| Abstract: | Appropriate Rochow contact masses have been investigated by the spatial resolution techniques SEM–EDX and SAM–AES. The results gave evidence of the existence and the catalytic action of (X-ray)-amorphous copper–silicon (Cu–Si) surface species, i.e. extremely highly dispersed particles or two-dimensional species. The well-known Rochow promoter zinc seems to act as a moderator rather than as a real accelerator. It ensures a stable rate for the reaction by neutralizing the detrimental action of silicon impurities. The silicon impurities make the whole of the silicon surface reactive and in this way cause a general blockade of the silicon surface by inactive copper species. Zinc localizes the reaction. The silicon surface remains partly free, and active Cu–Si surface species can be formed by lateral diffusion of copper onto the silicon surface that is still free. © 1997 by John Wiley & Sons, Ltd. |
