Elementare Anregungen und kombinierte Streuung in einem System nicht im Gleichgewicht befindlicher Phononen

Abstract

Renormalisation of the long-wave optical phonon spectrum due to the strongly nonequilibrium quasimonochromatic distribution of acoustic phonons with a frequency equal to half that of the optical phonon is studied. It is shown that in such systems of acoustic phonons long-lived long-wave excitations are presen whose frequency is close to that of the optical phonon. These elemmentary excitations are manifest in the light combinational scattering spectrum and lead to a complex structure of the Stokes scattering line.