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RESEARCH PRODUCT
On simfitting MER Mössbauer data to characterize Martian hematite
Richard V. MorrisIris FleischerDavid G. AgrestiGöstar Klingelhöfersubject
MartianMeridiani PlanumHistoryMorin transitionAnalytical chemistryMineralogyHematiteSpectral lineComputer Science ApplicationsEducationvisual_artQuadrupoleMössbauer spectroscopyvisual_art.visual_art_mediumHyperfine structureGeologydescription
Mossbauer spectra of Eagle Crater outcrop rocks in Meridiani Planum were acquired by the Mars Exploration Rover (MER) Opportunity. Sixty spectra, containing ~20 to 60% hematite by area, were simultultaneously fit (simfit) in a self-consistent manner to a single chi-squared minimum, where relations among parameters from different spectra were defined for both sol (Martian day) and acquisition temperature (200–280 K). Different spectral models were compared, hematite being modeled optimally with two sextets. Sextet S1 (~35% of total sextet area) has narrower linewidths, a larger magnetic hyperfine field, and a quadrupole shift that changes smoothly from positive to negative values as the temperature increases through the bulk Morin transition temperature. Sextet S2 has broader linewidths, a likely skewed line shape, a smaller hyperfine field, and a quadrupole shift that remains negative at all temperatures, implying the S2 phase is weakly ferromagnetic at all temperatures.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2010-03-01 | Journal of Physics: Conference Series |