bluuebunny/crossref_metadata_2025_split huggingface dataset:
Raman spectral studies of dehydration of Sr(BrO3)2 · H2O
Authors: Srinivasan T. K. K. , Devanathan T. 
Published: May 2005

AbstractRaman spectra of single‐crystal Sr(BrO3)2 · H2O were examined at 298 and 356 K from the fully hydrated to the totally anhydrous state. The Raman spectrum of the anhydrous compound, when compared with that of the hydrate, showed significant alterations in both the internal and lattice regions. The changes in the ν2–ν4 region revealed the existence of non‐equivalent BrO3− groups in the anhydrous compound. It is inferred from a relative comparison of the Raman and infrared spectra in the lattice region and thermal motion analysis that largeamplitude motions are operative for the BrO3− in the anhydrous compound.
Raman and infrared spectra, conformational stability and vibrational assignment for 1,1,1‐trifluoro‐2‐methoxypropane
Authors: Durig J. R. , Larsen R. A. , Kelley Rosalyn , Sun Feng‐Yi , Li Ying‐Sing 
Published: May 2005

AbstractThe Raman spectra of gaseous, liquid and solid 1, 1, 1‐trifluoro‐2‐methoxypropane, CF3(CH3)CHOCH3, and the corresponding methoxy‐d3 isotope, CF3(CH3)CHOCD3, together with the infrared spectra of the gases and solids were recorded from 3500 to 30 cm−1. A comparison of the vibrational spectra obtained for the fluid phases with those obtained for the amorphous and annealed solids indicates the predominance of two conformers in the fluid phases at ambient temperature. Owing to possible steric hindrance, it is suggested that the most stable conformer is the gauche‐2 form, which has the methoxy group trans with respect to the carbon‐carbon bond of the perfluoromethyl group. This conformer is the one present in the solid. The other conformer in appreciable abundance in the fluid states is probably the gauche‐1 form, which has the methoxy group trans to the carbon‐carbon bond of the methyl group. From a temperature study of the Raman spectrum of the liquid, the enthalpy difference between these conformers was determined to be 180 ± 100 cm−1 (515 ± 286 cal mol−1). The asymmetric torsional frequencies for the gauche‐2 and gauche‐1 conformers are 93 and 53 cm−1, respectively, and from these data and the enthalpy difference the values for the potential constants governing the internal rotation have been estimated. The normal modes have been assigned based on group frequencies, isotopic shifts, depolarization values and infrared band contours. The barrier to internal rotation of the methyl group is calculated to be 1275 cm−1 (3.65 kcal mol−1) from the torsional frequency of 234 cm−1 of the solid.
Influence of addition of potassium chloride to silver colloids
Authors: Zhang P. X. , Fang Y. , Wang W. N. , Ni D. H. , Fu S. Y. 
Published: May 2005

AbstractThe influence on silver colloids of the addition of KCI was directly investigated by means of transmission electron microscopy (TEM). It was found that the particle size increased and the surfaces of the crystal particles of the silver became covered with an overlayer. Additionally, the pattern of aggregation was found to be chain‐like. These changes were very different from those caused by adding pyridine. The mechanism affecting the colloid and the intensity of the surface‐enhanced Raman scattering signals of adsorbed molecules on adding KCl to silver colloid is discussed.
Analysis of small samples using fourier transform Raman spectroscopy
Authors: Williams K. P. J. 
Published: May 2005

AbstractThe fourier transform (FT) Raman method, the main technique for overcoming background fluorescence in Raman spectroscopy, was applied to small samples which proved difficult to study using visible laser Raman methods. Various examples are given and the minimum sample size for FT‐Raman spectroscopy has been shown to be in the microgram range.
Low‐frequency Raman and infrared scatterings in single crystals of sodium acid phthalate, NaC8H5O4 · ½H2O
Authors: Miniewicz A. , Lefebvre J. , Fontaine H. , Marqueton Y. 
Published: May 2005

AbstractPolarized, low frequency (5–400 cm−1) Raman scattering spectra in single crystals of sodium acid phthalate (NaAP) were measured at 295 and 115 K. Similarly, infrared scattering measurements were performed by FTIR reflection and transmission techniques at room temperature. Symmetry assignments and band descriptions consistent with the crystal structure of NaAP are reported. The effects of crystal anisotropy on polar phonons and LOTO splittings were observed and are commented upon.
Behaviour of the high‐frequency component of the OH stretching Raman band of water in H2O2H2O mixtures
Authors: Zhelyaskov V. , Georgiev G. , Nickolov Zh. , Miteva N. 
Published: May 2005

