Structural order and vibrational relaxation of phenylacetylene in benzene in liquid solutions and frozen matrices at low temperatures. Raman spectra of phenylacetylene in benzene at 77 K

Raman spectra of the nu(S)(C=C) stretching mode of phenylacetylene (PA) dis solved in benzene have been recorded in liquid solutions at room temperatur e and in solid-state frozen matrixes at 77 K as a function of concentration . The spectra at low temperature reveal spectacular changes in comparison w ith those observed in liquid solutions. The results given in this paper ill ustrate the change of the mechanisms of vibrational relaxation due to struc tural reorganization around the molecular oscillator due to different molec ular environments.