Effect of matrix on vibrational relaxation: NH and ND X 3Σ− in rare gas solids

Lifetimes of the v″=1 level of NH and ND in solid rare gases at 4 K are measured. In each matrix, a strong isotopic effect is found with ND relaxation rate a factor of about 100 slower than that of NH. For each isotope a strong dependence upon the host lattice is observed. The rates increase dramatically with decreasing mass of the host matrix, and the relaxation in solid Ne is almost four orders of magnitude faster than in Kr. The rates show only mild temperature dependence.