An Another Protocol to Make Sulfur Embedded Ultrathin Sections of Extraterrestrial Small Samples

Abstract

Another protocol to make sulfur embedded ultrathin sections was developed for STXM–XANES, AFM–IR and TEM analyses of organic materials in small extraterrestrial samples. Polymerized liquid sulfur—instead of low-viscosity liquid sulfur—is the embedding media in this protocol. Due to high viscosity of the polymerized sulfur, the embedded samples stay near the surface of polymerized liquid sulfur, which facilitates trimming of glassy sulfur and ultramicrotomy of tiny embedded samples. In addition, well-continued ribbons of ultramicrotomed sections can be obtained, which are suitable for the above mentioned analyses. Because there is no remarkable difference in Carbon XANES spectra of Murchison IOM prepared by this protocol and by the conventional protocol, this protocol gives another alternative to prepare sulfur embedded ultramicrotomed sections.

Nanoscale mineralogy and organic structure in Orgueil (CI) and EET 92042 (CR) carbonaceous chondrites studied with AFM‐IR spectroscopy

“…The detailed procedure was checked under the microscope before setting into the ultramicrotome as described in Noguchi et al. (2020). Before slicing sample sections, the sulfur droplet was cut in four edges using a DIATOME diamond knife trim 45°.…”

“…The fragment of Orgueil chondrite was prepared using ultramicrotomy after sulfur embedding at Kyushu University (Fukuoka, Japan), following a procedure optimized and developed by Noguchi et al. (2020). Ultrapure sulfur powder (S 8 ; 99.998%, Sigma‐Aldrich) was put down to a stainless steel stub located at a heated plate and heated to 170–180 °C.…”

“…The detailed Table 1. Studied samples and summary of different sample preparations used for conventional Fourier-transform infrared (FTIR) spectroscopy, micro-FTIR, and AFM-IR analysis (more details described in following sections) procedure was checked under the microscope before setting into the ultramicrotome as described in Noguchi et al (2020). Before slicing sample sections, the sulfur droplet was cut in four edges using a DIATOME diamond knife trim 45°.…”

“…We checked the quality of this sulfur droplet through its transparence, before inserting the Orgueil grain into it. All the detailed procedure was checked under the microscope before setting into the ultramicrotome as described in Noguchi et al (2020). Before slicing sample sections, the sulfur droplet was cut in four edges using a DIATOME diamond knife trim 45º.…”

The evolution of organic material on Asteroid 162173 Ryugu and its delivery to Earth

“…3) as a control to compare the effects of FIB sample preparation on the OM. A sub mm grain of Ivuna was embedded in molten S for ultramicrotome following the methods outlined in Noguchi et al 2021 59 . 110 nm were sliced using a Leica UC7 at CEITEC-Muni and deposited on SiO grids.…”