Electron Number Densities in Analytical Inductively Coupled Plasmas as Determined via Series Limit Line Merging

Abstract

A convenient and a rapid technique is introduced to estimate the electron number densities, ne, in inductively coupled plasmas. The method is based on previously reported observations that the principal quantum number of the last discernible line in a series limit depends on ne. The spatially integrated ne values, as determined from the spectra of H, Li, Mg, Al, Ca, and K emitted in a pure Ar plasma ranged between ∼4 × 1014 and ∼3 × 1015 cm−3 for various forward powers and observation heights. These results agreed with ne values derived from other methodologies such as the Stark broadening and absolute continuum intensity.