Nanoscopic Approaches in Earth and Planetary Sciences
The properties of matter at extreme length scales and the respective processes can differ markedly from the properties and processes at length scales directly accessible to human observation. This scale-dependent behaviour is possible in both directions; towards very large and very small scales. Scientists explore the frontiers of these extreme length scales in an effort to gain insight into yet unknown properties and processes. While the exploration of larger scales has been established since the Renaissance era, a comprehensive investigation of small scales was impeded by the limitations of optical microscopy. These imitations were overcome in the 20th century. Since then, a continuous series of developments in analytical power has taken place. Today these developments allow studies of properties and processes even at the molecular or atomic scale (often referred to as nanoscience). These modern nanoscientific possibilities have triggered new innovative projects in geosciences, providing fascinating insights into small scales. Therefore, nanogeoscience has become a very important geoscientific subdiscipline.
Ion microprobe analysis: Basic principles, state-of-the-art instruments and recent applications with emphasis on the geosciences
Published:January 01, 2010
Bärbel W. Sinha, Peter Hoppe, 2010. "Ion microprobe analysis: Basic principles, state-of-the-art instruments and recent applications with emphasis on the geosciences", Nanoscopic Approaches in Earth and Planetary Sciences, Frank E. Brenker, Guntram Jordan
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An ion microprobe is an instrument that uses a finely focused primary ion beam to erode, or ‘sputter’ a solid sample and to collect secondary ions ejected during that process into a mass spectrometer generating a spatially resolved mass spectrum. The underlying technique, Secondary Ion Mass Spectrometry (SIMS), has become a standard tool for the in-situ study of trace-element concentrations and isotope ratios in the fields of geochemistry, geochronology, biogeochemistry and cosmochemistry. an overview of the most recent developments in SIMS is given by Chabala et al. (1995), Ireland (1995), Mac Rae (1995), Becker (2005), Betti (2005), Deloule & Wiedenbeck (2005), Deloule (2006) and McPhail (2006). Secondary ion mass spectrometry offers parts per million (ppm) or better detection limits for almost all elements, imaging capabilities, periodic table coverage (h–U), and isotope analyses of major and trace elements. The following three examples illustrate the unique power of the SIMS technique in measuring and imaging isotope ratios and trace element distributions.
Firstly, the lateral distribution of elements of interest and isotope ratios can be measured. Figure 1 demonstrates the lateral resolution of SIMS imaging with the Cameca NanoSIMS 50. a spatial resolution of 50 nm is possible, even for biological samples. Scans of a cell culture were taken at appropriate mass number to recognize bacterial cells (CN−, major molecular ion image) on a nucleopore polycarbonate filter, to identify photosynthetic active cells by their incorporation of 13C-labelled bicarbonate (13C/12C ratio, isotope ratio image), and to recognize species with the help of a halogen marker (19F−, trace element ion image) that binds to the ribosome of the cell.