Knowledge Bank

Previous work in this $laboratory1$ characterized the $E1\Sigma g+$ state of $Li2(v=0-12)$ and gave an indication of the possibility of the existence of a double minimum potential in this state. A shallow outer minimum near $v=12$ was also predicted by an ab initio $calculation.2$ The present work extends the measurements through $v=18$. Several low J levels from $v=13$ and 14 exist in the inner minimum portion of the potential with the remaining levels above the barrier showing a sudden dramatic increase in internuclear distance consistent with the existence of a double minimum. At the present time no transitions have been assigned in the outer minimum. However, the pulsed OODR spectra are uncharacteristically complex in this energy region.