Secondary Ion Mass Spectrometry Methodology for Nanoparticles

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With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Schweikert at Texas A&M University and his group will develop an innovative methodology for the analysis of individual nanoparticles, NPs. The uniqueness of NPs, due to their functionalities not present in bulk size, is well documented. A nuanced understanding of their functionalities depends on their accurate characterization. Generally the analysis is done on a large number (ensemble) of NPs. However, there is likely some variation in the NP population and ensemble averaging can limit insight into the relationships between size, composition and chemical reactivity of NPs. This is especially the case for very small NPs, where minor changes in size, shape, and composition can significantly affect chemical reactivity. The research involves custom-built instrumentation and will focus on probing very small NPs ( 50 nanometers) one by one. Briefly, a NP is bombarded with an individual cluster of 400 gold atoms. The impact of such a "nanoprojectile" at hypervelocity (30 km/s) generates abundant ion emission from an area of ~10 nanometer in diameter. The ejecta from each impact are mass-analyzed and recorded individually. NPs representative of current nanomaterials research will come from laboratories in the US, UK, France and Australia. The new tools for investigating NPs will facilitate the development of efficacious and safe nano-scale materials.