Vibrational spectra of a GaS single crystal

The Raman and infrared active long wavelength phonons of a GaS single crystal were studied at different temperatures in the 10–600 cm^?1 range. Properly polarized Raman spectra could be obtained with the 4880 Å exciting line and the previous assignment of the E_1g modes controversed recently could be confirmed. Infrared spectra were recorded in the 30–600 cm^?1 region. The vibrational frequencies of the crystal were also calculated using a method developed by Wieting and six new frequencies corresponding to infrared and Raman inactive modes have been proposed.We have observed that the degree of leakage of scattered intensity in unallowed polarizations increases when the wavelength of the exciting line moves off the exciton absorption front. The phonon at 74 cm^?1 was particularly sensitive and the question of the antiresonant behaviour of this compound is raised.     

Far infrared absorption of amorphous GaAs and Ge

Far infrared reflection spectra of amorphous GaAs and Ge have been obtained in the frequency region from 30–600 cm^?1. For each material, curves of ω?₂ vs frequency have been obtained whose corresponding reflectivity curves give a best fit to the data. The peak value of the abdorption coefficient is about 4000 cm^?1 for GaAs and 160 cm^?1 for Ge. The results are compared with Raman spectra and with theoretical calculations.     

Vibrational spectra of 1,3,5-trichlorotrifluorobenzene

Infrared (4000-80 cm^?1) and Raman spectra of a highly purified sample of 1,3,5-trichlorotrifluorobenzene in the solid, solution, and vapor states have been measured. Assignments of all the fundamental frequencies are made, completed by the use of calorimetric data.     

Vibrational spectrum of Li2B4O7 crystals

Polarized IR reflection spectra of Li₂B₄O₇ crystals are studied in a spectral range of 80–1600 cm^?1 and compared with their Raman spectra. Based on the results of the dispersion analysis of the spectra, the frequencies, damping constants, and oscillator strengths of all vibrations are determined. The inversion of frequencies of the longitudinal and transverse vibrations of the A ₁ and E symmetry in a range of 900–1150 cm^?1 is found. Based on the data thus obtained, the effective charges are calculated and the types of chemical bonds are analyzed for structural groups of the Li₂B₄O₇ crystal.     

Vibrational Assignment of N-Phenylphthalimide and 15N-Phenylphthalimide

Abstract

The i.r. spectra of N-phenylphthalimide and ¹⁵N-phenylphthalimide have been measured in 4000–100 cm^?1 frequency range as KBr and polyethylene pellets and as chloroform solutions. The Raman spectra (4000–50) cm^?1 of microcrystalline powder of the of the same compounds have also been investigated.

A detailed assignment of most of the observed frequencies has been proposed on the basis of the group vibrational concept, isotopic shift data and analogies with the spectra of related molecules. Some literature data have been discussed and some frequencies are reassigned.     

低温相偏硼酸钡晶体的红外反射光谱

本文报道了新型非线性材料——低温相偏硼酸钡晶体在室温下两种不同偏振成份的红外反射光谱(100—4000cm^-1波段),得到了200cm^-1以上频率范围内振动模的横模和纵模频率。利用“层状分子性结构”模型,参照喇曼光谱实验结果,对该晶体内振动模的归属给出了分析指认。 关键词：     

Raman spectrum of strontium titanate

The Raman spectrum of strontium titanate has been recorded using λ 4358 of mercury as exciter. The observed spectrum consists of 7 Raman lines, one of which is of low frequency, as expected from the recent theory of Cochran. 6 of these Raman lines have been interpreted as the first order spectrum arising from a small deviation of the cubic strontium titanate from its idealized symmetry. It has been shown that one normal mode of SrTiO₃ neglected by J.T.Last, will be really active in infrared absorption in the region of 440 cm^?1 and that it has to be taken into account in the interpretation of the infrared spectra of titanates. The four vibrational modes of the unit cell of SrTiO₃ correspond to frequencies of 90, 335, 441 and 620 cm^?1 observed in Raman effect. The large width of the Raman lines and the additional lines at 256 cm^?1 and 726 cm^?1 have been attributed to a splitting of the longitudinal and transverse optical modes. With the observed frequencies it has been found possible to account for in a satisfactory manner the specific heat of SrTiO₃ in the range 54·84° K to 1800° K.     

