The rovibrational Raman spectrum of water vapour v 1 and v 3

The OH stretching region in the Raman spectrum of water vapour has been observed and reproduced by computer simulation using rovibrational wave functions derived from the analysis of high-resolution absorption spectra. Relative intensity measurements allow the determination of the depolarization ratio and the ratio of the two non-vanishing second-order irreducible tensor components for v ₁. These quantities have been combined with the literature value for the cross section of this band to calculate the principal cartesian components of the v ₁ derived polarizability tensor. The cross section for the v ₃ vibration was also determined, and these results are considered in terms of the bond polarizability theory.     

Calculation of intensities of torsional-rotational bands in the IR absorption spectrum of hydrogen peroxide

We present the calculated intensity distributions in torsional-rotational IR absorption bands of hydrogen peroxide. The torsional components of the band intensities have been calculated based on the appropriate matrix element computations. The contribution of the rotational components has been calculated using the 3j-symbols technique. The calculations have proved the reliability of available data on rotational constants, barrier heights of internal rotation, and locations of torsional-rotational levels of hydrogen peroxide. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 153–158, March–April, 2008.     

Calculation of transition intensities for torsional vibrations in IR and Raman spectra of dihydroxybenzenes

We present the calculated intensity distribution for bands and lines in torsional IR and Raman spectra of dihydroxybenzenes. The calculations were based on calculated matrix elements for the components of the dipole moment and the polarizability tensor. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 598–603, September–October, 2007.     

Symmetry Analysis of Molecules Consisting of Two Coaxial Rotors Using the Extended Permutation–Inversion Groups

A general method for constructing permutation-inversion groups and their extensions to molecules containing two coaxial rotors is presented. Symmetry species of the dipole moment, tensor of polarizability, and total angular momentum operator are determined. General infrared and Raman selection rules, symmetry classifications of rotorsional, rotational, and torsional wavefunctions are derived. Theory is illustrated for the H₃D⁺₂complex.     

On the application of the theory of the brownian movement in a periodic potential to the study of inertial effects and dipole coupling

For a series of ten electron molecules (HF, H₂O, NH₃, CH₄) the molecular polarizability tensor and the derivatives with respect to the symmetry coordinates have been calculated from ab initio SCF wavefunctions using the finite field method as well as perturbation theory approaches. Raman intensities and degrees of depolarization derived from the finite field results agree well with the available experimental data.

The zeroth order bond polarizability model and the atom dipole interaction model have been analysed. Both models can be used to describe the computed static polarizabilities and the derivatives with respect to bond stretching, but fail for the derivatives with respect to the bending coordinates.     

Theoretical and experimental analysis of N2–H2 stimulated Raman spectra

The paper reports on a detailed study of the N₂–H₂ collisional line broadening coefficient. High resolution stimulated Raman spectra of nitrogen–hydrogen mixtures have been recorded at liquid nitrogen and room temperatures. Corresponding linewidth calculations have been performed at temperatures between 77 and 500?K using the semiclassical Robert and Bonamy model for J rotational quantum numbers varying between 0 and 11. Comparison between experimental data and calculated results shows good agreement at room temperature using an adjusted value for the kinetic diameter.     

Inversion relations,phase transitions and transfer matrix excitations for special spin models in two dimensions

The infrared and Raman active phonons (k=0) of orthorhombic TbF₃ and of isomorphous HoF₃ have been observed and attributed to the different irreducible representations of the factor groupD _2h. Moreover we investigated crystal-field excitations of the 4f-configuration of the Rare-Earth-ions and effects of their interaction with optical phonons, especially as a function of an external magnetic field. The infrared reflection spectra of these materials not only display reststrahlen bands of electric dipolar but also of magnetic dipolar type with a characteristic shape of the latter bands.On entering the ferromagnetic ordered state pertinent symmetry reductions (D _{2hC 2h}) become evident in the system of electronic transitions and optical phonons in TbF₃ by a change of selection rules and a magnetization-induced transfer of transition intensities to new components of the transition dipole or of the Raman polarizability tensor. These observations are in accordance with general symmetry considerations.The delocalization of the crystal-field excitations results in a Davydov splitting of the single-ion transitions.     

