Rayleigh wings

It is clear that the nematic phase exhibits a featureless Rayleigh wing and that several distinct solid phases can be formed depending on cooling rate [79]. This includes an apparently glassy phase. The vertical tick marks indicate the calculated frequencies of vibrational modes as obtained from density functional methods. 

The earliest and simplest nonresonant technique for studying intermolecular dynamics was spontaneous low-frequency Raman spectroscopy (also known as Rayleigh-wing spectroscopy) (8). In its most basic implementation, a reasonably powerful monochromatic laser beam travels through... 

Figure 6 The intermolecular portion (i.e., with the contribution of orientational diffusion excluded) of the Bose-Einstein corrected Rayleigh-wing spectrum of benzene at room temperature.

There is a long history of using Rayleigh-wing and related spectroscopies to study orientational dynamics of symmetric-top liquids (31). Liquids that have been studied include carbon disulfide (11,15,26,36-43), acetonitrile (26,44-47), benzene [(11,32,45,48-52), hexafluorobenzene (32,48,52), 1,3,5-trifluorobenzene (52)], mesitylene (32,44,50,52), chloroform (45,48,53), and methyl iodide (34,45,54,55). 

Keyes T, Kivelson D, McTague JP. Theory of k-independent depolarized Rayleigh wing scattering in liquids composed of anisotropic molecules. J Chem Phys 1971 55 4096-4100. 

Rivoire G, Wang D. Dynamics of CS2 in the large spectral bandwidth stimulated Rayleigh-wing scattering. J Chem Phys 1993 99 9460-9464. 

N. D. Gershon, E. Zamir, and A. Ben-Reuven. Rayleigh wing scattering from liquids of anisotropic molecules. Ber. Bunsen Ges. Phys. Chem., 75 316-319 (1971). 

M. A. Gray, T. M. Loehr, and P. A. Pincus. Depolarized Rayleigh-wing scattering in water and aqueous solutions, J. Chem. Phys., 59 1121-1127 (1973). 

P. A. Lund, O. F. Nielsen, and E. Praestgaard. Comparison of depolarized Rayleigh-wing scattering and far-infrared absorption in molecular liquids. Chem. Phys., 25 167-173 (1978). 

M. Schwartz and C. H. Wang. Temperature dependent study of Rayleigh wing scattering in liquid acetonitrile. Chem. Phys. Lett., 29 383-388 (1974). 

SRS peak in one of the Rayleigh wings. Our formulae indicate that there... 

O Faurskov Nielsen, DH Christensen, P-A Lund, E Praestgaard. Short time molecular dynamics in molecular liquids studied by depolarized Raman and Rayleigh-wing, and infrared absorption. Proceedings of the 6th International Conference on Raman Spectroscopy, Bangalore, London Heyden and Sun Ltd., 1978, pp 208-209. 

Faurskov Nielsen, P-A Lund, FM Nicolaisen, E Praestgaard. Rayleigh-wing scattering (20-400 cm ) of aqueous solutions. Proceedings of the 7th International Conference on Raman Spectroscopy, Ottawa, Amsterdam, New York North-Holland Publ. Comp., 1980, pp 480-481. 

E Dayan, J Loisel, L Berreby, E Dervil, JP Pinan-Lucarre. Depolarized Rayleigh wing from Raman spectra and local order in pure CeHs and CeF liquids and their binary mixtures. J Raman Spectrosc 26 341-344, 1995. 

N. M. Amer, Y. S. Lin, Y. R. Shen, The temperature dependence of Rayleigh-wing scattering from liquid crystalline MBBA, Sol. State Com-mun. 1975, 16, 1157. 

Rayleigh wing scattering is due to the orientational fluctuations of the anisotropic molecules. For typical liquids these orientational fluctuations are characteristic of the individual molecules movements and occur in a very short time scale (< 10 s). Consequently, the spectrum is quite broad. In liquid crystals studies of individual molecular orientation dynamics have shown that the relaxation time scale is on the order of picoseconds and thus the Rayleigh wing spectrum for liquid crystals is also quite broad. 

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