“…If, as we propose, the diabatic picture is the better first-order description of the spectrum, the probe stage of the excitation scheme used by Ekey and McCormack [10] and Chartrand et al [11] (Fig. 1), but the transition remains a strong one because of the low principal quantum number of the dominant n ¼ 2 configuration, r 1 u 2s 1 , in the Franck-Condon range of 4-6 a 0 (2-3 Å) of the B 00 B 1 R þ u state.…”