KINETIC-STUDY ON THE LOW-LYING EXCITED-STATES OF GA ATOMS IN AR

Decay kinetics of Ga(5s), Ga(5p) and Ga(4d) atoms in Ar were studied b y laser induced fluorescence technique. The ground state gallium atoms in the gas phase were generated by pulsed de discharge of trimethyl g allium and argon mixtures. Both pulsed discharge and YAG-DYE laser sys tem were controlled by a dual channel pulse generator and the delay ti me between the end of discharge and laser pulses was set 3.0-6.0 ms. T he Ga(5s) and Ga(4d) atoms were generated by single photon excitation from the ground state Ga atoms and radiative lifetimes as well as the total quenching rate constants in Ar were obtained from the pressure d ependence of the fluorescence decay rates. The Ga(5P) atoms were popul ated by a two-photon excitation method and the cascade fluorescence fr om Ga(5s) atoms were analyzed to extract quenching rate constant of Ga (5p) atoms by Ar in addition to radiative lifetimes of Ga(5p) state. T he magnitudes of the quenching rate constants by Ar for the low-lying excited states of Ga atoms are 1.6-3 X 10(-11) cm(3) molecule(-1)s(-1) , which are much larger than those for alkali, alkaline earth and Grou p 12 metals. Based on the measured rate constants, kinetic simulations were done to assign state-to-state rate constants.