Theme 3 colloquium: "Developments in Ultrafast Electron Imaging and Spectroscopy" (Lecture)
- Tuesday 15 May 2018Add to my calendar
- from 16:00
Prof. Claus Ropers (Georg August Universität Gottingen, Germany)
Novel methods in time-resolved electron microscopy, diffraction and spectroscopy promise unprecedented insight into the dynamics of structural, electronic and magnetic processes on the nanoscale. A key to the realization of such technologies is the generation of high-quality beams of ultrashort electron pulses. In this talk, our recent development of imaging and spectroscopy using localized electron emitters will be discussed. Specifically, two approaches employing high-coherence electron pulses from nanotips will be presented, namely Ultrafast Low-Energy Electron Diffraction (ULEED) and Ultrafast Transmission Electron Microscopy (UTEM). ULEED allows for the study of structural dynamics with high temporal resolution and ultimate surface sensitivity [1-2], while UTEM combines femtosecond [3-6] and even attosecond  resolution with the imaging and spectroscopy capabilities of an electron microscope.
Figure: Two complementary approaches to the study of ultrafast dynamics in solids, at surfaces and nanostructures: Ultrafast Low-energy electron diffraction (ULEED, left) probes structural dynamics at surfaces with electron pulses at kinetic energies of 20-200 eV. Ultrafast transmission electron microscopy (UTEM, right) allows for ultrafast imaging, diffraction and spectroscopy of thin films and nanostructures using high-energy electron pulses (100-200 keV).
 M. Gulde et al., "Ultrafast low-energy electron diffraction in transmission resolves polymer/graphene superstructure dynamics", Science 345, 200 (2014).
 S. Vogelgesang et al., "Phase ordering of charge density waves traced by ultrafast low-energy electron diffraction", Nat. Phys. 14, 184–190 (2018).
 A. Feist et al., “Ultrafast transmission electron microscopy using a laser-driven field emitter: Femtosecond resolution with a high coherence electron beam”, Ultramicroscopy 176, 63 (2017).
 A. Feist et al., “Nanoscale diffractive probing of strain dynamics in ultrafast transmission electron microscopy”, Struct. Dyn. 5, 014302 (2018).
 A. Feist, K. E. Echternkamp, J. Schauss, S. V. Yalunin, S. Schäfer, and C. Ropers, “Quantum coherent optical phase modulation in an ultrafast transmission electron microscope”, Nature 521, 200 (2015).
 K. E. Echternkamp, A. Feist, S. Schäfer, and C. Ropers, “Ramsey-type phase control of free electron beams”, Nature Phys. 12, 1000 (2016).
 K. E. Priebe, C. Rathje, S. V. Yalunin, T. Hohage, A. Feist, S. Schäfer, and C. Ropers, “Attosecond Electron Pulse Trains and Quantum State Reconstruction in Ultrafast Transmission Electron Microscopy”, Nat. Phot. 11, 793 (2017).
prof. Alex Khajetoorians