Perturbed-Stationary-State Theory of Atomic Inner-Shell Ionization by Heavy Charged Particles

Cross sections for inner-shell ionization by slow heavy charged particles, if compared to predictions given in the plane-wave Born approximation, are reduced strongly by the Coulomb deflection of the particle in the field of the target nucleus, and by the increase in binding energy of the target electrons induced by the presence of the particle. We use the framework of the perturbed-stationary-state approximation to incorporate these effects ab initio into the theory of inner-shell ionization and derive the binding effect given by Brandt, Laubert, and Sellin. Our result formally unifies the Coulomb deflection of the particle trajectory with the perturbation of the atomic states in their effect on the ionization cross section and suggests systematic ways for further improvements.