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ToF‐SIMS depth profiling of vitamin C layers using Cs+ and Xe+ ion beams

Cesium (Cs+) and xenon (Xe+) sputter beams of energy ranging from 150 to 1000 eV were used to depth profile a 70 nm vitamin C layer spin‐coated on silicon wafer. We have shown that under Xe+ beam we were able to maintain the molecular information throughout the profile. In particular, the intensity of the deprotonated molecular ion (C6H7O6)− in the steady‐state regime was the highest compared to other characteristic fragments. When Cs+ is used instead of Xe+, the molecular signals decrease as the Cs+ fluence increases so that no steady state is reached whatever the cesium beam energy. However, the fingerprint, i.e. molecular and fragment ions assigned to the ascorbic acid molecule, could be maintained at 500 eV. The reason for such observations could be related to the reactivity of the cesium implanted in the organic layer. The dependence of the sputtering yield with the beam energy was found to be linear for both Cs+ and Xe+ beams. Copyright © 2010 John Wiley & Sons, Ltd.