HYDROGEN IN AND ON NATURAL AND SYNTHETIC DIAMOND

Diamond, both natural and metastable as well as stable growth synthetic, is a material of particularly attractive physical properties. In the characterization of diamond, light volatiles appear to play a significant role both in the determination of properties and in the control of the growth process itself. Historically nitrogen was perceived as the dominant impurity in natural diamond, but in the past decade both oxygen and hydrogen have been shown to be prolific to largely the same degree. This paper takes stock of the state of the art in the study of hydrogen in and on diamond of both natural and synthetic genesis. This includes the study of the surface and bulk hydrogen depth distribution as assayed by traditional nuclear reaction analysis, as well as recent high resolution resonant nuclear reaction analysis of hydrogen as it formally addresses the true surface of diamond. These analytical approaches are valuably complemented by the more subtle use of time dependent perturbed angular distribution studies which are shown to pick out a molecular hydrogen component in the bulk of diamond. Positively charged muons may combine with electrons to form the atom "muonium", which for all practical purposes disports itself as a light isotope of hydrogen: muonium spin rotation studies are exploited in a radiation damage free manner to study the properties of hydrogen in diamond. Finally some specific work on hydrogen in CVD diamond (-like) materials is considered.