Simultaneous measurement of the average ion-induced electron emission yield and the mean charge for isotachic ions in carbon foils

Knowledge of the incident ion's atomic dumber (Z(1)) dependence of ion-induced electron emission yields can be the basis for a general understanding of ion-atom interaction phenomena and, in particular, for the design of Z(1)-sensitive detectors that could be useful, for example, in the separation of isobars in accelerator mass spectrometry. The Z(1) dependence of ion-induced electron emission yields, gamma, has been investigated using heavy ions C3+, O3+, F+3, Na3+, Al3+, Si3+, P3+, S3+, Cl3+ K3+, Ti3+, Cr3+, Mn4+, Fe4+, Co4+, Ni4+, Cu4+, Ga4+, As5+, Br5+, Ru7+, Ag7+, Sn7+, and I8+ of identical velocity (v = 2v(0), where v(0) is the Bohr velocity) normally incident on 50 mu g/cm(2) sputter-cleaned carbon foils. Measured yields as a function of Z(1) reveal an oscillatory behavior with pronounced maxima and minima. Contrary to previously reported yields that assumed a monotonically increasing empirical mean charge state for the exiting ion, the present work indicates the Z(1) oscillations in the experimentally measured yields, a fact masked in previous work. The strong Z(1) oscillations can only be observed by simultaneous measurement of the yield and the mean charge state.