Attempts were made to optimize the incorporation of H into the bulk in a form which was suitable for investigating its behavior using various experimental techniques. Photoluminescence studies had also illustrated the dramatic effect of H upon the centers which were created by radiation damage and subsequent annealing at 450C. They showed that a range of centers, which contained one H atom, became optically inactive if too much H was present; thus implying that they could capture more than one H atom.

E.C.Lightowlers: Materials Science Forum, 1995, 196-201, 817-24