bluuebunny/crossref_metadata_2025 huggingface dataset:
Raman spectra of gases. XXV—nitrocyclopropane
Authors: Durig J. R. , Sun F. Y. , Li Y. S. , Bush S. F.
Published: May 2005

The Raman spectrum of gaseous nitrocyclopropane, cC3H5NO2 has been recorded from 3500 to 30 cm−1. The interesting internal NO2 torsion was observed at 85±2cm−1 from which a barrier to internal rotation in the vapor state of 1680±70 cm−1 (4.8±0.2 kcal mol−1) was calculated. It is shown that this torsional frequency is consistent with the relative intensities of the vibrational excited states in the microwave spectrum. This barrier value is compared to those for several other NO2 substituted hydrocarbons as well as for the corresponding isoelectronic BF2 substituted molecules. The high barrier value supports the structural arguments that there is significant pseudo‐conjugation between the cyclopropane ring orbitals and the substituent NO2 group. A revised vibrational assignment is presented which is compared to the one previously given for the isoelectronic molecule, c‐C3H5BF2, as well as for c‐C3H5BCI2.
Assignment of charge transfer bands for a bridged binuclear metal complex by resonance Raman excitation profiles
Authors: Knorrs Christopher , Gafney Harry D. , David Baker A. , Braunstein Carlos , Strekas Thomas C.
Published: May 2005

Resonance Raman spectra obtained using laser excitation wavelengths varled to match each of two visible charge transfer absorption bands of a dimeric metal complex with two different diimine ligands vary significantly. The identification of characteristic ligand vibrations leads to the assignment of the two metal‐to‐ligand charge transfer transitions with respect to the ligand which accepts the charge in the excited state. The resonance Raman spectra provide information relating to the complex structures in solution.
A detailed study of the ν1 and 2ν2 region of the raman spectrum of single crystals of KN3
Authors: Khilji M. Y. , Sherman W. F. , Wilkinson G. R.
Published: May 2005

A convincing assignment of the bands in the ν1 and 2ν2 internal mode region of the Raman spectrum of single crystals of KN3 has been obtained. The Fermi resonances of the main (14, 14, 14) isotopic species of N and the two rare isotopic species, (14, 15, 14) and (15, 14, 14) have been analysed in detail. The temperature and pressure dependence of the Raman spectrum have been measured, and values of dν/dp calculated for the theoretically non‐resonating ν1 and 2ν2 levels.
Resonance Raman spectra of naphthalene and naphthalene‐d8 anions in THF
Authors: Christesen S. D. , Johnson C. S.
Published: May 2005

Raman spectra have been obtained for naphthalene and naphthalene‐d8 anions in tetrahydrofuran. Seven of the nine totally symmetric normal modes were observed, and a normal modes analysis was performed for the planar modes to obtain stretching force constants for the CC bonds. The changes in the force constants resulting from sodium reduction of naphthalene were found to be proportional to changes in τ bond orders obtained from ab initio Hartree‐Fock SCF calculations at the STO‐3G level. Raman shifts resulting from ion pair formation were within experimental errors.
Rare‐earth titanates and stannates of pyrochlore structure; vibrational spectra and force fields
Authors: Vandenborre M. T. , Husson E. , Chatry J. P. , Michel D.
Published: May 2005

Infrared absorption and polarized Raman spectra of rare‐earth titanates of pyrochlore structure Ln2Ti2O7 (Ln = Sm, Gd, Yb; Y) and Ln2Sn2O7 (Ln = La, Sm, Gd, Yb, Lu; Y) have been recorded. A valence force field calculation clearly supports the assignment of the frequencies. A comparison of the results with those of homologous zirconates and hafnates is presented.
Raman studies of vibrational and reorientational relaxation in rotator phase perfluorocyclohexane
Authors: Bailey R. T. , Crulckshank F. R.
Published: May 2005

Vibrational and reorientational relaxation have been studied in rotator phase perfluorocyclohexane using Raman line‐shape analysis. Two totally symmetric bands were investigated in the temperature range from 170 to 300 K. The results were compared with the predictions of the Kubo stochastic line‐shape theory. Activation enthalpies for molecular reorientation were consistent with previous NMR results.
Applications of four‐channel Raman difference spectroscopy to studies in hydrogen‐bonded systems
Authors: Takahashi H. , Asthana B. P. , Häfner W. , Kiefer W.
Published: May 2005

We report in this work on some potential applications and advantages of the four‐channel Raman detection technique developed recently at this laboratory. The capability of recording four different Raman signals simultaneously and processing them electronically by scaling of each signal in order to obtain a desired linear combination, has been fully exploited. The simultaneous measurement of I∥︁ and I⊥ of the Raman spectra of pyridine and a mixture of pyridine+methanol, thus allows us to derive the isotropic Raman bandwidths of ν1 and ν8b vibrations in the hydrogen‐bonded species C5H5N…︁HOCH3 and at the same time very small frequency shifts of vibrations of the non hydrogen‐bonded pyridine (in mixture) as compared to pure pyridine. The smallest shift that could be measured was 0.045 cm−1. It has been demonstrated that four‐channel Raman difference spectroscopy has a distinct advantage for studying the vibrations of complex systems such as a hydrogen‐bonded species.
A Raman study of solubilization of aromatics by non‐ionic surfactants
Authors: Cooney Ralph P. , Healy Thomas W. , Barraclough Colin G.
Published: May 2005

