Direct visualization of nanoscale electrostatic potentials

Off-axis electron holography combined with in situ electrical biasing inside a transmission electron microscope (TEM) provides a direct imaging of electrostatic potential distributions around TEM samples. The left image is an electron hologram taken with two tungsten probes, held with 0 (upper) and 2 V (lower), respectively. The reconstructed phase map on the right reveals electric potential distributions (as a false-color map) around the two probes.