012-01-01

    The highest frequency hydrogen bond fundamental of formic acid dimer, ν24 (Bu), is experimentally located at 264 cm−1. FTIR spectra of this in-plane bending mode of (HCOOH)2 and band centers of its symmetric D isotopologues (isotopomers) recorded in a supersonic slit jet expansion are presented....... Comparison to earlier studies at room temperature reveals the large influence of thermal excitation on the band maximum. Together with three Bu combination states involving hydrogen bond fundamentals and with recent progress for the Raman-active modes, this brings into reach an accurate statistical...... thermodynamics treatment of the dimerization process up to room temperature. We obtain D0 = 59.5(5) kJ/mol as the best experimental estimate for the dimer dissociation energy at 0 K. Further improvements have to wait for a more consistent determination of the room temperature equilibrium constant....

  13. 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.

  14. 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.

  15. Transcutaneous Raman spectroscopy of murine bone in vivo.

    Science.gov (United States)

    Schulmerich, Matthew V; Cole, Jacqueline H; Kreider, Jaclynn M; Esmonde-White, Francis; Dooley, Kathryn A; Goldstein, Steven A; Morris, Michael D

    2009-03-01

    Raman spectroscopy can provide valuable information about bone tissue composition in studies of bone development, biomechanics, and health. In order to study the Raman spectra of bone in vivo, instrumentation that enhances the recovery of subsurface spectra must be developed and validated. Five fiber-optic probe configurations were considered for transcutaneous bone Raman spectroscopy of small animals. Measurements were obtained from the tibia of sacrificed mice, and the bone Raman signal was recovered for each probe configuration. The configuration with the optimal combination of bone signal intensity, signal variance, and power distribution was then evaluated under in vivo conditions. Multiple in vivo transcutaneous measurements were obtained from the left tibia of 32 anesthetized mice. After collecting the transcutaneous Raman signal, exposed bone measurements were collected and used as a validation reference. Multivariate analysis was used to recover bone spectra from transcutaneous measurements. To assess the validity of the transcutaneous bone measurements cross-correlations were calculated between standardized spectra from the recovered bone signal and the exposed bone measurements. Additionally, the carbonate-to-phosphate height ratios of the recovered bone signals were compared to the reference exposed bone measurements. The mean cross-correlation coefficient between the recovered and exposed measurements was 0.96, and the carbonate-to-phosphate ratios did not differ significantly between the two sets of spectra (p > 0.05). During these first systematic in vivo Raman measurements, we discovered that probe alignment and animal coat color influenced the results and thus should be considered in future probe and study designs. Nevertheless, our noninvasive Raman spectroscopic probe accurately assessed bone tissue composition through the skin in live mice.

  16. In vivo Raman spectroscopy of cervix cancers

    Science.gov (United States)

    Rubina, S.; Sathe, Priyanka; Dora, Tapas Kumar; Chopra, Supriya; Maheshwari, Amita; Krishna, C. Murali

    2014-03-01

    Cervix-cancer is the third most common female cancer worldwide. It is the leading cancer among Indian females with more than million new diagnosed cases and 50% mortality, annually. The high mortality rates can be attributed to late diagnosis. Efficacy of Raman spectroscopy in classification of normal and pathological conditions in cervix cancers on diverse populations has already been demonstrated. Our earlier ex vivo studies have shown the feasibility of classifying normal and cancer cervix tissues as well as responders/non-responders to Concurrent chemoradiotherapy (CCRT). The present study was carried out to explore feasibility of in vivo Raman spectroscopic methods in classifying normal and cancerous conditions in Indian population. A total of 182 normal and 132 tumor in vivo Raman spectra, from 63 subjects, were recorded using a fiberoptic probe coupled HE-785 spectrometer, under clinical supervision. Spectra were acquired for 5 s and averaged over 3 times at 80 mW laser power. Spectra of normal conditions suggest strong collagenous features and abundance of non-collagenous proteins and DNA in case of tumors. Preprocessed spectra were subjected to Principal Component-Linear Discrimination Analysis (PCLDA) followed by leave-one-out-cross-validation. Classification efficiency of ~96.7% and 100% for normal and cancerous conditions respectively, were observed. Findings of the study corroborates earlier studies and suggest applicability of Raman spectroscopic methods in combination with appropriate multivariate tool for objective, noninvasive and rapid diagnosis of cervical cancers in Indian population. In view of encouraging results, extensive validation studies will be undertaken to confirm the findings.

