Studies on inverse optogalvanic and Penning ionization effects in ytterbium and neon transitions in Yb-Ne hollow cathode lamp

This paper presents novel observations on inverse optogalvanic effect in Yb transition at 679.9 nm (3P1→3S1) in contrast with the observed normal optogalvanic effect at 648.9 nm (3P0→3S1) transition and Penning ionization in Yb-Ne mixture by probing Ne transitions at 626.65 (1s3→2p5), 633.44 (1s5→2p8), 650.65 (1s4→2p8) and 659.89 nm (1s2→2p2) in Yb-Ne hollow cathode lamp. These conclusions are derived by studying the optogalvanic signals temporal profile probed by DCM dye based narrow line-width ~2 GHz, short pulse ~20 ns, high repetition rate 5.0 kHz tunable dye laser, as a function of discharge current. The observed inverse optogalvanic effect is attributed to the transfer of Yb population in the level 3P0 through radiative decay from the upper level 3S1 of the transition. This proposition is confirmed by recording the emission spectra of Yb-Ne hollow cathode lamp. The Penning ionization signature in Ne optogalvanic signals is due to the quasi-resonances between Yb and Ne energy levels. Penning signature observed in optogalvanic signal of Ne transition at 650.65 nm is unique and attributed to the increase in concentration of Ne metastable level 1s5 through radiative decay from the 2p8 level.