Distorted-wave Born approximation (DWBA) calculations are reported for inner shell ionization of Ar(2p), Ar(2s) and Ne(1s) in the energy range 2-3 keV. Comparison is made with experimental data of Bickert et al. Agreement between DWBA and experiment is very good and much better than in previous comparisons with first Born type theories. The results show the importance of taking proper account of the strong static potential of a 'heavy' atom, particularly in inner shell ionization where the ionization process takes place in a region in which the static potential is at its strongest. Some interesting structures outside the angular range of the experimental data are revealed, these would be worthy of further experimental investigation. The electron momentdensity of the 2s orbital is measured for the first time and found to be in good agreement with the Hartree-Fock calculations of Clementi and Roetti (1974).
The K-ionization cross section of Alumininm by electron impact was measured detecting quantitatively the A1-K X-rays emitted by thin targets of known mass thickness. The apparatus and the measurements are briefly described. The experimental results are considerably higher than the values of the theories using the Born approximation. The discrepancy increases with increasing energy of the incoming electron. At twenty-fold threshold energy for example, the measurements are higher than B~HoP'S 1 calculations by a factor of 1.7. It is shown that considering the process of K-ionization the influence of the nuclear field on the impact electron increases with decreasing atomic number. Thus, the calculations of R~GE and SCHWARTZ 2 using coulomb wave functions for the impact electron, are closest to the measurements (maximum deviation 16%). The formula of GRYZINSKI 3 based on classical calculations is a good approximation to the experimental results if multiplied by a factor 1.23.
Angular correlation measurements of the two final electrons following primary ionization of the Ar(2p) orbital are performed at 2 keV and 3 keV in a wide range of momentum transfer revealing a strong dependence of structural parameters on the kinematical conditions. Characteristic features are a dominant recoil structure at small momentum transfer, a breaking of symmetry around the direction of momentum transfer and a deviation of the recoil peak maximum from the axis of momentum transfer towards smaller deflection angles. The electron momentum density of the Ar(2p) orbital was extracted out of experimental data for the first time. Within experimental errors good agreement was found with results of Hartree-Fock calculations. Extension of the technique of electron momentum spectroscopy performed in slightly asymmetric coplanar kinematics to study electronic structure has been achieved.
Abstract. The absolute K-ionization cross sections of Ti and Ni by electron impact (impact energy__< 50 keV) was measured detecting the X-rays emitted by thin solid film targets of known mass thickness with a flow proportional counter. The experimental method, especially the correction procedures and the measurements are described, the results compared with calculations in different theoretical approaches. For impact energies above
Eo/EK>I.5 (EK=K-shell ionization energy) a systematic deviation of about +20%occurs in comparison with the best agreeing calculations of M.R.H. Rudge and S.B. Schwartz. A fit to Drawin's empirical formula reveals that the measurements are approximated better than _+ 10 % within the range of comparison.
ained numerically by Takeo" appear to belong to a very general type of effect, namely, the interference resulting from the existence of several paths, in this case two, connecting initial and final states.This "two path interference, " the archetype of which is met in the diffraction of particles (or waves) through two slits, is also responsible for the nodal structure of the wave function, as seen in Sec. II, and for interference fringes in the differential scattering cross section. What is perhaps particular to the case of the spectrum is that the different paths are distinguished by a temporal parameter rather than by a spatial one as is more common, and one might speak of a "two slits in time" interference effect, as is suggested by the pictorial representation of Fig. 2. ACKNOWLEDGMENTS
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