Raman spectra of the aromatic solubilizate in the ternary system, non‐ionic surfactant aromatic water, are indicative of benzene in a hydrophobic liquid‐like environment and of pyridine in a hydrophilie, possibly aqueous environment. The non‐ionic surfactants studied were of the alkylphenol‐ and alkyl‐polyoxyethylene type. Addition of traces of water to a solution of Triton X‐100 in benzene leads to the appearance of a water spectrum which suggests that 1:1 hydrogen‐bond complexes between individual ether groups of the polyoxyethylene chain and water have formed in reversed micelles.
Raman studies on dinucleoside monophosphates: 2—perturbation of carbonyl frequencies of purine and pyrimidine dinucleotides by association in aqueous solution
Authors: Gramlich V. , Klump H. , Schmid E. D.
Published: May 2005

Intermolecular interactions of guanine‐containing dinucleoside monophosphates in aqueous solution have been investigated by Raman spectroscopy. The measurements show that the dinucleotides ApG, GpA, UpG, GpC and GpG can form ordered structures under the conditions used. The association of these dinucleotides can be monitored by changes of the frequency and intensity of the C=O stretching vibrations due to hydrogen bond formation and by hypo‐ and hyper‐chromic effects in the ring vibrations of the bases.
The Raman and infrared spectra and normal coordinate analysis for 1,2‐diiodotetrafluorobenzene
Authors: Yadav R. A. , Singh I. S. , Sala O.
Published: May 2005

The Raman spectrum of 1,2‐diiodotetrafluorobenzene was recorded in the region 50–2000 cm−1 on a Jarrell‐Ash Model 25–300 double monochromator spectrometer using 5145 Å radiation from an argon‐ion laser. The depolarization ratios of the Raman lines were measured in CS2 and CHCl3 solutions. The infrared spectrum was recorded in CS2 and CHCl3 solutions in the region 180–200 cm−1 on a Perkin‐Elmer 180 spectrometer using a CsI cell. The fundamental vibrations were assigned on the basis of the frequencies and relative intensities of the bands observed in the Raman and infrared spectra and the depolarization ratios of the Raman lines. A normal coordinate analysis was also performed to check the vibrational assignments.
Raman spectroscopic studies on sodium metavanadate
Authors: Seetharaman S. , Bhat H. L. , Narayanan P. S.
Published: May 2005

Sodium metavanadate (NaVO3) has been reported earlier to exhibit ferroelectric behaviour below 380 °C, but unlike many other known ferroelectrics it does not show a very strong dielectric anomaly, indicating that the structural change during the ferroelectric phase transition may be only a slight modification of the paraelectric phase. This is in conformity with the x‐ray data at room temperature, which could be refined to the same R value either in space group C2/c or Cc. Further, it is known that NaVO3 occurs also in another polymorphic modification (β‐form), the structure of which has not been established. Raman spectroscopic studies of single crystals of the α‐form of NaVO3 have been carried out and a crystalline powder of the β‐form has been made. The Raman spectra have been interpreted in terms of the linear VO chains formed by VO4 tetrahedra sharing two corners with each other. The temperature variation of the intensity and width of the Raman lines through the phase transition has been measured and the observed LOTO splitting in the room temperature phase confirm the Ce ferroelectric space group.
Analysis of polarization measurements in Raman microspectroscopy
Authors: Turrell George
Published: May 2005

The Raman back‐scattering of isotropic and single‐crystal samples is analyzed using the known optical properties of wide‐aperture objectives and apparent depolarization ratios obtained in Raman microspectroscopy are considered.
Raman spectra of single crystals of LaOCl
Authors: Haeuseler H.
Published: May 2005

Single crystals of LaOCl have been grown from molten LaCl3 by a slow cooling technique. The Raman spectra of these crystals have been recorded and the frequencies and symmetries of the different lines determined by means of polarized Raman scattering.
Chromium oxide film thickness measurements using spontaneous Raman scattering
Authors: England W. A. , Jenny S. N. , Greenhalgh D. A.
Published: May 2005

Quantitative measurements of chromium oxide film thicknesses on pure chromium have been made using Raman scattering. The results are compared with those from argon ion erosion. Possible developments of the technique to the chemical mapping of corrosion film using Raman scuttering are discussed.
Infrared and Raman spectra and crystal structure of solid bromotrifluoromethane
Authors: Park Y. S. , Shnrvell H. F.
Published: May 2005

Infrared and Raman spectra of polycrystalline films of CF3 Br have been recorded at 77 K. All six fundamentals of the molecule have been observed in both spectra. Observed splittings of fundamentals have been attributed to Fermi resonance (ν1), bramine isotope splitting (ν3) and crystal splitting (ν4, ν5 and ν6). Some bands due to 13CF3 Br have also been identified. The crystal splittings can be explained if it is assumed that the structure is monuclinic with factor group C2h and two molecules per unit cell on sites of Cs symmetry.
Vibrational analysis and normal coordinate calculations of the o‐phthalic acid molecule
Authors: Colombo L. , Volovšek V. , Lepostollec M.
Published: May 2005

Raman and infrared vibrational spectra have been recorded for o‐phthalic acid as a single crystal, as a powder and in solution. The proposed assignment of the observed frequencies was made on the basis of a normal coordinate analysis and symmetry considerations of the crystal spectrum, which allowed the separation of internal vibrations of the A and B species.
The vibrational spectrum of the ammonia‐hydrogen cyanide system and the normal coordinate analysis of NX4CN (X=H or D)
Authors: Kanesaka Isao , Kawahara Hisakazu , Kiyokawa Yoshinobu , Tsukamoto Masaki , Kawai Kiyoyasu
Published: May 2005

