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Showing papers on "Raman spectroscopy published in 1979"


Journal ArticleDOI
TL;DR: In this article, the second-order Raman spectrum of pyrolytic graphite has been studied and the dependence of the first-order graphite Raman spectra on crystallite size has been shown.
Abstract: First- and second-order Raman scattering from graphite has been studied. The second-order spectra of single crystals and of highly oriented pyrolytic graphite are continuous and exhibit several well-defined bands which can be attributed to features in the density of vibrational states as determined from current lattice-dynamics models. The density of states deduced from the lattice-dynamics model of Nicklow, Wakabayashi, and Smith provides the best replication of the second-order Raman spectrum, but is nevertheless somewhat deficient in this regard, and in need of improvement. The dependence of the first- and second-order graphite Raman spectra on crystallite size has also been studied for a series of samples with typical dimensions ${L}_{c}$ and ${L}_{a}$ as small as 30 \AA{}. With decreasing crystal size the features in the second-order spectrum broaden noticeably and additional broad features appear in both the first- and second-order spectra. The additional first- and second-order features are also attributed to structure in the vibrational density of states and arise from the wave-vector selection-rule relaxation that results from finite-crystal-size effects. Evidence is presented to demonstrate that the above described spectral features are intrinsic and not associated with impurity excitations.

1,907 citations


Journal ArticleDOI
TL;DR: In this paper, a new resonance Raman phenomenon is proposed which is the Raman component of resonant Mie scattering, and in which the polarizability of the metal particles is modulated by the vibrations of the adsorbed molecules.
Abstract: Intense Raman scattering by pyridine molecules adsorbed on silver or gold aqueous sol particles of dimensions comparable to the wavelength is reported. The degree of intensity enhancement is strongly dependent on the excitation wavelength, with a sharp resonance Raman maximum for excitation at the wavelength of the Mie extinction maximum of the metal particles, and for the silver sols the Raman maximum is shown to follow the extinction maximum to longer wavelengths with increase in particle size. A new resonance Raman phenomenon is thus proposed which is the Raman component of resonant Mie scattering, and in which the polarizability of the metal particles is modulated by the vibrations of the adsorbed molecules. These observations confirm that surface plasma oscillations are involved in the intense Raman scattering already reported for molecules adsorbed at roughened silver surfaces. The metal dielectric function requirements for resonant Mie scattering enable the optimum excitation wavelength for plasma resonance-enhanced Raman studies at the surface of other metals to be estimated.

1,450 citations


BookDOI
01 Jan 1979
TL;DR: The Raman effect is a most useful tool for the study of molecular vibrations and molecular structure as mentioned in this paper, as well as about their vibrational energies can be obtained to a reasonable degree of satisfaction from their infrared and Raman vibrational spectra.
Abstract: The Raman effect is a most useful tool for the study of molecular vibrations and molecular structure. Information about the structure and symmetry of molecules, as well as about their vibrational energies can be obtained to a reasonable degree of satisfaction from their infrared and Raman vibrational spectra. The body of knowl edqe of the vibrational infrared and Raman spectra of molecules is immense and is now so well organized and understood that it is found to be represented in any stan dard upper level undergraduate curriculum in chemistry. The rotational energies of a molecule and quantitative details about its structure can only be obtained through the techniques of microwave, and high-resolution infrared and Raman spectroscopy of low pressure gases and vapors. The results of such investigations are of interest . not only to the academic scientists, but also to scientists and engineers who are active in applied fields of chemistry and physics, as well as the atmospheric sciences. This book deals with basic investigations of the Raman scattering of light by gases, with some attention also being given to liquid substances. After a brief in troductory chapter that delineates the historical development of Raman spectroscopy of gases, high-resolution rotation-vibrational and pure rotational Raman spectros copy is described in Chapters 2 and 3. The all-important intensity parameter, the Raman scattering cross section, is treated in Chapter 4, while the broadening of Raman lines due to the effects of intermolecular forces is taken up in Chapter 5."

