Double Electron Transitions in X-Ray Spectra

Elementary processes are considered, in which simultaneous transitions of an inner and an outer atomic electron result in the emission of one single light quantum. Considering the nuclear distance of the inner electron as small compared to that of the outer electron, formulae are developed for the probability of double transitions by dipole radiation. The occurrence of the $\mathrm{Cu} K{\alpha }_3$ satellite is given as a possible illustration of the case, where the inner transition alone occurs by dipole emission; a special consideration applies in this connection to the probability of simultaneous inner ionization and outer excitation. For the case of a forbidden inner transition, the simultaneous emission of a light quantum and an outer electron (radiative Auger effect) is discussed.