Vibrational energy transfer in O2(X 3Σg-,υ=2,3)+O2 collisions at 330 K -: art. no. 044309

Vibrational relaxation of O-2(X (3)Sigma(g)(-),upsilon=2,3) by O-2 molecules is studied via a two-laser approach. Laser radiation at 266 nm photodissociates ozone in a mixture of molecular oxygen and ozone. The photolysis step produces vibrationally excited O-2(a (1)Delta(g)) that is rapidly converted to O-2(X (3)Sigma(g)(-),upsilon=2,3) in a near-resonant adiabatic electronic energy-transfer process involving collisions with ground-state O-2. The output of a tunable 193-nm ArF laser monitors the temporal evolution of the O-2(X (3)Sigma(g)(-),upsilon=2,3) population via laser-induced fluorescence detected near 360 nm. The rate coefficients for the vibrational relaxation of O-2(X (3)Sigma(g)(-),upsilon=2,3) in collision with O-2 are 2.0(-0.4)(+0.6)x10(-13) cm(3) s(-1) and (2.6 +/- 0.4)x10(-13) cm(3) s(-1), respectively. These rate coefficients agree well with other experimental work but are significantly larger than those produced by various semiclassical theoretical calculations. (C) 2005 American Institute of Physics.