Spectroscopic observations, spin-orbit functions, and coupled-channel deperturbation analysis of data on theA Σ1u+andb Π3ustates ofRb2

Abstract

We present experimentally derived potential curves and spin-orbit interaction functions for the strongly perturbed $A\text{ }{^{1}\ensuremath{\Sigma}}_{u}^{+}$ and $b\text{ }{^{3}\ensuremath{\Pi}}_{u}$ states of the rubidium dimer. The results are based on laser-induced fluorescence and optical-optical double-resonance polarization spectroscopy measurements combined with earlier laser-induced fluorescence data. We used an analytic potential (Hannover form) incorporated in a discrete variable representation of the Hamiltonian matrix for numerical energy-level calculation. A previous vibrational assignment of the $A$ levels is confirmed, and very probable vibrational assignment for the $b$ levels is also obtained. Currently, the rms residual of our fit is $0.053\text{ }{\text{cm}}^{\ensuremath{-}1}$ as compared to the typical experimental uncertainties that are estimated to be $0.005\text{ }{\text{cm}}^{\ensuremath{-}1}$. Fitted diagonal and off-diagonal spin-orbit functions are obtained and compared with ab initio calculations by all electrons and effective core pseudopotential methods. Analysis of the computational results yields an explanation for the ubiquitous single minima in these spin-orbit functions, which can be represented approximately by Morse-type functions.