title: N-level Li2 multiphoton rotational wave packets: alignment effects in resonant multiphoton coherent excitation.
abstract: Using one color ultrafast pump-probe spectroscopy, the authors create N-level multiphoton rotational wave packets via resonant optical pumping between the A((1)Sigma(u) (+)) and E((1)Sigma(g) (+)) electronically bound states of Li(2) from a single optically state-selected rovibrational state |nu(A)=11, j(A)=28>. The authors find that excitation with a single amplitude shaped femtosecond pulse allows the direct observation of up to a six photon absorption, which generates a coherent superposition of 13 rotational states. The multilevel rotational wave packet is theoretically treated with the multipole moment formalism in order to characterize the experimentally observed time-dependent alignment. In particular, the authors find that the magnetic state distributions measured among coherently excited rotational states generated by the resonant multiphoton pumping reduces the measured coherence amplitudes by as much as 40%.
authors.affiliation: Department of Chemistry, University of California Berkeley, Berkeley, California 94720-1460, USA.
authors.forename: Elva A
authors.initials: EA
authors.lastname: Torres
authors.forename: Eliza-Beth W
authors.initials: EB
authors.lastname: Lerch
authors.forename: Xingcan
authors.initials: X
authors.lastname: Dai
authors.forename: Stefan
authors.initials: S
authors.lastname: Gilb
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Leone