AbstractThe Fourier deconvolution technique was applied to the analysis of Raman OH stretching spectra in H2O2H2O mixtures. An intensity decrease and a low‐frequency shift of the resolved high‐frequency component at 3635 cm−1 was established and can be used in the elucidation of physical models explaining the existence of weakly hydrogen‐bonded OH oscillators in liquid water.
Second spectral moment of vibrational hyper‐Raman and hyper‐Rayleigh spectra
Authors: Bancewicz T. , Kielich S. 
Published: May 2005

AbstractEquations for the second spectral moment of vibrational hyper‐Raman and hyper‐Rayleigh spectra are derived. It is shown that owing to the simultaneous dependence of the hyper‐Raman and hyper‐Rayleigh intensities on the irreducible spherical first‐ and third‐rank hyperpolarizability tensors, both the unnormalized and the normalized second moments of both the above types of scattering are geometry dependent. However, for some molecular symmetries and for some molecular vibrations, the irreducible first‐rank hyperpolarizability tensor vanishes; then the normalized second spectral moment of the second‐harmonically scattered rediation is independent of the scattering geometry, as in the linear case.
Resonance Raman scattering in multi‐mode Jahn–Teller systems
Authors: Hizhnyakov V. , Tehver I. , Zavt G. 
Published: May 2005

AbstractIn multi‐mode systems with a degenerate excited electronic state, resonance Raman scattering (RRS) can be effectively examined by the Fourier amplitude formalism, where RRS amplitudes are described by the Fourier transforms of phonon correlation functions. Model calculations of REPs of both totally and non‐totally symmetric modes have been carried out in the case of a weak vibronic coupling to off‐diagonal modes. The calculations demonstrate a high sensitivity of RRS to the Jahn–Teller effect for the vibraitons of both the discrete and the continuum spectrum.
Surface‐enhanced Raman scattering of cytosine and its derivatives in silver sol
Authors: Lee Heewon , Suh Se Won , Kim Myung Soo 
Published: May 2005

AbstractSurface‐enhanced Raman scattering of cytosine, cytidine, 2′‐deoxycytidine, and cytidine 5′‐monophosphate (5′‐rCMP) in silver sol was investigated. Cytosine seemed to adsorb on the silver surface as the neutral form. With cytosine and 5′‐rCMP, their orientations with respect to the surface changed from a horizontal to a perpendicular position as the surface concentration increased. Similar reorientation was induced for 5′‐rCMP by an increase in phosphoric acid concentration. Adsorption of the cytosine moiety on the surface seemed to occur through the π system of the ring in the horizontal position and through the lone pair of electrons on the N‐3 atom in the perpendicular position.
Polymerization of nitro compounds on silver surfaces during surface‐enhanced Raman scattering
Authors: Tsai W. H. , Boerio F. J. , Clarson S. J. , Montaudo Giorgio 
Published: May 2005

AbstractSurface‐enhanced Raman scattering (SERS) was observed from thin films formed by 1,4‐ and 1,3‐dinitrobenzene (DNB) spin‐coated onto silver island films from dilute solutions. During laser irradiation of 1,4‐DNB films on silver substrates at relatively high laser powers, new bands appeared near 1152, 1350, 1412 and 1460 cm−1 and bands near 1118, 1358 and 1372 cm−1 decreased in inensity. A band near 1598 cm−1 shifted to near 1605 cm−1. The bands near 1152 and 1412 cm−1 were assigned to stretching modes of ϕN andNN bonds of azo compounds, respectively, indicating that polymerization of 1,4‐DNB had occurred. The extent of polymerization was greatest when the surface coverage of adsorbed 1,4‐DNB was greatest and when the SERS experiments were carried out in a nitrogen atmosphere, indicating that reducing conditions were required for the polymerization. No polymerization was observed for 1,3‐DNB under similar circumstances. The difference was attributed to orientation of the adsorbed species. It was concluded that 1,4‐DNB was adsorbed with a horizontal configuration in which the aromatic rings were parallel to the substrate surface and both nitro groups were in contact with the surface while 1,3‐DNB was adsorbed with a vertical configuration in which the rings were perpendicular to the surface and only one nitro group was in contact with the surface.
Surface‐enhanced Raman spectroscopy of biomolecules. Part III.—Determination of the local destabilization regions in the double helix
Authors: Nabiev Igor R. , Sokolov Konstantin V. , Voloshin Oleg N. 
Published: May 2005

