A 19-state R-matrix investigation of resonances in e--He scattering at low energies: III. 11S-21S and 11S-23P differential cross sections

For pt.II see ibid., vol.23, no.20, p.3691-707 (1990). Fon and Lim (1989, 1990) have reported 11-state and 19-state R-matrix calculations of 1 1 S-2 3 S differential cross sections at low energies. The same R-matrix calculations of Fon and Lim are now extended to obtain the differential cross sections for excitation of the ground state of helium to the 2 1 S and 2 3 P states. Convergence studies are carried out between the R-matrix calculations and comparison are made between the R-matrix calculations and experiments. The 19-state R-matrix results are presented at scattering angles 30', 55', 60', 90', 120', 125' and 140' from the excitation thresholds up to 23.8 eV. The calculations are performed at more than seven hundred energy points in order to depict the observed resonant profiles.