Polarized Infrared and Raman Spectra of 2(3H)-Benzoxazolone

Abstract

The infrared spectra of 2(3H)-benzoxazolone have been measured from 4000 to 180 cm^?1. The polarized spectra of single crystals have been also obtained. The Raman spectra of polycrystalline samples and solutions have been recorded and the polarization of many lines has been determined. On the basis of the i.r. dichroism, Raman spectra and correlative arguments most of the fundamental vibrations have been assigned.     

Manifestation of interaction effects in Raman spectra of CdTe quantum-dot layers with ZnTe narrow barriers

The Raman spectra of superlattices consisting of layers of CdTe self-assembled quantum dots separated by ZnTe narrow barriers with thicknesses of 10 and 5 monolayers are investigated. It is found that, apart from the bands previously observed at frequencies of ～120 and ～140 cm^?1 for samples with thicker barriers (25 and 12 monolayers), the Raman spectra exhibit a band at ～147 cm^?1 in the frequency range of CdTe vibrational modes. This band is attributed to a symmetric vibrational mode of a pair of quantum dots with oppositely directed oscillations of the dipole moments. It is this type of vibrational mode in the material surrounding the ZnTe quantum dot that accounts for the shift of the band at ～200 cm^?1 near the LO mode of ZnTe vibrations toward lower frequencies.     

Electronic Absorption Spectra of Some Fluoroaminotoluenes

Abstract

The near ultraviolet absorption spectra of 2-fluoro-5-amino-; 3-fluoro-4-amino-, 3-fluoro-6-amino-and 4-fluoro-2-aminotoluene have been investigated in vapour phase. The strongest band appearing at 2887.5 Å (34621 cm^?1), 2966.1 Å (33704 cm^?1), 3026. 7 Å (33029 cm^?1) and 2891.4 Å (34575 cm^?1) in the respective molecules has been identified as the 0,0 band. All the bands have been analysed in terms of some ground and excited state fundamentals. The assignment of the fundamental frequencies to the probable modes of vibration have also been discussed.     

Molecular Dynamics simulations of borate glasses

Abstract

The results of Molecular Dynamics simulations of borate glass (B₂O₃) using three-particle interactions are presented. These calculations yield a glass consisting of randomly connected BO₃ triangles. Infrared and Raman spectra have been calculated and compared with experimental spectra. The calculated infrared spectra show two main bands, one at 650 cm^?1 and one at 1250 cm^?1, in agreement with experiment. The Raman spectra reproduce the experimental peak at 805 cm^?1 but the peak width is a factor of ten too large. Apparently, the simulated glasses have less short range order than the laboratory glasses.     

Far infrared absorption in bulk amorphous red phosphorous

Far infrared absorption measurements have been performed above 30 cm^?1 in bulk amorphous red P at 300 K. A number of low frequency spectral features are observed that are not present in the corresponding bulk amorphous As spectrum. Deep minima observed at 163 and 320 cm^?1 in α(ω) and in the Raman spectra suggest that the phonon density of states is essentially divided into 3 bands. A calculation of the mean effective charge of the bands indicates weak coupling to the lowest frequency band. A comparison with the results in a-As suggests a less rapid frequency variation in the infrared coupling parameter at low frequencies in a-$\text{P}$.     

Study of the ion mobility in a Li0.03Na0.97Ta0.4Nb0.6O3 solid solution by raman spectra

We have studied ion mobility in a Li_0.03Na_0.97Ta_0.4Nb_0.6O₃ solid solution by its Raman spectra. It has been revealed that, as the temperature of the solution is increased to approach the point of the phase transition to a state with a high conductivity with respect to lithium, the lines with frequencies at 77, 118, and 142 cm^?1, which refer, respectively, to librations of oxygen octahedra Nb(Ta)O6 as a whole and vibrations of Li and Na ions in octahedra, considerably broaden, decrease in intensity, and smear into the wing of the Rayleigh line. Remaining lines are preserved in the spectrum. We have observed that the width of the line with a frequency of 118 cm^?1 depends exponentially on temperature, while the width of the line with a frequency of 142 cm^?1 changes linearly with it, which makes it possible to attribute to the line with the frequency of 118 cm^?1 to vibrations of Li⁺ cations, whereas the line with the frequency of 142 cm^?1 should be attributed to vibrations of Na⁺ cations in AO₁₂ cuboctahedra. The average lifetime of Li⁺ ions in equilibrium positions and the jump barrier have been estimated to be ～8 × 10^?12 s and ～20 kJ/mol, respectively. This agrees well with the data in the literature on measurements of electric conductivity.     

