Phonon Raman spectra of colloidal CdTe nanocrystals: effect of size, non-stoichiometry and ligand exchange.
Phonon Raman spectra of colloidal CdTe nanocrystals: effect of size, non-stoichiometry and ligand exchange.
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胶体CDTE纳米晶体的声子拉曼光谱：大小，非岩石学和配体交换的影响。
DOI：
10.1186/1556-276x-6-79
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发表时间：
2011-01-12
影响因子：
--
通讯作者：
Zahn DR
中科院分区：
文献类型：
--
作者：
Dzhagan V;Lokteva I;Himcinschi C;Jin X;Kolny-Olesiak J;Zahn DR
共振拉曼光谱研究表明，不同粒径和组成的胶体CdTe NC表面的配体交换对声子谱有明显的影响。油酸配体交换吡啶的被发现显着改变的位置和宽度的纵向光学（LO）声子模式，以及其强度比的泛音。吡啶处理后，以及随着NC尺寸的减小，LO峰值频率以上的宽肩增强和锐化。低频模式约100 cm-1，这是通常与无序激活的声学声子出现在较小的NC，但吡啶处理后没有增强。令人惊讶的是，在低频肩膀的LO峰，通常分配给表面光学声子模式的功能，是不敏感的配体交换和随之而来的紧密包装的NC。增加的NC表面上的结构无序，应变和修改的电子-声子耦合进行了讨论，所观察到的配体交换的CdTe NC的声子谱的变化的可能原因。PACS：63.20。e，78.30。j，78.67。n，78.67.Bf
Resonant Raman study reveals the noticeable effect of the ligand exchange on the nanocrystal (NC) surface onto the phonon spectra of colloidal CdTe NC of different size and composition. The oleic acid ligand exchange for pyridine ones was found to change noticeably the position and width of the longitudinal optical (LO) phonon mode, as well as its intensity ratio to overtones. The broad shoulder above the LO peak frequency was enhanced and sharpened after pyridine treatment, as well as with decreasing NC size. The low-frequency mode around 100 cm-1 which is commonly related with the disorder-activated acoustical phonons appears in smaller NCs but is not enhanced after pyridine treatment. Surprisingly, the feature at low-frequency shoulder of the LO peak, commonly assigned to the surface optical phonon mode, was not sensitive to ligand exchange and concomitant close packing of the NCs. An increased structural disorder on the NC surface, strain and modified electron-phonon coupling is discussed as the possible reason of the observed changes in the phonon spectrum of ligand-exchanged CdTe NCs. PACS: 63.20.-e, 78.30.-j, 78.67.-n, 78.67.Bf