Knowledge Bank

In the B state of $Na3$, the three sodium nuclei can perform an almost free pseudorotational motion in the molecular plane. This purely vibrational movement is characterized by quantum numbers u (denoting the radial displacement amplitude) and j (the vibronic angular momentum). Recent work from this lab has shown that for $j>0$. each rotational level in the B state splits into two Coriolis components. Furthermore, this study indicates that the vibronic angular momentum is integer $quantized1$. The corresponding rotational analysis was based on a simple model assuming well separated vibronic bands--as is the case for $u\ge 1$--and rotational quantum numbers $J\le 13$. This talk reports new optical-optical double resonance experiments in which the frequency of the labeling laser was truned to a transition in the A-X system--previously investigated by the groups of $Demtrouder3$ and $Tiemann4$. A second laser was scanned across the u=0 and 1, j=0,1, 2, and 3 vibronic bands in the B-X system. Such a technique gives a greatly improved signal to noise ratio in comparison with our earlier studies in which labeling was done in the B state. The previously unrecorded u=0 spectrum is of particular theoretical interest because the j=0 and 1 sublevels lie somewhat closer together than the corresponding pairs in $u\ge 1$ states suggesting that these levels lie near (or even below) the pseudorotational barrier. Efforts are underway to determine the height of the barrier from an analysis of the u=0 spectrum.