“Secondary Ion Mass Spectrometry With Massive Projectiles”
Dr. Emile A. Schweikert, Texas A&M University
The performance of secondary ion mass spectrometry (SIMS) for molecular analysis has been notably enhanced with the introduction of clusters as projectiles, e.g., Bi52+, C601-3+. Yet their application for imaging mass spectrometry remains constrained by the small number of analyte-specific ions that are obtained per µm pixel. We describe current work aiming to advance the accurate identification and localization of a small number of surface molecules. In our approach a surface is bombarded with a massive projectile, specifically Au4004+. Its increased impact momentum in comparison to small polyatomic clusters or C60 results in enhanced secondary ion emission. Further, the surface is probed in an unusual event-by-event bombardment-localization-detection mode where an individual Au4004+ impact is localized in real-time and recorded with the secondary ions emitted in that event. The combination of the secondary ions and the location from which they originate results in mass-selected surface maps. The current capabilities of shot-by-shot massive cluster-SIMS are illustrated with the characterization of nano-objects and examples of mass-selected surface maps.
Emile A. Schweikert is a professor of chemistry and former head of the chemistry department at Texas A&M. His research group explores the extreme limits of analytical chemistry: the characterization of atto to zeptomole quantities of molecules. The aim is to detect such amounts of analyte within nanometric surface volumes. The goal is chemical imaging of surfaces with exquisite spatial resolution.