Knowledge Bank

Fluorescence spectra of $\mathrm{<mrow\; data-mjx-texclass="ORD">7</mrow>}Li2$, and $\mathrm{<mrow\; data-mjx-texclass="ORD">7</mrow>}Li2$, excited by the ultraviolet lines of Argon and Krypton ion lasers have been examined in the infrared region with a Fourier Transform Spectrometer. The various laser lines excited several $C1\Pi uX1\Sigma g-$ and $21\Sigma u\ast X1\Sigma g-$ transitions and the resulting fluorescence was assigned to the $2\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma u\leftarrow 2\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma g,c1\Pi u\leftarrow 11\Pi g,C1\Pi u-21\Sigma g$ and $21\Sigma u-11\Pi g$ transitions. None of these transitions have been previously observed and this was the first experimental observation of the $21\Sigma u$ ``double minimum'' state. The assignment and analysis of the spectra will be presented for both isotopes and the results will be discussed in relation to ab-initio calculations. Several perturbations were observed and their assignment and analysis will be presented.