  17. Synthesis, spectroscopic (FT-IR, FT-Raman, 13C, 1H, UV) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 2(2-Hydroxyphenyl)-N-(4-Methylphenyl) Nitrone.

    Science.gov (United States)

    Sheela, N R; Sampathkrishnan, S; Thirumalai Kumar, M; Muthu, S

    2013-05-15

    The title compound, 2(2-Hydroxyphenyl)-N-(4-Methylphenyl) Nitrone (2HPN4MPN) was synthesized and characterized by FT-IR, FT-Raman, UV-Vis and (1)HNMR, (13)CNMR spectral analysis. The molecular geometry, harmonic vibrational frequencies and bonding features of the title compound in the ground state are computed at three parameter hybrid functional Lee-Yang-Parr/6-311++G(d,p) levels of theory. The most stable conformer of 2HPN4MPN is identified from the computational results. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMF). The UV-Vis spectrum was recorded in chloroform solution. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) complements the experimental findings. The calculated HOMO and LUMO energies confirm that charge transfer occurs within the molecule. In addition, DFT calculations of the compound, Molecular Electrostatic Potential (MEP), Natural Bond Orbital analysis (NBO) and non-linear optical (NLO) properties are performed at B3LYP/6-311++G(d,p) level of theory. Finally, the calculations are applied to simulated FT-IR and FT-Raman spectra of the title compound which show good agreement with observed spectra. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Infrared spectra of thyroid tumor tissues

    Science.gov (United States)

    Tolstorozhev, G. B.; Skornyakov, I. V.; Butra, V. A.

    2010-07-01

    We used infrared spectroscopy methods to study thyroid tumor tissues removed during surgery. The IR spectra of the surgical material are compared with data from histological examination. We show that in malignant neoplasms, the spectra of proteins in the region of C=O vibrations are different from the spectra of these substances in benign tumors and in tissues outside the pathological focus at a distance >1 cm from the margin of the tumor. The differences in the spectra are due to changes in the supermolecular structure of the proteins, resulting from rearrangement of the system of hydrogen bonds. We identify the spectral signs of malignant pathologies.

  19. Structural changes in cartilage and collagen studied by high temperature Raman spectroscopy.

    Science.gov (United States)

    Fields, Mark; Spencer, Nicholas; Dudhia, Jayesh; McMillan, Paul F

    2017-06-01

    Understanding the high temperature behavior of collagen and collagenous tissue is important for surgical procedures and biomaterials processing for the food, pharmaceutical, and cosmetics industries. One primary event for proteins is thermal denaturation that involves unfolding the polypeptide chains while maintaining the primary structure intact. Collagen in the extracellular matrix of cartilage and other connective tissue is a hierarchical material containing bundles of triple-helical fibers associated with water and proteoglycan components. Thermal analysis of dehydrated collagen indicates irreversible denaturation at high temperature between 135°C and 200°C, with another reversible event at ∼60-80°C for hydrated samples. We report high temperature Raman spectra for freeze-dried cartilage samples that show an increase in laser-excited fluorescence interpreted as conformational changes associated with denaturation above 140°C. Spectra for separated collagen and proteoglycan fractions extracted from cartilage indicate the changes are associated with collagen. The Raman data also show appearance of new features indicating peptide bond hydrolysis at high temperature implying that molecular H 2 O is retained within the freeze-dried tissue. This is confirmed by thermogravimetric analysis that show 5-7 wt% H 2 O remaining within freeze-dried cartilage that is released progressively upon heating up to 200°C. Spectra obtained after exposure to high temperature and re-hydration following recovery indicate that the capacity of the denatured collagen to re-absorb water is reduced. Our results are important for revealing the presence of bound H 2 O within the collagen component of connective tissue even after freeze-drying and its role in denaturation that is accompanied by or perhaps preceded by breakdown of the primary polypeptide structure. © 2017 Wiley Periodicals, Inc.

