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Dependence of Secondary Electron Emission Coefficients on z 1 in Metal Targets under Bombardment with Bare Projectiles

1982; Institute of Physics; Volume: 21; Issue: 8R Linguagem: Inglês

10.1143/jjap.21.1216

1347-4065

Akio Kôyama, T. Shikata, Hideo Sakairi, Eiichi Yagi,

Nuclear Physics and Applications

The secondary electron emission coefficients are measured in targets under bombardment with He 2+ , C 6+ , N 7+ and O 8+ ions at an energy of 6.2 MeV/amu, the backward secondary electron emission coefficients γ back being measured for thick Al and Ag targets, and the backward and forward coefficients γ back and γ for for an Au foil target. γ back / z 2 1 decreases with z 1 in proportion to 1–0.005 z 2 1 . With the effective charge z * 1 , γ for / z *2 1 shows a similar decrease with z 1 . These decreases are caused by the decrease in the escape probability of secondary electrons from the surface with increasing z 1 , that is, increasing specific electronic energy loss S . This result implies that the surface barrier height U depends on S . A mechanism for the ion-induced increase in U is proposed, and the difference between the way γ back and S depend on the energy for N 7+ ions is explained by considering this dependence of U on S .