Physical Review A
Near-threshold photoionization by pulses with modulated frequency
Andrzej Raczyński, Jarosław Zaremba
Abstract
Model photoionization by a pulse with a modulated frequency is discussed. An approximation generalizing that of Weisskopf-Wigner is proposed, with a pole moving in the rhythm of the modulation. A model taking into account the ionization threshold is adopted, and relatively simple formulas for the nondecay probability and the photoelectron spectrum are obtained. A nonexponential character of the decay curves is demonstrated together with a raising and narrowing of the peaks in the photoelectron spectra.