Raman spectra and vibrational relaxation in molten thiocyanates

Temperature measurements of Raman spectra of thiocyanates of alkali metals in the interval from T-melt to T-melt+100 K are carried out. A method of correlation functions (CF) is discussed which allows one to apply for the analysis the intensity distribution over the whole band contour and which associates the experimental spectrum with the molecular motion characteristics. CF of vibrational relaxation are calculated. It is shown that the main mechanism of the vibrational relaxation and, consequently, the reason of broadening of isotropic components in Raman spectra of ionic melts is the phase relaxation process as a result of frequent quasi-elastic collisions of ions. (C) 2003 Elsevier B.V. All rights reserved.