Polarisation labelling spectroscopy of rubidium dimer: Highly excited 81∑u+, 91∑u+ and 81∏u states

Abstract Excitation spectra of rubidium dimer were investigated in the spectral range 28000 − 29700 cm-1 by polarisation labelling spectroscopy technique. Three hitherto unknown electronic states were observed and assigned as 8 Σ u + 1 , 9 Σ u + 1 and 8 Π u 1 . The experimental findings on the Σ u + 1 states were compared with theoretical predictions. The investigated electronic states are presently the highest ungerade states of Rb2 known experimentally and the 8 Π u 1 state has not been studied theoretically as yet.