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Two refractory Wild 2 terminal particles from a carrot‐shaped track characterized combining MIR / FIR /Raman microspectroscopy and FE ‐ SEM / EDS analyses
Author(s) -
Rotundi A.,
Rietmeijer F. J. M.,
Ferrari M.,
Della Corte V.,
Baratta G. A.,
Brunetto R.,
Dartois E.,
Djouadi Z.,
Merouane S.,
Borg J.,
Brucato J. R.,
Sergeant d'Hendecourt L.,
Mennella V.,
Palumbo M. E.,
Palumbo P.
Publication year - 2014
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/maps.12274
Subject(s) - raman spectroscopy , amorphous solid , mineralogy , analytical chemistry (journal) , chemistry , ultrafine particle , carbon fibers , raman microspectroscopy , materials science , nanotechnology , crystallography , chromatography , physics , composite material , optics , composite number
We present the analyses results of two bulk Terminal Particles, C2112,7,171,0,0 and C2112,9,171,0,0, derived from the Jupiter‐family comet 81P/Wild 2 returned by the Stardust mission. Each particle embedded in a slab of silica aerogel was pressed in a diamond cell. This preparation, as expected, made it difficult to identify the minerals and organic materials present in these particles. This problem was overcome using a combination of three different analytical techniques, viz. FE ‐ SEM / EDS , IR , and Raman microspectroscopy that allowed identifying the minerals and small amounts of amorphous carbon present in both particles. TP 2 and TP 3 were dominated by Ca‐free and low‐Ca, Mg‐rich, Mg,Fe‐olivine. The presence of melilite in both particles is supported by IR microspectroscopy, but is not confirmed by Raman microspectroscopy, possibly because the amounts are too small to be detected. TP 2 and TP 3 show similar silicate mineral compositions, but Ni‐free and low‐Ni, subsulfur (Fe,Ni)S grains are present in TP 2 only. TP 2 contains indigenous amorphous carbon hot spots; no indigenous carbon was identified in TP 3. These nonchondritic particles probably originated in a differentiated body. This work found an unanticipated carbon contamination following the FE ‐ SEM / EDS analyses. It is suggested that organic materials in the embedding silica aerogel are irradiated during FE ‐ SEM / EDS analyses creating a carbon gas that develops a strong fluorescence continuum. The combination of the selected analytical techniques can be used to characterize bulk Wild 2 particles without the need of extraction and removal of the encapsulating aerogel. This approach offers a relatively fast sample preparation procedure, but compressing the samples can cause spurious artifacts, viz. silica contamination. Because of the combination of techniques, we account for these artifacts.