Raman spectra, collision-induced

Proffitt M, Frommhold L (1979) New measurement of the trace of the helium diatom polarizability from the collision-induced, polarized, Raman spectrum. Phys Rev Lett 42 1473-1475... 

We note that in the infrared region of the spectrum, another collision-induced spectroscopy is well known that in the laboratory is usually observed in absorption. CILS is related to collision-induced absorption as ordinary Raman spectroscopy is related to the usual rotovibrational spectroscopy in the infrared. An extensive bibliography and a recent update of the literature concerning collision-induced absorption have been compiled previously. ... 

R. D. Amos, A. D. Buckingham, and J. H. Williams. Theoretical studies of the collision induced Raman spectrum of carbon dioxyde. Molec. Phys., 59 1519-1526 (1980). 

L. Frommhold. About the collision induced Raman spectrum of gaseous argon. J. Chem. Phys., 63 1687-1688 (1975). 

Johari. G.P. Molecular inertial effects in liquids Poley absorption, collision-induced absorption, low-frequency Raman spectrum and Boson peaks. J. Non-Cryst. Solids 2002. 307-310. 114. 

In the case of polarizability derivatives, however, the sparsity of results is not due to lack of interest, as this is a property that is just as important as the dipole moment derivative. Here the problem is that the calculations are more difficult, though not so much more difficult as to justify the comparatively small number of calculations in this area. There was a brief period of activity some five or six years ago in which various MC-SCF and Cl methods were tried on small molecules. ° Some earlier calculations are listed elsewhere.As with the quadrupole moment results, most of these could easily be improved upon with the aid of a large-scale multi-reference Cl calculation, which would be well within current capabilities. Some more recent polarizability derivative calculations, mostly SCF, may be found in Refs. 220 and 246-257. The most detailed of these is an M BPT calculation by Diercksen and Sadlej on CO. Another interesting group of calculations has considered the derivatives of the frequency-dependent polarizability. This shows some expected effects, for example that the frequency dependence in CI2 is noticeable, and some unexpected results, for example that the intensity of the V4 Raman-active mode of CH has a very marked frequency dependence. Dacre has provided some calculations on the polarizability of rare-gas dimers, which is of interest to the collision-induced Raman spectrum of such systems. Calculations of hyperpolarizabilities are confined to small systems. A recent example is for LiH. An example of the use of hyperpolarizability derivatives can be found where some fairly crude calculations were nevertheless useful in distinguishing two possible mechanisms in the collision-induced Raman spectrum of CO2. 

Fig 5 The Raman spectrum of CS2 at 297K separated into reorientational +++++ and collision-induced components. 

The first simulation work on the collision induced light scattering spectrum (OILS) of molecular fluids by Frenkel and McTague [90] calculated the effect of the DID on the Rayleigh and Raman spectra of diatomic molecules. A recent paper by Ladanyi [91] extends this work and we briefly outline the details of their calculations. 

Verzhbitskiy et reported a collision-induced Raman band by mixtures of sulfur hexafluoride and dinitrogen. A systematic analysis brings forth evidence of double ineoherent seattering (DRS) by this mixture with both moleeules undergoing two Raman-allowed transitions. The band is found to be almost fully depolarized. In a subsequent paper Chrysos and Verzhbitskiy" extraeted the isotropie spectrum of the above-mentioned band. 

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