电子探针Fe价态原位分析的原理和方法

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KeyLaboratoryofContientalEvolutionandEarlyLife/DepartmentofGeology，NorthwestUniversity，Xi'an7O69，Cina） AbstractThe redox state is not only a key factor in assssing planetary habitability，but also a crucial variable connecting Earth’s interior spheres and surface environment via mass recycling and co-variation. Iron （Fe），as the most abundant multivalent element in terrestrial planets，its oxidation state （expressed as Fe3+/ （2号 £Fe or Fe3+/Fe2+ ）being the most important parameter reflecting the oxygen fugacity of the system. This study thoroughly investigates the application and theoretical foundation of electron probe microanalysis（EPMA） in the determination of Fe oxidation states in geological samples.We comprehensively analyzed the principles of X-ray emission and absorption，self-absorption efect，and crystal field theory，providing a detailed elucidation of the spectral characteristics of Fe's L -series lines. Accordingly，we compared the advantages and disadvantages of the peak shift method and the flank method，and examined the damage inflicted on samples under electron bombardment.The results demonstrate that EPMA holds extensive application potential and overwhelming advantages in the determination of Fe oxidation state，but the analytical protocol and condition must be optimized to enhance test accuracyand reliability according to the characteristics of diferent samples.

This research ofers theoretical support and practical guidance for further development and promotion of Fe valence determination methods，holding significant implications for earth science research.

Keywordsoxygen fugacity；Fe oxidation state；EPMA；peakshift method； flank method； self-absorptioneffect

氧含量和氧化还原状态是星球宜居性的最重要评价标准之一，也是驱动地球以及类地行星各圈层形成和协同演化的重要变量之一，深刻影响了核幔分异、大陆形成、大气成分、生物演化等重大地质过程。（剩余33462字）