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Breaking resolution limits in ultrafast electron diffraction and microscopy

Baum, Peter and Zewail, Ahmed H. (2006) Breaking resolution limits in ultrafast electron diffraction and microscopy. Proceedings of the National Academy of Sciences of the United States of America, 103 (44). pp. 16105-16110. ISSN 0027-8424. PMCID PMC1637544.

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Ultrafast electron microscopy and diffraction are powerful techniques for the study of the time-resolved structures of molecules, materials, and biological systems. Central to these approaches is the use of ultrafast coherent electron packets. The electron pulses typically have an energy of 30 keV for diffraction and 100–200 keV for microscopy, corresponding to speeds of 33–70% of the speed of light. Although the spatial resolution can reach the atomic scale, the temporal resolution is limited by the pulse width and by the difference in group velocities of electrons and the light used to initiate the dynamical change. In this contribution, we introduce the concept of tilted optical pulses into diffraction and imaging techniques and demonstrate the methodology experimentally. These advances allow us to reach limits of time resolution down to regimes of a few femtoseconds and, possibly, attoseconds. With tilted pulses, every part of the sample is excited at precisely the same time as when the electrons arrive at the specimen. Here, this approach is demonstrated for the most unfavorable case of ultrafast crystallography. We also present a method for measuring the duration of electron packets by autocorrelating electron pulses in free space and without streaking, and we discuss the potential of tilting the electron pulses themselves for applications in domains involving nuclear and electron motions.

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Additional Information:© 2006 by The National Academy of Sciences of the USA. Contributed by Ahmed H. Zewail, August 30, 2006. Published online before print October 20, 2006, 10.1073/pnas.0607451103. We thank Profs. Jeff Kimble and Ferenc Krausz for their careful reading of the manuscript and valuable suggestions and Nuh Gedik and Songye Chen for experimental help with UEC in the initial stage. This work was supported by the Gordon and Betty Moore Foundation and the National Science Foundation. P.B. was supported by the Alexander von Humboldt Foundation. Author contributions: P.B. and A.H.Z. performed research and wrote the paper. The authors declare no conflict of interest.
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Alexander von Humboldt FoundationUNSPECIFIED
Subject Keywords:ultrafast imaging; femtosecond electron pulses; electron autocorrelation
Issue or Number:44
PubMed Central ID:PMC1637544
Record Number:CaltechAUTHORS:BAUpnas06
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Official Citation:Peter Baum and Ahmed H. Zewail Breaking resolution limits in ultrafast electron diffraction and microscopy PNAS 2006 103 (44) 16105-16110; published ahead of print October 20, 2006, doi:10.1073/pnas.0607451103
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9266
Deposited By: Archive Administrator
Deposited On:03 Dec 2007
Last Modified:02 Oct 2019 23:58

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