Coincidence measurements in coplanar asymmetric geometry are reported for electron impact ionization of helium leaving the residual ion either in its ground state or in an n = 2 excited state. Cross sections are placed on an absolute scale by extrapolation of the generalized oscillator strength to the optical limit. Scattered electron energies of 570 and 1500 eV are considered with ejected electron energies of 10, 20 and 40 eV. Comparison is made with theoretical calculations in the first Born approximation using parametric potentials. Clearly, certain features of the experimental results can only be explained by multiple-scattering effects.
Abstract. The differential cross sections for the Kr (e, 3 e) Kr + + reaction are calculated (by using correlated wave function) in the case of high incident energy (5 keV) for the three terms of the final Kr ÷ + (4p 4) ion. We have performed an ab initio calculation on the basis of the first Born approximation using correlated wave functions for the target. The agreement with the first available (e, 3 e) experimental data is fairly good. Other typical experimental situations are proposed and discussed.
We report on (e, 2e) experiments for excitation-ionization of
helium
made in asymmetric geometry at intermediate incident energy and low
momentum transfer. The results are compared with Born 1 calculations. Some
degree of agreement is obtained and seems to be improved by correction for
post-collision interactions. But it cannot be expected that such simple models
will correctly reproduce processes that depend so strongly on correlations.
a b s t r a c tThe Canonical Function Method (CFM) is a powerful method that solves the radial Schrödinger equation for the eigenvalues directly, without having to evaluate the eigenfunctions. It is applied to various quantum mechanical problems in Atomic and Molecular physics in the presence of regular or singular potentials. It has also been developed to handle single and multiple channel scattering problems, where phaseshift is required for the evaluation of the scattering cross-section. Its controllable accuracy makes it a valuable tool for the evaluation of vibrational levels of cold molecules, a sensitive test of the Bohr correspondence principle and a powerful method for tackling local and non-local spin dependent problems.
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