X-ray absorption near-edge spectra of transition metal disulfides FeS2 (pyrite and marcasite), CoS2, NiS2 and CuS2, and their isomorphs FeAsS and CoAsS

Abstract

Abstract. Metal K-and L3-, sulfur K-and arsenic K-and L3-edge X-ray absorption near-edge spectra of a series of metal disulfides, FeS2 (both pyrite and marcasite), COS2, NiS2, and CuS2, and their isomorphs, FeAsS and CoAsS, are presented. The features in this region of these spectra are interpreted using band structure and molecular orbital calculations in terms of the transitions from the ls or 2p3/2 state to unoccupied states. The 3d transition metal L3-edge spectra of these materials show dependence on the degree of multiplet splitting in the final state, and thus offer less information on the electronic ground state. There are substantial differences in the spectra of the isostructural materials, whereas the spectra of the isotopes pyrite and marcasite show several similarities, illustrating the dependence of near-edge region on electronic structure.

The oxidation states of copper and iron in mineral sulfides, and the oxides formed on initial exposure of chalcopyrite and bornite to air

“…10. Apart from that for chalcocite, the experimental spectra are generally in good agreement with the corresponding spectra reported previously, such as those by Sugiura (1981), Petiau et al (1988), Li et al (1994Li et al ( , 1995, Mosselmans et al (1995), Pattrick et al (1997), Lavrentyev et al (2004) and von Oertzen et al (2005.…”

Hard X-ray photoelectron and X-ray absorption spectroscopy characterization of oxidized surfaces of iron sulfides

“…the Fe K-edge spectra are commonly attributed to electron transitions from the core Fe 1 s to vacant Fe 3d e g states mixed with Fe 4p and with S 3p * states (1 s-3d transitions are forbidden by dipole selection rules) [43][44][45][46][47][48]. The resonances c correspond to Fe 4p,s states mixed with S 3p * orbitals; the peak d is due to transition to Fe 4p,s states [43][44][45][46][47][48], and the feature e can be assigned to transitions to atomic S 3p orbitals and multiple scattering resonances [45] or Fe 4sp-S 3d states [60]. The Fe K-edge XANES measured in the PFY mode do not change as a result of oxidation and etching and correspond to the bulk pyrite.…”

“…The XAS spectra of NiAs-structured pyrrhotite and stoichiometric troilite FeS have been measured, calculated and analyzed in a number of studies; the spectroscopic features are largely similar to those in pyrite, despite different electronic structures, and their detailed description can be found in the literature [43][44][45][46][47][48][49][50][51][52][53][54][55][56]. The main differences observed in the S K-edge XANES (Fig.…”

“…A number of XANES studies on iron sulfides have been reported previously [33,[43][44][45][46][47][48][49][50][51][52][53][54][55][56], but the difference between TEY and PFY Kedge spectra of air-oxidized and chemically etched materials has not been analyzed yet. Here, samples of each mineral (i.e., pyrite and pyrrhotite) polished in air were compared with those treated with an acidic ferric chloride solution to probe the effect of exposure to the leaching (etching) medium in hydrometallurgy and natural environments, and in materials science.…”

Surface oxidation studies of chalcopyrite and pyrite by glancing-angle X-ray absorption spectroscopy (REFLEXAFS)

“…In the pre-edge region (Fig. 2), the feature at 7106.5 eV is assigned to a transition from the Fe ls states to states which are mainly Fe 3deg in character (with some Fe 4p and S 3p or O 2p contribution) (Mosselmans et al, 1995). As Fe is octahedrally coordinated in both pyrite and common Fe oxides, the change in intensity of the feature is due to a combination of a change in the oxidation state of the Fe and a change from low spin Fe (pyrite) to high spin Fe.…”