Empirical corrections to the energy loss of ⁴He ions in oxides

A survey of the experimental energy loss of 4He ions shows systematic differences between elemental solids and gases. The solid-gas differences are proposed as an empirical first-order correction to obtain solid-target values from gas-target stopping cross sections. These corrections are of the order of 20% for 4He ions of 1 MeV. A series of experiments on the energy loss of 4He ions in oxygen and nitrogen in solid oxides and nitrides are in agreement with the empirical correction factor proposed.