MECHANISM OF INELASTIC PHONON-SCATTERING ON THE QUADRUPOLAR O-H-2 IMPURITY IN P-H-2 MATRIX

A quantum-mechanical problem on inelastic phonon scattering by a quadr upolar pair defect is discussed. As an example of the physical system, where this mechanism is of great concern, the solution of o-H-2 molec ules in p-H-2 matrix is considered. The effective relaxation time tau( p) of a phonon collision with a pair defect as a function of the phono n frequency is calculated. Due to intrinsic degrees of freedom, pair d efects give rise to the resonance phonon scattering above a certain te mperature T-0, which for o-H-2 -p-H-2 mixtures is approximately 6 divi ded by 7 K.