PERTURBATION-FACILITATED ALL-OPTICAL TRIPLE RESONANCE SPECTROSCOPY OF THE NA2 B 3-PI-U STATE

Abstract

The Na2 b 3PI(u) state has been studied by the continuous wave (cw) all-optical triple resonance (AOTR) technique. The AOTR technique used here corresponds to a perturbation-facilitated optical-optical double resonance (PFOODR) excitation through A 1SIGMA(u)+ approximately b 3PI(u) mixed intermediate levels from the ground state to the 2 3PI(g) state and stimulated emission pumping (SEP) of the 2 3PI(g) --> 3PI(u) transition. This sub-Doppler high-resolution PFOODR-SEP technique has allowed us to reach many b 3PI(u) levels (OMEGA=0, 1, 2, perturbed and unperturbed, including low v below the A1 SIGMA(u)+ potential minimum and higher vibrational levels up to v = 57). Based on these new high resolution data and previous results from high resolution spectroscopy, we have determined a new set of deperturbed molecular constants from the b 3PI(u) state up to nu=57, the corresponding RKR potential energy curve and the A 1SIGMA(u)+ approximately 3PI(u) spin-orbit interaction constants. This represents an example of a powerful and general technique for observing a "dark" (e.g., triplet) perturbing state when only the "bright" (e.g., singlet) perturbed state is well known from single photon spectroscopy