Global analysis of data on the $A\ ^{1}\Sigma^{+}$ $\sim$ $b\ ^{3}\Pi$ states of NaK

NaK electronic states have been extensively studied over recent years. Many of these studies have involved the lowest excited states, $A\ ^{1}\Sigma^{+}$ and $b\ ^{3}\Pi$, as they offer pathways to higher states. These states have regained attention as they are used as intermediaries in the production of ultracold molecules. Recently, the $b\ ^{3}\Pi_{0}$ $\sim$ $A\ ^{1}\Sigma^{+}$ spin-orbit interactions have been examined [1,2]. However analysis was based on band-by-band local deperturbation which is not consistent with experimental errors limits. In this study, we collect existing (published and unpublished) data from various experiments (FT-LIF, PLS and PFOODR) performed at Orsay and Lyon (Ross et al.), Warsaw (Kowalczyk et al.) and Lehigh (Huennekens et al.) universities. Transitions from $D\ ^{1}\Pi$, $B\ ^{1}\Pi$, and $C\ ^{1}\Sigma^{+}$ states simultaneously to the $A$ $\sim$ $b$ and $X$ states constitute the bulk of the data as the upper term energy values can be deduced precisely from the well known $X$ state parameters. Combined data will be modeled using a global deperturbation approach employing the discrete variable representation (DVR) so as to fit potential energy and spin-orbit functions.\\ 1. P.~Burns et al., J.~Chem.~Phys. {\bf 122}, 074306 (2005). \\ 2. R.~Ferber et al., J.~Chem~.Phys.{\bf 112}, 5740 (2000).