期刊
CHEMICAL SCIENCE
卷 8, 期 12, 页码 8170-8178出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c7sc02826a
关键词
-
资金
- Air Force Office of Scientific Research [FA9550-15-1-0204]
- Department of Energy [DE-SC0014051]
- U.S. Department of Energy (DOE) [DE-SC0014051] Funding Source: U.S. Department of Energy (DOE)
Spectroscopically following charge carrier dynamics in catalytic materials has proven to be a difficult task due to the ultra fast time scales involved in charge trapping and the lack of spectroscopic tools available to selectively probe surface electronic structure. Transient extreme ultraviolet reflection-absorption (XUV-RA) spectroscopy is able to follow surface electron dynamics due to its element, oxidation-state, and surface specificity, as well as the ultrafast time-resolution which can be achieved with XUV pulses produced by high harmonic generation. Here, we use ultrafast XUV-RA spectroscopy to show that charge localization and small polaron formation in Fe2O3 occur within similar to 660 fs. The photoexcitation of hematite at 400 nm initially leads to an electronically-delocalized ligand-to-metal charge transfer (LMCT) state, which subsequently evolves into a surface localized LMCT state. Comparison of the charge carrier dynamics for single and polycrystalline samples shows that the observed dynamics are negligibly influenced by grain boundaries and surface defects. Rather, correlation between experimental results and spectral simulations reveals that the lattice expansion during small polaron formation occurs on the identical time scale as surface trapping and represents the probable driving force for sub-ps electron localization to the hematite surface.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据