The C(2)1Πu state in Rb2. Observation and deperturbation.

We report a systematic study of the C(2)1Πuelectronic state in rubidium dimer, observed in polarization labelling spectroscopy experiment through the C ← X1Σg+ transitions recorded under rotational resolution in two isotopologues 85Rb2 and 85Rb87Rb. Regularity of the vibrational progressions was distorted by numerous interactions with the surrounding 21Σu+, 23Πuand 33Σu+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.