Detuning and the excitation delay in photo-stimulated vibrational state transitions in HF under the classical field...

A theoretical and computational analysis of the influence of detuning on the excitation delay in photo-stimulated vibrational state transitions in HF under the classical field approximation is presented. A discrete representation of the time dependence of the probability weights for the states involved in the excitation is generated by numerical solution of the time-dependent Schrödinger equation as an initial value problem. A transition matrix is constructed at each time-step and the resulting sequence of transition matrices is used to quantify the time flow of probability among the state weights. It is shown that detuning of the stimulating radiation results in an increase in the excitation delay, despite the fact that oscillations in the probability weights increase in frequency with detuning, because decreasing probability of transition dominates the rate. The analysis is extended to multi-photon transitions involving 3 and 4 states. It is also applied to probability weights obtained in the rotating wave approximation, which is shown to result in an overestimate of the excitation delay, despite faithfully predicting the dominant oscillation frequency and amplitude.