The effects of possible contamination by sample holders on samples to be returned by Hayabusa2

Abstract

Chemical compositions of materials used for new sample holders (vertically aligned carbon nanotubes [VACNTs] and polyimide film), which were developed for the analysis of Hayabusa2‐return samples, were determined by instrumental neutron activation analysis and/or instrumental photon activation analysis, to estimate contamination effects from the sample holders. The synthetic quartz plate used for the sample holders was also analyzed. Ten elements (Na, Al, Cr, Mn, Fe, Ni, Eu, W, Au, and Th) and 14 elements (Na, Al, K, Sc, Ti, Cr, Zn, Ga, Br, Sb, La, Eu, Ir, and Au) could be detected in the VACNTs and polyimide film, respectively. The VACNT data show that contamination by this material with respect to the Murchison meteorite is negligible in terms of the elemental ratios (e.g., Fe/Mn, Na/Al, and Mn/Cr) used for the classification of meteorites due to the extremely low density of VACNTs. However, for the Au/Cr ratio, even small degrees (1.7 wt%) of contamination by VACNTs will change the Au/Cr ratio. Elemental ratios used for the classification of meteorites are only influenced by large amounts of contamination (>60 wt%) of polyimide film, which is unlikely to occur. In contrast, detectable effects on Ti isotopic compositions are caused by >0.1 and >0.3 wt% contamination by VACNTs and polyimide film, respectively, and Hf isotopic changes are caused by >0.1 wt% contamination by VACNTs. The new sample holders (VACNTs and polyimide film) are suitable for chemical classification of Hayabusa2‐return samples, because of their ease of use, applicability to multiple analytical instruments, and low contamination levels for most elements.

The universal sample holders of microanalytical instruments of FIB, TEM, NanoSIMS, and STXM-NEXAFS for the coordinated analysis of extraterrestrial materials

“…The coordinate analysis proposed in this study has been further developed by related studies (Kodama et al 2020;Shirai et al 2020;Uesugi et al 2020). Kodama et al (2020) described the development of a surface treatment technique using FIB to obtain high-quality electron back-scattered diffraction (EBSD) patterns from minerals in AMMs.…”

“…Uesugi et al (2020) developed a vertically aligned carbon nanotube (VACNT) holder for synchrotron-based CT and XRD analyses. Shirai et al (2020) stated that the elemental abundances of VACNT, polyimide film, and synthetic quartz glass will be used for the analysis of the Ryugu samples to evaluate possible contaminations during the sample handling process. They concluded that these materials showed low levels of contaminants and are therefore adequate for use as sample holders for the Ryugu samples.…”

The universal sample holders of microanalytical instruments of FIB, TEM, NanoSIMS, and STXM-NEXAFS for the coordinated analysis of extraterrestrial materials

“…The coordinate analysis proposed in this study, which involves utilizing instruments, devices, and methods, has been further developed by related works (Kodama et al 2020;Shirai et al 2020;. Kodama et al (2020) described the development of a surface treatment technique by FIB for obtaining high-quality electron back-scattered diffraction (EBSD) patterns from minerals in AMMs.…”

The universal sample holders of microanalytical instruments of FIB, TEM, NanoSIMS, and STXM-NEXAFS for the coordinated analysis of extraterrestrial materials

“…Next, we applied rastered ion imaging by the Japan Agency for Marine-Earth Science Technology (JAMSTEC) NanoSIMS 50L ion microprobe (Ametek CAMECA, Inc., Gennevilliers Cedex, France) to acquire an isotope map of oxygen ( 18 O/ 16 O ratio) and elemental maps of Si and Mg as 24 Mg 16 O, Al as 27 Al 16 O, Ca as 40 Ca 16 O, and Fe as 56 Fe 16 O for the sample (Fig. 5d).…”