RAMAN-SPECTRA OF DRADP-50 DIPOLAR GLASS

Raman spectra of an Rb0.5(ND4)0.5D2PO4 (DRADP-50) mixed crystal have b een carefully investigated in the 15-300 K temperature range for all f undamental polarization geometries. The spectra have been interpreted in terms of vibrational modes of principal structural units and critic ally discussed in comparison with published data on analogous (deutera ted and protonated) compounds. Analysis of the temperature dependence of peak positions and halfwidths has made it possible to estimate two characteristic temperature regions (approximately 200-220 K and approx imately 100-120 K) where incipient cluster formation and freezing of i ndividual structural units takes place in this compound on cooling thr ough the dipolar glass transition.