Vibrational relaxation is studied and the IR absorption spectra of CD₃F in Xe, Kr, and Ar are obtained for the solid and liquid phases near the melting point. For CD₃F in Xe and Kr, it was found that the rate of the process τ^-1 decreases and the main absorption bands of the CD₃F molecule become broader on phase transition to the crystal state. For CD₃F in Ar, the main absorption bands do not change their shapes and the quantity τ^-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 models, 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. Original Russian Text