正辛烷的高压拉曼光谱研究

 采用金刚石对顶砧高压装置，在室温下对正辛烷（C₈H₁₈）进行了原位高压拉曼光谱研究，实验的最高压力为13GPa。在实验的压力范围内，正辛烷的拉曼峰位随压力的升高均向高频移动，峰强逐渐减弱，峰形变宽。常态为液态的正辛烷在0.8 GPa时，拉曼频移随压力的变化曲线出现了拐点，发生了液－固相变；在6.8 GPa时，伴随着原拉曼峰的消失或劈裂，以及新拉曼峰的出现，此时正辛烷可能发生了固－固相变。该相变压力低于已有的低碳数正烃烷的压致相变结果。正烃烷的压致相变压力点，具有随着结构链长的增加，其相变压力降低的规律。

Raman Scattering Studies of n-Octane under High Pressure

High pressure Raman spectra of n-octane were investigated by diamond anvil cell (DAC) at pressure up to 7 GPa and ambient temperature. The result shows that the liquid-solid phase transition of n-octane takes place around 0.8 GPa. Within the experimental pressure range, the Raman shift of n-octane moves to higher frequency, while the peak intensity decreases, and the width of peaks broaden with increasing pressure. A turning point is observed in the curve of pressure-dependent Raman shift when the pressure increases up to 6.8 GPa. This result indicates that a solid-solid phase transition for n-octane has been finished at this pressure. The pressure-induced phase transition pressure in alkanes decreases with the length of their chains increasing.