Knowledge Bank

In a previous laserspectroscopic study of the $A2\Pi \leftarrow X2\Sigma$ transition of NaAr five vibrational levels $v=0\dots 4$ of the $X2\Sigma$ state have been $observeda$. Recently, we have performed an improved high-resolution investigation of this transition yielding experimental information on two more vibrational levels $v=5$ and $6.135$ absorption lines have been observed starting from $v=5$ and leading to $v\prime =6\dots 8$ of $A2\Pi$. Only a few lines connecting $v=6$ with $v\prime =5\dots 7$ could be detected. Therefore the assignment of rotational quantum numbers is very tentative in this case. Our preliminary results for the spectroscopic parameters of these levels are (in units of $cm-1$) $$\begin{array}{cccc} & T_{v}-T_{o}& 10^{2}B_{v}&10^{5}D_{v}\ v=5&34.22(10)&1.72(2)&2.3(2)\v=6&35.09(20)&0.52(4)&---\end{array}$$ The $X2\Sigma$ interaction potential has been determined in form of an analytical HFD function using our standard method of $approachb$. In addition, the spectral distribution of the fluorescence $A\leftarrow X$ has been recorded showing the well-known reflection structure and allowing a determination of the repulsive part of the $X2\Sigma$ potential.