High precision isotope micro-imaging of materials

Secondary ion mass spectrometry (SIMS) is widely used to identify the isotope ratio of the micro-area of materials. We demonstrate that the precision and spatial resolution of an ion microscope using SIMS coupled with a newly developed solid-state ion imager can be extended to two-dimensional isotope ratio imaging with permil-precision. An isotopic map for oxygen clearly reveals the distribution of 4% enrichment of ¹⁶ O in spinel particles embedded in melilite from a Ca-Al-rich inclusion of a carbonaceous chondrite. This characterization technique called isotopography thus provides the eyes to see small heterogeneity of isotope abundance in micro-scale. It is likely to find broad application in earth, material, and life science research.