RADIATIVE LIFETIMES, QUENCHING CROSS-SECTIONS AND POPULATION MECHANISMS OF THE C-1-PI(U),2(3)PI(G) AND 1(3)DELTA(G) STATES OF LI-7(2)

The laser- and collision-induced fluorescence of Li-2 molecules in a h eat-pipe, excited by a tunable frequency-doubled mode-locked cavity-du mped cw dye laser into selected rovibrational levels of the (CIIu)-I-1 , state, was observed with spectral resolution using a monochromator a nd with temporal resolution using the single-photon counting technique . The effective lifetimes of the directly excited (CIIu)-I-1, state an d of the collisionally excited 2(3)II(g), and 1(3) Delta(g) states wer e measured as a function of the lithium vapor pressure and the argon b uffer gas pressure. This yields the radiative Lifetimes and collisiona l quenching cross sections of the three states. It is shown that the p opulation mechanism of the 2(3)II(g), and I-3 Delta(g), states is the collisional energy transfer from the (CIIu)-I-1, state. Measurement of the total fluorescence intensities emitted from the excited states un der cw laser excitation provides the cross sections for the collisiona l population transfer.