Optical emission spectroscopy, thermodynamical and thermal disequilibrium aspects in an inductively coupled plasma torch. Experimental applications to - mixtures
Résumé
The purpose of this article is to study experimentally and theoretically the spectral line ratios O 700.22 nm/N 746.87 nm with a sample gas mixture of and (notably for pure air) in an inductively coupled plasma (ICP) torch. We study theoretically the influence of the thermal disequilibrium on the composition and on the volumic enthalpy in a plasma produced in an ICP torch, and we show that the lower temperature in the plasma is set by the power supplied by the inductive coil. If the temperature (or heavy species temperature for plasma out of thermal equilibrium) is sufficiently low (<5000 K), we show that the thermal disequilibrium has no influence on intensity spectral line ratios (O 700.22 nm/N 746.87 nm). We compare these results with those obtained experimentally in the case of - mixtures, and we show that the determination of monatomic spectral line ratios (O 700.22 nm/N 746.87 nm) solely depends on the initial sample gas composition introduced in the ICP torch.