Quantum-Mechanical Approach to Collision-Induced Radiative Emissions

Charge exchange is a process that occurs in an atomic collision where an electron from one of the colliding particles is transferred to the other; typically from a neutral atom or molecule to an ion. Electrons transferred into an excited energy state then decay into a lower-energy state and emit photons during this process. This phenomenon of collision-induced radiative emissions is of great interest in astrophysics and experimental x-ray spectroscopy research since it helps understand the production of x-rays in astrophysical settings. On the theoretical side, obtaining a description of these radiative emissions involves numerical work since a closed-form solution is not possible. Using standard numerical approaches, one needs to rely on models and approximations, especially in collision problems involving many-electron systems. Consequently, results obtained in this way can be at odds with experimental observations and/or results from different theoretical methods. In this dissertation, the main method is the two-centre basis generator method performed within the independent electron model. It is a dynamical approach to solving atomic collision problems and has shown to be reliable in describing charge exchange and other electronic processes. This work gives an extensive view on the applicability of this approach in the context of collision-induced radiative emissions where present results from a variety of ion-atom and ion-molecule collisions are benchmarked with results from previous studies