  20. Analysis of Genomic DNAs from Nine Rosaceae Species Using Surface-Enhanced Raman Scattering.

    Science.gov (United States)

    Lu, Qiu; Lang, Tao; Fan, Shuguo; Chen, Wen; Zang, Deqing; Chen, Jing; Shi, Minzhen

    2015-12-01

    Surface-enhanced Raman scattering (SERS) of genomic DNA was used to determine genetic relationships and species identification of nine plants from three subfamilies of Rosaceae. Genomic DNA was extracted, and the SERS spectra were obtained by using a nanosilver collosol at an excitation wavelength of 785 nm. Adenine and ribodesose were the active sites of genomic DNAs in the silver surface-enhanced Raman spectra. The strong peak at 714 cm(-1) was assigned to the stretching vibration of adenine, the strong peak at 1011cm(-1) contributed to the stretching vibration of the deoxyribose and the scissoring vibrations of cytosine, and the strong peak at 625 cm(-1) is the stretching vibration of glycosidic bond and the scissoring vibrations of guanine. The three-dimensional plot of the first, second, and third principal components showed that the nine species could be classified into three categories (three subfamilies), consistent with the traditional classification. The model of the hierarchical cluster combined with the principal component of the second derivative was more reasonable. The results of the cluster analysis showed that apricot (Prunus armeniaca L.) and cherry (Prunus seudocerasus Lindl.) were clustered into one category (Prunoideae); firethorn (Firethorn fortuneana Li.), loquat (Eriobotrya japonica Lindl.), apple (Malus pumila Mill.), and crabapple (Malus hallianna Koehne.) were clustered into a second category (Pomoideae); and potentilla (Potentilla fulgens Wall.), rose (Rosa chinensis Jacd.), and strawberry (Fragaria chiloensis Duchesne.) were clustered into a third category (Rosoideae). These classifications were in accordance with the traditional classification with a correction rate of clustering of 100%. The correct rate of species identification was 100%. These five main results indicate that the genetic relationship and species identification of nine Rosaceae species could be determined by using SERS spectra of their genomic DNAs.

  1. Quantum fluctuations in the stimulated--Raman-scattering linewidth

    International Nuclear Information System (INIS)

    MacPherson, D.C.; Swanson, R.C.; Carlsten, J.L.

    1988-01-01

    Measurements of the single-shot power spectrum of stimulated Raman scattering from an H 2 Raman generator at 10 and 32 atm using a Fabry-Perot interferometer are presented. The results show that the single-shot linewidth can be much narrower than the ensemble average predicted by quantum mechanics. However, when the spectra of numerous shots are averaged together the resulting linewidth is in close agreement with the predicted result. In addition, the power spectrum exhibits large shot-to-shot fluctuations within the gain-narrowed profile which may be related to observed soliton decay in stimulated Raman scattering

  2. Use of the Raman spectrometer in gemmological laboratories: Review

    Science.gov (United States)

    Kiefert, Lore; Karampelas, Stefanos

    2011-10-01

    The current paper gives an overview of the development of Raman spectrometry in gemmological laboratories. While before 1990s, no commercial gemmological laboratory possessed such an instrument, all larger international labs have acquired these instruments by now. The Raman spectrometer is routinely used for the detection of emerald fillers, HPHT treatment of diamonds, analysis of the nature of a gemstone, analysis of gemstone inclusions and treatments, and the characterisation of natural or colour enhanced pearls and corals. Future developments in gemstone research lie in the closer analysis of the features of Raman and PL spectra and in the combination of several instruments.

  3. Determining the Authenticity of Gemstones Using Raman Spectroscopy

    Science.gov (United States)

    Aponick, Aaron; Marchozzi, Emedio; Johnston, Cynthia R.; Wigal, Carl T.

