The resonance Raman spectra of Cu#Se at liquid nitrogen temperature, excited by seven Ar and Kr ion hse&nes, have been stlidied and the excitation profles compared with the theoretical ones. According to the position of the scanered frequencies in the absowtion band it is observed that the relative intensities of the overtones may or may not decrease as the vibrational quantum mmnber increases_ 1, hlhJductioll In a previous paper [l] the resonance Raman effect of solid Cu3P!Q at room temperature was reported and the experimental excitation profiles obtained, after intensity correction discussed therein It was pointed out that the fundamental and its first overt-one did not peak at the same frequency.
The better signal/noise ratio at low temperature and the complete splitting of the degenerate frequencies, the sample is cocled below 200 K, allow more reliable intensity measurements to be made. In the present study the resonance Raman spectra of the Cu3PS4 at liquid nitrogen temperature were obtained and the experimental excitation profiles discussed_ Considering, as an approximation, only the denominator in the Nafie et al_ formulation [2] the theoretical profiies were calculated. In order to check this approximation, the profdes obtained from the zomplete expression developed by Mingardi et al. [3] (see also refs. [4-61) have been obtained too_ The dependence of the Raman intensiries on the scattered frequency is discussed.
2. Exp&mentaI
Cu3PS4 was prepared by heating (500Β°C) copper chloride with phosphorus pentasulphide as previousiy described [I]-* Vi&i.n~ Professor, from Chemistry Division of National Research Council, Ottawa, Canada.