Volume 177, 2015

Mapping atomic motions with ultrabright electrons: towards fundamental limits in space-time resolution

Abstract

The long held objective of directly observing atomic motions during the defining moments of chemistry has been achieved based on ultrabright electron sources that have given rise to a new field of atomically resolved structural dynamics. This class of experiments requires not only simultaneous sub-atomic spatial resolution with temporal resolution on the 100 femtosecond time scale but also has brightness requirements approaching single shot atomic resolution conditions. The brightness condition is in recognition that chemistry leads generally to irreversible changes in structure during the experimental conditions and that the nanoscale thin samples needed for electron structural probes pose upper limits to the available sample or “film” for atomic movies. Even in the case of reversible systems, the degree of excitation and thermal effects require the brightest sources possible for a given space-time resolution to observe the structural changes above background. Further progress in the field, particularly to the study of biological systems and solution reaction chemistry, requires increased brightness and spatial coherence, as well as an ability to tune the electron scattering cross-section to meet sample constraints. The electron bunch density or intensity depends directly on the magnitude of the extraction field for photoemitted electron sources and electron energy distribution in the transverse and longitudinal planes of electron propagation. This work examines the fundamental limits to optimizing these parameters based on relativistic electron sources using re-bunching cavity concepts that are now capable of achieving 10 femtosecond time scale resolution to capture the fastest nuclear motions. This analysis is given for both diffraction and real space imaging of structural dynamics in which there are several orders of magnitude higher space-time resolution with diffraction methods. The first experimental results from the Relativistic Electron Gun for Atomic Exploration (REGAE) are given that show the significantly reduced multiple electron scattering problem in this regime, which opens up micron scale systems, notably solution phase chemistry, to atomically resolved structural dynamics.

Associated articles

Article information

Article type
Paper
Submitted
14 Қаз. 2014
Accepted
12 Қар. 2014
First published
29 Қаң. 2015

Faraday Discuss., 2015,177, 467-491

Mapping atomic motions with ultrabright electrons: towards fundamental limits in space-time resolution

S. Manz, A. Casandruc, D. Zhang, Y. Zhong, R. A. Loch, A. Marx, T. Hasegawa, L. C. Liu, S. Bayesteh, H. Delsim-Hashemi, M. Hoffmann, M. Felber, M. Hachmann, F. Mayet, J. Hirscht, S. Keskin, M. Hada, S. W. Epp, K. Flöttmann and R. J. D. Miller, Faraday Discuss., 2015, 177, 467 DOI: 10.1039/C4FD00204K

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements