Observation of a soft optical phonon in Rochelle salt
Volkov A. A., Goncharov Yu. G., Kozlov G. V., Kryukova E. B., Petzelt J.
A resonant absorption line (v~ 20 cm-1) has been found in the submillimeter dielectric spectra of Rochelle salt. This line forms at low temperatures (TS 150 K) as a result of the temperature dependence of a known soft relaxation mode.