347 citations


Journal ArticleDOI
Rogers Hall Stolen1
TL;DR: Raman and Brillouin gains in fibers are a factor of 2 higher if linear polarization is maintained as mentioned in this paper.Birefringent single-mode fibers are used to demonstrate this gain difference.
Abstract: Raman and Brillouin gains in fibers are a factor of 2 higher if linear polarization is maintained. Birefringent single-mode fibers are used to demonstrate this gain difference. Threshold powers of 200 mW have been achieved in Raman oscillators.

285 citations


Book ChapterDOI
01 Jan 1979
TL;DR: In this article, the photographic technique of recording high-resolution Raman spectra of gases allows the precise measurement of wavenumber shifts and the accurate determination of molecular constants derived therefrom.
Abstract: The photographic technique of recording high-resolution Raman spectra of gases allows the precise measurement of wavenumber shifts and the accurate determination of molecular constants derived therefrom The corresponding methods and results are treated in Chap3 for pure rotational and in Chap2 for rotational-vibrational Raman spectra

284 citations


Journal ArticleDOI
TL;DR: In this paper, the properties of the metaphosphate vibration in binary metal oxide glasses have been investigated and it has been shown that the vibrational frequency of the metal cation and the glass network is correlated with its mass, charge, and ionic radius.
Abstract: Thirty different binary metal oxide glasses having the metaphosphate composition have been prepared containing cations from the following groups: alkali metals, alkaline earths, transition metals, and lanthanide and actinide metals. Far infrared absorption assigned to the cation vibration in its oxygen cage has been measured for these glasses. Empirical ionic models are proposed correlating the absorption maximum with the cation mass, charge, and ionic radius. Discrepancies between the observed and predicted vibrational frequency indicate a more covalent interaction between the metal cation and the glass network. Raman intensities and vibrational frequencies of the network metaphosphate vibrations have been obtained and provide additional evidence about the cation–site interaction.

272 citations



Journal ArticleDOI
Elias Burstein1, Y.J. Chen1, C.Y. Chen1, S. Lundquist1, Erio Tosatti1 
TL;DR: In this paper, the authors attributed the very large Raman scattering cross-section of adsorbed molecules, such as pyridine and CN-, on Ag is attributed to mechanisms involving either electron-hole pair excitations in the surface region of the metal or charge-transfer excitations between the metal substrate and the adsorbbed molecules.