    1998-04-01

    The benefits of laser spectroscopy in the undergraduate curriculum have been the focus of several recent articles in this journal. Raman spectroscopy has been of particular interest since the similarities of Raman to conventional infrared spectroscopy make the interpretation of spectral data well within undergraduate comprehension. In addition, the accessibility to this technology is now within the reach of most undergraduate institutions. This paper reports the development of an experiment using Raman spectroscopy which determines the authenticity of both diamonds and pearls. The resulting spectra provide an introduction to vibrational spectroscopy and can be used in a variety of laboratory courses ranging from introductory chemistry to instrumental analysis.

  4. Infrared and Raman Spectroscopy of Liquid Water through "First-Principles" Many-Body Molecular Dynamics.

    Science.gov (United States)

    Medders, Gregory R; Paesani, Francesco

    2015-03-10

    Vibrational spectroscopy is a powerful technique to probe the structure and dynamics of water. However, deriving an unambiguous molecular-level interpretation of the experimental spectral features remains a challenge due to the complexity of the underlying hydrogen-bonding network. In this contribution, we present an integrated theoretical and computational framework (named many-body molecular dynamics or MB-MD) that, by systematically removing uncertainties associated with existing approaches, enables a rigorous modeling of vibrational spectra of water from quantum dynamical simulations. Specifically, we extend approaches used to model the many-body expansion of interaction energies to develop many-body representations of the dipole moment and polarizability of water. The combination of these "first-principles" representations with centroid molecular dynamics simulations enables the simulation of infrared and Raman spectra of liquid water under ambient conditions that, without relying on any ad hoc parameters, are in good agreement with the corresponding experimental results. Importantly, since the many-body energy, dipole, and polarizability surfaces employed in the simulations are derived independently from accurate fits to correlated electronic structure data, MB-MD allows for a systematic analysis of the calculated spectra in terms of both electronic and dynamical contributions. The present analysis suggests that, while MB-MD correctly reproduces both the shifts and the shapes of the main spectroscopic features, an improved description of quantum dynamical effects possibly combined with a dissociable water potential may be necessary for a quantitative representation of the OH stretch band.

  5. Discriminating basal cell carcinoma from its surrounding tissue by Raman spectroscopy.

    Science.gov (United States)

    Nijssen, Annieke; Bakker Schut, Tom C; Heule, Freerk; Caspers, Peter J; Hayes, Donal P; Neumann, Martino H A; Puppels, Gerwin J

    2002-07-01

    The objective of this in vitro study was to explore the applicability of Raman spectroscopy to distinguish basal cell carcinoma from its surrounding noncancerous tissue; therefore, identifying possibilities for the development of an in vivo diagnostic technique for tumor border demarcation. Raman spectra were obtained in a two-dimensional grid from unstained frozen sections of 15 basal cell carcinoma specimens. Pseudo-color Raman images were generated by multivariate statistical analysis and clustering analysis of spectra and compared with histopathology. In this way a direct link between histologically identifiable skin layers and structures and their Raman spectra was made. A tissue classification model was developed, which discriminates between basal cell carcinoma and surrounding nontumorous tissue, based on Raman spectra. The logistic regression model, shows a 100% sensitivity and 93% selectivity for basal cell carcinoma. The Raman spectra were, furthermore, used to obtain information about the differences in molecular composition between different skin layers and structures. An interesting finding was that in four samples of nodular basal cell carcinoma, the collagen signal contribution in spectra of dermis close to a basal cell carcinoma, was markedly reduced. The study demonstrates the sensitivity of Raman spectroscopy to biochemical changes in tissue accompanying malignancy, resulting in a high accuracy when discriminating between basal cell carcinoma and noncancerous tissue.

