Role of molecular anchor groups in molecule-to-semiconductor electron transfer
Role of molecular anchor groups in molecule-to-semiconductor electron transfer
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DOI：
10.1021/jp064436y
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发表时间：
2006-12-21
影响因子：
3.3
通讯作者：
Willig, Frank
中科院分区：
文献类型：
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作者：
Ernstorfer, Ralph;Gundlach, Lars;Willig, Frank
利用瞬态吸收光谱研究了两种不同锚定基团从多环芳香族发色团苝到纳米结构 TiO2 锐钛矿的异相电子转移 (ET) 动力学。紫外光电子能谱和线性吸收光谱的数据表明，发色团的供体态位于导带下缘上方约 900 meV 处。满足宽带限制后，多相 ET 反应的速率仅受电子耦合强度的控制，而不受 Franck-Condon 因素的影响。使用羧酸和膦酸作为各自的锚定基团测量了两个不同的电子转移时间常数，即 13 和 28 fs。 ET 时间常数的差异可以通过施主轨道在各自锚定基团上的不同延伸来解释，以达到半导体的空电子态。时间常数是通过简单的速率方程模型提取的。通过将速率方程模型与光学布洛赫方程模型进行比较，验证了在超快时间尺度上应用该模型的有效性。
The dynamics of heterogeneous electron transfer ( ET) from the polycyclic aromatic chromophore perylene to nanostructured TiO2 anatase was investigated for two different anchor groups with transient absorption spectroscopy in an ultrahigh vacuum. Data from ultraviolet photoelectron spectroscopy and from linear absorption spectroscopy showed that the donor state of the chromophore was located around 900 meV above the lower edge of the conduction band. With the wide band limit fulfilled the rate of the heterogeneous ET reaction was only controlled by the strength of the electronic coupling and not reduced by Franck-Condon factors. Two different time constants for the electron transfer, i.e., 13 and 28 fs, were measured with carboxylic acid and phosphonic acid as the respective anchor groups. The difference in the ET time constants was explained with the different extension of the donor orbital onto the respective anchor group to reach the empty electronic states of the semiconductor. The time constants were extracted by means of a simple rate equation model. The validity of applying this model on this ultrafast time scale was verified by comparing the rate equation model with an optical Bloch equation model.