Wanted: Amplitudon mode in Raman spectra of BCCD

Polarised Raman scattering by the low-frequency totally symmetric modes in modulated phases of deuterated Betaine Calcium Chloride Dihydrate was measu red in order to identify the amplitudon mode. The spectra are similar to th ose of non-deuterated compound. Detailed analysis based on fitting the coup led-mode lineshape to the experimental data allows to suggest the temperatu re dependence of the bare amplitudon mode, as well as to ascribe the previo usly observed sharp intensity minimum to the coupling of the amplitudon wit h the activated transverse acoustic mode.