Abstract Near-infrared (NIR) Raman spectroscopy has been used to analyze intermolecular bonding in solid C 70 , treated for 2 h under pressures in the range 0.8–2 GPa at temperatures between 350 and 600 K. The spectra obtained are analyzed in detail with the aim of finding spectral lines characteristic for the monomer C 70 , the dimer C 140 , and possibly for higher oligomers. In agreement with earlier studies, several new modes are observed in the NIR Raman spectra, in sharp contrast to what is found in Raman studies using visible light excitation. From the relative intensities of the characteristic dimer stretch line at 88 cm −1 and a mode at 457 cm −1 , characteristic for the monomer, a semi-quantitative estimate for the dimer fraction in the material can be found as a function of pressure and temperature. From these results a reaction map, similar to that recently derived for C 60 , can be drawn. The data obtained indicate that C 70 is almost completely polymerized into large, random oligomers (or polymers) after long-time treatment at elevated temperatures (>500 K) and pressures (>1.2 GPa). The phase diagram of C 70 is updated and briefly discussed in the light of this and other recent high pressure studies.

中文翻译：

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高压和高温下 C 70 中的分子间键合

摘要 近红外 (NIR) 拉曼光谱已用于分析固体 C 70 中的分子间键合，在 0.8-2 GPa 的压力和 350 至 600 K 之间的温度下处理 2 小时。获得的光谱被详细分析为目的是找到单体 C 70、二聚体 C 140 和可能的更高级低聚物的谱线特征。与早期的研究一致，在 NIR 拉曼光谱中观察到了几种新模式，与使用可见光激发的拉曼研究中发现的形成鲜明对比。从 88 cm -1 处的特征二聚体拉伸线和 457 cm -1 处的模式的相对强度，单体的特征，可以发现材料中二聚体分数的半定量估计作为压力和温度。从这些结果得到反应图，类似于最近为 C 60 导出的，可以绘制。获得的数据表明，在高温 (>500 K) 和压力 (>1.2 GPa) 下长时间处理后，C 70 几乎完全聚合成大的无规低聚物（或聚合物）。C 70 的相图根据该研究和其他最近的高压研究进行了更新和简要讨论。