A comprehensive theoretical treatment of laser-assisted electron-atom radiative recombination in the presence of short laser pulses is presented. Our formulation lacks various unphysical effects observed in previous works, such as oscillations and high-energy tails in the spectrum of emitted radiation; however, it accounts for a contribution from the field-free process. As a result, the energy distribution of emitted radiation consists of a point spectrum embedded in a continuum. We demonstrate that the features of the latter are determined by the laser field. For instance, in the case of a train of pulses, comb structures appear in the radiation spectrum. We attribute them to constructive interference between probability amplitudes of recombination assisted by each pulse from the train. Finally, we show that the vector potential describing the laser field is encoded in the spectrogram of emitted radiation. This suggests the use of the spectrogram for a complete temporal reconstruction of the laser field, irrespective of whether it is an isolated pulse or a pulse train.

• Received 14 July 2021
• Accepted 31 August 2021

DOI:https://doi.org/10.1103/PhysRevA.104.033112