TY - JOUR
T1 - Fe-redox changes in Itokawa space-weathered rims
AU - Hicks, L. J.
AU - Bridges, J. C.
AU - Noguchi, T.
AU - Miyake, A.
AU - Piercy, J. D.
AU - Baker, S. H.
N1 - Funding Information:
We would like to thank the Hayabusa project team for providing returned Itokawa samples for FIB lift‐out section preparations and XAS analysis. Dr Fernando Cacho‐Nerin (Beamline I14) and Dr Konstantin Ignatyev (Beamline I18) are thanked for help with the synchrotron analyses at the Diamond Light Source synchrotron, Oxfordshire, UK, during Beamtime sessions sp19138‐1/2, and sp19641‐1. Dr Mohsen Danaie is also thanked for support in use of the E01 and E02 instruments at ePSIC (sessions mg23232‐2 and mg26303‐1/2). L. J. Hicks, J. C. Bridges, J. D. Piercy, and S. H. Baker were supported by funding from STFC, UK. T. Noguchi was supported by Grant‐in‐Aid for Scientific Research (A) 24244088. A. Miyake was supported by Grant‐in‐Aid for Scientific Research (S) 16H06348. We thank the I14 Beamline scientists for the Python code that allows for the XRF maps to be aligned in order to produce XANES maps for analysis in (see Samples and Methods section). The authors would also like to thank the two anonymous reviewers and the Associate Editor for their constructive feedback which helped to improve the paper. Mantis
Publisher Copyright:
© 2021 The Authors. Meteoritics & Planetary Science published by Wiley Periodicals LLC on behalf of The Meteoritical Society (MET).
PY - 2020/12
Y1 - 2020/12
N2 - Synchrotron Fe-K X-ray absorption spectroscopy and transmission electron microscopy have been used to investigate the mineralogy and Fe-redox variations in the space-weathered (SW) rims of asteroidal samples. This study focuses on the FIB lift-out sections from five Itokawa grains, returned by the Hayabusa spacecraft, including samples RB-QD04-0063, RB-QD04-0080, RB-CV-0011, RB-CV-0089, and RB-CV-0148. Each of the samples featured partially amorphized SW rims, caused by irradiation damage from implanted low mass solar wind ions, and the impacting of micrometeorites. Using bright-field and HAADF-STEM imaging, vesicular blistering and nanophase Fe metal (npFe0) particles were observed within grain rims, and solar flare tracks were observed in the substrate host grain, confirming the presence of SW zones. We use Fe-K XANES mapping to investigate Fe-redox changes between the host mineral and the SW zones. All SW zones measured show some increases in the ferric-ferrous ratio (Fe3+/ΣFe) relative to their respective host grains, likely the result of the implanted solar wind H+ ions reacting with the segregated ferrous Fe in the surface material.
AB - Synchrotron Fe-K X-ray absorption spectroscopy and transmission electron microscopy have been used to investigate the mineralogy and Fe-redox variations in the space-weathered (SW) rims of asteroidal samples. This study focuses on the FIB lift-out sections from five Itokawa grains, returned by the Hayabusa spacecraft, including samples RB-QD04-0063, RB-QD04-0080, RB-CV-0011, RB-CV-0089, and RB-CV-0148. Each of the samples featured partially amorphized SW rims, caused by irradiation damage from implanted low mass solar wind ions, and the impacting of micrometeorites. Using bright-field and HAADF-STEM imaging, vesicular blistering and nanophase Fe metal (npFe0) particles were observed within grain rims, and solar flare tracks were observed in the substrate host grain, confirming the presence of SW zones. We use Fe-K XANES mapping to investigate Fe-redox changes between the host mineral and the SW zones. All SW zones measured show some increases in the ferric-ferrous ratio (Fe3+/ΣFe) relative to their respective host grains, likely the result of the implanted solar wind H+ ions reacting with the segregated ferrous Fe in the surface material.
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U2 - 10.1111/maps.13611
DO - 10.1111/maps.13611
M3 - Article
AN - SCOPUS:85099333006
SN - 1086-9379
VL - 55
SP - 2599
EP - 2618
JO - Meteoritics and Planetary Science
JF - Meteoritics and Planetary Science
IS - 12
ER -