Secondary Ion Mass Spectrometry with Massive Projectiles

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Drs. Emile Schweikert, Stanislav Verkhoturov, and Richard Rickman of Texas A&M University are supported by the Analytical and Surface Chemistry Program with co-funding from the Office of International Science and Engineering to investigate the nature of the molecules and molecular fragments that are ejected when a surface is bombarded with energetic massive clusters. The latter are composed of hundreds of atoms of gold or bismuth and are accelerated prior to impact to hypersonic velocities. The purpose of the project is to identify the ionized ejecta from single massive projectile impacts and relate the observation to the nature and abundance of the chemical species originally present in the nanometric size volume perturbed by a projectile. This work combines the localization of a single projectile shot via electron emission microscopy, with the detection of the concurrent ionized emission via mass spectrometry. The data from a sequence of such impact emission events can be displayed as a chemical map showing the distribution of molecules with an anticipated sub-100nm lateral resolution. The development of mass spectrometry with extremely high spatial resolution will enhance "chemical vision" at a level where current capabilities are limited. Technology for chemical mapping with the sub-100nm resolution is critical for characterizing nanoparticles and mapping biological structures such as single cells. Members of the research team are thus exposed to a wide-range of interdisciplinary science.