Triatomic Vibrational Energies

The generator coordinate approximation theory isformally applied to H ₃ ⁺ . Asecular equation with an eigenvector ofthree dimensions and matrix elements ofsix dimensions results. Numerical solutions of this equation are thevibrational energy levels ofH ₃ ⁺ .     

Scanning Tunneling Vibrational Spectroscopy

A new method for studying of vibronic transitions by scanning tunneling microscope (“nitraresonator electron-vibronic scanning tunneling spectroscopy of adsorbates”) is proposed. Results of experiments carried out by STM “Omicron” where electron-vibronic series of field emission resonances were observed are presented. Frequencies of the resonances correspond to ones of local vibrations of titan oxide and adsorbed hydroxil particles.     

Vibrational relaxation in liquids

A new theory is presented for vibrational energy relaxation in a liquid. It is shown that a vibrationally excited probe molecule relaxes through interaction with the density fluctuations in the surrounding solvent fluid. This interaction occurs through a potential V(k), which is expressed in terms of the intermolecular force between the excited probe molecule and the surrounding fluid molecules. By assuming spherically symmetric solvent particles the T ₁ energy relaxation time for direct V-T processes is related to the translational dynamic structure factor for the fluid S(k, ω_v), evaluated at the vibrational resonance frequency. It is shown that this is described by gas-like particle motions on a very short distance scale corresponding to k vectors lying well beyond the first or second peaks of the fluid structure factor S(k). Such motions can be pictured as high-frequency, short-distance distortions of the local equilibrium configuration of the solvent particles around the probe. T ₁ ^-1 is found to be proportional to ρ_e T ^1/2 ω_v ^-3. The V-V energy exchange relaxation time is also calculated. This is found to be proportional to S(k, ω′) evaluated at a frequency ω′, corresponding to the vibrational energy missmatch. An energy gap law for the V-V process is derived.     

Vibrational Spectrum of Tribromoethanol

Abstract

The molecular structure of tribromoethanol has been studied by Ab Initio theoretical calculations. The IR spectrum has been recorded in the range 4000—200 cm^?1. Whereas, the Raman spectrum has been determined by means of a SPEX 1403 spectrometer using the 5145Å exciting line of a Spectra—Physics 164 Ar ion laser. Depolarization ratios were also measured. The fundamental vibrations of CBr₃CH₂OH as well as some overtones, combinations and difference bands were assigned.     

Vibrational Spectrum of Bromal

Abstract

The molecular structure of tribromoacetaldehyde, Bromal, has been studied by Ab Initio theoretical calculations. The IR spectrum has been recorded in the range 4000–200 cm^?1. The Raman spectrum has been studied with a SPEX 1403 spectrometer using the 5145Å exciting line of a Spectra-Physics 164 Ar ion laser. Depolarization ratios were also measured. The fundamental vibrations of Br₃ CCOH and also some overtones, combinations and difference bands were assigned.     

Vibrational intensities in methane

The absorption intensities of the two infra-red active vibrations in methane have been obtained from a perturbation calculation on the equilibrium wave functions derived in the preceding paper. The perturbation field is the change in the potential field due to the nuclei which results from moving the nuclei in the vibrational coordinate concerned, and a simplified form of second order perturbation theory, developed by Pople and Schofield, is used for the calculation. The main approximation involved is the neglect of f and higher harmonics in the spherical harmonic expansion of the nuclear field. The resulting dipole moment derivatives are approximately three times larger than the experimental values, but they show qualitative features and sign relationships which are significant.

The experimental intensity measurements are interpreted and discussed in relation to these results.     

Vibrational spectrum of perfluoroethane

We have obtained IR absorption spectra of a C₂F₆ gas and a C₂F₆ cryosolution in Xe (T = 163 K) in the fundamental and overtone ranges. We have interpreted 28 bands of ¹²C¹²CF₆ and three bands of ¹³C¹²CF₆. In the spectral ranges that correspond to vibrations that are combinations with ν₁, ν₇, and ν₅, we observe multiplets, which we attribute to interactions of the type of Fermi resonances between the states ν₁(A _1g ) ∼ ν₆(A _1g ), ν₇(E _g ) ∼ ν₆ + ν₁₁(E _g ) ∼ 2ν₈(E _g ), ν₅(A _2u ) ∼ ν₈ + ν ₁₁(A _2u ). We reveal an anomalous intensity distribution in the spectrum of an asymmetric isotopologue. For the basic and isotopic configurations of perfluoroethane, we calculate the coefficients of shapes of vibrations and the intensities of absorption bands. We reveal that the behavior of the groups ¹²CF₃ and ¹³CF₃ is indifferent to the excitation of doubly degenerate stretching vibrations ν₇(E _g ) and ν₁₀(Eu).     

Vibrational excitation dynamics in photodesorption

Quantum state specific detection of photodesorbed molecules enables measuring their final state distributions in the translational and internal degrees of freedom, which contain a wealth of information about the desorption mechanism and dynamics. Vibrational state populations are of particular interest because of the information they contain about the lifetime and nature of the electronic excited states responsible for desorption. The measured vibrational distributions for nondissociative photodesorption of diatomic molecules tend to resemble Boltzmann distributions with temperatures of 600–1200 K for desorption from metal surfaces, and 1700–2000 K for semiconductors and oxides. Two-dimensional quantum dynamics calculations of the desorption process show that these vibrational distributions can be reproduced only if the intramolecular equilibrium bondlength in the electronic excited state is remarkably similar to that of the ground state. In particular, the results are inconsistent with a desorption mechanism in which the intramolecular bondlength change upon excitation is similar to that of electron capture in the gas phase.     

