15-stateR-matrix investigation of resonances in the inelastic scattering of electrons from atomic hydrogen at energies up to 13.06 eV

Abstract

A 15-state R-matrix calculation has been carried out at 530 energies ranging from the n =2 threshold up to n =5 threshold at 13. 06 eV to map out the resonant profiles for the n =2 inelastic integral and differential cross sections, and the angular distribution of the spin asymmetry in the inelastic scattering of spin-polarized electrons by the spin-polarized hydrogen atoms at angles 0', 30', 55', 70', 90', 125', and 180' for the 1s~2s transition. The calculations are compared with the experiments and the feasibility studies of using the electron-energy-loss experiments in the investigation of resonances with positions higher than the n =2 threshold have been carried out.

B-spline methods inR-matrix theory for scattering in two-electron systems

“…As already mentioned in the introduction, this has been one of the fundamental problems in scattering and as such it has received considerable attention in the low-energy region. In particular, the region in between the N = 2 and N = 3 thresholds has been investigated by theoreticians (Callaway 1982, Konovalov and McCarthy 1994, Fon et al 1994, Bartschat et al 1996a, b, Bray et al 1996 as well as experimentalists (Williams 1988), and for the B-spline inner region we will focus our attention on this problem. In this region, the H target in the 1s state can be excited to two states, the 2s and 2p states, whereas the 3 n Feshbach resonances and the 1 P o shape resonance above the N = 2 threshold in H − can be excited resonantly.…”

“…Callaway (1982) performed a pseudostate calculation, whereas Konovalov and McCarthy (1994) used the J -matrix approach. Bartschat et al (1996b) presented results obtained using the intermediate-energy R-matrix approach (IERM), while the standard R-matrix approach has also been used to investigate this scattering problem, initially with a six-state target description (Burke et al 1967), then with a more extensive 15-state description (Fon et al 1994) and more recently using the R-matrix pseudostate approach (RMPS) (Bartschat et al 1996a). Finally, the convergent close-coupling approach (CCC) has also been applied to the study of resonant scattering (Bray et al 1996).…”

“…Many approaches have been pursued to study this process and a good estimate for the quality of the theoretical approach can be obtained from detailed comparisons. Among the applied methods are pseudostate calculations (Callaway 1982), the J -matrix method (Konovalov and McCarthy 1994), the standard R-matrix approach using a 15-state target expansion (Fon et al 1994), the R-matrix approach with pseudostates (Bartschat et al 1996a), the intermediate energy R-matrix method (Bartschat et al 1996b) and the convergent close coupling approach (Bray et al 1996). A more extensive list of methods has been given by Bartschat et al (1996b).…”

Theoretical study of electron-impact excitation of H(1s) into the states using a two-dimensionalR-matrix propagator

“…The method is able to incorporate a large set of target states and pseudostates representing highly excited levels and the continuum of the target. These play an important role even at low energies by influencing the distribution of flux amongst the elastic and inelastic channels (see for example Callaway 1982, Fon et al 1994, Konovalov and McCarthy 1994, Odgers et al 1995, Dunseath et al 1997.…”