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Published February 16, 2011 | public
Journal Article

Irreversible Chemical Reactions Visualized in Space and Time with 4D Electron Microscopy


We report direct visualization of irreversible chemical reactions in space and time with 4D electron microscopy. Specifically, transient structures are imaged following electron transfer in copper-tetracyanoquinodimethane [Cu(TCNQ)] crystals, and the oxidation/reduction process, which is irreversible, is elucidated using the single-shot operation mode of the microscope. We observed the fast, initial structural rearrangement due to Cu^+ reduction and the slower growth of metallic Cu^0 nanocrystals (Ostwald ripening) following initiation of the reaction with a pulse of visible light. The mechanism involves electron transfer from TCNQ anion-radical to Cu^+, morphological changes, and thermally driven growth of discrete Cu^0 nanocrystals embedded in an amorphous carbon skeleton of TCNQ. This in situ visualization of structures during reactions should be extendable to other classes of reactive systems.

Additional Information

© 2011 American Chemical Society. Received: December 6, 2010. Published: January 21, 2011. This work was supported by the National Science Foundation and the Air Force Office of Scientific Research in the Physical Biology Center for Ultrafast Science and Technology (UST) supported by the Gordon and Betty Moore Foundation at Caltech.

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