Analysis and transition probabilities of the B1Πu→X1Σg+ band system of Na2 excited by the 4579Å Ar+ laser line

The fluorescence spectrum of Na-2 induced by the 4579.35 Angstrom 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(1)Pi(u) excited state close to the dissociation limit. We have observed seven fluorescence series for the B(1)Pi(u) --> X(1)Sigma(g)(+) band system corresponding to the excitation transitions: upsilon' = 27, J' = 31 <-- upsilon " = 7, J " = 31; upsilon' = 28, J' = 43 <-- upsilon " = 7, J " = 43; upsilon' = 24, J' = 3 <-- upsilon " = 6, J " = 3; upsilon' = 15, J' = 55 <-- upsilon " = 0, J " = 55; upsilon' = 31, J' = 42 <-- upsilon " = 8, J " = 42; upsilon' = 29, J' = 25 <-- upsilon " = 8, J " = 24 and upsilon' = 23, J' = 39 <-- upsilon " = 5, J " = 38. Some series are reported for the first time. Dunham coefficients and Franck-Condon factors valid for all quasibound vibrational energy levels upsilon' = 28-33 of the B(1)Pi(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(1)Pi(u) and X(1)Sigma(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 Delta J' = +/- 1, +/- 2,..., +/- 20 for some bands of most intense fluorescence series Q(31) at upsilon' = 27 was also analyzed. (C) 2000 Elsevier Science Ltd. All rights reserved.