Kinetics and mechanisms for the decay of Paschen (1<i>s</i>) resonance state argon atoms

Abstract

Measurements of effects of pressure and temperature on the decay constants of excited Ar atoms (3p54s1) have been made in electron beam pulse irradiated Ar gas (100–700 Torr) by means of fast absorption spectrophotometry. Interpretation of the pressure and temperature dependence of the decay constants leads to the conclusion that the resonance state Ar (1s) species decay via formation of electronically excited molecular intermediates in this pressure range. The resonance state atoms are shown to decay in a manner consistent with a sequence of elementary steps involving collisional stabilization and radiative decay of excited molecules. Observed small positive temperature coefficients of all Ar (1s) species are attributed to effects of temperature on collision frequencies with virtually zero energies of activation at 153 to 300 K.