Optical Near-field Electron Microscopy

The project will establish a new hybrid imaging technique, Optical Near-field Electron Microscopy (ONEM), that harnesses the best of two worlds: firstly, the non-invasiveness of probing a sample with light, and secondly, the high spatial and temporal resolution offered by electron optical read-out. Interactions and dynamics at interfaces are crucial throughout science and technology, be it in material science, in battery research, or in membrane biology. Imaging these interactions with nanometre spatial resolution and millisecond time resolution, without labelling, without damaging the specimen, and without limitations in observation time is a huge challenge. ONEM is based on the photoelectric effect: visible light illuminates a sample within a liquid cell, and the resulting near-field interference pattern is converted into an electron flux within a nearby photocathode. The spatial variations in electron flux are imaged using aberration corrected electron optics within a low energy electron microscope. We will build the first ONEM prototype, and use it for studies on electro-plating, and on protein oligomerization in in artificial lipid membranes. These experiments will show that ONEM enables label- and damage-free imaging at 3 nm resolution and high frame rates (up to kHz), over extended periods. They will open the door to investigations of a wide range of electrochemical phenomena (corrosion, mass transport in batteries, liquid crystal switching), and to studies of membrane biology (pore formation, oligomerization, protein diffusion,...), that are out of reach for current imaging technology. The project will be conducted in close collaboration with user facilities and industry partners, in order to facilitate rapid commercialization of this disruptive new technology.