Angular dispersion of protons transmitted through thin gold films

Abstract

The angular distributions of protons travelling through thin polycrystalline gold targets (~15 nm) with incident energies in the range of 4-10 keV have been measured. The results confirm previous experiments at higher energies showing deviations from theoretical predictions based on the standard multiple scattering theory. In order to prove that the effect of crystal structure is one of the main causes of these deviations we have performed numerical simulations. To simulate the polycrystalline structure in a realistic way, we have made an analysis of the target by means of transmission electron microscopy (TEM) techniques. Including these characteristics in the simulation, together with the effect of vibrations and crystal disorder we analyzed the corresponding angular distribution. To evaluate the role of channeling, we also measured angular distributions of protons in a 〈100〉 gold foil and made the corresponding numerical simulations. The results show the critical influence of the target structure in the angular spectra of transmitted ions.

Multiple-scattering distributions and angular dependence of the energy loss of slow protons in copper and silver

“…Since the early 2000s several studies of the angular distributions and of the angular dependence of the energy loss of low-energy light ions have been published [7][8][9][10]. For polycrystalline samples, a simple model to evaluate the angular dependence of the energy loss of low-energy protons was proposed and successfully compared with experimental data of 9-keV protons transmitted through thin aluminium and gold films [7].…”

Surface roughness of thin gold films and its effects on the proton energy loss straggling

“…At the present time there is a great interest to carry out stopping power cross section measurements of light ions at low energies in metallic targets using a transmission geometry [1]. For this purpose it is necessary to provide self supported thin films with a precise thickness and a known surface roughness.…”

Multiple scattering of low energy ions in matter: Influence of energy loss and interaction potential

“…A complete review with typical applications of this theory is presented by Amsel et al [11]. Many studies in the low-energy regime containing theoretical and experimental angular distributions have been published [12][13][14][15][16][17][18].…”