234 citations


BookDOI
01 Jan 1979
TL;DR: In this article, the effect of long-range fluctuation in impurity potential on the Electron Light Scattering in Heavily Doped Semiconductors is discussed.
Abstract: Section I Hydrodynamic Instabilities and Critical Phenomena.- To Scale or not to Scale? - The Puzzle at the Lambda Point of Liquid 4He.- Transition to Turbulence in Couette-Taylor Flow.- Hydrodynamic Instabilities and Turbulence.- Light Scattering from Gels and a Single Polymer Chain near Phase Transitions.- Interferometric Studies of Thick Film Critical Behavior.- Section II Physics in Two Dimensions and Defects.- Melting and Liquid Crystals in Two Dimensions.- Light Scattering Studies of Molecular Orientation Fluctuations in Two Dimensions.- Multiphonon Boundary of the Excitation Spectrum.- Raman Scattering Spectra of Proustite and Pyrargyrite Crystals in Low Temperature Phases.- Finite Field Local Field Catastrophe - Application to the Spectra of KCNxCl1?x.- The Effect of Long Range Fluctuations in Impurity Potential on the Electron Light Scattering in Heavily Doped Semiconductors.- Resonant Scattering and Trapping of 29 cm?1 Acoustic Phonons in Ruby Crystals.- Section III Non-Local and Transient Phenomena.- Some Aspects of the Theory of Surface Polaritons.- Recent Developments in Non-Local Optics.- Resonant Brillouin Scattering of Exciton Polaritons.- Ultraslow Optical Dephasing of Pr3+:LaF3.- Picosecond Raman Gain Studies of Molecular Vibrations on a Surface.- Section IV Spins and Excitons.- Brillouin-Mandelstam Scattering of Light in Antiferromagnetic CoCO3.- Observation of Pure Spin Diffusion Without Charge Transport by Spin Flip Raman Scattering.- Spin-Flip Scattering from Photoexcited Excitons in SiC.- The Scattering of Light by Spin Waves on Ferromagnetic Surfaces.- Relaxation of Energy and Polarization in the Resonant Secondary Emission Spectra of Semiconductors.- Resonant Raman Scattering from Stress-Split Forbidden Excitons in CU2O.- Low Frequency Exciton and Raman Scattering Spectra of CoCO3.- Theoretical and Experimental Determinations of Raman Scattering Cross Sections in Simple Solids.- Section V Resonance Scattering and Charge Excitations.- Resonant Secondary Emission by Impurities in Crystals.- The Raman Scattering and Hot Luminescence of Self-Trapping Excitons.- Phenomenological Description of Light Scattering and Thermal Radiation.- Raman Scattering from Plasmon-Phonon Coupled Modes in GaP.- Interaction Between Localized Carriers in the Accumulation Layer and Extended Bulk LO Phonons in InSb and GaSb: Raman Interference Lineshapes.- Inelastic Light Scattering by the Two Dimensional Electrons in Semiconductor Heterojunction Superlattices.- On the Distinction Between Resonant Scattering and Hot Luminescence: Application of Theory to Experiment.- Section VI Phase Transitions.- Light Scattering Near Structural Phase Transition Points in Pure Crystals and in Crystals Containing Defects.- Raman Scattering From Charge Density Waves and Superconducting Gap Excitations in 2H-TaSe2 and 2H-NbSe2.- Quasielastic Light Scattering Near Structural Phase Transitions.- High Resolution X-Ray and Light Scattering Spectroscopy of Liquid Crystals.- Optics and Electrooptics of Chiral Smectics.- The Size, Shape and Polydisperity of Micelles of Amphiphillic Molecules.- Resonance Raman Studies of Visual Pigments.- A Nanosecond Probe of Hemoglobin Dynamics Using Time Resolved Resonance Raman Scattering.- Section VII Multi-Photon Spectroscopy.- Recent Results in Four-Photon Spectroscopy of Condensed Media.- Recent Progress in Four-Wave Mixing Spectroscopy in Crystals.- Coherent Raman Ellipsometry of Liquid Water: New Data on the Vibrational Stretching Region.- Time Resolved Coherent Anti-Stokes Raman Scattering in Weakly Disordered Molecular Crystals.- Intense Light Resonance Scattering: Spectra and Photon Correlations.- Section VIII Resonance Scattering and Surface Enhanced Raman Scattering.- Intensity Effects in Resonance Light Scattering.- The Spontaneous Diffraction of Light by Resonance Atoms.- Giant Raman Scattering by Molecules Adsorbed on Metals: an Overview.- Raman Spectroscopy of Molecular Monolayers in Inelastic Electron Tunneling Spectroscopy Junctions.- A Theory of "Giant Raman Scattering" by Adsorbed Molecules on Metal Surfaces.- Concluding Remarks.- Participants.- Author Index.

219 citations


Journal ArticleDOI
TL;DR: In this article, an extensive vibrational assignment of TTF and TTF•d4 is achieved, improving the previously reported one through the use of polarized infrared spectra of single crystals of the monoclinic form.
Abstract: An extensive vibrational assignment of TTF and TTF‐d4 is achieved, improving the previously reported one through the use of polarized infrared spectra of single crystals of the monoclinic form. Infrared spectra of the monoclinic and triclinic forms are compared and the different crystal field effects discussed. Powder Raman and infrared spectra of (TTF)Br1.0 and (TTF‐d4)Br1.0, Raman depolarization ratios and infrared spectra of (TTF)ClO4 and (TTF‐d4)ClO4 solutions are reported. The assignment of the ag, b1u, b2u, and b3u fundamental modes of (TTF)+ and (TTF‐d4)+ radicals allows the identification of most of the relevant frequency shifts following the ionization of the TTF structure. The possible use of the ionization shifts for the study of the electronic charge distribution in the conducting TTF systems is considered. The parallel investigation of the concentration effects on the visible and infrared absorption spectra of TTF+ in solution let us to identify anomalous infrared absorptions associated with ...

