Ultrafast elemental and oxidation-state mapping of hematite by 4D electron microscopy

Zixue Su, J. Spencer Baskin, Wuzong Zhou, John Thomas, Ahmed Zewail

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18 Citations (Scopus)
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Abstract

We describe a new methodology that sheds light on the fundamental electronic processes that occur at the subsurface 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, hematite, 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.
Original languageEnglish
Pages (from-to)4916-4922
Number of pages7
JournalJournal of the American Chemical Society
Volume139
Issue number13
Early online date8 Mar 2017
DOIs
Publication statusPublished - 5 Apr 2017

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