Origin of the Blue Shift in Ultraviolet Absorption Spectra of Nanocrystalline CeO2−x Particles
Origin of the Blue Shift in Ultraviolet Absorption Spectra of Nanocrystalline CeO2−x Particles
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DOI：
10.2320/matertrans1989.41.1104
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发表时间：
2000-08
期刊：
影响因子：
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通讯作者：
S. Tsunekawa;R. Sahara;Y. Kawazoe;A. Kasuya
中科院分区：
文献类型：
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作者：
S. Tsunekawa;R. Sahara;Y. Kawazoe;A. Kasuya
在单分散CeO 2-x 纳米粒子中观察到由于O 2p 和Ce 4 f 带之间的直接型电荷转移跃迁而产生的紫外吸收边蓝移，该纳米粒子是通过连续微乳化方法以甲苯溶胶形式生产的。基于经典点电荷模型，蓝移与各个组成离子感受到的静电势差密切相关，其中纳米颗粒的有效电荷和每单位表面的氧数均减少了一半。这是首次证明氧化物（离子）纳米粒子的电荷转移转变由于非量子尺寸效应而发生蓝移。
Blue shifts of the ultraviolet absorption edge due to the direct-type charge-transfer transition between O 2p and Ce 4 f bands are observed in monodisperse CeO 2-x nanoparticles, which are produced as toluene sols by a successive micro-emulsification method. The blue shift is closely proportional to the difference in the electrostatic potentials felt by the respective constituent ions on the basis of a classical point charge model in which both the effective charge and the number of oxygens per unit surface of the nanoparticles are reduced by half. This is the first demonstration of a blue shift in a charge-transfer transition of oxide (ionic) nanoparticles due to a non-quantum size effect.