195 citations


Journal ArticleDOI
TL;DR: Polarized and depolarized Raman spectra of alkali germanate glasses are given, together with Raman powder spectra from the crystalline compounds Li2O · 2 GeO2, 3 Li2 O · 8 GeO 2, 2 Li2 o · 9 GeOII, Li 2 o · 7 GeO II, 2 Na2O· 9 Ge O II, K2O O 2 O 2, K2 o O 2 and K 2 O O 2 as mentioned in this paper.
Abstract: Polarized and depolarized Raman spectra of alkali germanate glasses are given, together with Raman powder spectra of the crystalline compounds Li2O · 2 GeO2; 3 Li2O · 8 GeO2; 2 Li2O· 9 GeO2; Li2O · 7 GeO2; 2 Na2O · 9 GeO2; K2O · 2 GeO2; K2O · 4 GeO2 and K2O · 8 GeO2. The alkali germanate glasses: xA2O (1−x) GeO2 are studied in the composition range 0 < x < 0.333. The vibrational modes observed in the high energy range of the Raman spectra of the crystalline compounds are interpreted in terms of symmetrical and antisymmetrical O-Ge-O and Ge-O− stretch vibrations. The molecular structure of the germanate glasses is deduced from a comparison of the Raman spectra of the glasses with those of the crystalline compounds, together with a study of the polarization properties of the glass spectra. It is observed that 6-coordinated Ge atoms occur in a network structure which resembles the structures occurring in the crystalline compounds 2 Li2O · 9 GeO2 and 2 Na2O · 9 GeO2. In the region of 0.18 < x < 0.33 it is found that tetrahedra with one non-bridging oxygen atom are formed. These tetrahedra are probably present in a network as occurs in the crystalline digermanates Li2O · 2 GeO2 and K2O · 2 GeO2.

Journal ArticleDOI
TL;DR: In this paper, the backward Raman amplifier is shown to be a promising candidate for this application and gain, saturation, and limits to amplifier performance are described, and design tradeoffs and possible techniques for further improving the performance of such amplifiers are discussed.
Abstract: Application of efficient ultraviolet excimer lasers such as the 248 nm KrF laser to laser fusion requires that long laser pulses be efficiently converted to short pulses at high intensity. The backward Raman amplifier is shown to be a promising candidate for this application. Gain, saturation, and limits to amplifier performance are described. It is shown that pump beams of poor spatial quality may be converted to output beams of high spatial quality. Several common gaseous vibrational Raman scatterers are discussed, and it is shown that a simple KrF-pumped backward Raman amplifier using methane at atmospheric pressure will have a saturation fluence near 1 J/cm2and can produce an output five times as intense as the pump in a ten times shorter pulse with an efficiency of about 50 percent. Design tradeoffs and possible techniques for further improving the performance of such amplifiers are discussed.

Journal ArticleDOI
TL;DR: In this paper, the resonance Raman spectrum (RRS) of deoxy myoglobin (Mb) in the lowest frequency region was investigated, in which the Fe-N, (His) stretching frequency provided an important insight into molecular mechanism of biolo&al reactions catalyzed by the enzyme.

Journal ArticleDOI
TL;DR: In this article, a new and very efficient method for the calculation of the infrared and Raman spectral intensities of polyatomic molecules using ab initio Hartree-Fock theory is described.
Abstract: A new and very efficient method for the calculation of the infrared and Raman spectral intensities of polyatomic molecules using ab initio Hartree–Fock theory is described. The utility of the method is exemplified by an evaluation of the dipole and polarizability derivatives of the ethylene molecule employing a Gaussian basis set of double zeta quality, augmented by two sets of polarization functions. The predicted values of the vibrational intensities and the depolarization ratios are nearly within the experimental uncertainty which indicates that Hartree–Fock theory is capable of correctly describing these phenomena. The new method enables the efficient calculation of these properties by evaluating the dipole and polarizability derivatives as the first and second order contributions to the potential energy gradient of a molecule in the presence of a finite perturbing electric field. The calculations are thus performed at a single nuclear geometry and the molecular integrals are evaluated only once. The ...

