Characterization of nanometric inclusions via nanoprojectile impacts

Analysis of ultrasmall dendrimer encapsulated gold nanoparticles utilizing a 520 keV Au₄₀₀⁴⁺ projectile probe is presented. Cores of 55, 147, and 225 Au atoms encapsulated in poly(amido amine) dendrimer were investigated. An innovative methodology of event-by-event bombardment-detection was utilized. The comparison of mass spectra of these samples shows that the secondary ion yield of Au moieties varies linearly with the number of Au atoms. Further, the agglomerates locate preferentially between two branches of the dendrimer structure. This observation demonstrates the ability of our secondary ion mass spectrometry methodology to probe chemical environments around nanoscale inclusions.