Publication Date:
2008-09-20
Description:
The confined electronic structure of nanoscale materials has increasingly been shown to induce behavior quite distinct from that of bulk analogs. Direct atomic-scale visualization of nanowires of zinc oxide was achieved through their unique pancake-type diffraction by using four-dimensional (4D) ultrafast electron crystallography. After electronic excitation of this wide-gap photonic material, the wires were found to exhibit colossal expansions, two orders of magnitude higher than that expected at thermal equilibrium; the expansion is highly anisotropic, a quasi-one-dimensional behavior, and is facilitated by the induced antibonding character. By reducing the density of nanowires, the expansions reach even larger values and occur at shorter times, suggesting a decrease of the structural constraint in transient atomic motions. This unanticipated ultrafast carrier-driven expansion highlights the optoelectronic consequences of nanoscale morphologies.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yang, Ding-Shyue -- Lao, Changshi -- Zewail, Ahmed H -- New York, N.Y. -- Science. 2008 Sep 19;321(5896):1660-4. doi: 10.1126/science.1162049.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18801993" target="_blank"〉PubMed〈/a〉
Keywords:
Anisotropy
;
Crystallography
;
Electrons
;
Microscopy, Electron, Scanning
;
Nanowires/*ultrastructure
;
*Zinc Oxide
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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