  6. Thermal effects associated with the Raman spectroscopy of WO3 gas-sensor materials.

    Science.gov (United States)

    Garcia-Sanchez, Raul F; Ahmido, Tariq; Casimir, Daniel; Baliga, Shankar; Misra, Prabhakar

    2013-12-19

    Metal oxides are suitable for detecting, through conductive measurements, a variety of reducing and oxidizing gases in environmental and sensing applications. Metal-oxide gas sensors can be developed with the goal of sensing gases under specific conditions and, as a whole, are heavily dependent on the manufacturing process. Tungsten oxide (WO3) is a promising metal-oxide material for gas-sensing applications. The purpose of this paper is to determine the existence of a correlation between thermal effects and the changes in the Raman spectra for multiple WO3 structures. We have obtained results utilizing Raman spectroscopy for three different structures of WO3 (monoclinic WO3 on Si substrate, nanopowder, and nanowires) that have been subjected to temperatures in the range of 30-160 °C. The major vibrational modes of the WO3:Si and the nanopowder samples, located at ~807, ~716, and ~271 cm(-1), correspond to the stretching of O-W-O bonds, the stretching of W-O, and the bending of O-W-O, respectively; these are consistent with a monoclinic WO3 structure. However in the nanowires sample only asymmetric stretching of the W-O bonds occurs, resulting in a 750 cm(-1) band, and the bending of the O-W-O mode (271 cm(-1)) is a stretching mode (239 cm(-1)) instead, suggesting the nanowires are not strictly monoclinic. The most notable effect of increasing the temperature of the samples is the appearance of the bending mode of W-OH bonds in the approximate range of 1550-1150 cm(-1), which is related to O-H bonding caused by humidity effects. In addition, features such as those at 750 cm(-1) for nanowires and at 492 and 670 cm(-1) for WO3:Si disappear as the temperature increases. A deeper understanding of the effect that temperature has on the Raman spectral characteristics of a metal oxide such as WO3 has helped to extend our knowledge regarding the behavior of metal oxide-gas interactions for sensing applications. This, in turn, will help to develop theoretical models for

  7. Raman spectroscopic analysis of Mexican natural artists' materials

    Science.gov (United States)

    Vandenabeele, Peter; Ortega-Avilès, Mayahuel; Castilleros, Dolores Tenorio; Moens, Luc

    2007-12-01

    This work represents the Raman spectra of 15 natural artists' materials that were obtained from local market in Mexico. Some of these products are not endemic to the region, but are often used in local conservation practice. Other materials are of local origin and have been used for centuries by local craftsmen. The Raman spectra that are reported here are: Chia oil, linseed oil, Campeche wax, beeswax, white copal, dammar, colophony, mastic, pixoy, chapopote, chucum, aje gum, gutta gum, peach gum and gum Arabic. The sample of pixoy was mixed with TiO 2, although it was not clear whether this was done intentionally or not. The Raman spectrum of chapopote, the local name for bitumen, contained features of carbonaceous and terpenoid matter. The Raman spectra of chapopote and chucum suffered severely from fluorescence, resulting in noisy Raman spectra. Aje gum and gutta gum are not gums, since they are resinous (terpenoid) in nature. Aje is a rare animal resin originating from Coccus axin.

  8. Spectroscopic, DFT, and XRD Studies of Hydrogen Bonds in N-Unsubstituted 2-Aminobenzamides

    Directory of Open Access Journals (Sweden)

    Malose Jack Mphahlele

    2017-01-01

    Full Text Available The structures of the mono- and the dihalogenated N-unsubstituted 2-aminobenzamides were characterized by means of the spectroscopic (1H-NMR, UV-Vis, FT-IR, and FT-Raman and X-ray crystallographic techniques complemented with a density functional theory (DFT method. The hindered rotation of the C(O–NH2 single bond resulted in non-equivalence of the amide protons and therefore two distinct resonances of different chemical shift values in the 1H-NMR spectra of these compounds were observed. 2-Amino-5-bromobenzamide (ABB as a model confirmed the presence of strong intramolecular hydrogen bonds between oxygen and the amine hydrogen. However, intramolecular hydrogen bonding between the carbonyl oxygen and the amine protons was not observed in the solution phase due to a rapid exchange of these two protons with the solvent and fast rotation of the Ar–NH2 single bond. XRD also revealed the ability of the amide unit of these compounds to function as a hydrogen bond donor and acceptor simultaneously to form strong intermolecular hydrogen bonding between oxygen of one molecule and the NH moiety of the amine or amide group of the other molecule and between the amine nitrogen and the amide hydrogen of different molecules. DFT calculations using the B3LYP/6-311++G(d,p basis set revealed that the conformer (A with oxygen and 2-amine on the same side predominates possibly due to the formation of a six-membered intramolecular ring, which is assisted by hydrogen bonding as observed in the single crystal XRD structure.

