Raman Investigation of Nanosized TiO2: Effect of Crystallite Size and Quantum Confinement

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• 作者：Xiangxin Xue ; Wei Ji ; Zhu Mao ; Huijuan Mao ; Yue Wang ; Xu Wang ; Weidong Ruan ; Bing Zhao ; John R. Lombardi
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：April 19, 2012
• 年：2012
• 卷：116
• 期：15
• 页码：8792-8797
• 全文大小：343K
• 年卷期：v.116,no.15(April 19, 2012)
• ISSN：1932-7455

文摘

The influence of the TiO₂ particle size on the enhanced Raman spectroscopy properties was systematically investigated on the nanometer-size scale. We report on the enhanced Raman spectrum of 4-mercaptobenzoic acid adsorbed on TiO₂ nanoparticles. The results presented in this study highlight the major findings that the intensities of both the molecular lines and the phonon modes of TiO₂ are strongly size-dependent. The TiO₂ crystallite size estimated using the Scherrer equation varied from 6.8 to 14.2 nm; as a function of crystal size, a large increase in intensity is observed, with a maximum near 10.9 nm and a subsequent decline at larger sizes. Moreover, we have investigated quantum confinement effects between TiO₂ and the adsorbed molecules and attribute this to a charge-transfer resonance, which is responsible for the Raman enhancement.