LASER-INDUCED FLUORESCENCE STUDIES ON THE PHYSICAL QUENCHING OF SUPERTHERMAL O(D-1)

Vacuum-ultraviolet laser-induced fluorescence (VUV LIF) method was emp loyed to study the physical quenching (collisional deactivation) of su perthermal O(D-1) atoms with N-2 molecules. The superthermal O(D-1) at oms were produced by the photodissociation of O-2 at 157-nm laser ligh t. As these species have their first resonance transition in the VUV r egion, the probe laser was used to excite O(2p(1)D) atoms to the O(3s( 1)D) states at 115.217 nm. A tripling cell was used for the frequency tripling of the dye laser at 345.65 nm in xenon gas to generate 115.21 7 nm probe laser Light. We measured the rate constant of the physical quenching of superthermal O(D-1) by collision with N-2, which is 2.40 +/- 0.03 x 10-(10) cm(3) molecule(-1) s-(1).