Light Scattering from Rotons in Liquid Helium

A theory of light-scattering processes in liquids in which two excitations are created or annihilated is developed. The basic ideas are similar to those in the Lorentz-Lorenz theory of the propagation of light in material media. The spectrum of scattered light is expressed in terms of an integral over two density-density correlation functions. The angular dependence and polarization of the scattered light is determined. The results are compared with recent light-scattering experiments on He II.

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“…Then H (2) can be expressed in terms of S(Ic, o>). From (2.13) we replace the first G by its approximation (2.…”

Section: )mentioning

confidence: 99%

“…At low temperatures when U^> kgT, f^ is small and the most important process is (c). Then setting /^ = 0 in (5.4) we find U^(2) (C0) = |7TQ! 4x fdkgHk)ZHk)(^)%(Q-2u u )…”

mentioning

confidence: 99%

Raman Scattering in Liquid Helium

Stephen

1969

Phys. Rev.

123

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“…Equation (14) gives only two conditions in contrast to the general case (13). It means that from the point of view of binding the problem of two …”

Section: Threshold Of the Disintegration Into Two Rotonsmentioning

confidence: 97%

“…The situation changes, however, for rotons. The point is that a bound state is formed near the region in momentum space where the particles have equal velocities vl =v2 (13) For usual particles in three-dimensional space, Eq. (13) gives three conditions in momentum space.…”

Section: Threshold Of the Disintegration Into Two Rotonsmentioning

confidence: 99%