Excimer formation in argon, krypton, and xenon discharge afterglows between 200 and 400 K

Abstract

The decay of the VUV continuum radiation has been measured in the afterglow of a pulsed dc discharge in argon, krypton, and xenon at pressures between 1 and 100 Torr and temperatures between 200 and 400 K. By comparing the results with those obtained in absorption studies, it is inferred that the precursor to the R*2 excimers is the R* (1s5) metastable state. The reaction rates for the formation of excimers R*2 in three-body collisions are obtained as a function of temperature T: The three-body reaction rate can also be represented in an Arrhenius plot, yielding activation energies Ea(Ar) =−0.007 eV, Ea(Kr) =−0.020 eV, and Ea(Xe) =−0.016 eV. The destruction of the R*(1s5) state by two-body collisions results either in the formation of R*2 excimers or in the transition to the nearby R*(1s4) resonance state. Reaction rates for these processes could not be obtained separately, but the resulting total two-body reaction rate is given in graphical form in the paper.