RESEARCH PROFILE: Molecular analysis of nanoscale objects with MS

摘要

Despite the dearth of material in a nanoscale object, a new secondary ion MS (SIMS) technique can extract the detailed molecular information that's required for chemical analysis of such tiny particles. Previous methods have been decidedly limited: lasers have been used to extract elemental information, but retrieving molecular information from nanoscale objects has been an elusive goal. In a recent AC paper (DOI 10.1021/ac9014337), Emile Schweikert and colleagues at Texas A&M University and Argonide Corp. reported the success of an important test case: the molecular-level SIMS analysis of a mixture of two distinct nanoscale objects--alumina "whiskers" 2 nm wide that were "decorated" with polystyrene spheres 30 nm in diameter. In SIMS, a primary ion is used to study surface structure. The ion is fired in a high-flux beam at the surface, ane emerging secondary ions are then analyzed by MS. Mapping by MS is precise with SIMS techniques, which can now address surfaces below the micrometer level on an xy-axis, but the fineness doesn't cover the lower range of the nanoscale. The Schweikert team's approach does not, in fact, produce a map with nanometer resolution, but it does provide molecular data about nanoscale objects within the larger field of view--a molecular summary of the nanometer-level terrain probed in the instrument's field of view.