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Spectroscopy

Electron beams are not only tools for imaging the micro-, nano-, and atomic-scale structure of materials but also offer a fundamental spectroscopic probe for chemical analysis. Combined with the imaging capabilities of the transmission electron microscope (TEM), spectroscopic measurements can be performed at high spatial resolution for compositional analysis, characterization of bonding and electronic structure, and measurement of physical and chemical properties at the nanoscale.


In the Electron Microscopy Group, our research focuses on electron energy loss spectroscopy (EELS) and x-ray energy dispersive spectroscopy (EDS) conducted in the scanning transmission electron microscope (STEM). In EELS, this research includes the study of low-energy excitations (0 – 10 eV) at infrared, visible, and ultraviolet energies, for example for the study of the optical properties of plasmonic gold and silver nanoparticles. These projects make use of the advanced monochromated EELS capabilities of the Titan STEM in the Wolfson Electron Microscopy Suite as well as simultaneous development and application of spectral data-processing techniques (e.g. multivariate statistical analysis, model fitting, spectral tomography).


EELS at higher energies (50 – 2000 eV) and EDS (1 – 20 keV) represent complementary research areas in the group. Combined with tomographic approaches, our research aims to apply three-dimensional analysis with simultaneous recovery of detailed chemical phase information (e.g. quantitative composition analysis, spatially mapping changes in electronic structure and bonding) for materials from meteorites to catalysts.