Generalized kinetics of radiation processes in the field of ultrashort pulses: a physico-mathematical model

We propose a physicomathematical model of the generalized kinetics of radiation processes in the field of ultrashort pulses, based on the use of the probability of a photoprocess at a given moment of time instead of the standard approach, which uses a time-constant photoinduced transition rate. Basic expressions are obtained for the population of the upper energy level of a two-level system excited by a pulse with an exponential envelope. A significant difference between the proposed model and the results of the standard approach is shown in the case of ultrashort pulses with a duration shorter than the phase relaxation time of a two-level system.