Photoassociative laser-induced fluorescence of XeCl* and kinetics of XeCl(B) and XeCl(C) in Xe

Laser induced fluorescence studies have been done with XeCl molecules, which demonstrate photoassociation (free--bound absorption) as well as conventional bound--bound absorption from the XeCl(X) van der Waals molecules. The XeCl(X) and Xe+Cl pairs were generated by a pulsed dc discharge through 1--6 Torr Xe/Cl2 mixtures. Experiments also were done with Xe/HCl mixtures. The time and wavelength resolved XeCl(B--X) and XeCl(C--A) excitation and fluorescence spectra are reported. Model calculations were done to demonstrate that the laser excitation spectra for XeCl(B,v = 0-3) show laser-assisted photoassociation. The time resolved decay of the XeCl(B,v' = 0) and XeCl(C,v' = 0,1) states was used to measure the radiative lifetimes 11.1 +- 0.2 and 131 +- 10 ns, respectively, and the XeCl(B) and XeCl(C) coupling and quenching rate constants. The transfer and quenching rate constants for XeCl(B) by Xe are assigned as (11 +- 1) x 10-11 and (2.3 +- 0.3) x 10-11 cm3 molecule-1 s-1, respectively; although, the sum is known with greater certainty than the individual values. The quenching rate constants of XeCl(B,v' = 0) by Cl2 and HCl are (4.3 +- 0.2) x 10-10 and (6.3 +- 0.5) x 10-10 cm3 molecule-1 s-1. Evidence is presented to show that the B--C coupling rate constants are comparable to the XeCl(B,C) vibrational relaxation rate constants for XeCl(B,v' = 2) in collisions with Xe