THE STRUCTURE OF A C-H BY NEUTRON AND X-RAY-SCATTERING

Whilst the short-range order in a-C:H is of central importance in explaining its mechanical properties, it is order at intermediate distances that is likely to account more fully for the electronic and optical properties. The role of hydrogen would appear to be significant in promoting tetrahedral bonding - but no direct study of the hydrogen sites has been made. It is in this context that the preliminary results of neutron diffraction measurements, and of some novel synchrotron X-ray experiments, are presented and discussed. The X-ray diffraction studies were carried out using a technique which may prove useful for as-deposited films in which the angle of incidence is fixed at, or near, the critical angle. The results of a "reverse Monte Carlo" computer modelling study of the neutron data are presented.