The vibrational spectrum of NX4CN (X=H or D) at 77 K is reported. The splittings of the internal modes of the NX ion are slight and the internal modes and the librations correspond well in frequency with those in related compounds. The observed bands are assigned on the basis of normal coordinate analysis to the crystal structure of D and C symmetries, where there are slight differences in the calculated frequencies by use of the same force constants. In 2NX3·XCN ν4 of the NX ion splits, resulting in an associated species of [X3NX…︁NX3]+. Associated species and the site of the CN− ion are discussed with CN stretchings observed in 2NX3·XCN and NX3·2XCN.
Single crystal Raman studies on magnesium sulphite trihydrate, MgSO3·3H2O and MgSO3·3(H, D)2O
Authors: Lutz H. D. , Henning J. , Buchmeier W. , Engelen B.
Published: May 2005

The Raman and infrared spectra of MgSO3·3H2O and of deuteriated and isotopically dilute samples of this hydrate were recorded from 100 to 4000 cm−1 at 90–300 K and analysed with regard to the bonding structure of the water of crystallization, the space group of this compound, i.e. P212121, Pnma or Pn21a, and assignment and coupling (with the H2O and D2O librations) of the internal modes of the sulphite ions. The orientational behaviour of single crystal Raman studies on isotopically dilute samples are firstly used for assigning the uncoupled OH (OD) stretching modes to the H positions in the lattice. From the three types of water of crystallization (in the case of space group P212121 or Pn21a), the orientationally disordered H2O1 and H2O11 are involved in very strong hydrogen bonds, uncoupled OH (OD) modes 3027 (2282) and 2930 (2240) cm−1, caused by the strong hydrogen bond acceptor strength of the sulphite ions. Both water molecules are extremely distorted with OH (OD) mode splittings up to 393 (218) cm−1, the largest known so far. H2O111 forms weak bifurcated hydrogen bonds. Both the stretching and bending vibrations of the sulphite ions coincide with rotational modes of the water molecules.
Bifurcated hydrogen bonds in water
Authors: Giguère Paul A.
Published: May 2005

A new model is proposed for liquid water, based on recent studies of the Raman spectra as a function of temperature. It features two kinds of hydrogen bonds: in addition to the well known linear hydrogen bonds (LHB), predominant in cold water, there are some bifurcated hydrogen bonds (BHB) between three water molecules. These three‐centered bonds, mainly electrostatic, have an average energy of 2.5 kcal mol−1, about half of that of the LHB. Their characteristic OH stretching frequency is around 3420–3440 cm−1, compared with 3220 cm−1 for the LHB. In addition, there are a few percent of nearly free OH groups, i.e. non‐hydrogen‐bonded (NHB), with a stretching frequeney of ca 3615 cm−1. Reorientation between these three states occurs through rotation of the H2O molecules about one of their OH bonds. Thus, on melting, one third of the hydrogen atoms move out of the tetrahedral framework to occupy interstitial sites in the open ‘shafts’ characteristic of the ice structure. As in the case of ice, Fermi resonance between the ν1 and 2ν2 levels has little impact on the vibrational spectra of liquid water and iee. The hybrid molecule, HDO, does not form LHB with H2O or D2O, hence its simpler spectra. The BHB model can account much better than previous models for the thermodynamic anomalies of water.
Laser microzone damage in surface‐enhanced Raman scattering by pyridine on cooper electrodes
Authors: Mernagh Terrence P. , Cooney Ralph P.
Published: May 2005

Surface‐enhanced Raman scattering (SERS) by pyridine on anodized copper electrode surfaces has been shown to arise from laser damage zones. On the basis of pH dependence studies, the intensely scattering species appears to be a copper complex. Evidence for semi‐macroscopie laser damage zones (ca 0.1 mm in diameter, ca 500 nm or ca 1400 atom layers in depth) emerges from laser perforation of thin film electrodes, visual examination, scanning electron micrescopy (SEM), Raman line intensification for laser illumination during the oxidation‐reduction cycle (ORC), uniform laser‐flux perturbations of the cyclic voltammograms and laser interruption intensity studies. These results argue for a much reduced metal surface enhancement factor for this system and against the use of copper SERS effects in studies of electrosorption on undamaged surfaces. SERS from this system at excitation wavelengths greater than 620 nm is expected to involve conventional (non‐surface)resonance enhancement arising from copper(II)‐pyridine complexes (λmax ⩾ 590 nm) formed by copper corrosion within the laser damage zone. On the basis of these findings the Cu/pyridine system has been classified as SERS Type III.
Raman intensities of propane in the gas phase
Authors: Martin J.
Published: May 2005

An experimental and theoretical study of the vibrational Raman intensities of propane in the gas phase is presented. The absolute scattering coefficients and depolarization ratios corresponding to clearly separated spectral zones (made up of one or more vibrational modes) have been measured. The absolute scattering coefficients and depolarization ratios for each normal vibrational mode have been determined theoretically using the hypothesis that bond polarizabilities are transferable. Ethane parameters from previous work and the vibrational eigenvectors deduced from a propane force field given in the literature were used to apply this hypothesis.
Tuning metal island films for maximum surface‐enhanced Raman scattering
Authors: Aroca Ricardo , Martin Fernando
Published: May 2005

Enhancement factor calculations based on the electromagnetic model of surface‐enhanced Raman scattering (SERS) are presented for a series of metals. The specific dependence of SERS on the excitation and vibrational frequencies, and the aspectratio of spheroidal particles, are discussed. It is suggested that the results are relevant for experiments carried out on metal‐island surfaces.
Vibrational spectra of chlorocyclopropane
Authors: Green P. M. , Wurrey C. J. , Kalasinsky V. F.
Published: May 2005

