Prof. Amit Kohn (TAU)
Department of Materials Science and Engineering, Tel Aviv University
Off-axis electron holography (OAEH) is a method applied in transmission electron microscopy (TEM) in order to reconstruct the phase of an electron wave after it has traversed through a thin sample. When applied at nanometer scale spatial resolution, the reconstructed phase enables to extract both electrostatic and magnetic fields.
For this talk, I will focus on the measurement of electrostatic potentials as a tool to characterize bonding and charge redistribution in crystals. I will describe the experiment and data analysis followed by examples from current research on measuring the mean-inner-potential in sapphire and graphite, and charged-defect distributions in nanoscale MgO×Al2O3 spinel. The latter example also demonstrates the ability in the TEM to complement OAEH measurements with additional characterization of the same crystals, in this case electron energy-loss spectroscopy for detecting the distribution of anti-site charged point defects.