Abstract

The variation of the energy loss versus the exit angle in channeling experiments using H+, He+, and H+ fragments produced by the incidence of H-2(+) on thin gold crystals oriented in the 100 > direction has been investigated in the low-velocity range, corresponding to energies below 10 keV/u. The experimental results for H+ and He+ were compared with computational simulations performed with the MARLOWE code, considering an impact-parameter-dependent energy loss based on electron density calculations and low-energy stopping power models. The comparisons provide information on the impact-parameter dependence of the energy loss for channeled ions and serve as a test of theoretical models in the present low-energy range. A molecular effect is observed for the transmitted H+ fragments corresponding to H-2(+) incidence. This effect is explained based on geometrical considerations and a vicinage effect in the energy loss of correlated protons.