Crystallographic and crystallochemical controls on oxygen isotope analysis of hematite by SIMS

A corundum reference material for oxygen isotope analysis by secondary ionization mass spectrometry

“…{0001} or {112̄0} designated as ⊥ c and ∥ c , respectively), and (2) density of atomic packing relative to the primary ion beam; these are named c 60 and c 60′. 15…”

“…{0001} or {11 20} designated as tc and kc, respectively), and (2) density of atomic packing relative to the primary ion beam; these are named c60 and c60 ′ . 15 The incident angle between the secondary ion optical axis (the z-direction in CAMECA instruments) and the primary ion optical axis (nominally 30°) is modied by the secondary ion extraction eld acting on the primary ion beam. For the conditions used (primary accelerating potential −13 kV; secondary accelerating potential +10 kV), the incident angle is ∼22°.…”

“…Variability of ±3& in d 18 O values was reported for SHRIMP-SI analyses of an isotopically homogeneous hematite reference material in different crystallographic orientations. 15 Crystal orientation effects can be a result of channelling whereby a larger fraction of primary ions becomes implanted deeper into the lattice compared to other orientations. 25 In these cases, momentum transfer to the near-surface layers and removal of secondary ions becomes less efficient resulting in a decrease in sputtering rate and a corresponding increase in C s concentration at the projected depth.…”

“…Moreover, crystal orientation can potentially create instrumental bias effects in SIMS oxygen isotope analysis that have not been systematically evaluated for corundum. Because corundum is isostructural with hematite (space group R 3̄ c ), 14 and crystal orientation effects have been previously reported for oxygen isotope analysis of hematite by ion microprobe (SHRIMP-SI), 15 it appears prudent to quantify the extent of these effects also for corundum.…”

High-precision apatiteδ37Cl measurement by SIMS with a 1012Ω amplifier Faraday cup

“…Matrix effect is a very complex topic, which involves the degree of ionisation of elements during sputtering, and is related to factors such as the mineral composition 56 and crystal orientation. 42,57 It not only acts on concentration measures, 58 but also impacts isotope ratio analysis. 56,59 Previous SIMS apatite isotope analyses showed the impact of matrix effect on the measured chlorine isotope ratios.…”