Finetuning laser-pulse frequencies for optimizing information content of femtosecond nonlinear spectroscopy: <i>Ab initio</i> simulations

We have performed a series of numerical ab initio experiments, in which we simulated several popular nonlinear femtosecond signals-time-resolved fluorescence, transient-absorption pump-probe, and electronic two-dimensional-for different carrier frequencies of the pump and probe pulses. As a system under study, we took the molecule of pyrazine in the gas phase. Our results demonstrate that variation of frequencies of the pulses increases the amount of information extracted from the spectroscopic signals, helps explore rarely visiting areas of the potential energy landscapes, and compensates for the unavailability of extra-broadband transform-limited pulses.