Argon and copper optical emission spectra in a Grimm glow discharge source: mathematical simulations and comparison with experiment

The spectral line intensities of 605 argon atom lines and 103 copper atom and ion lines were calculated for a Grimm-type glow discharge source under typical conditions of glow discharge optical emission spectrometry, The calculations were based on the Einstein transition probabilities for radiative decay and on the level populations of excited levels of the argon atoms and copper atoms and ions, which were computed previously in a comprehensive self-consistent modeling network for the behavior of the various species present in a glow discharge (argon atoms and ions, sputtered atoms and ions, in various levels, and electrons). To the authors' knowledge, the optical emission spectra of argon atoms and of copper atoms and ions have been calculated in this explicit way for the first time. The spectra were integrated over the entire cell axis, to simulate end-on observation. Moreover, the spatial dependence of some spectral lines along the cell axis was elucidated. Finally, the effects of voltage and pressure on the calculated spectral line intensities were investigated and comparisons were made with experimental data. The agreement between theory and experiment was satisfactory for argon; for copper there was still some discrepancy, indicating that the model, in spite of its comprehensive nature, still has some shortcomings.