Emission spectroscopic diagnostics of weakly ionized argon-diluted plasmas: glow discharge and inductively coupled plasma

Abstract

An extensive study of Mn, Fe, Ti, Cr, Cu emission spectra from a Grimm-type glow discharge (GDOES) and an inductively coupled plasma (ICP), in argon, was performed, using the formalism of population functions (experimental Boltzmann plots) and transition rate diagrams. Emission characteristics of both spectral sources were compared, with the following results: in both discharges the excitation of neutral metal atoms (Me I) is dominated by electron impact (EI), however, in the excitation of singly charged ions (Me II) the charge transfer between Ar+ ions and Me I plays a significant role, especially in GDOES. Relative populations of singly charged excited ions compared to the population of excited neutral atoms of the same element are much higher in ICP than GDOES. Deviations from local thermodynamic equilibrium were identified. Besides charge transfer reactions with Ar+ ions they are caused by a low electron density in the plasma. The experimental ‘excitation temperatures’ follow a pattern predicted by computer simulations with a collisional-radiative model: they are lower than the actual electron temperature, while this deviation is greater for the Me I system than Me II.

A simultaneous atomic absorption and emission spectrometer with dielectric barrier discharge for atomization and excitation

“…24 The variation trend of the AES signal is similar to that of T exc and n e , which may be important reasons for the changes in the AES signal. It is worth mentioning that combining this system with other diagnostic approaches in the future, such as the transition rate diagrams reported by Weiss et al, [25][26][27] may provide a clearer description of the excitation processes.…”

The spectroscopic study of metallic lines emitted from a pulsed atmospheric pressure gas discharge source with brass and stainless steel cathodes

“…a Grimm-type cell) for the depth proling of conductive thin layered surfaces. 6,7 In Weiss 8 the formalism of the transition rate (TR) was employed as a good tool for the description of the excitation process involved in GD plasmas. The emission spectra of Mn, Fe, Ti, Cr, and Cu are used for making the population function diagram.…”

Metastable states in sputtered sample atoms: a tutorial review in perspective of elementary plasma processes

“…35,36 A similar situation exists in chromium, 37 and also in copper metastable ions enhancing the population of doubly-excited copper neutral atoms. 38 So far, no systematic data appear to be available for considering collisional interaction between the plasma particles and metastable states of various transition metal atoms. The elementary processes and corresponding cross-sections have been overwhelmingly considered by the interaction of the electron and plasma gas atom/ions with the sample atoms in their ground states.…”