Analysis and transition probabilities of the B-1 Pi(u)-> X-1 Sigma(+)(g) band system of Na-2 excited by the 4579 angstrom Ar+ laser line

The fluorescence spectrum of Na-2 induced by the 4579.35 Angstrom line of a n argon ion laser has been analyzed with special emphasis on determination of accurate relative intensities and on the observation of higher vibration al levels in the B(1)Pi(u) excited state close to the dissociation limit. W e 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 <-- upsil on " = 8, J " = 42; upsilon' = 29, J' = 25 <-- upsilon " = 8, J " = 24 and upsilon' = 23, J' = 39 <-- upsilon " = 5, J " = 38. Some series are reporte d for the first time. Dunham coefficients and Franck-Condon factors valid f or all quasibound vibrational energy levels upsilon' = 28-33 of the B(1)Pi( u) excited electronic state are also reported. The radiative transition pro babilities and radiative lifetimes for the observed fluorescence series wer e 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 tran sition dipole moment function. The transition probabilities and lifetimes a gree with the observed measurements usually within the experimental uncerta inty. A very weak rotational satellite structure with jumps with Delta J' = +/- 1, +/- 2,..., +/- 20 for some bands of most intense fluorescence serie s Q(31) at upsilon' = 27 was also analyzed. (C) 2000 Elsevier Science Ltd. All rights reserved.