A good understanding of excitation mechanisms of various elements in spectral sources employing argon as the discharge gas is essential for important methods of atomic emission spectroscopy that are used for the analysis of the chemical (elemental) composition of inorganic materials. In this study, the excitation of atomic and ionic spectra of Cu, Mn, Ti, Fe, Cr was investigated, in a glow discharge and an inductively coupled plasma (ICP). The spectra were analyzed using the formalism of population functions (experimental Boltzmann plots) and by examining relative rates of the radiative transitions observed. Various deviations from the state of local thermodynamic equilibrium (LTE) were identified that had not been known in these sources before.
