EPITAXY AND DOMAIN GROWTH OF PB ON NI(001)

We study the growth of the c(2 x 2) structure of Pb on Ni(001) with hi gh-resolution x-ray diffraction. By monitoring the adsorbate-substrate and the adsorbate-adsorbate interference diffraction peaks, we are ab le to determine the registry and growth process of the first overlayer . Pb atoms change from hollow site to non-hollow site growth as covera ge increases. Results at higher substrate temperatures indicate a diff erent growth process at low coverage. We propose a model of adsorbate aggregation at sites in line with Ni atoms around pinning centres to a ccount for the observed results.