The end groups in these and the other polysilanes herein are normally not of any substantial significance andinclude such groups as OH, H and groups conforming to the definition of R.sub.a.More preferred for use in the process are aryl or aralkyl polysilanes in which either R.sub.a is aromatic or aralkyl and R.sub.b, R.sub.c and R.sub.d are aliphatic or R.sub.a and R.sub.c are aromatic or aralkyl