Absolute angle-differential cross sections for electron-impact excitation of neon within the first 3.5 eV above threshold

Abstract

Absolute angle-differential cross sections for excitation of neon atoms to the four 2p 5 3s and to selected 2p 5 3p levels have been determined as a function of electron energy up to 3.5 eV above threshold at the scattering angles of 0• , 45• and 180• . In addition, the cross sections were recorded as function of scattering angle from 0• to 180• at 18 eV for the 2p 5 3s levels and at 19.3 eV for the 2p 5 3p levels, respectively. The cross sections were also determined theoretically using the Breit-Pauli B-spline R-matrix method with non-orthogonal orbital sets. Very good agreement is found both in terms of absolute values and in terms of the energies and widths of the numerous resonant features, thereby allowing for (re)classifications with significantly improved accuracy compared to earlier work.

Large-scale pseudostate calculations for electron scattering from neon atoms

“…The predicted resonance structure was subsequently confirmed experimentally [13]. Very good agreement at low energies was also achieved for the energy-dependent differential cross sections for excitation of the 2p 5 3s and 2p 5 3p states [14,15]. The key feature of the BSR method and the published suite of computer codes [16] is the possibility to employ nonorthogonal sets of term-dependent oneelectron orbitals.…”

“…Despite the fact that the previous BSR calculations [12][13][14][15] very accurately reproduced the low-energy near-threshold resonance structure, they did not account for coupling to the target continuum. Consequently, they cannot be considered fully converged regarding, for example, the absolute values of the excitation cross sections.…”

Benchmark calculations for near-threshold electron-impact excitation of krypton and xenon atoms

“…As two representatives of work in this area, we mention here the papers by Zeman et al [21] and by Grum-Grzhimailo and Bartschat [22]. More recently, however, the semi-relativistic BSR mentioned above was very successful in describing the resonance structure in e-Ne and e-Ar scattering, both for angle-integrated [11,23,24] and angle-differential [25][26][27] cross sections. For e-Xe collisions, on the other hand, significant differences between theory and experiment remained [26].…”

Oleg Zatsarinny (1953–2021): Memories by His Colleagues

“…We show just one example, namely the excitation of the four lowest excited states in Ne from threshold to 20 eV, measured at the backward scattering angle 180 • with an energy width of 10 meV for the incident electron beam. In Figure 7 we compare the respective experimental cross sections (left side) with those of the B-spline R-matrix calculations (right panels) [18]. Amazing agreement is observed in both the absolute size and in the detailed resonance structure, which shows characteristic changes for the four final excited Ne(2p 5 3s) levels.…”

“…To begin with, figure 1 shows our results for the production of metastable neon atoms in the (2p 5 )3s [3/2] 2 and the (2p 5 )3s [1/2] 0 states by electron impact in the near-threshold regime. The sum of these two excitation cross sections has been used by Brunt et al [18,45] and Buckman et al [44] to analyse the details of the resonance structure (see also the review by Buckman and Clark [19]). After renormalizing the experimental data through dividing them by an overall factor of 1.29, and including the cascade contributions, we obtain essentially perfect agreement with the shape of the experimental data as a function of energy in the nearthreshold region, while we differ from Zeman and Bartschat [17] by nearly a factor of 2 in the predicted height of the first maximum.…”