EXAMINATIONS OF CHARGE-TRANSFER BETWEEN IONIZED HE AND P, S, AND CL IN A MICROWAVE-INDUCED PLASMA

Charge transfer between monomer helium ions and nonmetals has been pos tulated to be the source of high nonmetal ion populations in high elec tron density (> 10(14) e(-)/cm(3)) discharges. In this study, overpopu lations of excited Cl, P, and S ion energy levels in a helium microwav e-induced plasma are examined using ion and atom line emission intensi ty data and charge transfer theory. The resonance emission lines from phosphorous, sulfur, and chlorine were examined. To examine these high ly energetic lines, wavelengths in the vacuum-ultraviolet and the ultr aviolet-visible (UV-visible) spectral regions were monitored. Energy-l evel population calculations were performed on similar UV-visible emis sion data from the literature. Charge transfer ionization cross sectio ns are calculated for these elements. To obtain an indication of the s ignificance of charge transfer, these parameters are compared to the b ehavior that would be expected if the plasma were in local thermodynam ic equilibrium, and kinetically dominant processes such as CT were not considered. These evaluations, with the aid of energy-level diagrams, help to explain the spectroscopic behavior of these nonmetals in the helium discharge.