Depth profiling and standardization from the back side of a sample for accurate analyses: Emphasis on quantifying low-fluence, shallow implants in diamond-like carbon.

Rationale: Back-side thinning of wafers is used to eliminate issues with transient sputtering when analyzing near-surface element distributions. Precise and accurate calibrated implants are created by including a standard reference material during the implantation. Combining these methods allows accurate analysis of low-fluence, shallow features even if matrix effects are a concern.

Water on Mars: Insights from apatite in regolith breccia Northwest Africa 7034.

Determining the source of planetary water from the hydrogen isotope compositions of crustal samples is complicated by the overprinting of isotopically diverse source material by geologic and atmospheric processes. As Mars has no plate tectonics, crustal material, which may have isotopically exchanged with the martian atmosphere, is not recycled into the mantle keeping the water reservoirs in the mantle and atmosphere mostly isolated, buffered by the crust. As the only known martian samples that are regolith breccias with a composition representative of the average crust of Mars, Northwest Africa (NWA) 7034 and its paired stones provide an important opportunity to investigate the water content and hydrogen isotope composition of the martian crust.

Best Practices for Determination of Initial Be/Be in Early Solar System Materials by Secondary Ion Mass Spectrometry.

Beryllium-10 ( = 1.4 Ma) is a short-lived radionuclide present in the early Solar System. It is produced solely by irradiation reactions and can provide constraints on the astrophysical environment of the Sun's formation.

Tracking Radionuclide Fractionation in the First Atomic Explosion Using Stable Elements.

Compositional analysis of postdetonation fallout is a tool for forensic identification of nuclear devices. However, the relationship between device composition and fallout composition is difficult to interpret because of the complex combination of physical mixing, nuclear reactions, and chemical fractionations that occur in the chaotic nuclear fireball. Using a combination of in situ microanalytical techniques (electron microprobe analysis and secondary ion mass spectrometry), we show that some heavy stable elements (Rb, Sr, Zr, Ba, Cs, Ba, La, Ce, Nd, Sm, Dy, Lu, U, Th) in glassy fallout from the first nuclear test, Trinity, are reliable chemical proxies for radionuclides generated during the explosion.

Ultrahydrous stishovite from high-pressure hydrothermal treatment of SiO2.

Stishovite (SiO(2) with the rutile structure and octahedrally coordinated silicon) is an important high-pressure mineral. It has previously been considered to be essentially anhydrous. In this study, hydrothermal treatment of silica glass and coesite at 350-550 °C near 10 GPa produces stishovite with significant amounts of H(2)O in its structure.

Anomalous fractionation of sulfur isotopes during sputtering.

Secondary ion mass spectrometric (SIMS) measurements of sulfur isotope ratios obtained during sputtering with a Cs(+) beam and detection of negative secondary ions show a strong dependence of isotope fractionation on secondary ion energy for ions with approximately 2-10 eV excess kinetic energy (approximately 9 per thousand/eV), and a weak dependence for ions with approximately 10-approximately 350 eV (0.05 per thousand/eV). Variable collection of the low-energy ions could thus result in variable measured sulfur isotope ratios.