Vibrational properties of hierarchical systems

The vibrational properties of one-dimensional hierarchical systems are investigated and results are obtained for both their eigenvalues and eigenvectors. Two cases are considered, the first one with a hierarchy of spring constants and the latter with a hierarchy in the masses. In both cases the eigenspectrum is found to be a zero-measure, two-scale Cantor set with a fractal dimension between 0 and 1. The scaling properties of the spectra are calculated using renormalization group techniques and are verified by extensive numerical work. The low-frequency density of states and low-temperature specific heat are calculated and a singularity is found in the scaling behavior. The eigenvectors are found to be either extended or critical and self-similar. A transfer matrix formalism is introduced to calculate the scaling properties of the envelope of the critical eigenvectors. Furthermore, a connection is established between the hierarchical vibration and diffusion problems, as well as to the same problems in random systems, thus showing the universality of the observed features.     

Vibrational spectroscopic study of budesonide

The Raman spectrum of budesonide is reported for the first time, and molecular assignments are proposed on the basis of ab initio BLYP DFT calculations with a 6‐31 G* basis set and vibrational wavenumbers predicted on a quasi‐harmonic approximation. Comparison with previously published infrared data has explained several spectral features, and the relative band intensities in the CO and CC stretching regions are interpreted. The results from this study provide data that can be used for the preparative process monitoring of budesonide, an important steroidal pharmaceutical in various dosage forms, and its interaction with excipients and other components. Copyright © 2007 John Wiley & Sons, Ltd.     

瘦长红珊瑚的振动光谱研究

瘦长红珊瑚是台湾贵珊瑚中最主要的品种,其颜色分布独具特色。以瘦长红珊瑚为研究对象,采用电子探针、X射线粉晶衍射、红外光谱和拉曼光谱对其进行测试分析。结果显示样品的矿物成分为高镁方解石,次要成分的含量稳定,样品中的生物成因方解石存在晶格畸变。实验探测到的代表有机质成分的1 517/1 128cm-1和1 296/1 016cm-1成套谱峰表明样品的红色与该有机成分有关。     

Vibrational spectra of benzophenone conformers

We have used direct quantum DFT methods to calculate the parameters of the adiabatic potential of four benzophenone conformers. According to the data obtained, the existence of only one conformer is possible (C₁ symmetry) for the free benzophenone molecule, for which torsional vibrations of the benzene moieties are reproduced and for which we calculated the vibrational spectrum in the anharmonic approximation of the theory of molecular vibrations. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 561–564, September–October, 2007.     

Vibrational Properties of Pertechnetyl Fluoride

Abstract

Pertechnetyl fluoride, TcO₃F, had been prepared some years ago¹, but its vibrational spectrum was only recently recorded and interpreted². The spectroscopic study reveals that, as expected, TcO₃F posseses C_3v symmetry, and the values found for the fundamental vibrations are in good agreement with those previously estimated by Müller et al.³ in a paper concerning with the vibrational behaviour of MO₃X^n? species, and some systematic relations among them (cf. also⁴).     

Vibrational properties of Cu nanowires

We have calculated local vibrational density of states (LDOS) of a center atom (CA) of a rectangular Cu nanowire with the axial orientation of 〈100〉, using a real space Green’s function approach with force constants extracted from interaction potentials based on the embedded atom method. The LDOS of a center atom of a strained nanowire is found to exhibit quite distinctive characteristics as compared to that of a strain-free nanowire, the most striking feature of which is the existence of high frequency modes above the bulk band even for small strain of 2.5%. We further find that these high frequency modes are shifted to even higher frequencies when the nanowire is exposed to an increasing axial strain.     

Vibrational Spectra of Layer Crystals

Abstract

Layer crystals have received considerable attention of spectroscopists because of the wide range of electrical and optical properties they possess. The group of layered chalcogenide crystals contains insulators, semiconductors, metals, and superconductors at moderately high temperature. The layered halide crystals act as reliable hosts for Jahn-Teller, ESR, and other optical experiments. The layerlike nature of such crystals leads to experimentally distinguishable lattice optical properties. The existence of layer and crystal symmetries is clearly manifested in the vibrational spectra of these crystals which have been determined in recent years by means of infrared and Raman investigations of the zone center modes. The large anisotropy of electrical properties leads to LO-TO splitting, while the small interlayer interaction gives rise to Davydov-type splitting besides low frequency interlayer modes. Thus investigations of such crystals have been a considerable addition to our knowledge of the vibration spectra of crystals, in general. In fact, a few of these studies provide very transparent examples of the subject.     

Vibrational spectroscopy of ion-irradiated pentacene

In this paper we present a study of the evolution of the IR and Raman spectrum of pentacene before, during and after irradiation with energetic ion beams, demonstrating the complex chemistry induced by incoming ions. The formation of a “new” aromatic network has been evidenced. Dehydrogenation occurs and the evolution towards what we call an Ion Produced Hydrogenated Amorphous Carbon is a function of the ion dose as well. The results my have noteworthy relevance in astrophysics in view of the presently believed widespread presence of PAHs and their compounds in ours as well as other galaxies.