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4D visualization of embryonic, structural crystallization by single-pulse microscopy

Kwon, Oh-Hoon and Barwick, Brett and Park, Hyun Soon and Baskin, J. Spencer and Zewail, Ahmed H. (2008) 4D visualization of embryonic, structural crystallization by single-pulse microscopy. Proceedings of the National Academy of Sciences of the United States of America, 105 (25). pp. 8519-8524. ISSN 0027-8424. PMCID PMC2438388. doi:10.1073/pnas.0803344105.

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In many physical and biological systems the transition from an amorphous to ordered native structure involves complex energy landscapes, and understanding such transformations requires not only their thermodynamics but also the structural dynamics during the process. Here, we extend our 4D visualization method with electron imaging to include the study of irreversible processes with a single pulse in the same ultrafast electron microscope (UEM) as used before in the single-electron mode for the study of reversible processes. With this augmentation, we report on the transformation of amorphous to crystalline structure with silicon as an example. A single heating pulse was used to initiate crystallization from the amorphous phase while a single packet of electrons imaged selectively in space the transformation as the structure continuously changes with time. From the evolution of crystallinity in real time and the changes in morphology, for nanosecond and femtosecond pulse heating, we describe two types of processes, one that occurs at early time and involves a nondiffusive motion and another that takes place on a longer time scale. Similar mechanisms of two distinct time scales may perhaps be important in biomolecular folding.

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Kwon, Oh-Hoon0000-0001-7114-8617
Additional Information:©2008 by the National Academy of Sciences. Contributed by Ahmed H. Zewail, April 7, 2008 (received for review April 1, 2008). Published online before print June 18, 2008, doi: 10.1073/pnas.0803344105. We thank Mr. Young Shik Shin for his help in the preparation of specimens and two referees for their helpful comments. This work was supported by the National Science Foundation, the Air Force Office of Scientific Research, and the Gordon and Betty Moore Foundation. Single-pulse biological imaging is supported in part by the National Institutes of Health. Author contributions: O.-H.K., B.B., H.S.P., J.S.B., and A.H.Z. designed research, performed research, contributed new reagents/analytic tools, analyzed data, and wrote the paper. The authors declare no conflict of interest.
Funding AgencyGrant Number
Air Force Office of Scientific Research (AFOSR)UNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:diffraction; imaging; structural dynamics; ultrafast electron microscopy
Issue or Number:25
PubMed Central ID:PMC2438388
Record Number:CaltechAUTHORS:KWOpnas08
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Official Citation:Oh-Hoon Kwon, Brett Barwick, Hyun Soon Park, J. Spencer Baskin, and Ahmed H. Zewail 4D visualization of embryonic, structural crystallization by single-pulse microscopy PNAS 2008 105 (25) 8519-8524; published ahead of print June 18, 2008, doi:10.1073/pnas.0803344105
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11194
Deposited By: Archive Administrator
Deposited On:23 Jul 2008 16:24
Last Modified:08 Nov 2021 21:34

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