Observation and Analysis of the 6 $^{\mathrm{1}}\Sigma _{\mathrm{g}}^{\mathrm{+}}$ and 3 $^{\mathrm{1}}\Pi_{\mathrm{g}}$ states of Rubidium Dimer

Detailed knowledge of the excited electronic states of Rubidium dimer is of significant importance to a number of areas of research such as, the production of ultracold ground state molecules, cold atom-molecule collisions, and the development of new \textit{ab-initio} molecular electronic structure methods. The potential energy curves and transition dipole moments of dozens of electronic states of Rb$_{\mathrm{2}}$ have been calculated. However, only few low-lying electronic states have been experimentally studied and assigned. We report our experimental work and analysis of the 6$^{\mathrm{1}}\Sigma_{\mathrm{g}}^{\mathrm{+}}$ and 3$^{\mathrm{1}}\Pi_{\mathrm{g}}$ electronic states. In the experiment large number of ro-vibrational levels of the two states were observed using narrow band \textit{cw} TiSa and dye laser in double resonance cascade configuration. The intermediate states used in the experiment are from the mutually perturbed A$^{\mathrm{1}}\Sigma_{\mathrm{g}}^{\mathrm{+\thinspace }}$\textasciitilde b$^{\mathrm{3}}\Pi_{\mathrm{u}}$ pair of states. Potential energy curve was generated for each state from the term values of the observed levels.