MANIPULATION OF ROVIBRATIONAL WAVE-PACKET COMPOSITION IN THE LI-2 E((1)SIGMA(-PULSES()(G)) SHELF STATE USING INTERMEDIATE STATE SELECTION AND SHAPED FEMTOSECOND LASER)

The composition of a rovibrational wave packet in the E((1) Sigma(g)()) state of Li-2 is controlled using a combination of intermediate sta te selection and femtosecond optical pulse shaping techniques. Interme diate state selection is accomplished using a cw laser to prepare a st eady state population of a single rovibrational level in the A((1) Sig ma(u)(+)) state of Li-2, which acts as the initial state for subsequen t ultrafast pump/probe studies in the ''shelf'' region of the E((1) Si gma(g)(+)) state, An initial set of relative amplitudes of the wave pa cket eigenstates is defined by the intermediate level. Femtosecond opt ical pulse shaping, performed using a grating pair and a mechanical am plitude mask, is then used to further alter the wave packet compositio n. Quantitative changes in the Fourier transform of the pump/probe tra nsient demonstrate that combining these two techniques can be a facile approach to manipulating wave packet composition, with the ultimate g oal of controlling wave packet evolution into a desired final form. (C ) 1997 American Institute of Physics.