Maximal coherence in a three-level autoionising atom for the generation of subpicosecond pulses in the extreme ultraviolet

We discuss the possibility of using a three-level ladder atomic system, with a final autoionizing state, for the efficient generation of short radiation pulses in the extreme ultraviolet through a process of sum-frequency mixing in the presence of maximal coherence. The results of numerical calculations are presented, investigating the effects of photoionization, dynamic Stark shift and electron impact dephasing on the conversion efficiency in a single atom model. The results of this investigation can be useful in identifying a real candidate for a possible experiment.