Translational energy dependences of relative cross sections for Hg(63P1 → 63P0) fine-structure changing collisions with N2 and CO have been measured with a crossed-beam apparatus over the energy range between 800 and 3750 cm-1. A negative energy dependence is obtained for Hg-CO, but a positive energy dependence is observed for Hg-N2, with an energy threshold for appearance of Hg(63P0) around 900 cm-1. These results are explained using the characteristics of the intermolecular potentials for Hg-N2 and Hg-CO. The existence of the energy threshold around 900 cm-1 for N2 suggests simultaneous vibrational excitation of N2. The translational energy dependence has also been measured under beam-gas conditions over the energy range between 450 and 3350 cm-1. From a comparison with Hg(63P1 → 63P0) intramultiplet deactivation cross sections for Hg-N2 and Hg-CO obtained in gas cell experiments, absolute values of the cross sections for this intramultiplet transition are estimated as a function of the average translational energy under the beamgas conditions. There is no clear threshold for Hg-N2 in the beam-gas experiment and it is suggested that a higher rotational temperature of N2 induces a shift of the energy threshold effectively lower.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry