APPLICATIONS OF THE HIGH-RESOLUTION SCANNING PROTON MICROPROBE IN THE EARTH SCIENCES - AN OVERVIEW

The proton microprobe uses a focused beam of high-energy protons to generate X-rays in a sample that is to be analyzed. The major advantage of the proton microprobe as compared with the electron microprobe lies in its much lower X-ray background. This makes possible analyses at the 5-10-ppm concentration level with a resolution of 1 μm. The principles of operation of the proton microprobe are reviewed and the instrument compared with the ion probe and synchrotron X-ray microprobe. Examples of its use in analyzing finely zoned dolomite and in investigating the late-stage concentration of elements on grain boundaries in garnet lherzolite xenoliths are reviewed. The proton and X-ray microprobes are likely to contribute increasing amounts of high-quality trace-element data in the near future. © 1990.