We have measured the spectrum, intensity, and polarization of light Raman scattered from rotons and higher energy quasiparticle excitations in liquid He⁴ for temperatures between 1.16 and 2.14^∘{}K. The effect on the spectrum of the temperature-dependent energy and lifetime of the rotons is clearly visible. At a scattering angle of 90^∘{} the light is highly depolarized and about three orders of magnitude weaker than the Brillouin scatering from the phonons.
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Greytak et al. (1969) studied this question.
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