An investigation of the laser optogalvanic effect for atoms and molecules in recombination-limited plasmas

Abstract

In this paper the nature, the characteristics, and the potential applications of the optogalvanic effect are explored in a broad set of experiments. The optogalvanic effect was investigated, for the Ar, Ne, He, Ar +, He +, Cu and Na atoms and N2, H~, CO, CN, NH2, He2, and CuO molecules in recombination-limited hollow cathode plasmas, with the use of dye lasers. Comparative studies of the time dependence of transitions from metastable and non-metastable states of neutrals and non-metastable states of ions were made. Autoionizing transitions in Cu(I) were found to yield very strong OGE signals. An examination of the various processes known to be important in such plasmas indicates that associative ionization is a very effective means for coupling light energy into the plasma. Measurement of Rydberg transitions in the helium dimer suggests that optogalvanic spectroscopy in recombination plasmas may be useful as a way to study such molecules with repulsive ground states by generating them 'from the top down ' by recombination.