Bound-state energies, oscillator strengths and photoionisation cross sections have been calculated for members of the lithium isoelectronic sequence with nuclear charge Z in the range 3 < 2 s 10. Two independent approaches to the problem give virtually the same results. Detailed comparisons with experiment and other theoretical results indicate that the present data are of high accuracy.
A comparison is made of experimental far-wing profiles for the system Li(2P → 3D)He with quantum calculations of thermally averaged free-free continua. Using input adiabatic potentials and transition moment functions from both ab initio and semi-empirical approaches, the comparison shows: (i) new ab initio potentials for Li * (2P, 3P, 3D)He reproduce the spectral positions of the observed rainbow satellites well; the height of the 3D barrier predicted agrees with experiment to within ±15 cm −1 , whereas its position is too large by 0.3 a 0 ; (ii) potentials obtained with various semi-empirical methods reproduce the satellite structure qualitatively, but are generally too repulsive in the 3D state at intermediate and large internuclear separations; (iii) transition moment functions for the asymptotically forbidden 2P → 3P transitions reproduce, with different degrees of accuracy, the intensity of the red-wing satellite related to the 3P potential extremum around 12 a 0 . The vibrational energies in the 2P and 3D states calculated with the ab initio potentials reproduce to within a few cm −1 those obtained from rotationally resolved band spectra reported in the literature.
We report results for the Lorentzian profiles of the Li I, Na I and K I doublets and the Na I subordinate doublet broadened by helium perturbers for temperatures up to 3000 K. They have been obtained from a fully quantum-mechanical close-coupling description of the colliding atoms, the Baranger theory of line shapes and new ab initio potentials for the alkali-helium interaction. For all lines except the 769.9 nm K I line, the temperature dependence of the widths over the range 70 ≤ T ≤ 3000 K is accurately represented by the power law form w = aT b with 0.37 < b < 0.43. The 769.9 nm K I line has this form for 500 ≤ T ≤ 3000 K with b having the higher value of 0.49. Although the shifts have a more complex temperature dependence, they all have the general feature of increasing with temperature above T ∼ 500 K apart from the 769.9 K I line whose shift decreases with temperature.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.