Observation of levels near dissociation in the X 1Σ+g state of 7Li2

Abstract

The fluorescence spectrum of ⁷Li₂ excited by a Kr⁺ (5682 Å) laser has been observed and analyzed. The laser simultaneously excites the A¹Σ⁺_u and the B¹Π_u states of the ⁷Li₂ molecule. The analysis reveals two very interesting things: (a) the A–X spectrum consists of the transitions involving v″ levels of the entire ground state potential well (5≤v″≤36) and thus we have made the very first observation of the levels near the dissociation limit in the ground state of ⁷Li₂, which suggests that D″_e=8521.5±4 cm⁻¹; and (b) the B–X spectrum is actually enhanced by the fluorescence from the A state which is an interesting single frequency analog of ‘‘modulated population spectroscopy’’ or ‘‘optical–optical double resonance’’ which we call ‘‘coupled laser induced fluorescence series’’ (CLIFS).