Stopping Power of Some Pure Metals for 25-250-keV Hydrogen Ions

Electronic stopping powers for a hydrogen beam at energies between 25 and 250 keV are measured in the metals Ni, Cu, Ag, Sn, and Au using the straightforward technique of measuring the energy loss of a beam traversing a thin target foil. The metal foils, fabricated specifically for this purpose, are self-supported and thin enough to ensure an energy loss of 10% or less for a 25-keV proton beam. The measured stopping powers are given relative to accepted published values at 250 keV. The results are compared to those of other authors, primarily at the lowenergy end of the present measurements where a comparison with the theory of Lindhard and Scharff is also possible. Available information about stopping powers of hydrogen beams in other elements together with the present results are represented as a function of $z_2$, the atomic number of the target material. A periodic structure in this diagram is observed which can be related to the filling of electronic shells in the target atoms.