Knowledge Bank

The rovibrational structure of the transition $B2\Sigma \leftarrow X2\Sigma$ of LiAr has been investigated by means of high-resolution laser spectroscopy using a supersonic beam for production of the $moleculesa$. About 100 absorption lines could successfully be assigned for each isotopomer $\mathrm{<mrow\; data-mjx-texclass="ORD">7</mrow>}LiAr$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">6</mrow>}LiAr$ providing in addition the vibrational numbering of the observed levels $v=0\dots 3$ of the $B2\Sigma$ state. The analysis of the experimental observations was complicated by the occurrence of perturbations between rovibrational levels of the $B2\Sigma$ and of the $A2\Pi$ state which have not been taken into account, up to now. For the $B2\Sigma$ interaction potential we used a Morse-van der Waals potential as an analytical expression reproducing the observed energy levels with an error margin of $0.015cm-1$. The van der Waals parameter $C6$ was fixed to its theoretical value. Our preliminary results for the $B2\Sigma$ state of $\mathrm{<mrow\; data-mjx-texclass="ORD">7</mrow>}LiAr$ are $Rc=6.24(5)$ {\AA} and $Dc=33.8(2.0)cm-1$.