Vibrational Relaxation and IR Spectra of CD_3F in Solid and Liquid Xe, Kr, and Ar

摘要

Vibrational relaxation is studied and the IR absorption spectra of CD_3F in Xe, Kr, and Ar are obtained for the solid and liquid phases near the melting point. For CD_3F in Xe and Kr, it was found that the rate of the process #tau#~(-1) decreases and the main absorption bands of the CD_3F molecule become broader on phase transition to the crystal state. For CD_3F in Ar, the main absorption bands do not change their shapes and the quantity #tau#~(-1) insignificantly increases its value on such a phase transition. The results obtained, together with results of gas-phase experiments, and the literature data for low-temperature matrices are discussed in terms of simple models of vibrational relaxation caused by isolated binary collisions (IBC) and collective interactions. At low temperatures, using the IBC model significantly underestimates the rate of vibrational relaxation in the solid phase. Within the framework of cell-like modes, this fact can be connected with an increase in the relative efficiency of rotational channels of deactivation of the excitation energy because of the perturbation of orientational motion in more dense media.