Abstract

The spectral consequences of the introduction of varying concentrations of heavy rare gas atoms into a reduced-pressure helium ICP have been examined. A term-dependent quenching of He(I) emission was observed and is consistent with previous work on a kinetic model for this ICP. In addition, the ionization behavior of the added rare gases has been studied, and a simple rule seems to emerge from the results: the first ionization potential of helium represents an upper bound to the plasma energy available (probably through collisional processes) to excite and/or ionize added species. Although spectroscopic temperatures can be calculated from the state population distributions for the added neutral gas atoms, the fact that the values vary with concentration and with the chemical identity of the species betrays the fact that the plasma is not in local thermodynamic equilibrium with respect to neutral atoms. Quite differently, the results for plasma positive ions show the same statistically determined spectroscopic temperatures; thus, it appears that these ions are nearly equilibrated and also suprathermal in population distribution.

Temporal evolution of laser-induced ionization and recombination processes in argon-helium mixture

Shu Hu, Ke Huang, Feng Zhu, Baodong Gai, Juntao Li, Yannan Tan, and Jingwei Guo
Opt. Continuum 2(12) 2516-2528 (2023)

Spectroscopic Study of the Early Helium Afterglow*

William S. Bickel and C. R. Burnett
J. Opt. Soc. Am. 55(11) 1504-1508 (1965)

Collisional Transfer of Excitation Energy in Helium*

Robert M. St. John and Tsu-Wei Nee
J. Opt. Soc. Am. 55(4) 426-432 (1965)

Photon-echo studies of collisional relaxation in weakly ionized noble-gas mixtures

M. R. Woodworth
Opt. Lett. 8(6) 307-309 (1983)

Suppression of self-absorption effect in laser-induced breakdown spectroscopy by employing a Penning-like energy transfer process in helium ambient gas

Rinda Hedwig, Ivan Tanra, Indra Karnadi, Marincan Pardede, Alion Mangasi Marpaung, Zener Sukra Lie, Koo Hendrik Kurniawan, Maria Margaretha Suliyanti, Tjung Jie Lie, and Kiichiro Kagawa
Opt. Express 28(7) 9259-9268 (2020)