Abstract
The emission of negative secondary ions from 23 elements was studied for 10 keV O + 2 and 10 keV In + impact at an angle of incidence of 45°. Partial oxidation of the sample surfaces was achieved by oxygen bombardment and/or by working at a high oxygen partial pressure. It was found that the emission of oxide ions shows an element-characteristic pattern. For the majority of the elements investigated these features are largely invariant against changes of the surface concentration of oxygen. For the others (apparently those with a high reactivity) admission of oxygen (in addition to O + 2 bombardment) strongly changes the relative intensities of oxide ions: a strong increase of MO 3 − signals (M stands for the respective element) is accompanied by a decrease of MO − and M − intensities. Different primary species (In + instead of O + 2) frequently induce changes of both the relative and the absolute negative ion intensities. Carbon — in contrast to all other elements — does not show any detectable oxide ion emission but rather intense cluster ions C n − (detected up to n = 12) whose intensities oscillate in dependence on n.
Published Version
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