Collisional relaxation of translational energy and finehyphen;structure levels of the O(3Pj) atom created in the photodissociation of SO2at 193 nm

摘要

Collisionhyphen;induced energy transfer and intramultiplet relaxation processes of O(2p4thinsp;3Pj)j=0, 1, and 2 have been studied, using a vacuumhyphen;ultraviolet laserhyphen;induced fluorescence technique. The O(3Pj) atoms are produced from the photodissociation of SO2at 193 nm. Doppler profiles of the O(3P2) atoms have been measured as a function of time delay between pump and probe laser pulses. The translational energy andjhyphen;level population of the O(3Pj) atoms are thermalized at 300 K after a number of collisions with either He, Kr, Xe, N2, or CO2. A Monte Carlo calculation using the hardhyphen;sphere collision model provides the cross sections for relaxation of the translational energy; 21plusmn;3 Aring;2for He, 25plusmn;3 Aring;2for Kr, and 25plusmn;5 Aring;2for Xe. Assuming the principle of detailed balancing among thejlevels, the cross sections for the collisionhyphen;induced intramultiplet transition over the collision energy range 1ndash;6 kcalthinsp;molminus;1are obtained from the time evolution of thejhyphen;level populations: cross sections for thej=2rarr;1 transition are 2.4plusmn;1.2 Aring;2for Kr and 1.4plusmn;0.7 Aring;2for Xe.