Experimental Test of a Two-Layer Model Characterizing Emission-Line Profiles

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Abstract
Deuterium Lyman-α line profiles, generated from a microwave-powered lamp containing flowing mixtures of deuterium in helium, were examined spectroscopically under high resolution. The primary purpose was to test a simple two-layer model describing the line shape emerging from a discharge zone containing both emitting and absorbing atoms. This simple model characterized the experimentally obtained line shapes under varying conditions of atom densities and line self-reversal. The kinetic (translational) temperature of the discharge could be calculated from the data. Resonance interaction between ground-state D(2S) atoms and excited D(2P) atoms is offered as an explanation for the experimentally observed line asymmetries. The presence of line self-reversal significantly amplifies the small spectral shifts between the absorption and emission lines. These shifts can be calculated from the model.