基于电子顺磁共振波谱法的土壤环境持久性自由基的检测方法研究  

Study on Method of Environmental Persistent Free Radicals in Soils by Electron Paramagnetic Resonance Spectroscopy

作　　者：蒋倩[1] 唐昊冶[1] 刘云[1] 陆国兴[1] 倪俊[1] 涂勇辉[1] 范巧君 龚华[1] 马作豪 JIANG Qian;TANG Haoye;LIU Yun;LU Guoxing;NI Jun;TU Yonghui;FAN Qiaojun;GONG Hua;MA Zuohao(CAS Key Laboratory of Soil Environment and Pollution Remediation,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China)

机构地区：[1]中国科学院土壤环境与污染修复重点实验室(南京土壤研究所),南京210008

出　　处：《土壤》2023年第2期379-389,共11页Soils

基　　金：国家重点研发计划项目(2020YFC1807200,2018YFC1803100)资助。

摘　　要：本研究以不同类型土壤为研究对象,分别对电子顺磁/自旋共振波谱仪(EPR/ESR,X-波段连续波)的中心磁场、微波功率、调制幅度等主要测试参数进行调试与优选,确立EPR测定土壤环境持久性自由基(EPFRs)的仪器参数优选方法及参考值。结果表明,根据样品实测频率ν(约9.82 GHz)与EPFRs的g因子可设置谱仪中心磁场约3502 G。微波功率可采用微波功率饱和曲线法、微波衰减相邻6 dB信号比较法优选,两法各有优缺点,建议结合选用。若与27 dB相比,微波衰减设置为≤15 dB,低场峰(g=2.0030~2.0035)有由于功率饱和而引起其自旋浓度被不同程度抑制的趋势,并且27 dB左右(25~30 dB)被认为是该峰的较优微波衰减值。然而,高场峰(g=2.0004)对其响应存在差异,高衰减值为较佳。此外,调制幅度应小于峰-峰宽(3.28 G),若兼顾研究较窄峰(约1 G),1 G较为适宜。本EPR谱仪测试参数优选方法可确保g因子的准确度、EPR图谱的分辨率与超精细分裂等信息的可靠性,为土壤与环境固态样品EPFRs的测定提供科学依据,促进该项技术的应用与发展。A method for the determination of environmental persistent free radicals(EPFRs)in soil by electron paramagnetic/spin resonance spectroscopy(EPR/ESR)was established.In this paper,the central magnetic field,microwave power and modulation amplitude of the EPR spectrometer(x-band continuous wave)are tested and optimized.Based on the measured microwave frequencyν(9.82 GHz)and the g factor of the EPFRs,the central magnetic field of the spectrometer can be set to about 3502 G.The microwave power saturation curve method and the microwave attenuation comparison method are used to optimize the microwave power.The two methods have their advantages and disadvantages,should be applied complementarily by both.Compared with 27 dB,microwave attenuation is set to≤15 dB,and the peak(g=2.0030~2.0035)is suppressed by more or less due to power saturation.Therefore,about 27 dB or 25-30 dB is considered to be the optimal microwave attenuation value of this peak.However,the response of the other peak of higher magnetic field(g=2.0004)is different,and the peak intensity is stronger at the higher attenuation value.In addition,the modulation amplitude should be smaller than the least peak-peak width(3.28 G),and 1 G is suitable if the narrower peak(1 G)is also studied.This method can be applied to the determination of EPFRs in soils and environmental solid samples,and it can ensure the accuracy of g factor,the resolution and the reliability of superfine splitting of EPR spectra.

关 键 词：电子顺磁共振 电子自旋共振 波谱法 环境持久性自由基 土壤 

分 类 号：O482.53[理学—固体物理] X53[理学—物理] S1[环境科学与工程—环境工程]