Quantum model simulation of complete S0→S1 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 population 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 population transfer to the vibrational ground or low excited states in the electronically excited state. The underlying mechanisms of the transfer are, however, different, i.e., suppression and compensation of intrapulse pump-dump processes for the negatively and positively chirped pulses, respectively. The process induced by the negatively chirped laser pulse is applied to design complete S-0-->S-1 population transfer to the lowest vibrational states of the first electronically excited state of 9-(carbazolyl)-anthracene (C9A) which could not be observed by means of traditional, i.e., continuous wave or ns spectroscopy. (C) 2000 American Institute of Physics. [S0021-9606(00)00444-X].