CAGE EXIT PROBABILITY VERSUS EXCESS ENERGY IN THE PHOTODISSOCIATION MATRIX-ISOLATED HCL

Dissociation efficiencies for excitation of the repulsive A (1) Pi sta te of HCl were recorded in Xe, Kr, and Ar matrices for photon energies between 5 and 10 eV from the content of dissociation products and qua ntum efficiencies were derived with the absorption spectra. Influence of temperature and preparation conditions was investigated. The quantu m efficiency rises monotonically in Xe from an excess energy of 1.4 eV above the gas phase dissociation energy on, saturates around 2.4 eV a nd remains then essentially constant up to 4 eV. In Ar and Kr, it satu rates around 2 eV and in Ar an absolute efficiency of about 0.18 is de termined at 3.7 eV. Results of molecular dynamics calculations and a s tatistical model agree qualitatively but the observed saturation at lo w excess energies is not well described and the absence of a temperatu re effect in Ar needs further consideration. (C) 1996 American Institu te of Physics.