Quantum close-coupling calculations of the Ba(6p P-1(1)->6p P-3(j)) excitation transfer and Ba(6p P-3(j->j')) intramultiplet transition cross-sections in collisions with helium

Cross-sections for Ba(6p P-1(l) --> 6p P-3(j)) excitation transfer and intramultiplet transitions among the Ba((6)p (3)p(j)) states induced by collisions with He(S-1) have been calculated by a close-coupling treatment based on the BaHe SCF-CI/pseudopotential potential curves. The cross-sections are calculated from the translational energy in the range 0-2 eV. In order to facilitate comparison of theory with experiment the calculated cross-sections have been averaged over relative energy with a Maxwell-Boltzmann distribution. Excellent agreement with experiment was found for the Ba((6)p P-1(l) --> 6p P-3(2)) cross-section at T = 693 K: sigma(th) = 1.8 x 10(-16) cm(2), whereas sigma(exp) = 2.0 +/- 0.6 x 10(-16) cm(2) as determined by Breckenridge, W. H., and Merrow, C. N., 1988 J. chem. Phys., 88, 2329. The calculated cross-sections for collisional intramultiplet mixing in Ba(6p P-3(j)) at T = 1100 K are as follows: sigma(th) = 2.9 x 10(-19) cm(2) for the j = 2 --> j' = 1 transition and sigma(th) = 1.1 x 10(-19) cm(2) for the j = 1 --> j' = 0 transition. The corresponding experimental values are, respectively, 1.0 x 10(-19) cm(2) and < 5.0 x 10(-19) cm(2) as reported by Kallenbach, A., and Kock, M., 1989, J. Phys. B, 22, 1705.