压强对二元溶液相变、费米共振的影响——二元溶液与纯液体压强效应比较

分别测量了CCl4和C6H6二元溶液和纯液体在不同压强下(0～11GPa)的拉曼光谱。结果表明二元溶液的压强效应明显不同于纯液体的压强效应:2种液体混合,由于体密度增加,分子间距离减小,分子间相互作用能增加,拉曼光谱线频移(兰移)速度增大,二元溶液频移速度大于纯液体的频移速度;谱线劈裂(相变)提前和固有频差Δ0随压强增加而加大;苯的ν1+ν6～ν8、四氯化碳的ν1+ν4～ν3费米共振消失压强减小;不同压缩系数的分子频移速度不同,密度较小的CCl4分子,化学键长,力常数小,压缩系数大,容易压缩。密度大的C6H6分子,化学键短,力常数大,压缩系数小,不易压缩。CCl4分子大多拉曼频移速度大于C6H6分子相近频率的频移速度。并对高压下分子谱线归属、认证有参考价值,对不同环境下的高压效应、分子间相互作用、溶剂效应等研究提供了方法和思路。

The effect of pressure on binary solution phase transition and fermi resonance--comparing pressure effect for binary solution and pure liquid

The Raman spectra of binary solution (CCl4 and C6 H6) and pure liquid were measured up to pressures of 11 GPa. The results show that pressure effect on binary solution is different from that on pure liquid: When mixing two liquids, owing to the changes in the density of the solution, intermolecular distance decreases and interaction energy increases, the frequency shift (blue shift) of spectral bands increases, and the frequency shift of binary liquid is faster than pure liquid frequency shift. Phase transitions (spectral bands splitting) change earlier and natural frequency difference delta0 increases with increasing pressure, while the Fermi resonance bands nu1 + nu6 and nu8 of benzene and nu1 + nu4 and nu3 of CCl4 disappear as the pressure decreases gradually, the spectral bands with different compressibility have different speed, whereas CCl4 has smaller density, longer bond, smaller force constant and larger compressibility and is easy to compress, C6H6 has larger density, smaller bond, larger force constant, smaller compressibility and is hard to compress. The frequency shift of CCl4 is faster than benzene. In this paper we provide good reference on Raman bands assignment and certification under high pressure, and also provide methods and ideas for study of the different environment of high pressure effect, intermolecular interaction and solvent effect.