Development of a system for determination of the C-13/C-12 isotopic ratio with high spatial resolution

Stable carbon isotopes play an important role in the interpretation of biological activity, particularly when the fossil record is studied. In combination with morphological and chemical data, isotopic information can be useful in paleontology and astrobiology. In this paper the development of a microanalytical ion beam system for the measurement of the carbon isotope ratio with high spatial resolution and good statistics is presented. The technique used is elastic scattering of alpha particles with an energy of 2.75 MeV. At this energy the C-13 cross-section is enhanced relative to the Rutherford cross-section and while the C-12 cross-section is reduced. The optimisation of the system is described, including sample preparation and the design of the particle detection system for high efficiency combined with good energy resolution. Finally, some results from the initial test run of the system are shown and discussed. (C) 2004 Elsevier B.V. All rights reserved.