Carrier dynamics in TiO2 and Pt/TiO2 powders observed by femtosecond time-resolved near-infrared spectroscopy at a spectral region of 0.9-1.5 μm with the direct absorption method
Carrier dynamics in TiO2 and Pt/TiO2 powders observed by femtosecond time-resolved near-infrared spectroscopy at a spectral region of 0.9-1.5 μm with the direct absorption method
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DOI：
10.1021/jp047531k
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发表时间：
2004-12-30
影响因子：
3.3
通讯作者：
Kuroda, H
中科院分区：
文献类型：
--
作者：
Iwata, K;Takaya, T;Kuroda, H
用直接吸收法测量了TiO_2和Pt/TiO_2粉末在0.9-1.5 μ m波长范围内的飞秒时间分辨近红外光谱。宽吸收带的电荷载流子，主要是自由和捕获的电子，观察到的TiO 2和Pt/TiO 2。在光照射后，吸收带形状随着时间常数160 A而变化，这最可能反映了所产生的自由电子的捕获。人口衰减曲线的载流子在1 ps后，获得了三种不同的泵浦光功率，以及解释的二阶衰减动力学与一个共同的二阶速率常数，表明nongeminate重组的电子-空穴对。当Pt负载到TiO 2上时，观察到2.3 ps的额外衰减过程。该衰减分量表示所产生的电子从TiO 2转移到Pt，这与已知的Pt助催化剂的总体催化活性的增加一致。
Femtosecond time-resolved near-infrared spectra of TiO2 and Pt/TiO2 powders are measured at the wavelength region of 0.9-1.5 mum with the direct absorption method. Broad absorption bands of charge carriers, mainly free and trapped electrons, are observed for TiO2 and Pt/TiO2. The absorption band shape changes with a time constant of 160 A after the photoirradiation, which most probably reflects the trapping of the generated free electrons. Population decay curves of the carriers after 1 ps, obtained for three different pump light powers, are well-explained by the second-order decay kinetics with a common second-order rate constant, indicating nongeminate recombination of the electron-hole pairs. When Pt is loaded to TiO2, an additional decaying process of 2.3 ps is observed. This decay component represents the transfer of generated electrons from TiO2 to Pt, which is consistent with the known increase of overall catalytic activities by the Pt cocatalyst.