H_2O-CO_2体系融合二氧化硅毛细管样品原位显微激光拉曼光谱研究

使用配备Linkam冷热台的显微激光拉曼光谱仪,采用融合二氧化硅毛细管样品,在-120～31℃温度区间,1 200～1 500cm-1光谱区间上,原位采集H2O-CO2体系流体包裹体的拉曼光谱,并针对CO2特征拉曼光谱展开分析。结果表明,融合二氧化硅毛细管样品中的流体具有代表性。通过对毛细管样品进行拉曼光谱采集,该实验获得了流体包裹体中CO2气相、CO2液相、CO2固相、CO2水合物相和CO2水溶液相的特征光谱。光谱分析结果显示,在实验温度区间上,CO2固相和CO2水合物相特征峰的稳定性,有助于鉴别拉曼光谱;同时,CO2气相、CO2液相和CO2水溶液相费米共振峰峰位因CO2压力或密度影响而发生变化。此外,该实验在温度变化过程中,鉴定了不同相的拉曼特征光谱。结果表明,激光拉曼光谱结合显微测温技术能够有效鉴别包裹体中不同的流体相,获得相变过程,确定相变温度。

In-situ Raman microspectroscopy study of fluids in the H_2O-CO_2 system in optical fused silica capillary

A Raman micro-spectrometer combined with a Linkam heating-freezing stage was used to acquire Raman spectra of fluids in a H2O-CO2 system in optical fused silica capillary sample at the temperature from-120 ℃ to 31 ℃ and in the 1200 and 1500 cm-1 regions.The results show that the fluids in fused silica capillary are the representative of loading fluids.Through the acquisition of Raman spectra of fluids in capillary,the Raman spectra of vapor CO2,liquid CO2,solid CO2,CO2 hydrate and CO2 in aqueous solution in fluid inclusion are characterized.These spectra reveal that the characteristic peak positions in solid CO2 and CO2 hydrate spectra are stable in the range of experimental temperature,which is helpful in identifying the bands in Raman spectra,and that the Fermi resonance peak positions of the spectra of vapor CO2,liquid CO2 and CO2 in aqueous solution are changed with the variation of pressure or the density of CO2.This study also analyzed the Raman spectra of different phases at different temperatures,which indicates that the technique of Raman micro-spectroscopy combined with micro-thermometry can effectively identify the different phases in fluid inclusions,catch on the process of phase changes,and determine the temperatures of phase changes.