DIRECT AND INDIRECT MEASUREMENTS OF HYDROGEN

We have demonstrated that the content of hydrogen in carbon-based films can be reliably calculated from a measurement made either directly using forward recoiled hydrogen or indirectly using backscattered helium. The method makes use of the surface signal height ratio of a sample of unknown composition to a standard of known composition. This approach allows elimination of several experimental parameters. The method assumes validity of Bragg's rule, potential deviations from which account for the majority of the absolute uncertainty in the hydrogen fraction. In general however, we have found agreement in hydrogen content between the two techniques for several carbon-based films.