Excitation of singly ionized argon species in helium-matrix glow discharge plasma—role of the energy transfer from helium metastables

Abstract

When a small amount of argon is added to the helium plasma in a Grimm-type glow discharge radiation source, the interaction between helium and argon species is investigated from analyzing the intensities of emission lines of of argon ion (ArII). The excitation energy as well as the term multiplicity concerning the optical transitions to which the ArII emission lines are identified are significant factors for determining their emission intensities in the helium-matrix plasma. In the case where the excitation energy of ArII lines is higher than the internal energy of the helium metastable states, the emission intensity in the helium-matrix plasma is observed to be much weaker than that obtained only with argon gas. On the other hand, the intensity is enhanced when the excitation energy is slightly lower. In the excited levels of argon ion having quartet multiplicity, closer interactions with the triplet rather than the singlet metastable level of helium atom are recognized, with the singlet helium metastable in the argon excited levels having doublet multiplicity.