Evaluation method for Raman depolarization measurements including geometrical effects and polarization aberrations

In this article, we address the notoriously difficult problem to quantitatively link measured Raman depolarization values to theoretical polarizability tensor quantities, since quantum calculations do not incorporate experimental parameters. For this, we introduce a numerical model to calculate, for realistic experimental configurations, effective Raman line strength functions, Φ, which find their way into depolarization ratios, ρ. The model is based on interlinked integrations over the angles in the light collection path and a finite Raman source volume along the excitation laser beam. The model deals also with the conditional aperture parameters, associated with more than one optical component in the light collection path. Finally, we also can take into account polarization aberrations introduced by the sample cell windows. The procedure was fully tested for Raman depolarization spectra of selected hydrogen isotopologues. Distinct aspects affecting Raman depolarization data were validated, namely: (1) excitation polarization impurities; (2) extended Raman excitation volumes; (3) Raman light collection over finite solid angles; and (4) polarization aberrations introduced by optics in the light collection path. The correction of the experimental measurement data for the aforementioned effects resulted in depolarization ratios for the Q₁(J " ) Raman lines of H₂ and T₂, which mostly differed by less than 5% from those obtained by quantum‐calculations. Copyright © 2013 John Wiley & Sons, Ltd.     

Measurement of the Raman polarizability anisotropy for the v = 1 pure rotational Raman transition in H 2 by rotational Raman spectroscopy

A combination of stimulated Raman pumping and rotational Raman spectroscopy is used to accomplish the first measurement of the polarizability anisotropy γ_11,13 (355 nm) for the S₁₁ (1) transition in molecular hydrogen H₂. Saturation of the Q₀₁(1) transition connecting the |X¹ Σ⁺ _g, v = 0, J = 1 > state to the |X¹ Σ⁺ _g, v = 1, J = 1 > state in H₂ by stimulated Raman pumping is the critical element in this experiment. The observed intensities of the rotational Raman lines for these states allow an estimate of γ_11,13 (355 nm) as 0.358 ± 0.004 ų. A comparison of this value to that obtained from fundamental ab initio calculations in H₂ also is possible for the first time.     

Can Raman spectroscopy detect cumulenic structures of linear carbon chains?

The molecular and vibrational structures of cumulenic carbon chains are investigated by density functional theory calculations and compared with that of hydrogen‐capped polyynes. The small value of bond length alternation (BLA) along the CC bonds sequence obtained by geometry optimization of uncapped C_n chains and vinyl‐capped carbon chains confirms their cumulenic structure. It is demonstrated that for finite length chains the structural parameters are determined by end effects as far as the Peierls distortion, expected for very long molecules, does not occur. The Raman spectra of such molecules are calculated to verify the possibility of identifying markers of cumulenic chains by means of vibrational spectroscopy. As expected, the longitudinal mode consisting of the BLA oscillation, which is responsible for the strongest Raman transition of polyynes, becomes very weak for cumulenes; this behaviour is rationalized in terms of local polarizability derivatives. However, other longitudinal modes can be observed in the Raman spectra of C_n chains. The wavenumber behaviour and the optical activity of these modes are interpreted on the basis of the phonon dispersion branch of an ideally infinite cumulenic polymer. Raman intensities computed for chains of different lengths allow to conclude that cumulenic molecules could be detected and identified by means of Raman spectroscopy. Copyright © 2009 John Wiley & Sons, Ltd.     

Accurate depolarization ratio measurements for all diatomic hydrogen isotopologues

The Raman depolarization ratios for individual Q₁(J”) branch lines of all diatomic hydrogen isotopologues – H₂, HD, D₂, HT, DT, and T₂ – were measured, for all rotational levels with population larger than 1/100 relative to the Boltzmann maximum at room temperature. For these measurements, the experimental setup normally used for the monitoring of the tritiated hydrogen molecules at KArlsruhe TRItium Neutrino experiment was adapted to optimally control the excitation laser power and polarization, and to precisely define the Raman light collection geometry. The measured Raman depolarization values were compared to theoretical values, which are linked to polarizability tensor quantities. For this, the ‘raw data’ were corrected taking into account distinct aspects affecting Raman depolarization data, including (1) excitation polarization impurities; (2) extended Raman excitation volumes; and (3) Raman light collection over finite solid angles. Our corrected depolarization ratios of the hydrogen isotopologues agree with the theoretical values (based on ab initio quantum calculations by R.J. LeRoy, University of Waterloo, Canada) to better than 5% for nearly all of the measured Q₁(J”) lines, with 1σ confidence level. The results demonstrate that reliable, accurate Raman depolarization ratios can be extracted from experimental measurements, which may be substantially distorted by excitation polarization impurities and by geometrical effects. Copyright © 2013 John Wiley & Sons, Ltd.     