  9. Ultrastable and Compact Deep UV Laser Source for Raman Spectroscopy, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Deep-ultraviolet (DUV) Raman spectroscopy is a powerful method to isolate and extract the unique signatures of numerous chemical bonds present within complex...

  10. Nanomechanics of single keratin fibres: A Raman study of the alpha helix -> beta sheet transition and water effect

    OpenAIRE

    Colomban, Philippe; Paquin, Raphaël

    2007-01-01

    International audience; The use of micro-Raman spectroscopy, through chemical bond nano-scale probes, allows the changes in conformations (α helix -> β sheet), chain orientation, disconnection of disulfide bonds (-20%) and the increase of intra and inter-chain distances during the strain to be distinguished. The combination of micro-Raman spectroscopy and a allows a quantitative measure of the extension of chemical bonds in the peptidic chain during loading. The nano-structural transformation...

  11. Hemoglobin structural dynamics as monitored by resonance Raman spectroscopy

    International Nuclear Information System (INIS)

    Spiro, T.G.

    1981-01-01

    Resonance Raman spectra of the heme group are now understood at a level sufficient to provide a useful monitor of several heme structural features. Some porphyrin vibrational frequencies are sensitive to Fe oxidation state, or π-electron distribution, and give insight into the electronic structure of O 2 , CO and NO hemes. Others are sensitive to Fe spin-state, via the associated geometry variation, and provide an accurate index of the porphyrin core size. When examined during the photolysis of CO-hemoglobin via short laser pulses, these frequencies indicate that conversion from low- to h+gh-spin Fe 11 takes place within 30 ps of photolysis, presumably via intersystem-crossing in the excited state, but that the subsequent relaxation of the Fe atom out of the heme plane takes longer than 20 ns, probably because of restraint by the protein. Axial ligand modes have been identified for several heme derivatives. The Fe-imidazole frequency in deoxyhemoglobin is appreciably lowered in the T quaternary structure, as determined in both static and kinetic experiments, suggesting molecular tension or proximal imidazole H-bond weakening in the T state. (author)

  12. Laser Raman spectroscopy of snake venom neurotoxins: conformation.

    Science.gov (United States)

    Tu, A T; Jo, B H; Yu, N T

    1976-01-01

    Laser Raman spectra of neurotoxins of Pelamis platurus (yellow-bellied sea snake) and Laticauda semifasciata (broad-banded blue sea snake) were investigated. The amide I band appeared at 1672 cm-1 for both toxins, which presents an indication of anti-parallel beta structure. Since this agrees well with the result from the CD-ORD studies of snake neurotoxin, it was concluded that snake neurotoxins mainly consist of beta structure. The amide III band appeared at 1245 cm-1 for P. platurus toxin and 1248 cm-1 for L. semifasciata toxin. The four disulfide bonds present in the toxin have a very similar geometry. After vigorous heat treatment, the backbone configuration of the toxin molecule basically remained the same although it was partially denatured. The major peak at 512 cm-1 was not altered by the heat treatment but a new shoulder appeared at 546 cm-1. This suggests that a new type of S-S stretching vibration (trans-gauche-trans) was produced as a result of heat treatment. However, the majority of the S-S vibrations remained in the gauche-gauche-gauche orientation. A substantial change in the interactions between a tyrosine aromatic ring and neighboring residues was apparently the alteration caused by the heat treatment.

  13. Time-resolved resonance Raman spectroscopy of radiation-chemical processes

    International Nuclear Information System (INIS)

    Tripathi, G.N.R.

