SPECTRA AND RELAXATION OF HG ATOMS AND MOLECULES IN LOW-TEMPERATURE MATRICES .1. CH4, CD4, AND MIXED CH4 AR, CD4/AR MATRICES/

The absorption spectra in the P-3(1) <-- S-1(0) range and those of the prompt and long-lived emission components as well as their decay time s are recorded for Hg atoms isolated in CH4, CD4, and mixed CH4/Ar mat rices at T congruent-to 12 K using the dye-laser excitation. The resul ts are compared to those obtained in the previous work for Ar, Kr, and Xe matrices. The rate of the P-3(1) --> P-3(0) intramultiplet relaxat ion is only slightly increased, while that of the P-3(0) --> S-1(0) em ission shows an important increase due to the coupling to internal mod es of methane molecules. The evidence of this coupling is the vibratio nal structure of the emission spectrum involving nontotally symmetric mu2(E), nu3(F), and nu4(F) normal modes of CH4 or CD4 molecules.