THE DOUBLY-EXCITED 1-(3)-SIGMA(G)(-) STATE OF LI-7(2)

This paper reports the first experimental observation of the doubly ex cited valence (2p+2p)(3) Sigma(g) state of Li-7(2). We used cw perturb ation-facilitated optical-optical double resonance (PFOODR) fluorescen ce excitation and resolved fluorescence spectroscopic techniques. All the observed levels have been detected through perturbations by the 2. (IIg)-I-3 state. The deperturbed primary molecular constants of this 1 (3) Sigma(g)(-) state are T-e=34 045.354(43) cm(-1), omega(e)=216.820 (37) cm(-1), B-e=0.673 69(47) cm(-1), R(e)=2.670 81(94) Angstrom and D -e=4279.306(43) cm(-1). The equilibrium internuclear distance of the 1 (3) Sigma(g)(-) state is smaller than that of the X (1) Sigma(g)(+) g round state.