Radiation damping of autoionizing resonances

Radiative decay of resonances is investigated in detail for electron - ion recombination cross sections of He-like ions of carbon and iron. Relativistic close-coupling calculations are carried out using the Breit - Pauli R-matrix method, combined with a perturbative treatment for radiative and autoionization decay, as well as with the relativistic distorted-wave method. Good agreement is found with the synchrotron-storage ring experimental data for C V by Mannervik et al , and the electron-beam ion-trap data for Fe XXV by Beiersdorfer et al . Radiation damping is considerably more significant for Fe XXV than C V; however, contrary to claims by Gorczyca and Badnell and Robicheaux et al , it is unlikely to be of importance in general since the radiative decay rates are orders of magnitude smaller in atomic species other than the He-like and the H-like ions.