Polarization of Li(nd → 2p, n = 3–5) emission resulting from He2+–Li collisions

Abstract

The excitation of a ground state Li atom to its 1s2nd (n = 3–5) excited states in a collision with He2+ is investigated using the two-center atomic orbital close-coupling method. The Li(nd → 2p) emission cross-sections are calculated in the collision energy range of 1–150 keV u−1 and compared with the available experimental cross-sections and other theoretical results in the overlapping energy range, showing good overall agreement. The linear polarization degrees of the radiation from the nd 2D3/2–2p 2P1/2, nd 2D3/2–2p 2P3/2 and nd 2D5/2–2p 2P3/2 (n = 3–5) transitions in Li are also calculated from the ndm magnetic substate populations. It is found that polarization degrees for nd → 2p (n = 3–5) transitions exhibit sharp minima at ∼3 keV u−1 which originate from the peaks in the Li(nd → 2p) (n = 3–5) emission cross-sections at about the same energy.