Electronic stopping of protons at intermediate velocities

Abstract

At intermediate velocities, near the stopping power maximum, most theories fail in the description of electronic energy transfer mechanisms. Only theories which go beyond perturbation theory are applicable in this velocity regime. A single-center coupled-channel code which includes dynamic curved projectile trajectories and which is based on an expansion of the time-dependent electronic wave function in terms of atomic wave functions is applied to the calculation of stopping powers. These time-consuming calculations may serve as a benchmark test for other models and allow for an accurate determination of the importance of different processes leading to the energy loss of ions in gases or insulators. Improved stopping, ionization and total reaction cross sections are computed for protons penetrating atomic H target at energies of 10 to 500 keV/u. The results are compared to experimental data and to the predictions of the first-order plane-wave Born approximation.