Formation of Ar+(4p) by He(2 3S)+Ar+(2P3/2) excitation transfer and He++Ar(3P2) charge transfer in the helium flowing afterglow

Abstract

Arii lines have been observed by addition of Ar into the He flowing afterglow. The effect of ion collection in the He afterglow and the energetics lead us to conclude that the He(2 3S)+Ar+(3p5 2P3/2ο) excitation transfer gives the ten Ar+(4p 4P5/2,3/2,1/2ο,4p 4D7/2,5/2,3/2,1/2ο, 4p 2D5/2,3/2ο,4p 2P1/2ο) levels in the 19.22–19.80 eV range, while the He++Ar(4s 3P2ο) charge transfer populates the three Ar+(4p 2P3/2ο,4p 4S3/2ο, 4p 2S1/2ο) levels in the 19.87–19.97 eV range. The relative rate constants for excitation of individual Ar+(4p) ions have been measured. The favored exit channel is the 4p 4P3/2ο level in the former reaction, and the 4p 2P3/2ο level in the latter reaction. Since these channels are 0.5–0.6 eV below the entrance channels, attractive entrance potentials are probably important for both reactions.

Single-electron loss and capture for 1.0-5.0 keV colliding with He

“…Currently, single-electron loss and capture processes for some species in collision with helium at keV energies are of considerable interest (Atan et al 1991, Wu et al 1988, 1989. Important motivations result particularly from the need to understand the mechanism of energy and particle loss in magnetically confined plasmas and their application to the pumping of argon ion lasers (Tsuji et al 1993). A survey of the data (Wu et al 1988(Wu et al , 1989 indicates that there are few published measurements for the Ar + -He system over a wide energy range but to our knowledge, no previous theoretical and experimental studies of this system have been made in the low-keV energy range.…”

Experimental and theoretical investigations of single-electron capture and loss in He+-Ar collisions

“…For single-electron capture there is a strong disagreement between some of them in the energy range 1.5-5.0 keV and for the loss process there are no data in this energy range. More recently, renewed interest has arisen in energy-transfer reactions between raregas metastable atoms and rare-gas ions because of their application to the pumping of rare-gas ion lasers, where electron capture processes were found to be important (Tsuji et al 1993). However, no theoretical calculation of the cross sections for charge-exchange collisions from heavy target atoms by He + ions is available in the literature to the best of our knowledge.…”