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Showing papers on "Raman spectroscopy published in 1976"


Journal ArticleDOI
F. L. Galeener1, G. Lucovsky1
TL;DR: In this article, longitudinal optical (LO) vibrational modes account for several previously unexplained peaks in the Raman spectra of vitreous Ge${\mathrm{O}}_{2}$ and Si${O}
Abstract: We show that longitudinal optical (LO) vibrational modes account for several previously unexplained peaks in the Raman spectra of vitreous Ge${\mathrm{O}}_{2}$ and Si${\mathrm{O}}_{2}$. Identification of LO modes in these and other glasses reduces the complexity of the spectra that must be explained by simple structural models. It also follows that long-range (Coulomb) forces should be included in complete theories of the vibrational properties of many glasses.

417 citations


Journal ArticleDOI
TL;DR: A comparative study of the series of tungsten and molybdenum, α-XM12O40n− (X = BIII, SiIV, GeIV, PV, AsV) was carried out by using i.r. and Raman spectroscopy.

359 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of water and defects on the Raman spectrum of fused silica have been studied and it has been shown that water in the melt is preferentially trapped at the defect sites.
Abstract: We have studied the effects of water and defects on the Raman spectrum of fused silica Intensities of defect lines at 604 and 490 cm−1 were found to increase with fictive temperature and to decrease with increasing OH content The results suggest that water in the melt is preferentially trapped at the defect sites The increased sensitivity obtained by using an optical fiber as the sample enabled us to see for the first time the Si– (OH) stretching vibration at 970 cm−1 The Si–(OH) intensity agrees with that of the 1100 cm−1 dangling oxygen line in a silica fiber weakly doped with K2O A comparison with other spectral features shows that the Raman cross section for the Si–O stretch is extremely weak This weak cross section contributes to the weak Raman intensity of the 1100 cm−1 lines in both fused and crystalline SiO2 and also explains why the dangling oxygen stretching vibration is not observed by Raman scattering in neutron damaged silica Measurements of the much stronger 3690 cm−1 OH stretching vi

292 citations



Journal ArticleDOI
TL;DR: In this paper, order-disorder phenomena in binary oxides with fluorite-related structures were studied by Raman spectroscopy, showing broad bands, defects leading to selection rule breakdown.
Abstract: Order-disorder phenomena in binary oxides with fluorite-related structures were studied by Raman spectroscopy. Raman spectra of disordered phases show broad bands, defects leading to selection rule breakdown. For well-ordered structures, the scattering active modes observed are those allowed by crystal symmetry. Broadening of Raman peaks occurs when order defects are present: antiphase boundaries, distribution of different cations on equivalent crystallographic positions.

221 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that a single dye-laser pulse can induce a Kerr effect at Raman-shifted frequencies. But this effect was shown to induce a small fraction of the power required to produce stimulated instabilities.
Abstract: A new effect is demonstrated in which a laser pulse can be made to induce a Kerr effect only at Raman-shifted frequencies. This permitted the observation of a Raman spectrum with a single dye-laser pulse. The pulse power required is a small fraction of that required to produce stimulated instabilities. The spectral information emerges in a coherent beam, phase matching is not necessary, and spectra can be obtained at any scattering angle.

182 citations


Journal ArticleDOI
TL;DR: In this article, the Raman spectra of various types of niobium oxides have been studied along with their i.r. spectra and the spectra interpreted in the light of the structures of the oxides.

162 citations



Journal ArticleDOI
TL;DR: In this article, a new technique for use in coherent anti-Stokes Raman scattering experiments allows the simultaneous generation of an entire Q-branch spectrum of the anti-stokes radiation from a molecular gas using a single laser pulse.
Abstract: A new technique for use in coherent anti‐Stokes Raman scattering experiments allows the simultaneous generation of an entire Q‐branch spectrum of the anti‐Stokes radiation from a molecular gas using a single laser pulse. With this technique the stringent requirements of the previous techniques concerning laser linewidth and frequency stability are significantly relaxed. The excellent temporal resolution (20 nsec) makes the technique very attractive for temperature and concentration measurements of molecular gases, even in nonstationary media.

