Paper AS2-ThM11
Chemical Speciation of Engineered Nanoparticle Surface Chemistry with Secondary Ion Mass Spectrometry

Thursday, October 21, 2010, 11:20 am, Room Cochiti A

As the sizes of nanostructures decrease, the surface-to-volume ratios increase immensely such that the smallest nanoparticles are theoretically seen by their surroundings as only the chemistry exposed on the surface and not the bulk of the nanoparticle interiors. We believe that the ability to track the surface chemistry of nanoparticles vs. size and vs. environmental exposures will show dramatically altered surface chemistry, and thus altered chemical reactivity of the nanoparticles. This concept has widely been suspected and/or believed to be true within the nanoparticle field, but experimentalists have yet to devise a standard approach at measuring what the surface chemistry is and to what extent that surface chemistry can be altered in real-world conditions. Since we are interested only in the surfaces of the nanoparticles and not necessarily the bulk, we have worked to develop a new paradigm for monitoring the surface chemistry of engineered nanoparticles with secondary ion mass spectrometry (SIMS). When kept in a static mode analysis, SIMS can be highly surface-sensitive to just a few nm, where other commonly employed techniques for measuring nanoparticle chemistries either cannot separate bulk vs. surface information, or only arrive at surface information indirectly. We will present progress made towards reaching our aims, including nanoparticle preparation considerations, sensitivity of SIMS to monitoring changes in the nanoparticle surfaces, and projections into the future of this methodology for such a purpose.