Experimental study of the and states of NaK by polarization labeling spectroscopy technique

The polarization labeling spectroscopy technique is used to study the 6 1 Π ←X 1 Σ + and 7 1 Π ←X 1 Σ + band systems of the NaK molecule located in the UV range. For both excited states accurate molecular constants are derived which describe the 6 1 Π state to 68% and the 7 1 Π state to 71% of their potential well depths. The parameters deduced from the experiment are compared with the recent theoretical calculations.