RAMAN-SPECTROSCOPY OF CARBON MATERIALS - STRUCTURAL BASIS OF OBSERVED SPECTRA
RAMAN-SPECTROSCOPY OF CARBON MATERIALS - STRUCTURAL BASIS OF OBSERVED SPECTRA
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DOI：
10.1021/cm00011a018
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发表时间：
1990-09-01
影响因子：
8.6
通讯作者：
MCCREERY, RL
中科院分区：
文献类型：
--
作者：
WANG, Y;ALSMEYER, DC;MCCREERY, RL
采用波长为293 ~ 1064 nm的激光，研究了石墨及相关sp2碳材料的一阶和二阶拉曼光谱特征。广泛的碳材料被认为是，包括高度有序的热解石墨（HOPG），粉末和随机取向的石墨，玻璃碳在不同的热处理温度下制备。特别令人感兴趣的是硼掺杂的高度有序热解石墨（BHOPG），其中硼取代降低了局部晶格对称性，但不破坏有序结构。在2950，3654，和~ 4300 cm-1的新的二阶带的报告和分配的泛音和组合。在有序硼化HOPG中观察到1360 cm-1处的D带，其先前被分配给无序碳，并且其泛音在HOPG中很强。观察到的D带的拉曼位移随激光波长而变化，但这些位移基本上与所涉及的碳的类型无关。得出结论，D带是由于对称性破缺发生在sp2碳材料的石墨平面的边缘或BHOPG中的硼原子。观测结果与石墨材料的声子态密度预测一致，基本和高阶拉曼特征可归属于理论预测的石墨材料的晶格振动。D波段频率的激光波长依赖性似乎是由不同声子群的散射引起的，也许是通过共振增强机制。然而，结果与不同尺寸的石墨微晶的共振增强不一致。
The first-and second-order Raman spectral features of graphite and related sp2 carbon materials were examined with laser wavelengths ranging from 293 to 1064 nm. A wide range of carbon materials was considered, including highly ordered pyrolytic graphite (HOPG), powdered and randomly oriented graphite, and glassy carbon prepared at different heat-treatmenttemperatures. Of particular interest is boron-doped highly ordered pyrolytic graphite (BHOPG), in which boron substitution decreases local lattice symmetry but does not disrupt theordered structure. New second-order bands at 2950, 3654, and~ 4300 cm'1 are reported and assigned to overtones and combinations. The D band at 1360 cm'1, which has previously been assigned to disordered carbon, was observed in ordered boronated HOPG, and its overtone is strong in HOPG. The observed Raman shift of the D band varies with laser wavelength, but these shifts are essentially independentof the type of carbon involved. It is concluded that the D band results from symmetry breaking occurring at the edges of graphite planes in sp2 carbon materials or at boron atoms in BHOPG. The observations are consistent with the phonon density of states predicted for graphitic materials, and the fundamental and higher order Raman features are assignable totheoretically predicted lattice vibrations of graphite materials. The laser wavelength dependence of the D band frequency appears to result from scattering from different populations of phonons, perhaps through a resonance enhancement mechanism. However, the results are inconsistent with resonance enhancement of graphite microcrystallites of varying size.