Identification of the Calcium, Aluminum, and Magnesium Distribution within Millimeter-Sized Extraterrestrial Materials Using Nonresonant X-ray Raman Spectroscopy in Preparation for the Hayabusa2 Sample Return Mission.

The nondestructive investigation of millimeter-sized meteoritic materials is often hindered by self-absorption effects. Using X-ray-based analytical methods, the information depth for many elements (Z < 30) is in the range of up to only a few hundred micrometers, and for low-Z elements (Z < 20), this is reduced even further to only a few tens of micrometers. However, the investigation of these low-Z elements, in particular calcium, aluminum, and magnesium, is of great importance to planetary geologists and cosmochemists, as these elements are regularly used to characterize and identify specific features of interest in extraterrestrial materials, especially primitive chondritic material. In this work, nonresonant inelastic X-ray scattering from core electrons was performed at beamline ID20 of the ESRF in a direct tomography approach in order to visualize these low-Z elements within the millimeter-sized meteoritic samples. The obtained 3D elemental distribution volumes were compared to results from X-ray fluorescence-CT and absorption CT experiments and were found to be in good agreement. Additionally, several regions of interest could be identified within the inelastic scattering volumes, containing information that is not available through the other presented means. As such, the proposed approach presents a valuable tool for the nondestructive investigation of low-Z elemental distributions within millimeter-sized extraterrestrial materials, such as the samples of the Hayabusa2 sample return mission.

A portable on-axis laser-heating system for near-90° X-ray spectroscopy: application to ferropericlase and iron silicide.

A portable IR fiber laser-heating system, optimized for X-ray emission spectroscopy (XES) and nuclear inelastic scattering (NIS) spectroscopy with signal collection through the radial opening of diamond anvil cells near 90°with respect to the incident X-ray beam, is presented. The system offers double-sided on-axis heating by a single laser source and zero attenuation of incoming X-rays other than by the high-pressure environment. A description of the system, which has been tested for pressures above 100 GPa and temperatures up to 3000 K, is given. The XES spectra of laser-heated Mg0.67Fe0.33O demonstrate the potential to map the iron spin state in the pressure-temperature range of the Earth's lower mantle, and the NIS spectra of laser-heated FeSi give access to the sound velocity of this candidate of a phase inside the Earth's core. This portable system represents one of the few bridges across the gap between laser heating and high-resolution X-ray spectroscopies with signal collection near 90°.

Formation of iron containing aggregates at the liquid-air interface.

The early stages of the formation of inorganic aggregates, composed of iron compounds at the solution-air interface, were investigated in situ. The properties of the solution-air interface were changed by using different Langmuir layers. In order to get insight into the evolution of the sample system in situ, the processes were studied by X-ray scattering and spectroscopy techniques. The formation of aggregates was detected under cationic as well as under anionic Langmuir layers. The observed compounds lack long range order which indicates the formation of amorphous structures. This is supported by extended X-ray absorption fine structure measurements showing only minor order in the formed aggregates.

Dissolution of iron oxide nanoparticles inside polymer nanocapsules.

The structure of poly(organosiloxane) nanocapsules partially filled with iron oxide cores of different sizes was revealed by small angle X-ray scattering and X-ray diffraction. The nanocapsules are synthesized by the formation of a poly(organosiloxane) shell around iron oxide nanoparticles and the simultaneous partial dissolution of these cores. Due to the high scattering contrast of the iron oxide cores compared to the polymer shell, the particle size distribution of the cores inside the capsules can be measured by small angle X-ray scattering. Additional information can be revealed by X-ray diffraction, which gives insights into the formation of the polymer network and the structure of the iron oxide cores. The study shows how the crystallinity and size of the nanoparticles as well as the shape and width of the size distribution can be altered by the synthesis parameters.