ANOMALOUS OPTOGALVANIC LINE-SHAPES OF ARGON METASTABLE TRANSITIONS IN A HOLLOW-CATHODE LAMP

Anomalous optogalvanic line shapes were observed in a commercial hollow cathode lamp containing argon buffer gas. Deviations from Gaussian line shapes were particularly strong for transitions originating from the P-3(2) metastable level of argon. The anomalous line shapes can be described reasonably well by the assumption that two regions in the discharge are excited simultaneously, each giving rise to a purely Gaussian line shape, but with different polarities, amplitudes, and linewidths.