New spectroscopic data, spin-orbit functions, and global analysis of data on the AΣu+1 and bΠu3 states of Na2

Abstract

The lowest electronically excited states of Na2 are of interest as intermediaries in the excitation of higher states and in the development of methods for producing cold molecules. We have compiled previously obtained spectroscopic data on the A 1Sigmau+ and b 3Piu states of Na2 from about 20 sources, both published and unpublished, together with new sub-Doppler linewidth measurements of about 15,000 A<--X transitions using polarization spectroscopy. We also present new ab initio results for the diagonal and off-diagonal spin-orbit functions. The discrete variable representation is used in conjunction with Hund's case a potentials plus spin-orbit effects to model data extending from v=0 to very close to the 3 2S+3 2P12 limit. Empirical estimates of the spin-orbit functions agree well with the ab initio functions for the accessible values of R. The potential function for the A state includes an exchange potential for S+P atoms, with a fitted coefficient somewhat larger than the predicted value. Observed and calculated term values are presented in an auxiliary (EPAPS) file as a database for future studies on Na2.

Global analysis of data on the spin-orbit-coupledA1Σu+andBai1, Ahmed2, Beser3 et al. 2011Phys. Rev. ASelf Cite

“…For Na 2 [22], data now extend almost continuously from the lowest vibrational levels to the atomic limit.…”

“…5. A representation of the apparatus is shown in [22]. The experimental setup used here was similar to the one used previously for Rb 2 [48].…”

“…As in previous implementations of this technique (see [48] and [22] and references therein), a circularly polarized pump laser beam, tuned to a chosen transition, creates an anisotropic distribution of magnetic sublevel populations (net orientation) in one or more ground state rovibrational levels. The counterpropagating linearly polarized probe laser beam can be considered to be made up of equal parts left and right circular polarization.…”

“…Two two-photon steps were used to efficiently connect the FR molecular state, via X(v = 73, J = 2) to X(v = 0, J = 0). Recently, the methods available for analyzing and modeling spectroscopic data on highly perturbed states have been extended [18][19][20][21][22][23][24][25][26][27] As is evident from the discussion below, each effort to perform a "global analysis" of all available data on these two electronic states raises additional questions about what Hamiltonian elements and functions are required, and what data is required to determine the parameters so as to achieve a fit with residuals comparable to experimental uncertainties. There has been impresssive progress in data acquisition and analysis for the heteronuclear A and b states from work on NaK [28][29][30][31][32] to more recent work on NaRb [19,23], NaCs [24], KCs [25,26], and RbCs [21,27].…”

“…There have also been a succession of studies of the A and b states of the lighter homonuclear alkali dimer species Li 2 [33][34][35][36], Na 2 [22,[37][38][39][40][41], K 2 [18,20,[42][43][44][45][46] and Rb 2 [47,48]. For Na 2 [22], data now extend almost continuously from the lowest vibrational levels to the atomic limit.…”