Electron impact excitation at forward scattering

At forward scattering, the recent generalized Lassettre expansion using a s ingle real Regge pole, the momentum dispersion method (MDM) of Haffad er al and the forward scattering function of Avdonina et al all yield results fo r H 1s-2p excitation that agree excellently with those obtained by the conv ergent close-coupling approximation of Pray et al down to about twice the t hreshold energy. Measured electron impact data for Cd and Xe are used to de monstrate the utility of the analytical continuation in energy and angle of the MDM and to guide measurements in the difficult to measure angular regi me near and at zero scattering angles.