极化子
离域电子
材料科学
原子物理学
放松(心理学)
电子
氧化物
光谱学
分子物理学
化学物理
凝聚态物理
物理
心理学
量子力学
社会心理学
冶金
作者
Chaoyu Guo,Xiangzhi Meng,Huixia Fu,Qin Wang,Huimin Wang,Ye Tian,Jinbo Peng,Runze Ma,Yuxiang Weng,Sheng Meng,Enge Wang,Ying Jiang
标识
DOI:10.1103/physrevlett.124.206801
摘要
Understanding the nonequilibrium dynamics of photoexcited polarons at the atomic scale is of great importance for improving the performance of photocatalytic and solar-energy materials. Using a pulsed-laser-combined scanning tunneling microscopy and spectroscopy, here we succeeded in resolving the relaxation dynamics of single polarons bound to oxygen vacancies on the surface of a prototypical photocatalyst, rutile TiO_{2}(110). The visible-light excitation of the defect-derived polarons depletes the polaron states and leads to delocalized free electrons in the conduction band, which is further corroborated by ab initio calculations. We found that the trapping time of polarons becomes considerably shorter when the polaron is bound to two surface oxygen vacancies than that to one. In contrast, the lifetime of photogenerated free electrons is insensitive to the atomic-scale distribution of the defects but correlated with the averaged defect density within a nanometer-sized area. Those results shed new light on the photocatalytically active sites at the metal-oxide surface.
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