Time Dependence of Resonant Photoprocesses Induced by Electromagnetic Pulses with Various Durations

The time dependence (on the pulse duration and on current time) of resonant photoprocesses induced by electromagnetic pulses of various durations (including ultrashort and quasi-monochromatic pulses) is analyzed using perturbation theory. Pulses with the Gaussian and exponential envelopes, as well as the Lorentzian and Gaussian spectral profiles of a photoprocess cross section are considered. Simple analytic expressions are obtained for the probability in the long-time limit. The time dependence for a given pulse duration is investigated analytically in the monochromatic and ultrashort limits and numerically for intermediate values of parameters. Specific features of the temporal dynamics, which are common for resonant photoprocesses and depend on the pulse shape and the spectral cross section profile are established.