The fine features in the Rayleigh wings of light scattered from various liquids, observed by Starunov, Tiganov, and Fabelinskii, and by Stegeman and Stoicheff, and associated with shear waves according to the Leontovich theory, are explained from a molecular correlation‐function point of view, based on the Kubo–Zwanzig–Mori theory. These features are attributed to a “bottleneck” effect, in which the short‐lived Brownian orientational motion (“tumbling”) is coupled to a long‐lived (hydrodynamic) sound mode. Line‐shape expressions and an estimate of the magnitude of the effect are given.
REFERENCES
1.
2.
G. I. A.
Stegeman
and B. P.
Stoicheff
, Phys. Rev. Letters
21
, 202
(1968
).3.
4.
5.
6.
A complete hydrodynamic treatment of these features has been made recently by P. A. Selwyn, Ph.D. thesis, Massachusetts Institute of Technology, Cambridge, Mass., 1970.
7.
8.
9.
10.
Lectures in Theoretical Physics, edited by W. E. Brittin and L. G. Dunham (Interscience, New York, 1959), Vol. 1, p. 120.
11.
Lectures in Theoretical Physics, edited by W. E. Brittin, B. W. Downs, and J. Downs (Interscience, New York, 1961), Vol. 3, p. 106.
12.
13.
The real part of always vanishes [A. Ben‐Reuven and R. A. Pasmanter (unpublished)].
14.
A possible imaginary contribution to is incorporated here in
15.
In light scattering, ω is the difference between the frequencies of the scattered and incident light beams.
16.
E. Zamir, N. D. Gershon, and A. Ben‐Reuven “Rayleigh‐Wing Scattering by Aromatic Liquids,” J. Chem. Phys. (to be published). The value of taken from the width of the Brillouin line (after correction for instrumental broadening), apparently applies to the longitudinal modes. We also apply it to the transverse modes, having no other choice.
17.
In quinoline the effect is enhanced by the fact that the pair‐correlation correction factor is smaller than unity (see Ref. 16).
18.
This cross relaxation, with the collisional channels having a shorter life time than the tumbling itself, apparently involves only a higher‐order correction. Its incorporation would result in having interference terms between the two contributions to Eq. (A9).
19.
For standard (polar) tensor components we use here the conventions of U. Fano and G. Racah, Irreducible Tensorial Sets (Academic, New York, 1959); see also Appendix to Ref. 7.
20.
Following the notation of Volterra, Ref. 5.
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© 1971 American Institute of Physics.
1971
American Institute of Physics
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