152 citations




Journal ArticleDOI
TL;DR: A theory for predicting the effective sample composition in the illuminated volume as a function of the flow rate, light intensity, and spectral characteristics of the photolabile species is presented.
Abstract: We have devised a method for obtaining the resonance Raman spectrum of a photolabile molecule before it is modified by light. The essence of this technique is that the sample is flowed through the light beam at a sufficiently high velocity so that the fraction of photoisomerized (or photodestroyed) molecules in the illuminated volume is very low. This rapid-flow technique has enabled us to measure the resonance Raman spectrum of unphotolyzed bovine rhodopsin in Ammonyx LO detergent solution and in sonicated retinal disc membranes. The major features of these spectra, which are very similar to one another, are the protonated Schiff base line near 1660 cm-1, the ethylenic line at 1545 cm-1, lines due to skeletal modes at 1216, 1240, and 1270 cm-1, and a line due to C-H bending at 971 cm-1. The resonance Raman spectrum of unphotolyzed isorhodopsin formed by the addition of 9-cis-retinal to opsin was also measured. The spectrum of isorhodopsin is more complex and differs markedly from that of rhodopsin. In isorhodopsin, the ethylenic line is shifted to 1550 cm-1, and there are six lines between 1153 and 1318 cm-1. The rapid-flow technique described here makes it feasible to control the extent of interaction between light and any photolabile molecule. We present a theory for predicting the effective sample composition in the illuminated volume as a function of the flow rate, light intensity, and spectral characteristics of the photolabile species.


Journal ArticleDOI
TL;DR: In this paper, a high-resolution study of the resonant scattering response of Cu metal in the x-ray regime was performed using synchrotron radiation, and it was shown that the linewidth of the emitted radiation becomes narrower than the lifetime-limited width of the fluorescent radiation.
Abstract: Intense tuneable synchrotron radiation was used to perform a high-resolution study of the resonant scattering response of Cu metal in the x-ray regime. One finds in the transition regime from fluorescence to resonant scattering that the linewidth of the emitted radiation becomes narrower than the lifetime-limited width of the fluorescent radiation.

Journal ArticleDOI
TL;DR: The Raman data demonstrate that retinal and opsin are joined by a protonated Schiff base and that the conformation of rhodopsin is (perhaps distorted) 12-s-trans.
Abstract: We have performed resonance enhanced Raman measurements of retinal isomers in solution (all-trans, 11-cis, 9-cis, and 13-cis) and cetyltrimethylammonium bromide (CTAB) detergent extracts of bovine rhodopsin near physiological temperatures (17 degrees C). In order to measure these photolabile systems, we have developed a general technique which allows Raman measurements of any photosensitive material. This technique involves imposing a molecular velocity transverse to the Raman exciting laser beam sufficient to ensure that any given molecule moves through the beam so that it has little probability of absorbing a photon. We have also measured the resonance Raman spectra of crystals of the same retinal isomers. The data show that each isomer has a distinct and characteristic Raman spectra and that the spectrum of 11-cis-retinal is quite similar but not identical with that of rhodopsin and similarly for 9-cis-retinal compared with isorhodopsin. In agreement with previous work, the Raman data demonstrate that retinal and opsin are joined by a protonated Schiff base. Due to the fact that the Raman spectra of 11-cis-retinal (solution) and rhodopsin show bands near 998 and 1018 cm(-1), a spectral region previously assigned to C-Me stretching motions, it is suggested that 11-cis-retinal in solution is compased of a mixture of 12-s-trans and 12-s-cis, and that the conformation of rhodopsin is (perhaps distorted) 12-s-trans.