    1983-01-01

    A tunable pulsed laser Raman spectrometer for time resolved Raman studies of radiation-chemical processes is described. This apparatus utilizes the state of art optical multichannel detection and analysis techniques for data acquisition and electron pulse radiolysis for initiating the reactions. By using this technique the resonance Raman spectra of intermediates with absorption spectra in the 248-900 nm region, and mean lifetimes > 30 ns can be examined. This apparatus can be used to time resolve the vibrational spectral overlap between transients absorbing in the same region, and to follow their decay kinetics by monitoring the well resolved Raman peaks. For kinetic measurements at millisecond time scale, the Raman technique is preferable over optical absorption method where low frequency noise is quite bothersome. A time resolved Raman study of the pulse radiolytic oxidation of aqueous tetrafluorohydroquinone and p-methoxyphenol is briefly discussed. 15 references, 5 figures

  14. Detection and quantitative analysis of ferrocyanide and ferricyanide: FY 93 Florida State University Raman spectroscopy report

    International Nuclear Information System (INIS)

    Mann, C.K.; Vickers, T.J.

    1994-01-01

    This report provides a summary of work to develop and investigate the feasibility of using Raman spectroscopy with tank waste materials. It contains Raman spectra from organics, such as ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetetraacteic acid (HEDTA), imino diacetic acid (IDA), kerosene, tributyl phosphate (TBP), acetone and butanol, anticipated to be present in tank wastes and spectra from T-107 real and BY-104 simulant materials. The results of investigating Raman for determining moisture content in tank materials are also presented. A description of software algorithms developed to process Raman spectra from a dispersive grating spectrometer system and an in initial design for a data base to support qualitative and quantitative application of remote Raman sensing with tank wastes

  15. Detection and quantitative analysis of ferrocyanide and ferricyanide: FY 93 Florida State University Raman spectroscopy report

    Energy Technology Data Exchange (ETDEWEB)

    Mann, C.K.; Vickers, T.J. [Florida State Univ., Tallahassee, FL (United States). Dept. of Chemistry

    1994-10-11

    This report provides a summary of work to develop and investigate the feasibility of using Raman spectroscopy with tank waste materials. It contains Raman spectra from organics, such as ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetetraacteic acid (HEDTA), imino diacetic acid (IDA), kerosene, tributyl phosphate (TBP), acetone and butanol, anticipated to be present in tank wastes and spectra from T-107 real and BY-104 simulant materials. The results of investigating Raman for determining moisture content in tank materials are also presented. A description of software algorithms developed to process Raman spectra from a dispersive grating spectrometer system and an in initial design for a data base to support qualitative and quantitative application of remote Raman sensing with tank wastes.

  16. Application of NIR Raman spectroscopy for detecting and characterizing early dental caries

    Science.gov (United States)

    Ko, A. C.; Choo-Smith, L.-P.; Zhu, R.; Hewko, M.; Dong, C.; Cleghorn, B.; Sowa, M. G.

    2006-02-01

    Early dental caries detection facilitates implementation of non-surgical methods for arresting caries progression and promoting tooth remineralization. We present a method based on Raman spectroscopy with near-IR laser excitation to provide biochemical contrast for detecting and characterizing incipient carious lesions found in extracted human teeth. Changes in Raman spectra are observed in PO 4 3- vibrations arising from hydroxyapatite of mineralized tooth tissue. Examination of various intensities of the PO 4 3- ν2, ν3, ν4 vibrations showed consistent increased intensities in spectra of carious lesions compared to sound enamel. The spectral changes are attributed to demineralization-induced alterations of enamel crystallite morphology and/or orientation. This hypothesis is supported by reduced Raman polarization anisotropy derived from polarized Raman spectra of carious lesions. Polarized Raman spectral imaging of carious lesions found on whole (i.e. un-sectioned) tooth samples will also be presented.

  17. Energy profile, spectroscopic (FT-IR, FT-Raman and FT-NMR) and DFT studies of 4-bromoisophthalic acid

    Science.gov (United States)

    Arjunan, V.; Thirunarayanan, S.; Mohan, S.

