Ion beam analyses in relation to the physical properties of diamond

Diamond is a remarkable material with many unique physical properties, embracing optical, thermal, and electrical characteristics. The interplay of independent diagnostic measurements and nondestructive ion beam probes, forms the basis of these investigations. A gross subdivision of diamonds into four types can be made on the basis, predominantly, of optical properties. Other criteria, such as electrical and thermal measurements, endorse this subdivision. This type-categorization is due to the impurity characteristics. Important among these is nitrogen, which may be determined by (α, n) reactions, and questions on the aggregation of nitrogen can be broached through arguments based on thermal conductivity data. From multielemental analysis by neutron activation, it is concluded that all diamonds contain remnant inclusions of the parental magma. The distribution and aggregation of these magma inclusions are still open questions which are probed by selected nuclear reactions, by backscattering, and by proton induced X-rays. An important diamond genesis feature is the water-richness of the magma: hydrogen analysis and profiles are determined by the resonant reaction (19F, αγ). One of the four types of diamond is semiconducting: the elimination of impurities responsible for this property and the final determination of the responsible element as boron, by (p, α) reaction, are considered. Although diamond has been a subject of study for more than a century, the specific contribution of ion probes to the important open questions is relevant and timely. (Auth.)