Superelastic collisions between slow electrons and excited Kr and Xe atoms. Possible reaction mechanism for rare-gas atoms

Abstract

Measurements of the electron energy distribution in krypton and xenon afterglow plasmas are used to determine the rate coefficients for superelastic collisions between excited np5(n+1)s Kr or Xe atoms and thermal electrons. The rate coefficient for electron impact de-excitation of the state Kr 3P2 is beta e2=(1.5+or-0.2)*10-10 cm3 s-1, for Kr 3P1 it is beta e1=5.2*10-10 cm3 s-1, for Kr 3P0 it is beta e0=9.8*10-10 cm3 s-1, for Xe 3P2 it is beta e2=(3.2+or-0.5)*10-10 cm3 s-1 and for Xe 3P1 it is beta e1<1*10-9 cm3 s-1. It is also shown that if the energy of the incident electron is in the range 0-0.2 eV, a binding of this electron with the excited atom in an autodetachment state of the negative ion, followed by its decay, is a quite possible channel of the reaction.