Analysis and transition probabilities for the Na2 B1Πu→X1Σ+g system using an excitation the 4727-Å Ar+ laser line

The fluorescence spectrum of Na-2 induced by the 4726.87 Angstrom line of an Argon ion laser has been analyzed with special emphasis on determination of accurate relative intensities. This work extends previous observations on Na-2 by using this excitation line. We have observed eight fluorescence series for the B(1)Pi(u) --> X(1)Sigma(g)(+) band system corresponding to the excitation transitions upsilon' = 9, J' = 38 <-- upsilon " = 1, J " = 37; upsilon' = 14, J' = 46 <-- upsilon " = 4, J " = 47; upsilon' = 14, J' = 81 <-- upsilon " = 3, J " = 80; upsilon' = 15, J' = 65 <-- upsilon " = 4, J " = 66; upsilon' = 12, J' = 36 <-- upsilon " = 3, J " = 36; upsilon' = 12, J' = 40 <-- upsilon " = 3, J " = 39 upsilon' = 17, J' = 45 <-- upsilon " = 6, J' = 45 and upsilon' = 18, J' = 63 <-- upsilon " = 6, J " = 63. The seven latter series are reported for the first time. Optically pumped laser transitions obtained in Na-2 vapor by using this excitation wavelength have been assigned. The radiative transition probabilities for the observed fluorescence series were calculated using hybrid potential energy curves for the B(1)Pi(u) and X(1)Sigma(g)(+) states constructed up to last vibrational levels and an nb initio transition dipole moment function. Radiative lifetimes for the rovibrational levels of the upper states pumped by the laser line have also been calculated. The transition probabilities and lifetimes agree with the corresponding observed measurements, usually within the experimental uncertainty. From the rotational satellite structure with Delta J' = +/-1 and +/-2 of some bands, for the most intense fluorescence series, collision-induced transition rates and average cross sections have been obtained. (C) 1998 Academic Press.