Journal ArticleDOI
TL;DR: In this article, the Stokes Raman spectra of pure and hydrogenated amorphous germanium and silicon are discussed and the resonance behaviour and the polarization ratio of the observed structures are presented and interpreted in terms of a dielectric constant-bond polarizability model.
Abstract: The Stokes Raman spectra of pure and hydrogenated amorphous germanium and silicon are discussed. First- and second-order structures due to the vibration of GeGe and SiSi bonds and also first-order structures due to GeH and SiH bonds are observed. The resonance behaviour and the polarization ratio of the observed structures are presented and interpreted in terms of a dielectric constant-bond polarizability model.



Journal ArticleDOI
01 Jan 1979
TL;DR: A review of the recent theoretical and experimental results which have occurred since the review of Zbinden [3] can be found in this paper. But the review is limited to infrared and Raman measurements since they are complementary to each other in their a...
Abstract: The mechanical properties of polymers are strongly influenced not only by the structure of the material but by the magnitude of the molecular orientation. Thus a great deal of interest exists in information about the molecular orientation in samples introduced by drawing or other forming processes. Several techniques of evaluation of this orientation exist such as birefringence, x-ray diffraction, sonic modulus, and fluorescence measurements [l, 2]. Vibrational analysis of oriented polymers provides a method of determining independently the molecular orientation both in the crystalline and amorphous phases of polymers. By using vibrational techniques, a number of macromolecules have been studied in the solid state for a variety of different processes. It is the purpose of this review to summarize the recent theoretical and experimental results which have occurred since the review of Zbinden [3]. Infrared and Raman measurements will be reported since they are complementary to each other in their a...

Journal ArticleDOI
TL;DR: In this paper, the authors used polarization coherent anti-Stokes Raman spectroscopy to detect weak Raman modes with cross sections as low as 2×10−4 times that of the 992−cm−1 mode of benzene.
Abstract: We show that by using polarization coherent anti‐Stokes Raman spectroscopy, the detection sensitivity of weak Raman modes is greatly enhanced. The spectra of the real part, the imaginary part, and the absolute magnitude of the resonant nonlinear susceptibility can be separately measured. Raman modes with cross sections as low as 2×10−4 times that of the 992‐cm−1 mode of benzene are detectable with less than 10‐kW‐peak‐power lasers.

Journal ArticleDOI
TL;DR: In this paper, the Raman spectra of 4-pyridine-carboxaldehyde-doped Al-${\mathrm{Al}}-2}$${O}}_{3}$-Ag tunnel junctions are shown to be strongly enhanced under conditions which permit the direct excitation of the surface plasmon modes of Ag.
Abstract: The Raman spectra of 4-pyridine-carboxaldehyde-doped Al-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$-Ag tunnel junctions evaporated onto Ca${\mathrm{F}}_{2}$ films and optical diffraction gratings show that the molecular Raman scattering is strongly enhanced under conditions which permit the direct excitation of the surface plasmon modes of Ag. This suggests that the surface plasmon is an intermediate state in surface-enhanced Raman scattering.

Journal ArticleDOI
TL;DR: In this article, a pressure-induced phase transition is observed at pressures above 25.6 kbar for anatase at 1 atm and at room temperature for the 197 cm-1 mode of six Raman active modes.

Journal ArticleDOI
TL;DR: In this paper, the surface enhanced Raman spectra of 2-, 3-, and 4-cyanopyridine adsorbed on silver electrodes suggest that the surface enhancement cross section of CN stretching vibration is strongly dependent upon the orientation of the CN group with respect to the electrode surface.

