Optical-Optical Double-Resonance Excitation Spectra of the (6d)1Πg, (7d)1Πg High-Lying Rydberg States in Na2

Two 1Πg states of Na2 for v ≤ 13 have been observed by using optical-optical double resonance (OODR) fluorescence excitation spectroscopy. The intermediate levels in B1Πu state are identified by the numerical calculations with the molecular constants for B1Πu ← X1Σg+ transitions and confirmed by the complementary A1Σu+ ← X1Σg+ polarization spectra. Absolute vibrational numberings of the (6d)1Πg and (7d)1Πg states are determined by comparing the experimental OODR excitation intensities with the simulated Franck-Condon factors. The Dunham coefficients and the Rydberg-Klein-Rees (RKR) potential energy curves of the (6d)1Πg, (7d)1Πg states are reported.