Spectroscopic evidence for sum frequency of forward and backscattered light in laser plasmas

This is the authors' abstract. We don't add key points for this paper.

Spectra of 90^∘{} scattered light from underdense plasmas evidence a line close to the second harmonic of laser frequency, whose red shift is consistent with frequency sum between incident laser light and Brillouin backscattered light. Time-resolved spectra give information on the dynamics of the process.