TY - JOUR
T1 - Reconstruction of pyrrhotite fracture surfaces
AU - Pettifer, Zoe E.
AU - Quinton, Jamie S.
AU - Harmer, Sarah L.
PY - 2022/6/30
Y1 - 2022/6/30
N2 - The interpretation of core level Synchrotron photoemisison spectra (SPES) collected from a pristine fracture surface of monoclinic pyrrhotite (Fe7S8), as a function of photon energy, has identified the three distinct surface species. The Fe 2p photoemission spectra show the Fe in pyrrhotite is high spin FeII in octahedral co-ordination. Comparison of bulk and surface sensitive spectra did not identify any changes due to the broad nature of the high spin Fe 2p spectra. However, the sulfur spectrum shows an undercoordinated monosulfide at 160.8 eV, a disulfide (161.7 eV) and polysulfide species (163.2 eV) at the surface. This indicates stabilisation of the surface involves reconstruction and results in chemical transformation of sulfur species. A high binding energy tail that extends to 167 eV has been attributed to ligand to metal charge transfer satellites (LMCT) and supported by the pre-edge features observed in Fe L2,3 and S L2,3 near edge X-ray absorption fine structure (NEXAFS). An accurate fit for the bulk pyrrhotite sulfide spectrum has been estimated by comparing spectra with different surface sensitivities, and thereby an accurate fitting method has been developed for the monoclinic pyrrhotite S 2p spectrum. This method may be used for future photoemission spectra to improve the analysis of similar samples and provide a basis for interpretation of pyrrhotite samples during mineral processing and environmental conditions.
AB - The interpretation of core level Synchrotron photoemisison spectra (SPES) collected from a pristine fracture surface of monoclinic pyrrhotite (Fe7S8), as a function of photon energy, has identified the three distinct surface species. The Fe 2p photoemission spectra show the Fe in pyrrhotite is high spin FeII in octahedral co-ordination. Comparison of bulk and surface sensitive spectra did not identify any changes due to the broad nature of the high spin Fe 2p spectra. However, the sulfur spectrum shows an undercoordinated monosulfide at 160.8 eV, a disulfide (161.7 eV) and polysulfide species (163.2 eV) at the surface. This indicates stabilisation of the surface involves reconstruction and results in chemical transformation of sulfur species. A high binding energy tail that extends to 167 eV has been attributed to ligand to metal charge transfer satellites (LMCT) and supported by the pre-edge features observed in Fe L2,3 and S L2,3 near edge X-ray absorption fine structure (NEXAFS). An accurate fit for the bulk pyrrhotite sulfide spectrum has been estimated by comparing spectra with different surface sensitivities, and thereby an accurate fitting method has been developed for the monoclinic pyrrhotite S 2p spectrum. This method may be used for future photoemission spectra to improve the analysis of similar samples and provide a basis for interpretation of pyrrhotite samples during mineral processing and environmental conditions.
KW - Fracture surface
KW - NEXAFS
KW - Pyrrhotite FeS
KW - Sulfide mineral
KW - Synchrotron photoemisison spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=85132704319&partnerID=8YFLogxK
UR - http://purl.org/au-research/grants/ARC/FT110100099
U2 - 10.1016/j.mineng.2022.107666
DO - 10.1016/j.mineng.2022.107666
M3 - Article
AN - SCOPUS:85132704319
SN - 0892-6875
VL - 184
JO - Minerals Engineering
JF - Minerals Engineering
M1 - 107666
ER -