title: Trace elemental analysis at nanometer spatial resolution by parallel-detection electron energy loss spectroscopy.
abstract: Parallel-detection electron energy loss spectroscopy (EELS) combined with scanning transmission electron microscopy (STEM) and a field emission source provides an unprecedented sensitivity for elemental microanalysis. By deflecting the energy loss spectrum across a parallel detector and computing the difference spectrum from sequentially collected energy-shifted spectra, the effects due to detector pattern noise are nearly eliminated so that signals less than 0.1% of the background can be readily detected. Measurements on a series of glass standard reference materials show that EELS provides both high spatial resolution and trace sensitivity at the 10 atomic ppm level for a wide range of elements including the alkaline earths, 3-d transition metals, and the lanthanides. For analytical volumes with dimensions of the order of 10 nm, this translates into near-single atom detectability.
authors.affiliation: Biomedical Engineering and Instrumentation Program, NCRR, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: R D
authors.initials: RD
authors.lastname: Leapman
authors.forename: D E
authors.initials: DE
authors.lastname: Newbury
mesh_terms: D004583:Electrons; D013057:Spectrum Analysis; D014131:Trace Elements / Q000032:analysis*
chemical_list: D014131:Trace Elements