Nanodomain analysis via coincidence ion mass spectrometry
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We report an example of elemental and chemical mass analysis on surface nanostructures by using the coincidence ion mass spectrometry (CIMS) technique. In the CIMS technique, the event-by-event operation mode of bombardment and coincidental detection of secondary ions are used for selection of secondary ions emitted from a different nanoscale spots on the surface. The nanostructures investigated were silver nanoparticles on aluminum silicate zeolite substrates. The ability of CIMS to characterize solely the 30nm particles, can to date not be duplicated with other techniques. Our approach should be applicable to mass analysis of periodic domains. Coincidental SI detection is based on the condition of coemission from an individual projectile impact. The latter defines the emission volume and ensures thus the accuracy of the nanophase analysis. To estimate the accuracy of our experiment, we assess the contribution of interfacial impacts, i.e. events where ion from the substrate is coemitted with ion from the nanoparticles due to finite size of emission volume (5nm). The magnitude of the interfacial contribution is evaluated with an "interference coefficient" k. Using a simple model of interference, we calculate k for our experimental conditions. 2004 Elsevier B.V. All rights reserved.