Electronic Stopping Cross Sections forH1andHe4Particles in Cr, Mn, Co, Ni, and Cu at Energies near 100 keV

Electronic stopping cross sections have been measured for 30- to 140-keV ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ and 50- to 120-keV ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ particles in Cr, Mn, Fe, Co, Ni, and Cu ($24\le Z_2\le 29$). In this $Z_2$ region the cross sections at a given energy show a steady decrease with increasing $Z_2$, thus confirming and extending earlier observations by others. The combined data show a dependence on $Z_2$ which is markedly similar to the periodic dependence of electronic stopping cross sections on the $Z$ of the projectile. The measurements were made utilizing high-resolution solid-state-detector spectra of the particles backscattered from thin films of the target materials evaporated on thick substrates. The probable error of the stopping-cross-section measurements is 3%.