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1. Phase‐Controlled Synthesis and Quasi‐Static Dielectric Resonances in Silver Iron Sulfide (AgFeS 2 ) Nanocrystals

   https://doi.org/10.1002/smll.202104975  

   Lee, Soohyung ; Hoyer, Chad E. ; Liao, Can ; Li, Xiaosong ; Holmberg, Vincent C. ( December 2021 , Small)

   Ternary metal‐chalcogenide semiconductor nanocrystals are an attractive class of materials due to their tunable optoelectronic properties that result from a wide range of compositional flexibility and structural diversity. Here, the phase‐controlled synthesis of colloidal silver iron sulfide (AgFeS₂) nanocrystals is reported and their resonant light–matter interactions are investigated. The product composition can be shifted selectively from tetragonal to orthorhombic by simply adjusting the coordinating ligand concentration, while keeping the other reaction parameters unchanged. The results show that excess ligands impact precursor reactivity, and consequently the nanocrystal growth rate, thus deterministically dictating the resulting crystal structure. Moreover, it is demonstrated that the strong ultraviolet‐visible extinction peak exhibited by AgFeS₂nanocrystals is a consequence of a quasi‐static dielectric resonance (DR), analogous to the optical response observed in CuFeS₂nanocrystals. Spectroscopic studies and computational calculations confirm that a negative permittivity at ultraviolet/visible frequencies arises due to the electronic structure of these intermediate‐band (IB) semiconductor nanocrystals, resulting in a DR consisting of resonant valence‐band‐to‐intermediate‐band excitations, as opposed to the well‐known localized surface plasmon resonance response typically observed in metallic nanostructures. Overall, these results expand the current library of an underexplored class of IB semiconductors with unique optical properties, and also enrich the understanding of DRs in ternary metal‐iron‐sulfide nanomaterials.

    

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2. Properties of iron sulfide, hydrosulfide, and mixed sulfide/hydrosulfide cluster anions through photoelectron spectroscopy and density functional theory calculations

   https://doi.org/10.1063/1.4964651  

   Yin, Shi ; Bernstein, Elliot R. ( October 2016 , The Journal of Chemical Physics)
3. Iron-Content-Dependent, Quasi-Static Dielectric Resonances and Oxidative Transitions in Bornite and Chalcopyrite Copper Iron Sulfide Nanocrystals

   https://doi.org/10.1021/acs.chemmater.0c04798  

   Lee, Soohyung ; Ghosh, Sandeep ; Hoyer, Chad E. ; Liu, Hongbin ; Li, Xiaosong ; Holmberg, Vincent C. ( March 2021 , Chemistry of Materials)

   null (Ed.)
4. Adsorption of Tetrathiomolybdate to Iron Sulfides and Its Impact on Iron Sulfide Transformations

   https://doi.org/10.1021/acsearthspacechem.0c00176  

   Miller, Nathan ; Dougherty, Maura ; Du, Ruochen ; Sauers, Tyler ; Yan, Candice ; Pines, Jonathan E. ; Meyers, Kate L. ; Dang, Y M. ; Nagle, Emily ; Ni, Ziqin ; et al ( November 2020 , ACS Earth and Space Chemistry)

   null (Ed.)

   Molybdenum (Mo) in marine sediments has been used as a paleoproxy to provide evidence for past oceanic euxinic and sulfidic conditions through its association with pyrite. Here, we examine the adsorption of Mo to the pyrite precursors mackinawite and greigite and assess the robustness of this association during iron sulfide phase transformations. Tetrathiomolybdate (MoS42–) adsorption experiments were done using mackinawite and greigite that had been characterized using powder X-ray diffraction and Raman spectroscopy. Adsorption of tetrathiomolybdate to mackinawite and to a primarily greigite mixture was similar. Both showed little change to the mineral phase upon adsorption. Relative to previously published data on pyrite, there was a much greater amount of Mo adsorption and a different mode of adsorption. A mackinawite/greigite mixture was also synthesized through an alternative method that more closely mimicked environmental conditions with a brief in situ aging to form an initial phase of iron sulfide, likely highly disordered mackinawite, and the near-immediate addition of MoS42–. X-ray photoelectron spectroscopy results support the adsorption of tetrathiomolybdate and its concomitant reduction to Mo(IV). The Mo-adsorbed mackinawite/greigite mixture was transformed through heating into a greigite/pyrite mixture while monitoring Mo release to the aqueous phase. Here, the sorption of Mo on the solid phase promoted the transformation of mackinawite into pyrite upon heating without diagenetic loss of Mo to the aqueous phase. These results support the early capture of MoS42– to less-stable forms of iron sulfide with negligible diagenetic loss during subsequent transformation. This work continues to point to Mo(VI) as a plausible oxidant of FeS to FeS2 within natural euxinic settings. 

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5. Chemical dynamics study on the gas-phase reaction of the D1-silylidyne radical (SiD; X 2 Π) with deuterium sulfide (D 2 S) and hydrogen sulfide (H 2 S)

   https://doi.org/10.1039/d1cp01629f  

   Goettl, Shane J. ; Doddipatla, Srinivas ; Yang, Zhenghai ; He, Chao ; Kaiser, Ralf I. ; Silva, Mateus X. ; Galvão, Breno R. ; Millar, Tom J. ( June 2021 , Physical Chemistry Chemical Physics)

   The reactions of the D1-silylidyne radical (SiD; X 2 Π) with deuterium sulfide (D 2 S; X 1 A 1 ) and hydrogen sulfide (H 2 S; X 1 A 1 ) were conducted utilizing a crossed molecular beams machine under single collision conditions. The experimental work was carried out in conjunction with electronic structure calculations. The elementary reaction commences with a barrierless addition of the D1-silylidyne radical to one of the non-bonding electron pairs of the sulfur atom of hydrogen (deuterium) sulfide followed by possible bond rotation isomerization and multiple atomic hydrogen (deuterium) migrations. Unimolecular decomposition of the reaction intermediates lead eventually to the D1-thiosilaformyl radical (DSiS) (p1) and D2-silanethione (D 2 SiS) (p3) via molecular and atomic deuterium loss channels (SiD–D 2 S system) along with the D1-thiosilaformyl radical (DSiS) (p1) and D1-silanethione (HDSiS) (p3) through molecular and atomic hydrogen ejection (SiD–H 2 S system) via indirect scattering dynamics in barrierless and overall exoergic reactions. Our study provides a look into the complex dynamics of the silicon and sulfur chemistries involving multiple deuterium/hydrogen shifts and tight exit transition states, as well as insight into silicon- and sulfur-containing molecule formation pathways in deep space. Although neither of the non-deuterated species – the thiosilaformyl radical (HSiS) and silanethione (H 2 SiS) – have been observed in the interstellar medium (ISM) thus far, astrochemical models presented here predict relative abundances in the Orion Kleinmann-Low nebula to be sufficiently high enough for detection. 

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