H(2p) excitation by 54.4 eV electrons

Abstract

In response to the recent measurements of the 54.4 eV e–H(2p) reduced Stokes parameters by Gradziel and O'Neill (2004 J. Phys. B: At. Mol. Opt. Phys. 37 1893) we perform corresponding calculations using two recently developed techniques. These are the propagating exterior complex scaling direct approach to the solution of the underlying Schrödinger equation, and the box-based convergent close-coupling method. We find the results to be almost identical to the Laguerre-based convergent close-coupling method of Bray and Stelbovics (1992 Phys. Rev. A 49 1066). Hence we are unable to explain the substantial discrepancy with experiment for the parameter in the vicinity of 30°.

A complete numerical approach to electron–hydrogen collisions

“…All the PECS calculations presented in this tutorial, and other publications emanating from this research [33][34][35][36][37][38][39][40][41][42][43], are in excellent agreement with other state-of-the-art computational methods and measurements, where available. We consider that the PECS method now offers complete solutions for e-H collisions in four important respects.…”

“…PECS reduced Stokes parametersP 1 ,P 2 andP 3 and related parameters P l , γ and P + for e-H 1s-2p scattering at E 0 = 54.4 eV. CCC box-based calculations (CCC-B) [40] and measurements of Yalim et al [65], Gradziel and O'Neill [64] and Williams and Mikosza [66] are also shown.…”

“…In figure 9, we reproduce our results for the reduced Stokes parameters for electronhydrogen 1s-2p scattering collisions at 54.4 eV from [40], and additionally include the related parameters P l , γ and P + . The PECS calculations are almost indistinguishable from the recent CCC-B (box based) results and theP 1 ,P 2 , P l and γ parameters are in excellent accord with the experimental results of Yalim et al [65], which have significantly smaller standard errors than Gradziel and O'Neill's measurements.…”

“…In addition to the PhD thesis [32], many publications [33][34][35][36][37][38][39][40][41][42][43] have emanated from the research described in this tutorial. However, the theoretical development here is the first to give the final form of the PECS equations for arbitrary initial states, and gives results for many targets and kinematics not included in these publications.…”

Electron Scattering by Atoms, Ions, and Molecules

“…The reduced Stokes parameters, P 1 , P 2 and P 3 for the H(2p) state at an incident electron energy of 54 eV. Closed squares, Yalim, Cvejanovic and Crowe (1997); closed and open circles, Williams and Mikosza (2006); closed triangles, Gradziel and O'Neill (2004); open triangles, O'Neill et al (1998);open squares, Nic Chormaic, Chwirot and Slevin (1993); open diamonds, Williams (1986); full line, the PECS theory of Bartlett et al (2005). Adapted from Williams and Mikosza (2006 More detailed reviews of angular and polarization correlation and superelastic scattering studies were given by Andersen, Gallagher and Hertel (1988) Andersen et al (1997), and Andersen and Bartschat (2001).…”