The gas‐phase Fourier transform infrared spectrum (4000‐400 cm−1) of chlorocyclopropane was recorded at a resolution of 0.5 cm−1. For the first time, gas‐phase Raman and solid‐phase infrared and Raman spectra were obtained for this molecule. Liquid‐phase Raman and infrared spectra were also recorded and, on the basis of all the data, a complete assignment of the 21 normal modes of vibration of chlorocyclopropane was made. The proposed assignment is in excellent agreement with assignments for other substituted cyclopropanes and, in particular, other chlorine‐substituted cyclopropanes.
Raman and far infrared spectra of crystalline acetylene, C2H2 and C2D2
Authors: Anderson A. , Andrews B. , Torrie B. H.
Published: May 2005

Raman and far infrared spectra of the orthorhombic and cubic phases of acetylene and deuterated acetylene have been obtained. In the orthorhombic phase, three of the four expected librations have been identified in the Raman spectrum and the two infrared active translations have been confirmed, for both samples. In the cubic phase, two of the three predicted librations in the Raman spectrum and the expected pair of translations in the far infrared spectrum have been observed, again for both samples. Splittings in the internal mode Raman spectra are, with one exception, in agreement with the predictions of group theory.
Rotational Raman optical activity in chiral symmetric tops
Authors: Barron L. D. , Johnston C. J.
Published: May 2005

A theory of rotational Raman optical activity in chiral symmetric top molecules is presented. The required rotational transition polarizability and optical activity tensors are calculated using irreducible tensor methods for axially symmetric systems. Selection rules on optically active rotational Raman scattering are found to be basically the same as for conventional rotational Raman scattering, namely ΔJ = 0, ±1, ±2 with ΔK = 0, but in addition to possessing an anisotropic polarizability, the molecule must be chiral and must possess an anisotropy in the electronic optical activity tensors. A measure of this optical activity anisotropy is provided by the dimensionless circular intensity difference in a resolved rotational Raman band or in the envelope of unresolved bands provided the envelope is resolved from the central sharp Rayleigh line. A group polarizability model is used to calculate the rotational Raman optical activity in a chiral (D3) conformation of triphenylborane.
Normal‐coordinate analysis of 5‐methyl‐2‐thiocytosine and its oxygen analogue and assignments of the Raman and infrared bands
Authors: Aruna S. , Shanmugam G.
Published: May 2005

The infrared and Raman spectra of 5‐methyl‐2‐thiocytosine and its oxygen analogue in the solid state were recorded in the range 4000–200 cm−1. Normal coordinate calculations were performed for these compounds using a simple Urey‐Bradley force field for the in‐plane vibrations and a valence force field for the out‐of‐plane vibrations of the planar skeleton. The assignments of the vibrational fundamentals were made on the basis of normal coordinate calculations and the frequency shifts of bands on N‐deuteriation, The assignments are discussed in relation to vibrational assignments of some related molecules.
Resonance Raman spectra of poly(L‐lysine), aromatic amino acids, L‐histidine and native and thermally unfolded ribonuclease A
Authors: Chinsky L. , Jolles B. , Laigle A. , Turpin P. Y.
Published: May 2005

Using excitation radiation of wavelength 248 nm, the peptide linkages of poly(L‐lysine) give rise to important pre‐resonance enhancements in the Raman spectra of the amide bands, specially of the amide II band located in the 1550–1570 cm−1 shift region. Using the same excitation wavelength, aromatic amino acids and histidine exhibit resonance enhancement, and their resonance Raman spectra are easily obtainable without a fluorescence background contribution. This background is very large, particularly in the case of phenylalanine when longer wavelength excitation is used. The Raman spectra of native and thermally denatured ribonuclease A have been investigated using 248 nm excitation radiation. These spectra show the major contribution of the tyrosine residues of the protein. It seems that the behaviour of the tyrosine doublet is not a completely adequate probe for following the unfolding of the protein.
Temperature dependence of the Raman spectrum of the plastic solid carborane p‐C2B8H10: Investigation of the phase transitions, orientational disorder and the behaviour of the so‐called ‘background’
Authors: Bukalov S. S. , Leites L. A.
Published: May 2005

The temperature dependence of the Raman spectrum of the plastic solid carborane p‐C2B8H10 was studied in the range 15–470 K. Unlike the icosahedral carboranes C2B10H12, this ‘stretched’ carborane has only one plastic phase, probably with anisotropic reorientations. A phase transition to an ordered crystal takes place at 188 K. In a sealed capillary the substance melts at 433 K. The Raman spectrum of p‐C2B8H10, originally having no background, acquired the background after the sample had been repeatedly heated and cooled. It was found that the background intensity depends on the thermal prehistory of the sample; it slowly diminishes on heating, and several degrees below the melting point the background disappears completely and re‐emerges in the spectrum of the melt.
Resolution enhancement in spectroscopy by maximum entropy fourier self‐deconvolution, with applications to Raman spectra of peptides and proteins
Authors: Ni Feng , Scheraga Harold A.
Published: May 2005

The method of maximum entropy extrapolation is applied to Fourier self‐deconvolution to enhance the inherently low resolution of the Raman spectra of peptides and proteins. Using computer‐simulated and real spectral data, a comparative study was made between the maximum entropy (MEM) and the conventional discrete Fourier transform (DFT) methods. The MEM provides better resolution with no side‐lobe formation, and is especially useful in the resolution enhancement of complicated Raman spectra of proteins. The MEM is also suitable for the spectral estimation of a short‐time record of noisy data, enabling the exposure time of protein solutions to the intense laser beam to be reduced significantly. The theory of maximum entropy spectral analysis is presented and the application of the techniques of digital resolution enhancement is discussed. It is pointed out that a combined use of different techniques should be made whenever possible in carrying out digital signal enhancement in order to reduce the chance of misinterpretation of spectral information.
Raman microspectroscopy of LiDNA fibres in ethanol and tert‐butanol
Authors: Mud J. , Otto C. , De Mul F. F. M. , Greve J.
Published: May 2005

