ELECTRON-SCATTERING BY CA ATOMS AND PHOTODETACHMENT OF CA- IONS - AN R-MATRIX STUDY

We have performed close-coupling calculations on electron scattering b y Ca atoms and on photodetachment of Ca- ions by using a six-state (S- 1- P-3- D-3- D-1- P-1- P-1) R-matrix method. We predict a strong inter action between (4s(21)S+epsilon d)D-2 and (4s4p(3)P+epsilon p)D-2 chan nels that gives rise to two relatively broad resonance peaks in the d- wave cross section. In addition, one obtains a strong and a weak peak in the total scattering cross section. Our calculations on the photode tachment cross section of Ca- ions yield results that are in good qual itative agreement with the experimental data by allowing for the openi ng of a detachment channel connected to the excited state 4s4p(3)P.