Electron scattering from optically pumped lithium atoms

Abstract

A series of superelastic scattering experiments is described in which electrons are scattered from lithium atoms optically pumped to the 2 P excited state. The incident electron energies were 5.2, 12.2, and 20 eV and superelastically scattered electrons with energies of 7, 14, and 21.8 eV were detected over the angular range from 0°to 140°. Both differential cross sections and the orientation and alignment parameters were deduced from the same measurements. A complete set of the four spin-averaged parameters, which fully characterize the electron impact excitation of the 2S-2 P transition in lithium, is presented. The experimental results are compared with those predicted from convergent-close-coupling ͑CCC͒ calculations and two distorted-wave calculations. Excellent agreement is found with the CCC calculations. ͓S1050-2947͑99͒06406-9͔

Taking the Convergent Close-Coupling Method beyond Helium: The Utility of the Hartree-Fock Theory

“…We see that there is a substantial dependence of the results on the total electron spin S. The importance of the continuum is quite small at this energy. The agreement of the calculations with the experiment of Karaganov et al [8] is quite extraordinary. Note that this experiment utilises the superelastic technique, which yields much better statistics than the traditional electron-photon coincidence experiments [1,2].…”

“…For each total electron spin S, at every scattering angle, there are two independent scattering (complex) amplitudes resulting in four independent theoretical predictions. While experiment [8] is available only for the spin-weighted parameters, it can be thought of as perfect for the spin-weighted case.…”

“…Alkali atoms such as Li and Na are easier to prepare in the laboratory, and yet their chemistry is very similar to that of H, having just one valence electron. This allowed for some very accurate measurements of e-Li [6][7][8], e-Na [9][10][11][12], and e-K [13][14][15] scattering systems. So the next stage in trying to understand the discrepancy for the e-H system was to extend the CCC method to the alkali atoms.…”

Octupole contributions to the generalized oscillator strengths of discrete dipole transitions in noble-gas atoms

“…The limiting behavior of the GOS as q 2 → 0 has been a subject of continuing interest because of the difficulty of measuring reliably the electron DCS's for atoms, ions and molecules at and near zero scattering angles [3,14,18]. This difficulty still plagues measurements of the DCS's [19,20], including the most recent measurements of the DCS's [21,22]. Thus a thorough understanding of the behavior of the GOS's near q 2 = 0 is imperative to guide measurements.…”

Fast electron and X-ray scattering as a tool to study target's structure

“…A lot was done recently in this domain, including problems of small angle scattering, minima in GOS etc, which is illustrated by the prominent number of recent publications (see e.g. [5][6][7][8][9][10][11]).…”