The conformation of low‐salt LiDNA in fibrous form has been studied by Raman microspectroscopy. The recorded spectrum of a fibre soaked in ethanol is very similar to that of a fibre at low relative humidity. From x‐ray experiments it is known that in the latter case the DNA adopts the C conformation. Therefore, it can be concluded that this is also the case in a low‐salt LiDNA fibre soaked in ethanol. Further, it has been observed that the DNA conformation did not change when the excess ethanol was allowed to evaporate. The C form is also found when the fibre is in contact with ethanol vapour only. These results are in agreement with x‐ray studies. However, our experiments with a LiDNA fibre in tert‐butanol are not in agreement with x‐ray results. Only when the tert‐butanol is absolutely free from water is a state intermediate between the B and C forms found.
Isotropic Raman band shape and vibrational relaxation for molecules in the liquid state: A Critical study of some band shape functions
Authors: Fujita Kazuyoshi , Fukuda Takuya , Fukushi Kohji , Kimura Masao
Published: May 2005

A band shape function for the isotropic Raman scattering described in terms of the band width in the weak coupling limit and the relaxation time of the bath mode has been proposed by summing the results of Berne et al. [J. Chem. Phys. 45, 1086 (1966)], Wang [Mol. Phys. 33, 207 (1977)] and Knauss [Mol. Phys. 36, 413 (1978)]. The results of band analyses with this function have been compared with those obtained from other conventionally used band shape and correlation functions. The present function is preferable for precise interpretation of vibrational relaxation mechanisms, particularly for those cases where temperature and concentration dependence of the band parameters are involved.
Anomalous Raman polarization observed on the protonated phenazine dication in concentrated sulphuric acid
Authors: Kihara Hayato , Gondo Yasuhiko
Published: May 2005

Anomalous polarization has been found for the b3g vibrations in the Raman spectrum of the protonated phenazine dication in concentrated sulphuric acid.
Pure rotational and vibration–rotational Raman spectra of 1H2, 1H2H and 2H2
Authors: Edwards H. G. M. , Farwell D. W. , Gorvin A. C. , Long D. A.
Published: May 2005

The pure rotational (S‐branch) and vibration‐rotational (Q‐branch) Raman spectra of 1H2, 1H2H and 2H2 have been recorded photographically and analysed with a precision greater than that achieved in earlier investigations to produce values of the bond lengths. From a combination of these results and those obtained from the species 2H3H, 1H3H and 3H2 a mean value of the bond length in the equilibrium configuration of re = 74.151±0.001 pm has been obtained.
CARS spectrometer with cw intra‐cavity excitation for high‐resolution Raman spectroscopy
Authors: Frunder H. , Matziol L. , Finsterhölzl H. , Beckmann A. , Schrötter H. W.
Published: May 2005

The construction of a cw CARS spectrometer is described, consisting of a single mode argon ion ring laser, an intra‐cavity sample cell and a tunable dye laser. The argon laser was first stabilized to an iodine absorption line. From an evaluation of the CARS spectrum of the Q‐branch of the rovibrational band of nitrogen, the vibration‐rotation interaction constant is obtained as αe = 0.0173850 ± 0.0000035 cm−1, in agreement with Bensten's result from the linear Raman spectrum of the total band. Finally, the stabilization of the argon laser to a hyperfine component in the Doppler‐free polarization spectrum of iodine is described.
Effect of electrolyte concentration on the Raman spectra of water in aqueous solutions
Authors: Rull F. , de Saja J. A.
Published: May 2005

Polarized Raman spectra of water in the ν(OH) and δ(OH2) regions have been recorded for aqueous solutions of electrolytes of types AB and AB2 (A = Li, Na, K, Ca; B = Cl, Br, I, NO3) over a wide concentration range. Variations in frequencies, intensities, band shapes and band widths with changes in concentration and in the nature of the ions are discussed.

The isotropic and anisotropic components of the intensity of the ν(OH) band have been analysed as a function of concentration. It is found that the function 45(a')2 is approximately independent of, or decreases slightly with, the concentration of the alkali metal halides whereas for the nitrates it increases linearly with concentration. The function 3(γ′)2 increases very slowly with concentration for both halides and nitrates. These results have been compared with those obtained for pure water when the temperature is varied over the range −20 to 120°C.

Despite the difference in nature of the two types of perturbation (ionic and thermal), all the results can be interpreted in terms of modifications of intra‐and inter‐molecular couplings and Fermi resonance between vibrational modes of water molecules.
Effect of hydrostatic pressure on the phase state and molecular structure of aqueous lysolecithins: A Raman spectroscopic study
Authors: Wong Patrick T. T. , Mantsch Henry H.
Published: May 2005

