E. Chahid1, K. Laghdas1*, R.H.G. Reid2

1 Département de Physique, Faculté des sciences, Université Chouaïb Doukkali, BP 20, 24000 El Jadida, Maroc

2 Department of Applied Mathematics and Theoretical Physics, Queen’s University Belfast, BT7 1NN, UK

* Corresponding author: E-mail: khalid_laghdas@yahoo.fr

Received: 25 March 2011; revised version accepted: 26 July 2011



     We present a theoretical study of electron-impact single ionization of  I50+  (1s22s) 2Se using a method that combines the distorted wave born approximation and  non-relativistic R-matrix method. In this method, the incident/scattered electron is described by the distorted- wave born approximation, while both the initial ground state and the final continuum states (I51++ e- ) are calculated by using the non-relativistic R-matrix method. With an initial state of the target ion, we have included only the 24- pole components of the interaction with ionizing electron, and produce five accessible continuum states with symmetries: 2Se, 2Po, 2De, 2Fo and 2Ge. We have calculated single differential cross sections for each residual ion states namely ( 1s2 ) 2Se, (1s 2s) 3Se (1s2p) 3Po , (1s2s) 1Se and (1s2p) 1Po.

    Total cross sections for production of I51+, in each of the five states, are calculated and presented for impact energies which is varies from threshold energy at 330.289au to 1700au . The contribution of excitation-autoionization processes for the total cross section, while not negligible, is not very significant, being of the order of a few percent. Good agreement was found between our theoretical results and the semi-empirical Lotz formula for the total cross section.


Keywords: R-matrix theory; Coulomb distorted wave; Born approximation; Continuum; Autoionization.

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