Observation and analysis of high-lying singlet gerade states of rubidium dimer

The structure of the excited electronic states of Rubidium dimer is important to a number of areas of research including, the production of ultracold ground state molecules, cold atom-molecule collisions, and the development of new \textit{ab-initio} molecular electronic structure methods. In the experiment we used optical double resonance technique to observe large number of ro-vibrational levels of the 5$^{\mathrm{1}}\Sigma _{\mathrm{g}}^{\mathrm{+}}$, 6$^{\mathrm{1}}\Sigma _{\mathrm{g}}^{\mathrm{+}}$, and 3$^{\mathrm{1}}\Pi_{\mathrm{g}}$ electronic states in the 24000-26000 cm$^{\mathrm{-1}}$ range. The Rb$_{\mathrm{2}}$ molecules were initially excited from the ground X$^{\mathrm{1}}\Sigma_{\mathrm{g}}^{\mathrm{+}}$ state to an intermediate level of the mixed A$^{\mathrm{1}}\Sigma _{\mathrm{u}}^{\mathrm{+}}$\textasciitilde b$^{\mathrm{3}}\Pi _{\mathrm{u}}$ manifold using a narrow band tunable TiSa laser. In the next step the probe laser, a narrow band dye laser tunable in the 13000-14000cm$^{\mathrm{-1\thinspace }}$range, excited the molecules further to the target states. The resonances of the probe laser were observed by detecting the total fluorescence from the excited states to the a$^{\mathrm{3}}\Sigma_{\mathrm{u}}^{\mathrm{+}}$ state in the 500nm range. Potential energy curve was constructed for each state from the term values of the observed levels.