AbstractSurface‐enhanced Raman (SER) spectra of nucleotides, calf thymus DNA and plasmid pAO 3 in the supercoiled and relaxed conformations adsorbed on colloidal silver were analysed. Two different techniques were used for the preparation of the silver hydrosol. All the compounds were adsorbed on the standard hydrosol with very low specificity with respect to the chemical nature of the adsorbate. ‘Activation’ of the standard hydrosol by Cl− ions induced adsorption sites highly specific to the adenine nucleotides. It was demonstrated that recording of highresolution SER spectra of nucleic acids and their components at 10−13 g is possible and that ‘activation’ of the silver hydrosol permits the selective detection of the sites of destabilization of double‐stranded helices and identification of the nucleotides in these sites.
Conformational stability, barriers to internal rotation, ab initio calculations and vibrational assignment of propionyl fluoride
Authors: Durig J. R. , Guirgis G. A. , Phan H. V. 
Published: May 2005

AbstractThe Raman (3100–10 cm−1) and infrared spectra (3100–30 cm−1) of propionyl fluoride in the gas and solid phases were recorded. Additionally, the Raman spectrum of the liquid and the qualitative depolarization ratios were also obtained. From these data a complete vibrational assignment is proposed for an s‐trans/gauche equilibrium in the gas and liquid phases, with the s‐trans conformer (the CH3 moiety is s‐trans to the fluorine atom) being the most stable form in both of these physical states and the only form present in the solid phase. A new potential function has been calculated from the data previously obtained from the far‐infrared spectrum of the gas. The determined potential coefficients are V1 = 328 ± 6, V2 = 239 ± 8, V3 = 417 ± 3, V4 = 30 ± 3 and V6 = −4 ± 2 cm−1, and values of 720 ± 8 (2.06 ± 0.02 kcal mol−1) and 297 ± 9 cm−1 (0.85 ± 0.02 kcal mol−1), respectively, were obtained for the s‐trans to gauche and gauche to gauche barriers to internal rotation of the CFO moiety. Additionally, the s‐trans conformer was determined to be 448 ± 17 cm−1 (1.28 ± 0.05 kcal mol−1) more stable than the gauche conformer. From the study of the Raman spectrum obtaind for the liquid at different temperatures, a value of 267 ± 12 cm−1 (0.76 ± 0.03 kcal mol−1) was determined for ΔH between the two conformers. The structural parameters, conformational stabilities, barriers to internal rotation and fundamental vibrational frequencies which were determined experimentally are compared with those obtained from ab initio Hartree‐Fock gradient calculations employing both the RHF/3‐21G and RHF/6–31G* basis sets, and with the corresponding quantities obtained for some similar molecules.
Hypersound velocities in tris‐sarcosine calcium chloride at room temperature
Authors: Prieto C. 
Published: May 2005

AbstractBrillouin scattering at room temperature has been used to determine the elastic constant tensor for the trissarcosine calcium chloride (TSCC): the frequency used was near 18 GHz. The sound velocity polar diagrams show an interesting behaviour: the quasi‐longitudinal and the quasi‐transversal branches are degenerate for a propagation direction inside the (010) plane.
Micro‐Raman spectra of crystalline uridine at high pressures
Authors: Huang Yining , Butler Ian S. 
Published: May 2005

AbstractMicro‐Raman spectra of crystalline uridine were obtained at room temperature and at pressures approaching 40 kbar with the aid of a diamond‐anvil cell. There is evidence for a phase transition at about 12 kbar which is probably associated with changes in the hydrogen‐bonding interactions between the two molecules present in the unit cell.
Raman and far‐infrared study of crystalline 1,1‐dichloroethylene, CH2CCl2 and CD2CCl2
Authors: Prystupa D. A. , Anderson A. , Torrie B. H. 
Published: May 2005

AbstractFar infrared spectra (30–200 cm−1) and Raman spectra (20–3200 cm−1) of crystalline CH2CCl2 and CD2CCl2 at 20 and 80 K are reported. The lattice spectra contain 29 Raman‐ and 15 infrared‐active modes, which are assigned on the basis of their isotopic frequency shifts. Crystal field splittings and shifts of internal modes are examined in detail. A centrosymmetric unit cell containing at least eight molecules is indicated by these spectra.
Raman and infrared study of crystalline methyltrichlorosilane
Authors: Prystupa D. A. , Anderson A. , Lefebvre J. H. , Torrie B. H. 
Published: May 2005

