SELECTIVE EXCITATION OF MOLECULAR VIBRATIONAL-STATES BY FEMTOSECOND IR LASER-PULSES

The coherent multiphoton excitation of molecular vibrational modes by femtosecond IR laser pulses is investigated by computer simulation. Optimized femtosecond-pulse pumping yields localization of population in a narrow range of the vibrational-level ladder by the end of the pulse. The final distribution of the localized population is determined by the power broadening and can be modified by varying the carrier laser frequency. Strong femtosecond-pulse pumping causes the localization of population during the pulse at very high vibrational levels up to the dissociation threshold, the number of photons absorbed being correlated with the instantaneous values of the laser field intensity. © 1990.