The Effect of Pressure on Binary Solution Phase Transition and Fermi Resonance ——Comparing Pressure Effect for Binary Solution and Pure Liquid
YANG Guang1, 2, ZHOU Mi1, 2, JIANG Xiu-lan3, ZHANG Peng2, LIU Tie-cheng2, XU Da-peng2, LI Zuo-wei1, 2*, GAO Shu-qin2, YANG Jian-ge4
1. State Key Laboratory of Superhard Materials, Changchun 130023, China 2. School of Physics, Jilin University，Changchun 130023, China 3. School of Science，Qingdao Technological University，Qingdao 266033, China 4. The Ordnance Engineering Department, Air Force Aviation University, Changchun 130022, China
Abstract：The Raman spectra of binary solution (CCl4 and C6H6) 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 Δ0 increases with increasing pressure, while the Fermi resonance bands ν1+ν6 and ν8 of benzene and ν1+ν4 and ν3 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.