AbstractThe Raman and infrared spectra between 30 and 3000 cm−1 of a new crystalline phase of methyltrichlorosilane, CH3SiCl3, at 20 K are reported. The spectra are consistent with a non‐centrosymmetric crystal structure with at least four molecules per unit cell. A glassy phase is also detected.
Vibrational study of crystal phase transitions in pyrrole (C4H5N) and C4D5N
Authors: Lautie A. , Romain F. 
Published: May 2005

AbstractInfrared and Raman spectra of crystalline pyrrole and pyrrole‐d5 were recorded in the range 5–4000 cm−1. The behaviour of internal and external modes was studied as a function of temperature between 200 and 5 K. Two phase transitions were observed at 67 and 30 K and their mechanism is discussed. For the incommensurate phase, between 67 and 30 K, the amplitude and phase modes were identified at about 20 and 10 cm−1, respectively; for the first, a critical exponent of 0.30 was determined. No evidence of NH …︁ π hydrogen bond participation in the transitions has been detected.
Distortion‐induced intensity of Raman modes of molecular units in different crystal orientations
Authors: Bhattacharjee R. 
Published: May 2005

AbstractUsing the principles of the theory of distortion‐induced activity of forbidden Raman modes of molecular units in differnt crystal orientations and the theory of distortion‐induced Raman intensities of different modes of molecular units adsorbed onto metal surfaces, the distortion‐induced intensities of different Raman modes of molecular units in differnt crystal orientations is discussed. An example of the intensities of ν1s, ν2s, ν3s and ν4s (where s represents the SO ion) of (NH4)2SO4 [D] single crystal in Ag, B1g, B2g B3g orientations is discussed to demonstrate the usefulness of the results of these theories.
Raman spectroscopic study of complex formation between dimethyl sulfoxide and chloroform
Authors: Rintoul L. , Shurvell H. F. 
Published: May 2005

AbstractThe sulfur‐oxygen stretching region of dimethyl sulfoxide (DMSO) in chloroform solutions has been studied by means of Raman spectroscopy. The number of linearly independent spectral components in the SO stretching band envelope was determined to be four by factor analysis. The overall band envelope was fitted with five Lorentz‐Gaussian functions using a non‐linear least‐squares procedure. The results were found to be consistent with the formation of 1:1 and 1:2 DMSOCHCl3 complexes, which give rise to bands centered at 1054 and 1032 cm−1, respectively. Equilibrium constants could not be calculated because of coincidences between bands of pure DMSO and bands due to the two DMSOCHCl3 complexes. The spectrum of a 0.0065 mole fraction DMSO solution in chloroform indicates a nearly complete conversion of DMSO species to the 1:1 chloroform complexes at this concentration. A very weak Raman band at 1018 cm−1 and an IR band of medium intensity at 1017 cm−1 in the spectra of pure DMSO were detected by the use of band‐fitting techniques. The assignments of these bands and the other bands in the methyl rocking region are discussed.
Ultraviolet resonance Raman spectroscopy of X—Proline bonds: A new marker band of hydrogen bonding at the imide CO site
Authors: Takeuchi Hideo , Harada Issei 
Published: May 2005

AbstractUV resonance Raman spectra of proline‐containing peptides were measured in order to study the effects of transcis isomerization and hydrogen bonding on the imide II [C(O)‐N stretch] vibration of the X‐Pro bond. The isomerization does not affect the imide II frequency noticeably but the hydrogen bonding at the CO site increases the frequency markedly, which varies from ca. 1445 cm−1 in the non‐hydrogen‐bonding state to ca. 1485 cm−1 in a strongly hydrogen‐bonded state (from 1440 to 1465 cm−1 for Pro‐Pro linkages). The large upward frequency shift on hydrogen bonding indicates that the imide II frequency can serve as a structural marker of X‐Pro bonds, particularly in distinguishing bent peptide backbones involving different hydrogen bonding states of the imide CO group. Applications of this marker band to structural studies of proline‐containing oligopeptides are demonstrated for tuftsin, bradykinin and gramicidin S.
Spectra and structure of small ring compounds. Part LVI—Raman and far‐infrared spectra, conformational stability vibrational assignments, normal coordinate analysis and ab initio calculations of chlorocyclobutane
Authors: Durig J. R. , Lee Min Joo , Little T. S. 
Published: May 2005

