Tunneling through the potential barrier of the B1Πu state of 7Li-7Li

A sub-Doppler experiment involving an effusive beam of lithium dimers and a continuous wave (cw) tunable dye laser is used to record the absorption spectrum of the B-X system. Predissociation due to tunneling through the potential barrier of the B state is studied in a small range of energy above the Li(2p)+Li(2s) dissociation limit by analyzing the shape of homogeneously broadened absorption lines and by measuring the fluorescence intensity of Li atoms. Experimental data are interpreted in the frame of a semiclassical dynamical model involving the shape of the potential barrier. Their accuracy should address an improvement of the potential shape through a full quantal dynamical model. (C) 1999 American Institute of Physics. [S0021-9606(99)01228-3].