硫酸钡三级中红外光谱研究

Research on the Third-order Mid-Infrared Spectroscopy of Barium Sulfate

采用中红外(MIR)光谱开展了硫酸钡分子结构研究.硫酸钡分子红外吸收模式主要包括:SO_(4)不对称伸缩振动模式(ν_(as-SO4-硫酸钡)),SO_(4)对称伸缩振动模式(ν_(s-SO4-硫酸钡))和SO_(4)不对称变角振动模式(δ_(as-SO4-硫酸钡)).采用变温中红外(TD-MIR)光谱进一步开展了温度变化对于硫酸钡分子结构影响的研究.在303 K~573 K的温度范围内,随着测定温度的升高,硫酸钡分子ν_(as-SO4-硫酸钡)、ν_(s-SO4-硫酸钡)和δ_(as-SO4-硫酸钡)对应的红外吸收频率和强度均发生明显改变.采用二维中红外(2D-MIR)光谱进一步开展了硫酸钡分子热稳定性研究.研究发现:在303 K~573 K的温度区间内,硫酸钡分子主要官能团(ν_(as-SO4-硫酸钡)、ν_(s-SO4-硫酸钡)和δ_(as-SO4-硫酸钡))对热敏感程度及变化快慢顺序都存在着较大的差异性,并进一步进行了机理的研究.本项研究拓展了三级MIR光谱在重要的无机盐(硫酸钡)分子结构及热稳定性的研究范围.

The molecular structure of barium sulfate was studied by using the mid-infrared(MIR)spectroscopy.The infrared absorption modes of barium sulfate molecules mainly include SO_(4) asymmetric stretching vibration mode(ν_(as-SO4-barium sulfate)),SO_(4)symmetric stretching vibration mode(ν_(s-SO4-barium sulfate))and SO_(4) asymmetric variable angle vibration modes(δ_(as-SO4-barium sulfate)).The effect of temperature change on the molecular structure of barium sulfate was further studied by variable temperature mid-infrared(TD-MIR)spectroscopy.In the temperature range of 303 K~573 K,the infrared absorption frequency and intensity of barium sulfate moleculesν_(as-SO4-barium sulfate),ν_(s-SO4-barium sulfate) and δ_(as-SO4-barium sulfate) change significantly with the increase of measurement temperature.The thermal stability of barium sulfate was further studied by two-dimensional mid-infrared(2D-MIR)spectroscopy.It is found that there are great differences in the thermal sensitivity and change order of the main functional groups(ν_(as-SO4-barium sulfate),ν_(s-SO4-barium sulfate) andδ_(as-SO4-barium sulfate))of barium sulfate molecule in the temperature range of 303 K~573 K,and the mechanism is further studied.This study expands the research scope of the third-step MIR spectroscopy in the molecular structure and thermal stability of important inorganic salts(barium sulfate).