We report a systematic study of the C(2)$^1\Pi_u$ electronic state in rubidium dimer, observed in polarization labelling spectroscopy experiment through the C $\leftarrow$ X$^{ 1}\Sigma^{ +}_{ g}$ transitions recorded under rotational resolution in two isotopologues $^{ 85}$Rb$_2$ and $^{ 85}$Rb$^{ 87}$Rb. Regularity of the vibrational progressions was distorted by numerous interactions with the surrounding 2$^1\Sigma^{ +}_{ \mathrm{ u}}$, 2$^3\Pi_{ \mathrm{ u}}$ and 3$^3\Sigma^{ +}_{ \mathrm{ u}}$ states. Deperturbation was performed by coupled-channels analysis taking into account spin-orbit and rotational interactions. Potential energy curves and parameters describing the off-diagonal matrix elements were determined as functions of internuclear distance. About 3000 line frequencies from the present study are reproduced with a standard deviation of 0.07 cm$^{ -1}$, in agreement with the experimental accuracy. Along with this, the model is consistent with all high resolution experimental data on the involved electronic states, available in the literature.
Categories: physics.chem-ph physics.atom-ph