The energy spectra of sputtered ions

The energy spectrum of Cu+ ions sputtered from Cu single crystals has been studied using a retarding potential energy selector method which incorporates a quadrupole mass filter as detector. The behaviour of the energy spectrum of Cu+ in the region of the 〈110〉, 〈100〉 focused ejection spots has been studied in detail and the results compared with those of M. W. Thompson1) who measured the energy spectrum of neutral Cu atoms sputtered along these directions. The Cu+ energy spectra show evidence for the existence of focusing mechanisms and the focusing energies of (55±2) eV and (150 + 10) eV, respectively, agree well with Thompson's results for the neutrals.