Modeling Quasi-Molecular Resonances with a New Quantum Treatment of Close Collisions

Quasi-molecular resonances are spectral features that form due to unbound close collisions between neighboring plasma particles in hot dense plasmas. We present a new method for modeling these quasi-molecular features in atomic spectral line shape profiles relevant for both stellar atmospheres and laboratory plasmas. Using a new change-of-basis approach, we remove a number of physical approximations that have previously been relied upon, including the independent perturbers assumption. With this model we calculate new hydrogen Lyman-α line shape profiles with H2+ resonances present, which are particularly relevant to DA white dwarf star atmospheres, and highlight additional physical regimes where this theory may offer significant improvements to current Stark broadening models. Finally we discuss this method’s rather unique treatment of radiator unitarity and possible applications to future opacity calculations.