Excitation of $sup 1$S and $sup 1$D autoionization states and resonance ionization of a helium atom by electron impact

The questions concerning the excitations of the /sup 1/S and /sup 1/D autoionization states of the helium atom by electrons are considered in this work. According to Fano's theory in the diagonalized approximation, the process of resonance tonization through an optically forbidden autoionization state is studied in the case of the (2s/sup 2/)/sup 1/S level. In the second Born approximation, simplified for high energies of the incident electron we estimated the role of transitions through the intermediate levels for the excitation of the (2p/sup 2/)/sup 1/S and (2p/su p 2/)/sup 1/D autoionization states. (auth)