Analysis and transition probabilities of the B1Π u→ X1Σ g+ band system of Na 2 excited by the 4579 Å Ar + laser line

Abstract

The fluorescence spectrum of Na 2 induced by the 4579.35 Å line of an argon ion laser has been analyzed with special emphasis on determination of accurate relative intensities and on the observation of higher vibrational levels in the B 1Π u excited state close to the dissociation limit. We have observed seven fluorescence series for the B 1Π u→ X 1Σ g + band system corresponding to the excitation transitions: v′=27, J′=31←v″=7, J″=31; v′=28, J′=43←v″=7, J″=43; v′=24, J′=3←v″=6, J″=3; v′=15, J′=55←v″=0, J″=55; v′=31, J′=42←v″=8, J″=42; v′=29, J′=25←v″=8, J″=24 and v′=23, J′=39←v″=5, J″=38 . Some series are reported for the first time. Dunham coefficients and Franck–Condon factors valid for all quasibound vibrational energy levels v′=28–33 of the B 1Π u excited electronic state are also reported. The radiative transition probabilities and radiative lifetimes for the observed fluorescence series were calculated by using hybrid potential energy curves for the B 1Π u and X 1Σ g + states constructed up to last vibrational levels and a transition dipole moment function. The transition probabilities and lifetimes agree with the observed measurements usually within the experimental uncertainty. A very weak rotational satellite structure with jumps with Δ J′=±1,±2,…,±20 for some bands of most intense fluorescence series Q(31) at v′=27 was also analyzed.