Journal ArticleDOI
TL;DR: In this article, the vibrational analysis of polyethylene terephthalate, polymethylene-d/sub 4/T/T4/4/T 4, polyethylenes-d-sub 4-T/t/T-4-T 4/4 t/T 2, polymethylenes-terephthalates-d−sub 4−4−T 4−T/4−4
Abstract: The vibrational analysis of polyethylene terephthalate, polyethylene-d/sub 4/ terephthalate, and polyethylene terephthalate-d/sub 4/ was carried out using a valence force field calculated from the infrared and Raman spectra of a series of low molecular weight aromatic esters. The Raman spectra for polyethylene-d/sub 4/ terephthalate and polyethylene terephthalate-d/sub 4/ are presented and band assignments for these compounds and polyethylene terephthalate are discussed. (auth)

Journal ArticleDOI
TL;DR: Raman measurements on the 1 T -polytype of TaS 2 are reported in this paper, where a large number of Raman-active peaks are observed below 400 cm -1, most of which are attributed to k = 0 optic phonons resulting from superlattice formation.

Journal ArticleDOI
TL;DR: New techniques in laser Raman spectroscopy are used to obtain spectra of aqueous solutions of lysozylme for frequency shifts as small as 5 cm−1, and a low‐frequency band observed in crystalline lysozyme is not found in the solution, indicating that this band cannot be attributed to an internal molecular vibration.
Abstract: Synopsis New techniques in laser Raman spectroscopy are used to obtain spectra of aqueous solutions of lysozyme for frequency shifts as small as 5 ern-'. In addition, Raman measurements are made on two crystalline forms of hen egg white lysozyme. The spectra obtained from the solution and from the crystal are found to be similar for frequencies above 100 cm-'. However, a low-frequency band at 25 cm-' observed in crystalline lysozyme is not found in the solution, indicating that this band cannot be attributed to an internal molecular vibration.

Journal ArticleDOI
TL;DR: In this article, the chemical and physical effects of 10−15 keV H1+, D1+ and He+ ion bombardments to graphite and SiC have been conducted using the techniques of Raman scattering and scanning electron microscopy (SEM).

Journal ArticleDOI
TL;DR: In this article, the Raman spectra of a series of cationic, anionic, and nonionic surfactants have been examined as pure solids or liquids, and in aqueous micellar solutions.
Abstract: The Raman spectra of a series of cationic, anionic, and nonionic surfactants have been examined as pure solids or liquids, and in aqueous micellar solutions. The spectra show that cationic surfactants such as hexadecyltrimethylammonium bromide (CTAB), dodecylammonium chloride (DAC), and decyltrimethylammonium bromide (DeTAB), along with anionic surfactants such as sodium laurate (NaL) and sodium lauryl sulfate (NaLS) exist in all-trans structures in the crystalline state. Aqueous micellar solution of these surfactants show additional Raman lines which correspond to a liquidlike nature of the micellar core. Raman spectral studies indicate that the ethylene oxide chains in nonionic surfactant such as Igepal CO-880 and Brij 35 assume dihedral helical structures. Nonionic liquid surfactants with shorter ethylene oxide chains such as Triton X-100 and Igepal CO-630 have a major part of the ethylene oxide chain in an open coil form. No significant differences are observed in Brij 35 in H/sub 2/O. However, micellization of Igepal CO-630 shows spectra which indicate a partial ordering of the ethylene oxide chains. The phase changes associated with the electrolyte-induced sphere-rod transition in micellar systems have also been examined by Raman spectroscopy. These studies show a greater ordering of the hydrocarbon chain in the rod-shaped compared to themore » sphere-shaped aggregates.« less

Journal ArticleDOI
01 Jun 1976-Polymer
TL;DR: In this article, a combined application of three different techniques for the study of polyethy-lenes crystallized from the melt under different circumstances, small-angle X-ray diffraction (SAXD), low frequency Raman spectroscopy to examine the longitudinal acoustic (LA) mode, and electron microscopy was presented.

