Comparison of proton and electron microbeam studies of mineral inclusions in diamond

The electron microprobe is now a well established method for in situ nondestructive analyses of the major and minor elements at concentrations above 500 ppm. The development of the proton microprobe over the last few years has led to a potentially even more powerful technique than the electron microprobe for the analyses of small inclusions in diamond, since it has sufficient sensitivity to detect the trace elements. In this paper we compare the analyses of mineral inclusions in a diamond matrix by proton microprobe with that of the electron microprobe. The light matrix of carbon represents a most favourable case for this comparison, as the continuum background processes are weaker and have their maximum yield well below the peaks of interest for geothermometry and other studies of the mineral inclusions. No evidence for molecular effects as contribution to the continuum background were observed for this macromolecule C-matrix.