QUANTITATIVE TRACE HYDROGEN DISTRIBUTIONS IN NATURAL DIAMOND USING 3D-MICRO-ERDA MICROSCOPY

A 3-D quantitative microscopy for minor distributions of surface and n ear-surface bulk hydrogen in solid samples has been developed. The tec hnique employs a 15 MeV Si7+ microbeam and a two-dimensional position sensitive detector (2D PSD) with event reconstruction in an Elastic Re coil Detection Analysis (ERDA) geometry. Lateral resolutions of 10 mu m and depth resolutions of 300 Angstrom at an MDL of 100 ppm are curre ntly possible. The technique is quantitative due to the use of an inte rnal implanted spot standard or by cross calibration to an H implanted reference sample using RES as a normalisation transfer. Hydrogen cont ent and configuration in diamond illuminates the genesis mechanism and environment. A hydrogen rich diamond exhibiting zoned cloud-like ense mbles of micro-inclusions as well as smaller pockets of these inclusio ns has been interrogated for its near-surface-bulk hydrogen distributi on. The sample has also been well characterised with optical microscop ies and with bulk optical spectroscopies. A striking correlation betwe en the hydrogen distribution and the optically visible inclusion have been obtained. This is the first direct evidence for aggregations of h ydrogen associated with cloudy inclusions in natural hydrogen rich dia monds. (C) 1998 Elsevier Science B.V.