Journal ArticleDOI
TL;DR: In this article, the clean two mode behavior was confirmed in the reststrahlen band region, and the infrared reflectivityspectra were analyzed by using a Kramers-Kronig dispersion relation and by curve fitting to two forms for the classical dielectric function, one an additive form and the other a factorized form.
Abstract: Thick layers of Ga1−x Al x As with uniform composition were grown by an isothermal liquid‐phaseepitaxial technique. Infrared reflectivity and Raman‐scattering spectra were measured with the same samples. The clean ’’two mode’’ behavior was confirmed in the reststrahlen band region, and the infrared reflectivityspectra were analyzed by using a Kramers‐Kronig dispersion relation and by curve fitting to two forms for the classical dielectric function, one an additive form and the other a factorized form. The experimental data are in good agreement with the calculated TO and LO frequencies, when the Chang‐Mitra model has been modified with the assumption of a nonlinear dependence of the oscillator strengths on composition. In the Raman spectra, the disorder‐activated LA mode near 200 cm−1, a mode near 250 cm−1, and a background‐level change were observed and attributed to atomic disorder. In the infrared reflectivity measurements the major disorder‐induced effect was the increase in the TO and LO damping constants.

Journal ArticleDOI
TL;DR: In this article, background-free coherent anti-Stokes Raman spectra (CARS) of carbon monoxide have been obtained in a rich methane-air flat flame, and the background rejection method, requiring only two laser frequencies, results in an increase in signal-tonoise of over 200 in the |x (3) | 2 spectrum in comparison with normal CARS.

Journal ArticleDOI
TL;DR: In this article, expressions for the generated antiStokes spectral density in coherent anti-Stokes Raman spectroscopy (CARS) are obtained, which take into account the finite linewidths of laser sources and which may be used to analyse observed spectra.
Abstract: Expressions for the generated antiStokes spectral density in coherent antiStokes Raman spectroscopy (CARS) are obtained, which take into account the finite linewidths of laser sources and which may be used to analyse observed spectra. Lorentzian and gaussian laser lineshapes are taken as special cases, which enable further analytic results for single and multiline CARS spectra to be derived. Emphasis is placed on scanning and broadband (multiplex) CARS techniques, and the choice of laser sources discussed from the spectral point of view. As examples of multiline spectra an analytical account of a periodic spectrum is presented and temperature measurement from Q-branch spectra is treated.


Journal ArticleDOI
Abstract: Raman spectra were measured at room temperature and at liquid nitrogen temperature on six rare-earth zirconates, RE2Zr2O7 (RE=Nd, Sm, Gd, Dy, Er, and Yb). The spectra of the three compounds with large rare-earth ions exhibited most of the expected Raman bands of the pyrochlore structure but with large, temperature-independent half-widths that could be related to the loss of translational symmetry imposed by incipient randomization of oxygen vacancies over two available anion sites. Compounds with the smaller rare-earth ions have the fluorite structure, in which the disorder arises from the complete random distribution of seven oxygen ions over eight crystallographically equivalent sites. This degree of disorder reduces the Raman spectrum to a broad featureless density-of-states continuum.

Journal ArticleDOI
TL;DR: In this article, the authors employed coherent anti-Stokes Raman spectroscopy (CARS) to map the temperature field with high spatial precision throughout a small, highly sooting, laminar propane diffusion flame.

Journal ArticleDOI
TL;DR: In this article, the formation of supported molybdate catalysts was investigated using laser Raman spectroscopy, and the effect of variations in the preparation procedure was investigated.

Journal ArticleDOI
TL;DR: It is concluded that the Raman technique for remote sensing of subsurface water temperature has been brought from theoretical and laboratory stages to the point where practical utilization can now be developed.
Abstract: The application of Raman scattering to remote sensing of subsurface water temperature and salinity is considered, and both theoretical and experimental aspects of the technique are discussed. Recent experimental field measurements obtained in coastal waters and on a trans-Atlantic/Mediterranean research cruise are correlated with theoretical expectations. It is concluded that the Raman technique for remote sensing of subsurface water temperature has been brought from theoretical and laboratory stages to the point where practical utilization can now be developed.