Webinar: In Situ Electron Energy Loss Spectroscopy for Nanoscale Characterization of Materials Dynamics
The use of electron energy-loss spectroscopy (EELS) for determining changes in nanoscale composition and electronic structure of materials during in situ experiments in the transmission electron microscope is discussed. In situ electron microscopy allow samples to be exposed to a range of stimuli including heat, cold, light, electric fields, magnetic fields, gases, and liquids. These stimuli trigger phase transformations and allow the structure and composition of materials to be studied under conditions closer to their working state in technological applications. In situ observation of the material can reveal critical information about reaction pathways and transient intermediates that may not be observable from other methods. The evolution of the composition and bonding can be detected and quantified using EELS with a spatial resolution down to 0.1 nm when combined with the sub-nanometer electron probes associated with scanning transmission electron microscopy (STEM). This webinar will illustrate the application of core-loss and low-loss EELS for in situ materials characterization. Observations of in situ reductions, vacancy ordering, and gas-solid interactions can all be characterized with in situ STEM EELS. Aloof beam EELS approaches can be useful for probing near surface regions especially for systems susceptible to electron beam damage. For experiments in gases and liquids, EELS can also be used to probe compositional changes in the surrounding gas or liquid phase. This has been exploited to perform so-called operando approaches to catalyst characterization or electrolyte changes in electrochemistry. Recent developments in vibrational EELS are opening new doors for in situ characterization and is an area that is likely to grow as advanced monochromators become more widely available.
Peter A. Crozier, Ph.D., Professor, Arizona State University