Abstract
Polarised Raman scattering by the low-frequency totally symmetric modes in modulated phases of deuterated Betaine Calcium Chloride Dihydrate was measured in order to identify the amplitudon mode. The spectra are similar to those of non-deuterated compound. Detailed analysis based on fitting the coupled-mode lineshape to the experimental data allows to suggest the temperature dependence of the bare amplitudon mode, as well as to ascribe the previously observed sharp intensity minimum to the coupling of the amplitudon with the activated transverse acoustic mode.