Calculations of generalized oscillator strength for electron-impact excitations of krypton and xenon using a relativistic local-density potential.

Abstract

The generalized oscillator strength (GOS) of an atom is an essential factor in the differential cross section for inelastic scattering of fast charged particles. Recently, Takayanagi et al. [Phys. Rev. A 41, 5948 (1990)] have obtained the GOS for the excitation of atomic krypton to the 4${\mathit{p}}^{5}$${(}^{2}$${\mathit{P}}_{1/2}$)5s and 4${\mathit{p}}^{5}$${(}^{2}$${\mathit{P}}_{3/2}$)5s states from inelastic-scattering measurements using electron-energy-loss spectroscopy. The present study was undertaken with the twofold objective to determine the results of theoretical computations of the scattering parameters of the above experiment and to examine the suitability of a recently developed relativistic local-density-potential method [M. Vijayakumar, N. Vaidehi, and M. S. Gopinathan, Phys. Rev. A 40, 6834 (1989)] to study atomic-collision processes. Calculations have been done to obtain GOS for electron-krypton and electron-xenon collisions in the squared-momentum-transfer range of 0.01 to 10 atomic units. The well-known theory of Bethe has been used for the determination of the GOS in the first-order Born approximation. The present results are in fair agreement with previous Hartree-Slater and Hartree-Fock calculations and with the experimental data available in the literature. Furthermore, results of the present calculations predict that the GOS goes through a minimum, similar to the ``Cooper minimum'' in the photoabsorption cross section, as a function of the value of the momentum transfer. Experiments at slightly higher values of momentum transfer are suggested to verify the position of this minimum.