Quenching of He(21P1) atoms by normal argon atoms

The relaxation of the He(21S0) metastable state population in the helium and argon mixture (psub(He)=40 Pa, Psub(Ar=)=0;5.3 Pa) excited by an electron beam is investigated using the method of plasma kinetic spectroscopy. To make He(21S0) atoms indicative a small addition of neon is put into the gas mixture, and the NeI (lambda=632.8 nm) line afterglow is observed. It is shown that the curve of the time dependence of the line brightness is described by a sum of exponential components, whose probabilities are detrermined by the cross sections of inelastic He(21P1) and He(21S0) atom collisions with argon atoms. As a results of investigation into the effective probability dependence on psub(Ar) the rate constants are obtained for quenching He(21P1) and He(21S0) atoms by normal argon atoms at the gas mixture temperature of 600 K: (σsub(p)νsub(a)=(2.5+-0.5)x10-9 cm3s-1, (σsub(s)νsub(a))sub(Ar)=3.5+-0.3)x10-10 cm3s-1