The Raman spectrum of aqueous palmitoyl lysolecithin was monitored as a function of pressure between 1 bar and 26.1 kbar. The changes observed in these Raman spectra are discussed in terms of the effect of hydrostatic pressure on the phase state and the molecular structure of lysolecithins. At pressures between 1 and 1900 bar aqueous palmitoyl lysolecithin exists in a micellar state and at pressures above 1.9 kbar it converts into a series of three coagel phases. The critical pressures at 28°C are 1.9 kbar for the micellar to coagel I transition, 4 kbar for the coagel I to coagel II transition and 15 kbar for the coagel II to coagel III transition. The transition from the micellar phase to the coagel I phase has a high pressure hysteresis of 1.1 kbar, while the transitions between the three coagel phases show only negligible pressure hysteresis. The major change in structure occurs at 1.9 kbar where the cylindrical micellar phase converts to an interdigitated lamellar coagel phase; the structural changes at 4 kbar (coagel I/II transition) and at 15 kbar (coagel II/III transition) involve only a modification of the interchain packing.
Effect of vinyl groups on resonance Raman spectra of protoporphyrin‐IX
Authors: Sarkar M. , Verma A. L.
Published: May 2005

Resonance Raman (RR) spectra obtained with several excitation wavelengths are compared for the following porphyrin‐IX compounds: free‐base protoporphyrin‐IX, meso‐porphyrin‐IX and haematoporphyrin‐IX and copper‐protoporphyrin‐IX and copper‐mesoporphyrin‐IX dimethyl esters. Certain bands in the RR spectra of all the free‐base porphyrins or copper complexes are unaffected with respect to frequency, whereas there is a shift in the frequencies of some vibrational modes in some systems. From a comparative study of the systems which have identical geometrical arrangements, no extra features were found in the RR spectra of protoporphyrin which can be attributed directly to the vinyl group modes. This suggests that the vibrational modes of vinyl groups do not distort the excited electronic state substantially, and are not effective in vibronic coupling with the electronic states of the porphyrin macrocycle and therefore do not gain intensity under resonance excitation. Most of the vibrational modes are strongly coupled and there are no extra distinct features in the RR spectra of PP which may be associated with selective vibrational coupling of the vinyl group modes with the porphyrin skeletal modes.
Resonance CARS line shape analysis for a concentration series of a dye solution—a practicable method for the evaluation of third‐order susceptibilities
Authors: Pfeiffer M. , Lau A. , Werncke W.
Published: May 2005

An extension of the Fleming and Johnson procedure is presented for determining the molecular third‐order susceptibility parameters from three characteristic intensities within a CARS line profile (Imax, Imin, Imid). For CARS excitation close to a molecular one‐photon resonance, these three intensity values taken from one spectrum do not suffice for the determination of all relevant parameters. A simple procedure is given for overcoming this by combining the information from all the spectra within a concentration series, keeping the frequency of the CARS pump laser fixed. Uncertainty in the measured Imid value is overcome by applying a least‐squares fit of the spectra.

Results obtained from resonance CARS measurements for Rhodamine 6G in ethanol are given.
Photodissociation of Br2 and the electronic Raman spectra of Br under argon ion laser light
Authors: Chang Hua , Chen Shu‐Hui
Published: May 2005

The electronic Raman transitions of atomic bromine between the 2P1/2 and 2P3/2 states have been observed at 3685 cm−1 using excitation with 4880 Å radiation from an argon ion laser. The intensities of the Raman bands in the Stokes and anti‐Stokes sides were studied by varying the laser power and the pressure of Br2. A mechanism or photodissociation process for the production of these atoms by the intense laser radiation is proposed. The crossing between the potential curves of the B3π and 1π states could be important in reducing the population of Br* in the 2P1/2 excited state, and therefore the intensity of the observed Raman band at the anti‐Stokes side was only about 1% of the intensity of the Stokes band. This would be a good method for studying photodissociation by means of Raman scattering from the dissociation products excited by the same laser radiation.
Raman spectra of solid complexes of trihalides of antimony and bismuth with trihalides of aluminium and gallium
Authors: Shamir Jacob , Rafaeloff Rafael
Published: May 2005

Equimolar quantities of the trihalides of antimony and bismuth were fused with trihalides of aluminium and gallium and the solid products were studied by Raman spectroscopy. The spectra were interpreted on the basis of ionic structures prevailing in all these compounds, with the general formula [M15X2]+[M13X4]− (M15=Sb and Bi; M13=Al and Ga; X=CI and Br).
Vibrational dephasing of the ν3 mode of liquid allene
Authors: Zyung Taehyoung , Henderson Don O. , Her Jhy‐Yuan , Wilde Richard E.
Published: May 2005

The Raman spectrum of the ν3 mode of allene has been studied as a function of temperature throughout the temperature range of the liquid. Analysis of the spectral band shape shows that the vibrational dephasing is a fast‐modulation process. Evidence is presented for a vibrational‐rotational coupling involving the tumbling reorientation of the molecule. Dilution studies in GeH4 indicated significant resonant vibrational energy transfer.
Wavelength‐selective resonance Raman spectroscopy of a finite polyene: Solid‐state all‐trans‐β‐carotene
Authors: Mattioli T. A. , Haley L. V. , Koningstein J. A.
Published: May 2005

Two samples of solid all‐trans‐β‐carotene which differed in their degrees of crystallinity were studied using visible absorption and resonance Raman spectroscopy.

The absorption spectrum of a commercial crystalline β‐carotene sample revealed two bands at 18 450 and 20 040 cm−1 which were not present in the absorption spectrum of a prepared amorphous sample. Instead, the spectrum of the amorphous material showed a band at 19 268 cm−1 which is in a position approximately half way between the 18 450 and 20 040 cm−1 bands. From these observations these two latter bands are assigned to the Davydov components of the crystalline β‐carotene.

