Quantum model simulation of complete S-0 -> S-1 population transfer by means of intense laser pulses with opposite chirp

The effects of short (0.5-2 ps) chirped laser pulses on the vibrational pop ulation transfer from the electronic ground state S-0 to the excited state S-1 are investigated via numerical simulations of the wave packet dynamics. It is demonstrated for a model system that both positively and negatively chirped laser pulses with high intensities can achieve almost complete popu lation transfer to the vibrational ground or low excited states in the elec tronically excited state. The underlying mechanisms of the transfer are, ho wever, different, i.e., suppression and compensation of intrapulse pump-dum p processes for the negatively and positively chirped pulses, respectively. The process induced by the negatively chirped laser pulse is applied to de sign complete S-0-->S-1 population transfer to the lowest vibrational state s of the first electronically excited state of 9-(carbazolyl)-anthracene (C 9A) which could not be observed by means of traditional, i.e., continuous w ave or ns spectroscopy. (C) 2000 American Institute of Physics. [S0021-9606 (00)00444-X].