Sulfur K-edge X-ray absorption spectroscopy increasingly is used as a tool to provide speciation information about the sulfur chemical form in complex samples, with applications ranging from fossil fuels to soil science to health research. As part of an ongoing program of systematic investigations of the factors that affect the variability of sulfur K near-edge spectra, we have examined the X-ray absorption spectra of a series of organic symmetric disulfide compounds. We have used polarized sulfur K-edge spectra of single crystals of dibenzyl disulfide to confirm the assignments of the major transitions in the spectrum as 1s → (S-S)σ* and 1s → (S-C)σ*. We also have examined the solution spectra of an extended series of disulfides and show that the spectra change in a systematic and predictable manner with the nature of the external group.
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http://dx.doi.org/10.1021/acs.jpca.6b06790 | DOI Listing |
ACS Appl Mater Interfaces
December 2024
Institute of Energy: Sustainability, Environment, and Equity, Stony Brook University, Stony Brook, New York 11794, United States.
The aqueous zinc-sulfur battery holds promise for significant capacity and energy density with low cost and safe operation based on environmentally benign materials. However, it suffers from the sluggish kinetics of the conversion reaction. Here, we highlight the efficacy of molybdenum(IV) sulfide (MoS) to reduce the overpotential of S-ZnS conversion in aqueous electrolytes and study the discharge products formed at the solid-solid and solid-liquid interfaces using experimental and theoretical approaches.
View Article and Find Full Text PDFJ Chem Phys
November 2024
Department of Materials Science and Engineering, Monash University, Wellington Road, Clayton, Victoria 3800, Australia.
Alkylated benzothienobenzothiophenes are an important class of organic semiconductors that exhibit high performance in solution-processed organic field-effect transistors. In this work, we study the near-edge x-ray absorption fine-structure (NEXAFS) spectra of 2,7-didecyl[1]benzothieno[3,2-b][1]benzothiophene (C10-BTBT) at both the carbon and sulfur K-edges. Angle-resolved experiments of thin films are performed to characterize the dichroism associated with molecular orientation.
View Article and Find Full Text PDFPhys Chem Chem Phys
November 2024
Institut für Physikalische und Theoretische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
We investigate isothiocyanic acid, HNCS, by resonant and nonresonant Auger electron spectroscopy at the K-edge of carbon and nitrogen, and the L-edge of sulfur, employing soft X-ray synchrotron radiation. The C1s and N1s ionization energies as well as the S2s and S2p ionization energies are determined and X-ray absorption spectra reveal the transitions from the core to the virtual orbitals. Final states for all normal Auger electron spectra and the resonant ones recorded at the carbon and nitrogen edge are assigned and rationalized with theoretical spectra obtained with a wave-function based protocol.
View Article and Find Full Text PDFNat Commun
October 2024
Department of Physics, University of Hamburg and Center for Free-Electron Laser Science, Hamburg, Germany.
The photolysis of disulfide bonds is implicated in denaturation of proteins exposed to ultraviolet light. Despite this biological relevance in stabilizing the structure of many proteins, the mechanisms of disulfide photolysis are still contested after decades of research. Herein, we report new insight into the photochemistry of L-cystine in aqueous solution by femtosecond X-ray absorption spectroscopy at the sulfur K-edge.
View Article and Find Full Text PDFJ Am Chem Soc
October 2024
Stanford PULSE Institute, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States.
Metallo dithiolene complexes with biological and catalytic relevance are well-known for having strong metal-ligand covalency, which dictates their valence electronic structures. We present the resonant sulfur Kβ (1s3p) X-ray emission spectroscopy (XES) for a series of Ni and Cu bis(dithiolene) complexes to reveal the ligand sulfur contributions to both the occupied and unoccupied valence orbitals. While S K-edge X-ray absorption spectroscopy played a critical role in identifying the covalency of the unoccupied orbitals of metal dithiolenes, the present focus on XES explores the occupied density of states.
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