The resonance Raman spectrum of crystalline all‐trans‐β‐carotene revealed several frequencies for the backbone CC stretching mode, νcc, as the laser excitation wavelength was varied. This frequency was observed to vary between 1516 and 1525 cm−1. The amorphous carotene sample also exhibited a wavelength‐dependent Raman spectrum where νcc ranged from 1516 to 1522 cm−1 initially. On further exposure to laser radiation (30–60 min) at 514.5 nm, the range increased to an upper limit of 1525 cm−1, which was attributed to a photochemical product formed in both the crystalline and amorphous samples. The wavelength‐dependent νcc frequency of these carotene samples is interpreted as being due to resonance‐enhanced Raman bands of β‐carotene molecules with different effective double bond chain lengths originating from separate micro‐domains in the solid samples.
Time‐resolved resonance Raman study of photochromic 4‐(2′, 4′‐dinitrobenzyl)pyridine
Authors: Suzuki Shinichi , Isaka Hiroaki , Ito Shinichi , Hirukawa Shigeru , Matsubara Shinya , Takahashi Hiroaki
Published: May 2005

Two transient species involved in the photochromism of 4‐(2′, 4′‐dinitrobenzyl)pyridine have been detected by time‐resolved resonance Raman spectroscopy. Comparison of the spectra of the shorter and longer lived transient species with those of the anion and the N‐CH3 derivative, respectively, revealed that the shorter lived species is identical with the anion and the longer lived species is the NH quinoid tautomer. It is shown that the photochromism of this compound can be interpreted in terms of the involvement of the anion as the intermediate to the NH quinoid which is the photo‐activated transient blue substance usually observed.
Temperature‐dependent intensities of Raman bands of di‐n‐butylamine
Authors: De Carvalho L. A. E. Batista , Da Costa A. M. Amorim , Teixeira‐Dias J. J. C. , Barbosa Ester F. G. , Lampreia Isabel M. S.
Published: May 2005

Raman spectra of di‐n‐butylamine show bands whose temperature‐dependent intensities clearly suggest the occurrence of different conformers in simultaneous equilibria. In particular, the Raman spectrum of the solid phase is compared with that of n‐nonane in order to identify the more stable conformation. In addition, intensity rations vs temperature for pairs of Raman bands in the CH stretching region exhibit a smooth variation between the liquid and solid.
Single crystal Raman spectra of potassium peroxodisulphate. Assignment of the vibrations of the S2O ion
Authors: Eysel Hans H. , Rösinger Gerold
Published: May 2005

Raman spectra of oriented single crystals of potassium peroxodisulphate have been measured and revised x‐ray structural data are briefly presented. An assignment of the internal modes of the S2O82− ion was possible on the basis of intensities under different orientations.
Raman study of odd‐numbered C11C23n‐alkanes in their high‐temperature solid phases
Authors: Maissara M. , Devaure J.
Published: May 2005

The Raman spectra of solid odd‐numbered n‐alkanes were analysed in the frequency ranges corresponding to the LAM‐1 and the methyl rocking modes, in order to specify the nature and the quantity of the gauche forms occurring in the high‐temperature phases. The evolution of the LAM‐1 frequency under different pressure and temperature conditions is discussed in connection with the interlamellar distances. In the high‐temperature phases, the relative quantity and the nature of the gauche forms located at the ends and near the ends of the chains was estimated as functions of the chain length and of temperature.
Ultraviolet resonance Raman bands of guanosine and adenosine residues useful for the determination of nucleic acid conformation
Authors: Nishimura Yoshifumi , Tsuboi Masamichi , Kubasek William L. , Bajdor Krzysztof , Peticolas Warner L.
Published: May 2005

The ultraviolet resonance Raman (UVRR) bands of several guanine‐ and adenine‐containing mononucleotides were measured, and were compared with the classical and UVRR spectra of 9‐ethylguanine, which contains no furanose ring, in order to assess the effect of sugar conformation on the UVRR spectrum. For several guanine mononucleotides containing different furanose rings some differences were found in the Raman bands normally attributed to the purine vibrations. A similar effect exists with different adenosine mononucleotides. The fact that these vibrations are allowed in the rigorous resonance Raman effect indicates that they are coupled to the electronic transitions of the base. Differences which are seen between cyclic nucleotides, ribonucleotides and deoxyribonucleotides probably arise from differences in the conformation of the attached furanose rings. This provides a method for the identification of conformationally sensitive vibrations of purine rings in nucleic acids.
The Raman spectrum of potassium metavanadate
Authors: Park Y. S. , Shurvell H. F.
Published: May 2005

Raman spectra of polycrystalline KVO3 have been recorded at various temperatures. Splittings have been observed for most fundamentals and the external mode region contains at least eight bands. The spectra are interpreted in terms of a group theoretical analysis based on the molecular symmetry and the known crystal structure. The frequency versus temperature plots for external modes of KVO3 indicate that a single crystal structure exists between 10 and 300 K.
15N isotopic effects on the Raman spectra of tribromoacetonitrile
Authors: Suero M. I. , McNeil L. E. , Márquez F.
Published: May 2005

[15N]Tribromoacetonitrile was synthesized with an isotopic content of 99.4% and its Raman spectrum was recorded in the range 4000–50 cm−1; depolarization ratios were also measured. The isotopic shifts arising from 15N were determined and interpreted. The fundamental vibrations of Br3CCN and also some overtones, combinations and difference bands were assigned. The molecular structure of tribromoacetonitrile was studied employing GAUSSIAN‐ 82 ab initio theoretical calculations and the Teller‐Redlich isotopic product rule was applied by assuming the following geometrical parameters: CN = 1.163 Å, CC = 1.479Å, BrC = 1.950Å, <BrCBr = 110.33° and <CCBr = 108.58°.
Raman and infrared spectra of solid tin tetrabromide
Authors: Zeng W. Y. , Anderson A.
Published: May 2005

