重铬酸钾三级中红外光谱研究

Research on Three-levels MID Infrared Spectrum of Potassium Dichromate(K_(2)Cr_(2)O_(7))

采用中红外(MIR)光谱开展了重铬酸钾分子结构研究.重铬酸钾红外吸收模式主要包括:Cr-O-Cr不对称伸缩振动模式(ν_(as-Cr-O-Cr-重铬酸钾))和CrO3不对称伸缩振动模式(νas-CrO3-重铬酸钾).采用变温中红外(TD-MIR)光谱进一步开展了温度变化对于重铬酸钾分子结构的影响研究.在293 K~523 K的温度范围内,随着测定温度的升高,重铬酸钾ν_(as-Cr-O-Cr-重铬酸钾)和νas-CrO3-重铬酸钾对应的红外吸收频率和强度均发生明显的改变.以重铬酸钾ν_(as-Cr-O-Cr-重铬酸钾)和νas-CrO3-重铬酸钾为研究对象,采用二维中红外(2D-MIR)光谱进一步开展了重铬酸钾热稳定性研究.研究发现:在293 K~523 K的温度区间内,重铬酸钾主要官能团(ν_(as-Cr-O-Cr-重铬酸钾)和νas-CrO3-重铬酸钾)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(包括:MIR光谱、TD-MIR光谱和2D-MIR光谱)在重要的无机盐(重铬酸钾)分子结构及热稳定性领域的研究范围.

The molecular structure of potassium dichromate(K_(2)Cr_(2)O_(7))was studied by mid infrared(MIR)spectroscopy.The infrared absorption modes of K_(2)Cr_(2)O_(7)mainly include:cr-o-cr asymmetric stretching vibration mode(ν_(as-Cr-O-Cr-K_(2)Cr_(2)O_(7)))and CrO3 asymmetric stretching vibration mode(νas-CrO 3-K_(2)Cr_(2)O_(7)).The effect of temperature change on the molecular structure of K_(2)Cr_(2)O_(7)was further studied by using the variable temperature mid infrared(TD-MIR)spectroscopy.In the temperature range of 293K to 523K,the infrared absorption frequency and intensity ofν_(as-Cr-O-Cr-K_(2)Cr_(2)O_(7))andνas-Cro 3-K_(2)Cr_(2)O_(7)changed obviously with the increase of the measuring temperature.The potassium dichromateν_(as-Cr-O-Cr-K_(2)Cr_(2)O_(7))andνas-CrO 3-K_(2)Cr_(2)O_(7)were used as research objects,and the thermal stability of potassium dichromate was further studied by two-dimensional mid infrared(2D-MIR)spectroscopy.It is found that the main functional groups(ν_(as-Cr-O-Cr-K_(2)Cr_(2)O_(7))andνas-CrO 3-K_(2)Cr_(2)O_(7))of potassium dichromate have great differences in thermal sensitivity and the order of change during the temperature range of 293K to 523K,and the mechanism is further studied.This study expanded the research scope of three-levels MIR spectra(which including MIR spectra,TD-MIR spectra and 2D-MIR spectra)in the molecular structure and thermal stability of important inorganic salts(potassium dichromate).