AbstractThe Raman (3100 to 10 cm−1) and far‐infrared (374 to 74 cm−1) spectra have been recorded of gaseous chlorocyclobutane. A series of Q‐branches observed in both of these spectra beginning at 158 cm−1 with successive transition falling to lower frequencies have been assigned to the ring puckering vibrations of both the low‐energy equatorial and high‐energy axial conformers. These data have been fitted to an asymmetric potential function of the form V (cm−1) = (5.13 ± 0.34) × 105X4 − (3.35 ± 0.14) × 104X2 + (3.79 ± 0.30) × 104X3 with a reduced mass of 198 amu. Utilizing this potential, the difference between the puckering angles for the two conformers was calculated to be 5° with the equatorial conformer having the larger value of 22°. This potential function is consistent with an energy difference between the equatorial and axial forms of 449 cm−1 (1.28 kcal mol−1) and a barrier to ring inversion of 827 cm−1 (2.36 kcal mol−1). Experimental values for the enthalpy difference between the two conformers have been determined for both the liquid and gas from relative intensities of a pair of Raman lines. The conformational stability, barrier to ring inversion, ro structural parameters, and fundamental vibrational frequencies, which have been determined experimentally, are compared with those obtained from ab initio Hartree‐Fock calculations employing both the 3–21G* basis sets, and to the corresponding quantities obtained for some similar molecules. The ab initio results indicate that the puckering angle for the equatorial conformers should be about 30°, with that for the axial conformer being about 8° smaller.
Concentration‐dependent depolarized Raman spectra of HCl and DCl in solution in liquid carbon dioxide
Authors: Stidham Howard D. , Ewen Mark E. 
Published: May 2005

AbstractThe depolarized component of Paman scattering by pure liquid HCl and DCl and of solutions of these acid halides in liquid CO2 are reported. At room temperature the band contours show no S branch intensity in pure acid halide liquid, but in solution in liquid CO2 and S branch is increasingly evident with increasing CO2 concentration. The frequency shifts are a function of the dielectric constant and refractive index of the solution. Reorientational correlation functions calculated from the anisotropic scattering decay more slowly in the first few tens of femtoseconds than predicted for monomeric acid halides, suggesting contribution to the composite correlation function by species of larger moments of inertia but vibrational frequencies identical with those of the monomers.
Electronic parameter determination for potassium chromate by coherent anti‐stokes Raman spectroscopy
Authors: Bostick J. M. , Carreira L. A. , Antcliff R. R. 
Published: May 2005

AbstractTwo separate methods of spectral analysis have been used to analyze the CARS spectra of K2CrO4 at pump wavelengths near its electronic transition. The Jacobian least‐squares line‐fitting method requires initial guesses for parameters and returns directly the best iteratively fitted parameters. These were then used to plot the relative magnitudes of the Lorentzian and dispersive components, i.e. imaginary and real terms, respectively, of these bands. The FREIGHT–CARS method of spectral phase extraction was used to yield directly the relative values of the Lorentzian and dispersive components. A comparison of the values obtained by both methods shows a fundamental agreement between the relative magnitudes of these parameters. In both analyses, the Lorentzian contribution to the resonance region is seen to approach a maximum near the electronic absorption.
Dispersion of depolarization ratio and reversal coefficient in vibrational resonance Raman scattering by polyatomic molecules
Authors: Morozov V. A. 
Published: May 2005

AbstractAnalytical expressions for the depolarization ratio and reversal coefficient in vibrational polyatomic Raman scattering are derived using the wave packet formulation. Some changes in the dispersion of the depolarization ratio and reversal coefficient caused by changes in the vibronic coupling and by various shifts of nuclear equilibrium positions on molecular electronic excitation which have not been reported before have been studied.
High‐frequency vibrational mode characterization of Zn(II), Ni(II) and Co(II) tetraphenylchlorins
Authors: Song Ok‐Keun , Ha Jong‐Seo , Yoon Minjoong , Kim Dongho 
Published: May 2005

AbstractThe detailed resonance Raman spectra of metallotetraphenylchlorins with B, Qx and Qy excitations and excitation profiles of Raman modes on the Qy absorption band have been reported. In metallotetraphenylchlorins, the character of the vibrational eigenvector and the localization of the modes in the pyrrole rings raised by the symmetry are different from those of metallooctaethychlorins. A recent normal mode calculation on Cu(II) tetraphenlchlorin based on the semi‐empirical quantam chemistry force field (QCFF/PI) method was utilized to elucidate the vibrational mode assignment of Zn(II), Ni(II) and Co(II) tetraphenylchlorins. For Raman excitation profiles on Qy(O, O) and Qy(O, 1) absorption bands, it is observed that some polarized Raman bands have contributions not only from A‐term scattering but from Herzberg‐Teller scattering. This can be explained by the symmetry lowering and the localized normal mode character of metallotetraphenylchlorins. For depolarized and anomalously polarized Raman bands, the vibronic coupling (interstate mixing) is strongly introduced.