Probing electrons in TiO2 polaronic trap states by IR-absorption: evidence for the existence of hydrogenic states.
Probing electrons in TiO2 polaronic trap states by IR-absorption: evidence for the existence of hydrogenic states.
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DOI：
10.1038/srep03808
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发表时间：
2014-01-22
影响因子：
4.6
通讯作者：
Wöll C
中科院分区：
文献类型：
--
作者：
Sezen H;Buchholz M;Nefedov A;Natzeck C;Heissler S;Di Valentin C;Wöll C
氧化物光化学中的一个重要步骤，电子进入浅陷阱态的加载，使用红外（IR）光谱研究了金红石型TiO 2粉末和单晶，r-TiO 2（110）取向的样品。在UV照射或通过暴露于H原子的n掺杂后，在约940 cm-1处观察到粉末的宽IR吸收线。 对于单晶衬底，从激发的陷阱电子到更高的最终状态所产生的红外吸收带显示在以前的工作中没有观察到的额外功能。根据我们对金红石中极化子结合能的新的高分辨率数据和理论研究，我们提出陷阱态对应于极化子，因此是本质上的。我们分配的最终状态探测的IR实验氢状态内的极化子电位。这些观察氧化物的光化学的影响将简要讨论。
An important step in oxide photochemistry, the loading of electrons into shallow trap states, was studied using infrared (IR) spectroscopy on both, rutile TiO2 powders and single-crystal, r-TiO2(110) oriented samples. After UV-irradiation or n-doping by exposure to H-atoms broad IR absorption lines are observed for the powders at around 940 cm−1. For the single crystal substrates, the IR absorption bands arising from an excitation of the trapped electrons into higher-lying final states show additional features not observed in previous work. On the basis of our new, high-resolution data and theoretical studies on the polaron binding energy in rutile we propose that the trap states correspond to polarons and are thus intrinsic in nature. We assign the final states probed by the IR-experiments to hydrogenic states within the polaron potential. Implications of these observations for photochemistry on oxides will be briefly discussed.