ECAMP 15

Using pulsed optical-optical double resonance fluorescence depletion spectroscopy, many ro-vibrations of the NaH D$^1\Sigma$ state have been observed. The ab initio calculations show that the adiabatic potential energy curve of the NaH D$^1\Sigma$ state has a very shallow double-well structure, with completely different well widths giving different rotational constants and vibration spacing, while the high-energy region is another very wide potential well confined by an outer turning points of ionic interaction (characterized by the 1/R leading term). In this potential well, the rotation constant and vibration spacing have significantly different characteristics in different energy ranges, from which we can deduce the interaction force between NaH diatomic molecules. Due to predissociation, the linewidths of some rotational vibration energy levels are more than ten times wider than those of conventional depletion signals. In this presentation, we construct a hybrid potential curve modified from a theoretical curve to better represent the observed ro-vibration energy levels.