MFD Spring Seminars- Distinguished Lecture Series

Speaker: David Muller , Cornell University

Talk Title: A new way to image atoms

Abstract: Electron microscopes use electrons with wavelengths of a few picometers and are potentially capable of imaging individual atoms in solids at a resolution ultimately set by the intrinsic size of an atom. Until very recently, the best resolution was more than an order magnitude worse than this. This was caused by two things – first the intrinsic aberrations in electron lenses are much worse than for optical lenses – it would be like trying to use a beer bottle as a magnifying glass. Second, electrons are multiply scattered inside the sample – a process described by Hans Bethe over 90 years ago. It’s been a headache for electron microscopists ever since, but with our recent advances in detector technology and ptychographic reconstruction algorithms, the resolution of the electron microscope is now limited only by the dose to the sample, and thermal vibrations of the atoms themselves [1]. These approaches have also allowed us to image the internal structures of both magnetic and ferroelectric vortices, skyrmions and merons, including their singular points that are critical for accurately describing the topological properties of these field textures. The reduced sensitivity to chromatic aberrations also makes these ptychographic approaches of interest for thick biological samples such as 3D reconstructions of whole cells.

Host: Mork Family Department

Location: James H. Zumberge Hall Of Science (ZHS) - 252

Audiences: Everyone Is Invited

Contact: Monique Garcia