Influence of plasmon-assisted charge exchange processes on ion-induced electron emission from metals

Abstract

Charge changing processes (electron capture and loss) of light ions moving inside metals contribute significantly to the electron emission at intermediate and low impact velocities. An improved method for the description of screening of the moving ion in the electron gas developed by Nagy et al. [Nucl. Instrum. Methods 1996;B115:58.] and Lifshitz et al. [Phys. Rev. A 1998;57:200] will be used to determine the velocity-dependent bound-state wave functions and binding energies related to the moving projectile. These wave functions and binding energies are the basic ingredients for the calculation of the electron capture and loss rates, which determine the equilibrium charge state fractions of the different projectile species, as well as for the calculation of the electron excitation during the charge transfer processes. Explicit calculations were performed for Mg. We compare the contribution of electron emission by decay of plasmons generated during the charge transfer processes with that of plasmon excitation by fast secondary electrons generated by binary ion–electron collisions. The total plasmon-mediated electron yield, obtained by summing the contributions of different mechanisms of each projectile species, weighted with the respective charge state fraction, will be compared with available experimental data.