Electron emission in asymmetric collisions with fast heavy projectiles via continuum charge transfer

Abstract. The ejection of electrons from light target atoms by bare heavy projectiles is described by means of electron capture to the continuum. Calculations of the energy distribution of the electrons are performed within the semiclassical impulse approximation and compared with other theories. As special cases, collisions of Kr with H and Ar with He are considered. Experimental data of the electron spectrum in the forward peak region in (Ar, He) collisions can be well explained. 1

Strong potential second Born theory for electron loss to the continuum in collision with heavy targets

Abstract. A second-order Born themy is formulaled for the description of forward electron emission from a light projectile in energetic collision with a heavy target atom. This theory is termed 'strong potential second Born theory ' $82) because it accounts for electron propagation in the strong tuget potential It is evaluated for the singly inelastic contribution to electron loss, while the first Born approximation is used for the simultaneous projectile-target exciwtion. From the SBZ theory, the 'impulse approximation ' of Hartley and Walters is derived. By comparison with experimental data for the Het t Ar system it is shown that both theories account well for the electron intensity, while the asymmetry of the forward peak is only correctly given by SB~. For larger emission angles. consideration of the target potential in the electronic final state is of increasing importuce. Then the SB? becomes inferior to the eleclron impact approximation. 1

A systematic study of relativistic (e, 2e) collisions in comparison with experiment

Abstract. Triply-differential cross sections for K-shell ionization by fast electron impact are calculated within the first-order Coulomb Born approximation for the case of a coplanar symmetric geometry. Comparison is made with experimental data on 300 keV and 500 keV eC+Cu, Agand Au. Far the two lightertargetr, the binarypeakregion is reasonably well described by a theory which uses semirelativistic electronic eigenfunctions to the target field, provided spin-flip is included. For the gold target, the Coulomb Born approximation seriously overestimates the data, pointing to the necessity of a fully relativistic description of the electronic states. Triply-differential cross sections for inner-shell ionization in electron-atom collisions provide a sensitive test for theoretical models since a coincident detection of the two momentum-analysed outgoing electrons allows for a complete determination of the collision kinematics (McCarthy and Weigold 1976, Ehrhardt ef a / 1986, Lahmam-Bennani 1991). For fast collisions where a first-order treatment of the electron-electron interaction should be appropriate and polarization effects may be neglected, the basic information to be extracted from (e, 2e) cross sections concerns thus the particulars of the electronic wavefunctions. For low-energy electron scattering it has become standard to use a Hartree-Fock-type function for the bound target electron, and numerically generated scattering states multiple partial wave expansion required for the evaluation of the cross section becomes, however, prohibitive at high projectile energies, and such elaborate wavefunc-tions have up to now only been employed for energies of 150 keV and below (F'indzol