Resonant absorption of femtosecond X-ray pulses by highly charged ions in plasmas

Within the framework of the total absorption coefficient (TAC) formalism, the absorption of x-ray laser pulses at the resonant 1s–2p transition in hydrogen-like aluminum ions in a plasma is calculated and analyzed, accounting for the fine-structure splitting of the upper level and Doppler broadening. The dependences of the TAC on the carrier frequency and duration of a Gaussian pulse, as well as on the optical thickness of the plasma layer, are computed. Characteristic features of these dependences are identified, which are attributed to the specific nature of ultrafast electromagnetic interaction and to the extinction of the laser pulse in the plasma.