    2018-04-01

    The stable conformer of 4-bromoisophthalic acid (BIPA) has been identified by potential energy profile analysis. All the structural parameters of 4-bromoisophthalic acid are determined by B3LYP method with 6-311++G**, 6-31G** and cc-pVTZ basis sets. The fundamental vibrations are analysed with the use of FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectra. The harmonic vibrational frequencies are theoretically calculated and compared with experimental FTIR and FT-Raman frequencies. The 1H and 13C NMR spectra have been analysed and compared with theoretical 1H and 13C NMR chemical shifts calculated by gauge independent atomic orbital (GIAO) method. The electronic properties, such as HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies are determined by B3LYP/cc-pVTZ method. The electron density distribution and site of chemical reactivity of BIPA molecule have been obtained by mapping electron density isosurface with molecular electrostatic potential (MEP). Stability of the molecules arising from hyperconjugative interactions, charge delocalizations have been analysed by using natural bond orbital (NBO) analysis. The thermodynamic properties and atomic natural charges of the compound are analysed and the reactive sites of the molecule are identified. The global and local reactivity descriptors are evaluated to analyse the chemical reactivity and site selectivity of molecule through Fukui functions.

  18. Raman spectroscopy for cancer detection and characterization in metastasis models

    Science.gov (United States)

    Koga, Shigehiro; Oshima, Yusuke; Sato, Mitsunori; Ishimaru, Kei; Yoshida, Motohira; Yamamoto, Yuji; Matsuno, Yusuke; Watanabe, Yuji

    2017-02-01

    Raman spectroscopy provides a wealth of diagnostic information to the surgeon with in situ cancer detection and label-free histopathology in clinical practice. Raman spectroscopy is a developing optical technique which can analyze biological tissues with light scattering. The difference in frequencies between the incident light and the scattering light are called Raman shifts, which correspond to the vibrational energy of the molecular bonds. Raman spectrum gives information about the molecular structure and composition in biological specimens. We had been previously reported that Raman spectroscopy could distinguish various histological types of human lung cancer cells from normal cells in vitro. However, to identify and detect cancer diagnostic biomarkers in vivo on Raman spectroscopy is still challenging, because malignancy can be characterized not only by the cancer cells but also by the environmental factors including immune cells, stroma cells, secretion vesicles and extracellular matrix. Here we investigate morphological and molecular dynamics in both cancer cells and their environment in xenograft models and spontaneous metastasis models using Raman spectroscopy combined with fluorescence microscopy and photoluminescence imaging. We are also constructing a custom-designed Raman spectral imaging system for both in vitro and in vivo assay of tumor tissues to reveal the metastasis process and to evaluate therapeutic effects of anti-cancer drugs and their drug delivery toward the clinical application of the technique.

  19. Vibrational spectra of opal-based photonic crystals

    International Nuclear Information System (INIS)

    Dovbeshko, G; Fesenko, O; Boyko, V; Romanyuk, V; Moiseyenko, V; Gorelik, V; Dolgov, L; Kiisk, V; Sildos, I

    2012-01-01

    Synthetic silica opals were investigated by infrared and Raman spectroscopies. Vibrational modes associated with molecular groups of opal globules and admixtures were detected. Similarities in Raman and infrared spectra of synthetic opal with reference fused and α-quartz indicate the presence of amorphous phase in opal globules. Also some spectral bands designate on modified optical stretching vibrations at 1000-1200 cm −1 and bigger amount of Si-H defects in photonic crystal.

  20. QM/MM methodology, docking and spectroscopic (FT-IR/FT-Raman, NMR, UV) and Fukui function analysis on adrenergic agonist.

    Science.gov (United States)

    Uma Maheswari, J; Muthu, S; Sundius, Tom

    2015-02-25

    The Fourier transform infrared, FT-Raman, UV and NMR spectra of Ternelin have been recorded and analyzed. Harmonic vibrational frequencies have been investigated with the help of HF with 6-31G (d,p) and B3LYP with 6-31G (d,p) and LANL2DZ basis sets. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by GIAO method. The polarizability (α) and the first hyperpolarizability (β) values of the investigated molecule have been computed using DFT quantum mechanical calculations. Stability of the molecule arising from hyper conjugative interactions, and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in Ternelin. Finally the calculated results were compared to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra. Molecular docking studies have been carried out in the active site of Ternelin and reactivity with ONIOM was also investigated. Copyright © 2014 Elsevier B.V. All rights reserved.