The rotational Raman spectra and cross sections of H2O, D2O, and HDO

We report the experimental rotational Raman spectra of H₂O, and of a mixture of D₂O and HDO in the vapor phase at room temperature, and their interpretation in terms of rotational–vibrational energies, wavefunctions, and transition moments of the molecular polarizability. These transition moments are based on high-level ab initio calculations of the wavelength dependent polarizability surface, and on wavefunctions where the rotational–vibrational coupling is considered in detail. As a byproduct of this analysis several tables have been compiled including scattering strengths and assignments for individual rotational transitions of the three species. From these tables the rotational Raman spectra can be simulated over the range of temperatures up to 2000 K for H₂O, and up to 300 K for D₂O and HDO.     

The far-infrared spectrum of deuterated hydrogen sulfide: The ground state rotational constants of D232S,D234S,HD32S,and HD34S

Pure rotation spectra of deuterated samples of hydrogen sulfide have been recorded between 25 and 280 cm^?1 with a Fourier transform spectrometer at an apodized resolution of 0.004 cm^?1. Accurate rotational and centrifugal distortion constants have been derived from the observed line positions for the four isotopic species D₂³²S, D₂³⁴S, HD³²S, and HD³⁴S. Finally, an extensive list of calculated and observed line positions, together with their calculated intensities is presented.     

The Raman spectra and cross-sections of the ν2 band of H2O, D2O, and HDO

We report the experimental Raman spectra of the ν₂ band of H₂O, D₂O, and HDO in the vapor phase at room temperature. A complete interpretation of the Raman intensities is carried out employing the variational rovibrational wavefunctions obtained from a Hamiltonian in Radau coordinates and an ab initio polarizability surface at 514.5 nm. We show the importance of the rotation-vibration coupling to obtain the correct line intensities. Several tables with the assignments of the individual rotational-vibrational transitions and their Raman scattering strengths are reported. From these tables, the ν₂ Raman spectra can be simulated up to 2000 K for H₂O, and up to 300 K for D₂O and HDO.     

c向静电场作用下α-LiIO3单晶的喇曼谱“串线”和谱线强度改变的机理

在c向静电场作用下,α-LiIO₃单晶的喇曼谱发生“串线”,并且谱线强度改变。本文分析了这一现象的起因:由于离子输运引起的空间电荷涨落使α-LiIO₃单晶的极化率张量和喇曼张量主轴方向发生涨落。前者产生o←→e光散射,散射光再发生一次喇曼散射,造成喇曼谱“串线”和谱线强度的改变;后者直接造成喇曼诺“串线”和谱线强度的变化。前者的贡献远大于后者。 关键词：     

Line shape analysis for Zeeman modulation spectroscopy

The technique of Zeeman modulation spectroscopy has been applied to the nitric oxide fundamental in order to compare the observed line shapes and intensities with theory. A predicted change of the sign of theg _J factor at high rotational states has been verified experimentally. The tunable laser source used in the experiment was a spin-flip Raman laser.     

Coherent anti-Stokes Raman spectroscopy (CARS) of thev 3 band of methane in supersonic molecular beams

Supersonic molecular beams of methane are investigated in the expansion region using coherent anti-Stokes Raman scattering (CARS). Raman spectra of thev ₃ vibration with resolved rotational structure at low temperatures are reported. Comparison with calculated CARS spectra shows that the rotational distribution in the beam may be well described by a Boltzmann distribution. Temperatures are the same for all three nuclear spin modifications within the experimental error.     

Generation of multi-color stimulated raman emission from two-color linearly or circularly polarized pump beams

A laser beam at two different frequencies separated by 587 cm^–1 is focused into pressurized hydrogen (rotational transition energy, 587 cm^–1) to generate multi-color stimulated Raman emission. The polarization state and the pulse energy are measured for each generated emission line using linearly and circularly polarized pump beams. The effect of the polarization is discussed by using a parameter characterizing the polarizability of hydrogen and a conservation rule for the angular momentum in four-wave mixing. Many rotational lines are generated with linearly polarized pump beams through a four-wave mixing process. This is in striking contrast to the results obtained by using a single-color circularly polarized pump beam which generates only one rotational line through a conventional stimulated Raman process.