| Abstract: | The author points to experimental results, published in the literature, which provide indirect evidence of overpopulations of highly excited levels of both argon and analyte species, with respect to the LTE populations, in the analytically favourable, non-thermal zone of toroidal ICPs. Considering this evidence and a mechanism proposed in the literature to explain results of measurements of spatial emission characteristics in ICPs, the author suggests the likeliness that the collisional-radiative model of Bates, Kingston, and MmcWhirter as elaborated by fujimoto for a so-called predominantly recombining plasma, might provide a key for understanding some basic phenomena in the non-thermal region of argon ICPs. The dominant mechanisms would then involve Penning ionisation by excited argon atoms (not exclusively metastables) and three-body ion-electron recombination. |
