Selenium Valence-to-Core X-ray Emission Spectroscopy and Kβ HERFD X-ray Absorption Spectroscopy as Complementary Probes of Chemical and Electronic Structure.

Justin T Henthorn,Serena Debeer

doi:10.1021/acs.inorgchem.1c02802

Justin T Henthorn, Serena Debeer

Open Access

https://doi.org/10.1021/acs.inorgchem.1c02802

Copy DOI

Abstract

Selenium X-ray absorption spectroscopy (XAS) has found widespread use in investigations of Se-containing materials, geochemical processes, and biologically active sites. In contrast to sulfur Kβ X-ray emission spectroscopy (XES), which has been found to contain electronic and structural information complementary to S XAS, Se Kβ XES remains comparatively underexplored. Herein, we present the first Se Valence-to-Core (VtC) XES studies of reduced Se-containing compounds and FeSe dimers. Se VtC XES is found to be sensitive to changes in covalent Se bonding interactions (Se–Se/Se–C/Se–H bonding) while being relatively insensitive to changes in Fe oxidation states as selenide bridges in FeSe dimers ([Fe2Se2]2+ vs [Fe2Se2]+). In contrast, Se Kβ HERFD XAS is demonstrated to be quite sensitive to changes in the Fe oxidation state with Se Kβ HERFD XAS demonstrating experimental resolution equivalent to Kα HERFD XAS. Additionally, computational studies reveal both Se VtC XES and XAS to be sensitive to selenium protonation in FeSe complexes.

Highlights

Selenium is an essential trace element that plays pivotal functions in biological[1−3] and environmental sciences.[4]
Se X-ray absorption spectroscopy has been implemented in some of these applications.[20−25] Se XAS is directly analogous to S XAS, which has recently been coupled with S X-ray emission spectroscopy (XES) as a complementary probe of electronic and chemical structure.[26,27]
While Se VtC XES shows little sensitivity to the Fe oxidation state in FeSe complexes, we have shown experimentally that it is sensitive to selenium protonation

Summary

INTRODUCTION

Selenium is an essential trace element that plays pivotal functions in biological[1−3] and environmental sciences.[4] selenium is a semiconductor with applications in the fields of nanoscience[5,6] and photovoltaics.[7−9] Other applications include energy storage[10,11] and glass manufacturing. Across many of these applications, there is great utility for an element-selective spectroscopy to better understand the electronic and chemical structure of the relevant selenium species. We report the first Se Kβ XES study of reduced Se compounds, including biologically relevant [Fe2Se2]n+ complexes

EXPERIMENTAL METHODS

RESULTS AND DISCUSSION

CONCLUSIONS

■ REFERENCES