Studies in the ionization of atoms and ions by photons

Three aspects of the ionization of atoms and ions by photons are discussed. (1) Analytic expression previously derived for neutral atoms are employed to describe inner shell nonrelativistic dipole photoeffect cross sections for positively charged atomic ions. The simple dependence of these cross sections on nuclear charge Z and ionic charge Z results from scaling. (2) A numerical calculation of the radiative corrections to the atomic photoeffect is performed for the K shell of a hydrogenlike atom to lowest order in radiation field assuming the polarization of the electron and photon are not observed. Dependence of these corrections on the photon energy and the detector's energy resolution are discussed. (3) A survey of the present status of the theory and experiment for Compton scattering is given. The validity of the various theoretical approaches is discussed. A formalism for the calculation of Compton scattering cross sections in a relativistic partial wave expansion in a central potential is developed.