Polarized Infrared and Raman Spectra and Ab-initio Calculations of Benzotriazole

Abstract

The i. r. spectra of benzotriazole have been measured from 4000 to 60 cm^?1: polarized spectra of single crystals have been also obtained. The Raman spectra of polycrystalline samples and solutions have been investigated. The structural parameters and vibrational frequencies have been determined from ab-initio Hartree-Fock gradient calculations using the 6–31G* basis set. A detailed arsignment of most of the observed bands has been proposed on the basis of the i. r. dichroism, Raman polarization data and frequency calculations.

     

Vibrational Spectra and Assignments for 3,4-Dibromothiophene

Abstract

The infrared spectrum of 3,4-dibromothiophene has been studied from 4000 to 200 cm^?1. The Laser Raman spectrum has also been recorded and depolarization values have been measured. An assignment of the 21 fundamental vibrations is proposed based on group frequency correlations, Raman polarization data and comparison with the spectra of parent and some halogeno-substituted molecules.     

Laser-Raman spectroscopy of living cells

Investigations into the laser—Raman shift spectra of bacterial and mammalian cells have revealed that many Raman lines observed at 4–6 K, do not appear in the spectra of cells held at 300 K. At 300 K, Raman activity, at set frequencies, is observed only when the cells are metabolically active; however, the actual live cell spectrum, between 0 and 3400 cm^?1, has been found to alter in a specific way with time as the cells' progress through their life cycles. Lines above 300 cm^?1, from in vivo Raman active states, appear to shift to higher wave numbers whereas those below 300 cm^?1 seem to shift to lower ones. The transient nature of many shift lines observed and the intensity of them when present in the spectrum indicates that, in vivo, a metabolically induced condensation of closely related states occurs at a set time in the life of a living cell. In addition, the calculated ratio between the intensities of Stokes and anti-Stokes lines observed suggests that the metabolically induced “collective” Raman active states are produced, in vivo, by non thermal means. It appears, therefore, that the energetics of the well established cell “time clock” may be studied by laser—Raman spectroscopy; moreover, Raman spectroscopy may yield a new type of information regarding the physics of such biological phenomena as nutrition, virus infection and oncogenesis.     

Etude par spectrometrie Raman des complexes de l'iode dans les alcools et les ethers

Laser Raman spectra of iodine-alcohol and iodine-ether solutions have been studied. It was found a new line at 167 cm^?1 for alcohols and at 170 cm^?1 for ethers which is tentatively attributed to an intermediate Hassel complex.     

The dielectric and lattice vibrational spectrum of cuprous oxide

The i.r. reflection and Raman spectra of single crystal specimens of cuprous oxide have been studied between 20 and 900 cm^?1 over a wide temperature range. The optical and dielectric parameters have been derived by Kramers-Krönig analysis and the effective dynamic charge calculated. The Raman spectrum is far more complex than a group theoretical analysis suggests and this is interpreted in terms of a selection rule breakdown in the crystal due to nonstoichiometry. Variable temperature and polarisation measurements have been made in order to characterise some of the structure in the spectrum. The implications of the results for the lattice dynamical calculations is discussed.     

Vibrational spectrum of Li2B4O7 crystals

The polarized infrared reflection spectra of Li₂B₄O₇ were studied in the spectral range 80–1600 cm^?1 and compared with Raman spectra. From the spectrum dispersion analysis, the frequencies, damping, and dielectric oscillator strengths were determined for all vibrational modes observed. A calculation of the effective charges and an analysis of the chemical-bond types of the Li₂B₄O₇ crystal structural units were carried out on the basis of the obtained data.     

Raman-brillouin light scattering determination of the structural correlation range in ges2 glass

Polarized Brillouin and low frequency (3 cm^?1 ? ω ? 40 cm^?1) Raman spectra of GeS₂ glass have been measured. Parameters determined from the Brillouin spectra have been used in the theory of Martin and Brenig to obtain from a fit of the Raman spectrum the structural correlation range, 2σ. We find 2σ = 8 ± 1 Å.