Ultrafast elemental and oxidation-state mapping of haematite by 4D electron microscopy
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We describe a new methodology that sheds light on the fundamental electronic processes that occur at the sub-surface regions of inorganic solid photocatalysts. Three distinct kinds of microscopic imaging are used that yield spatial, temporal and energy-resolved information. We also carefully consider the effect of photon-induced near-field electron microscopy (PINEM), first reported by Zewail et al. in 2009. The value of this methodology is illustrated by studying afresh a popular and viable photocatalyst, haematite, α-Fe2O3, that exhibits most of the properties required in a practical application. By employing high-energy electron-loss signals (of several hundred eV), coupled to femtosecond temporal resolution as well as ultrafast energy-filtered transmission electron microscopy in 4D, we have, inter alia, identified Fe4+ ions that have a lifetime of a few picoseconds, as well as associated photoinduced electronic transitions and charge transfer processes.
Su , Z , Baskin , J S , Zhou , W , Thomas , J & Zewail , A 2017 , ' Ultrafast elemental and oxidation-state mapping of haematite by 4D electron microscopy ' Journal of the American Chemical Society , vol 139 , no. 13 , pp. 4916-4922 . DOI: 10.1021/jacs.7b00906
Journal of the American Chemical Society
Copyright © 2017 American Chemical Society. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at: https://doi.org/10.1021/jacs.7b00906
DescriptionThis work was supported by the Air Force Office of Scientific Research (FA9550-11-1-0055) in the Gordon and Betty Moore Center for Physical Biology at the California Institute of Technology.
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