Timehyphen;resolved laser induced fluorescence measurement of excited states relaxation constants: Application to the quenching of mercury atoms by NO molecules

摘要

A timehyphen;resolved laser induced fluorescence arrangement is described, which allows direct study of energy transfers and of relaxation processes. A first application to the direct measurement of quenching cross sections of mercury excited (6thinsp;3P1) and metastable (6thinsp;3P0) atoms by NO molecules is reported. For Hg(6thinsp;3P1) our result: sgr;=80plusmn;5 Aring;2is in good agreement with previous works. On the contrary, our result for Hg(6thinsp;3P0): sgr;=85plusmn;5 Aring;2strongly disagrees with previous ones. The reasons for this discrepancy are reviewed. We emphasize that our measurement is direct and that it has to do with a system in which only Hg and NO are present. On the contrary, in the previous works nitrogen was present, generally at pressures several orders of magnitude greater than NO pressures.