摘要
利用碳化硅压腔在室温(25℃)下,研究了异辛烷(2,2,4-三甲基戊烷)在常压至1.2GPa条件下的拉曼光谱特征。研究结果表明,异辛烷CH2和CH3的碳氢伸缩振动的拉曼位移随着压力的增大均呈线性向高频方向移动,其拉曼位移与压力的函数关系为:ν2 873=0.002 8P+2 873.3;ν2 905=0.004 8P+2 905.4;ν2 935=0.002 7P+2 935.0;ν2 960=0.012P+2 960.9。在1.0GPa附近,异辛烷的拉曼位移出现突变,与显微镜下观察发生的异辛烷液-固相变一致。结合异辛烷在常压下的熔点数据,获得了异辛烷的液-固两相相图,并根据克拉贝龙方程获得了液-固相转变过程中的摩尔体积变化量ΔVm=4.46×10-6 m3.mol-1和熵变ΔS=-30.32J.K-1.mol-1。
The experimental study of the Raman spectral character for liquid isooctane（2,2,4-trimethylpentane,ATM） was conducted by moissanite anvil cell at the pressure of 0～1.2 GPa and the ambient temperature.The results show that the Raman peaks of the C—H stretching vibration shift to higher frenquencies with increasing pressures.The relations between the system pressure and peaks positions is given as following： ν2 873=0.002 8P＋2 873.3;ν2 905=0.004 8P＋2 905.4;ν2 935=0.002 7P＋2 935.0;ν2 960=0.012P＋2 960.9.The Raman spectra of isooctane abruptly changed at the pressure about 1.0 GPa and the liquid-solid phase transition was observed by microscope.With the freezing pressure at ambient temperature and the melting temperature available at 1 atm,the authors got the liquid-solid phase diagram of isooctane.According to Clapeyron equation,the authors obtained the differences of volume and entropy for the liquid-solid phase transition of isooctane： ΔVm=4.46×10-6 m3·mol-1 and ΔS=-30.32 J·K-1·mol-1.
出处
《光谱学与光谱分析》
SCIE
EI
CAS
CSCD
北大核心
2012年第3期676-680,共5页
Spectroscopy and Spectral Analysis
基金
国家自然科学基金项目(40873047)资助
关键词
碳化硅压腔
异辛烷
RAMAN光谱
高压
相变
Moissanite anvil cell
Isooctane
Raman spectroscopy
High pressure
Phase transition
作者简介
张菲菲，女，1982年生，北京大学地球与空间科学学院硕士研究生e-mail：feifeizhang@pku．edu．cn
通讯联系人e-mail：hfzheng@pku．edu．cn
