Zhang Dongju, Zhang R Q
Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR, China.
J Phys Chem B. 2005 May 12;109(18):9006-13. doi: 10.1021/jp046330d.
Nanocrystalline diamond (NCD) has attracted great attention both experimentally and theoretically in the past few years. The identification of the presence and the amount of NCD in amorphous carbon film has been a challenging issue. Although Raman spectroscopy has become a standard tool for the characterization of various carbon phases, a simple criterion for identifying NCD has not yet been well-established. In the present work, a theoretical study of the Raman spectra of the model compounds of NCD is presented on the basis of the density functional calculations. The reliability of the computational approach has been tested by comparing the predicated Raman spectra of several reference molecules to those obtained experimentally. To show the unique Raman spectrum of a NCD phase, a series of the model compounds of various carbon materials including tetrahedral and hexagonal clusters, and trans-polyacetylene fragments, were considered, and subsequently their Raman spectra below 2000 cm(-1) were calculated and compared with each other. The calculated results indicate that the relatively stronger broad peak at about 480 cm(-1) could be used as the signature of a NCD phase in the sample.
在过去几年中，纳米晶金刚石（NCD）在实验和理论方面都引起了极大关注。确定非晶碳膜中NCD的存在及其含量一直是一个具有挑战性的问题。尽管拉曼光谱已成为表征各种碳相的标准工具，但尚未建立一个用于识别NCD的简单标准。在本工作中，基于密度泛函计算对NCD模型化合物的拉曼光谱进行了理论研究。通过将几种参考分子的预测拉曼光谱与实验获得的光谱进行比较，检验了计算方法的可靠性。为了展示NCD相独特的拉曼光谱，考虑了一系列各种碳材料的模型化合物，包括四面体和六边形簇以及反式聚乙炔片段，随后计算了它们在2000 cm(-1)以下的拉曼光谱并相互比较。计算结果表明，约480 cm(-1)处相对较强的宽峰可作为样品中NCD相的特征峰。
