Critical analysis of the charge-state dependence of the energy loss of channeled ions

A critical analysis of channeled-ion energy-loss experiments is presented with the goal of commenting on the presence of the Barkas effect of $Z_1^3$ corrections to the stopping power. Accurate charge-density values are obtained for silicon and used to evaluate Bloch and straggling effects in the data. The remaining contributions to the data show a clear $Z_1^3$ dependence that can be explained with an electron-gas model for the Barkas effect.