Journal ArticleDOI
TL;DR: Using a general formulation, this paper showed that using surface electromagnetic waves in an attenuated-total-reflection prism configuration should enhance the intensity of Raman scattering by a thin overlayer on a Ag surface by two orders of magnitude.
Abstract: Using a general formulation we show that by using surface electromagnetic waves in an attenuated-total-reflection prism configuration it should be possible to enhance the intensity of Raman scattering by a thin overlayer on a Ag surface by two orders of magnitude and that the use of surface electromagnetic waves may in fact make it possible to observe coherent anti-Stokes Raman scattering by the overlayer.

Journal ArticleDOI
TL;DR: In this paper, the first order Raman spectra of the Group IVa layer compounds SnS2 and SnSe2 are presented and the two Raman active modes of each compound have been identified and on the basis of their observed symmetry assigned in accord with group theoretical predictions.


Journal ArticleDOI
TL;DR: In this article, the authors present cross sections for Raman scattering from water vapor excited at the four argon-laser wavelengths 476.5, 488.0, 496.5 and 514.5 nm.
Abstract: We present cross sections for Raman scattering from water vapor excited at the four argon-laser wavelengths 476.5, 488.0, 496.5, and 514.5 nm. These cross sections, for the strong vibrational band centered at a shift near 3654 cm−1, are approximately 2.5 times larger than the corresponding N2Q-branch cross sections, and follow closely the expected (1/λR)4 dependence, where λR is the Raman scattering wavelength. We also report observations of the room-temperature depolarization and spectral profile of the band, and the overall spectral distribution of the scattering from 470 to 630 nm, for incident light at 488 nm. The latter observation indicates the absence of any other strong vibrational Raman-active modes.

Journal ArticleDOI
TL;DR: In this paper, the interference between resonant and background contributions is eliminated, and undistorted line shapes are obtained using polarization technqiues based upon four-wave mixing, and specific polarization conditions will suppress all signals with the exception of those arising from Raman modes.
Abstract: Background signals which appear in Coherent anti‐Stokes Raman spectroscopy and in the Raman‐induced Kerr effect can be eliminated using polarization technqiues based upon four‐wave mixing. Specific polarization conditions will suppress all signals with the exception of those arising from Raman modes. The interference between resonant and background contributions is eliminated, and undistorted line shapes are obtained.


Journal ArticleDOI
TL;DR: In this paper, the reversible thermal denaturation of bovine pancreatic ribonuclease A at pH 5 in 0.1 M NaCl over the range 32-70 degrees C was studied by Raman spectroscopy.
Abstract: The reversible thermal denaturation of bovine pancreatic ribonuclease A at pH 5 in 0.1 M NaCl over the range 32-70 degrees C as studied by Raman spectroscopy proceeds in a gradual manner consistent with a stepwise unfolding process rather than as a transition between two states. Conversion of residues from helical or pleated-sheet geometry to some intermediate geometry, as followed by means of the amide I and III lines, reveals that substantial amounts of the helical and pleated-sheet conformations remain at 70 degrees C. Changes in the strength of hydrogen bonding by the tyrosyl residues are indicated by the intensity ratio of the doublet at 830-850 cm(-1) and changes in the geometry of the disulfide bridges by the frequency and half-width of the Raman line near 510 cm(-1) due to the S-S vibration. Vibrations of C-S bonds in the methionines and cystines are used to monitor conformational changes in these residues. While there are small quantitative differences in temperature dependence among these probes, all agree in placing the malting temperature at or near 62 degrees C. The Raman data are quantitatively consistent with the six-stage scheme of unfolding of A.W. Burgess and H.A. Scheraga [(1975), J. Theor, Biol. 53, 403], except that no change in the environment of the tyrosines is seen until 45 degrees C.

Journal ArticleDOI
TL;DR: In this article, first and second order Raman scattering was observed in NbC and ZrN and the position of the Raman peaks showed satisfactory agreement with high values of the phonon density obtained from neutron scattering data.