Spectroscopic study of rare-gas excimer formation in a direct-current discharge with supersonic expansion

Abstract

Emission spectra of the rare-gas excimers Ar2*, Kr2*, and Xe2* were excited in a dc jet discharge with supersonic expansion. Absorption and fluorescence emission measurements provided atomic population densities for levels of the 1s manifold. Changes in intensities of the atomic resonance lines and the VUV bands were examined as the plasma was irradiated with laser radiation tuned to specific atomic transitions between levels of the 1s and 2p manifolds. This technique of optical pumping has established that excimers in the A 3Σ+u state are the main contributors to the observed bands from this source. Rate equations were developed to explain the observed intensity changes. Comparisons of the calculated and observed changes indicated that population mixing amongst levels of the 1s manifold caused by electron collisions is an important process in regulating the population in the 1s5 atomic level that leads to the formation of rare-gas excimers by collisions with ground level atoms.