High resolution scanning ion probes

High resolution (< 100 A) ion probes are shown to be feasible using either hydrogen ions from field ionization or heavy ions from an electro-hydrodynamic ion source. Low energy (approx. 25 keV) hydrogen ions are compared with electrons for use in microscopy, and the two are shown to entail similar amounts of radiation damage for thin (approx. 1 μg/cm2) light targets. The use of heavy ion beams in microanalysis is discussed, and the limitations on the spatial resolution are shown ro be inherent in the method, rather than due to instrumental resolution. Recent investigations made with the University of Chicago scanning transmission ion microscope of the interaction of molecular ions (H2+) with thin foils of carbon and polyethylene are discussed. (orig.)