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 molec-ular constants for B1Πu←X1Σg+ transitions and confirmed by the complemen-tary A1Σg+←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 Dnnham coef-ficients and the Rydberg-Klein-Rees (RKR) potential energy curves of the (6d)1Πg, (7d)1Πg states are reported.