Raman and infrared spectra of crystalline tin tetrabromide at temperatures between 20 K and the melting point, 304 K, are reported. No evidence of any solid‐state phase transition was found. Splittings of the four molecular modes are discussed in terms of crystal field effects and isotopic species. All twelve Raman and five of the nine infrared‐active lattice modes, predicted on the basis of a group theoretical analysis, have been observed. Since these peaks lie within a relatively narrow frequency range, and since the molecules are located on general sites in the unit cell, mixing between modes is likely to be considerable.
Infrared and resonance Raman spectroscopic studies of 1‐hydroxy‐9,10‐anthraquinone and its metal complexes
Authors: Dutta Prabir K. , Hutt Julie A.
Published: May 2005

Infrared and resonance Raman spectra of 1‐hydroxy‐9, 10‐anthraquinone, its deuteriated and deprotonated forms and its metal chelates with CuII, NiII and CoII ions are presented. Vibrational assignments of the carbonyl, hydroxyl and the chelating unit of this chromophore are emphasized. It is found that the different metal ions force delocalization of the electrons on the chelate rings to different extents. The intensities of the Raman bands under resonance conditions suggest that the electronic band in the visible region is mainly of a charge‐transfer type from the metal to the ligand.
Spectra and structure of organophosphorus compounds. XXXI—Raman and infrared spectra and conformational stability of ethylphonothioic dichloride
Authors: Durig J. R. , Hizer T. J.
Published: May 2005

The Raman (3500–10 cm−1) and infrared (3500–50 cm−1) spectra of solid ethylphosphonothioic dichloride, CH3CH2P(S)Cl2, and its deuteriated analog, CD3CH2P(S)Cl2, have been recorded. Additionally, the Raman spectrum of the liquid has been recorded and qualitative depolarization values have been obtained. From the fact that several distinct Raman lines disappear on going from the liquid phase to the solid state, it is concluded that the molecule exists as a mixture of the trans and gauche conformers in the liquid phase with the gauche conformer being the more stable form and the only one present in the solid Gtate. A variable temperature study of the Raman spectrum of the liquid did not yield an enthalpy difference between the conformers. Relying mainly on group frequencies and relative intensities of the infrared and Raman bands, a complete vibrational assignment is proposed for the gauche conformer. This assignment is supported by a normal coordinate calculation, which was carried out utilizing a modified valence force field to obtain the frequencies of the normal modes and the potential energy distribution. All of these results are compared with corresponding quantities for several other organophosphines.
Reorientational relaxation in liquid 1,4‐dioxane as studied by Raman spectroscopy
Authors: Fatima M. , Marques R. M. Ferreira , Da Costa A. M. Amorim
Published: May 2005

The anisotropic Raman spectra of liquid 1,4‐dioxane have been recorded at several temperatures and at different concentrations of aqueous and carbon tetrachloride solutions. The rotational dynamics of the 1,4‐dioxane molecules under these conditions is discussed in terms of appropriate correlation functions, reorientational relaxation times and second‐order rotational spectral moments.
Vibrational spectra, phase transitions and conformers of 1,4‐dichlorobut‐2‐yne
Authors: Karlsson A. , Klaeboe P. , Nielsen C. J.
Published: May 2005

The Raman and IR spectra of 1,4‐dichlorobut‐2‐yne (DCB) as a liquid at various temperatures and as an amorphous and as metastable and stable crystalline solids at low temperatures have been recorded in the 4000–20 cm−1 range. Additional IR and Raman spectra of a high‐pressure crystalline phase were obtained at ca 17 kbar pressure.

The broad unsymmetrical bands of DCB in the liquid and in the amorphous solid below 500 cm−1 suggest nearly free rotation in these phases at all of the temperatures investigated. Below ca 190 K a crystal containing the anti and above 190 K a crystal containing the gauche conformer of DCB were formed; the latter crystal is believed to be thermodynamically more stable at all temperatures. Only one high‐pressure crystal with molecules in the anti conformation was formed at room temperature. A phase transition reported at 232 K in the liquid, involving a conversion to an anti conformer, was not detected.

Complete vibrational assignments for both anti and gauche conformers are presented, supported by force constant calculations.
Conformational features of lipids and proteins in myelin membranes using Raman and infrared spectroscopy
Authors: Carmona P. , Ramos J. M. , De Cózar M. , Monreal J.
Published: May 2005

Myelin membrane and its proteolipid protein (PLP) have been examined by infrared and Raman spectroscopy to provide information about the secondary structure of proteins and conformation of lipid chains. Splitting of the amide I modes in the vibrational spectra and locations of amide A, I, II, III and V bands indicate that the polypeptide arrangement in both membrane systems is mainly helical. The β‐form is also present, its amount being higher in PLP. Raman spectra in the CC and CH stretching regions show significant differences concerning intra‐ and inter‐chain lipid order, which is greater in PLP.
Theory of Fermi resonances in Raman and infrared spectra
Authors: Monecke J.
Published: May 2005

Fermi resonances are analysed in the literature either by degenerate first‐order perturbation theory or by the coupled oscillator model of Schwartz and Wang. Here the perturbation treatment is generalized, taking into account the coupling not only between a fundamental and an overtone, but also with other eigenstates, required by a proper treatment of the Bose character of vibrations. The resulting expressions for the frequency shifts differ from those of both other models. Numerical differences from the first‐order perturbation treatment are small in most cases. However, the results can be used to relate the empirical interaction constant of the coupled oscillator model to an actual anharmonicity constant.