ON THE USE OF TIME-DOMAIN METHODS TO STUDY THE EXCITATION OF A MOLECULE BY A STRONG, LONG LASER-PULSE

Calculations which solve the time dependent Schrodinger equation on a grid are generally useful for studying the cw excitation of a molecule by a weak laser or the excitation by a short, strong laser pulse. Her e we show how time dependent methods can be applied to study excitatio n by strong, long pulses. Moreover, even though the molecule is driven by a time dependent field, one can identify energy eigenstates that p rovide the time scales on which various observables evolve. The calcul ations which illustrate the methodology are performed on a model of th e bound-to-bound electronic excitation of the I2 molecule. We study th e dependence of the excitation probability on time, power, and laser f requency. We find that the I2 molecule driven by a strong laser emits at many frequencies below and above the laser frequency.