The interaction of C-atoms and CHn-radicals with uncleaned and argon cleaned silicon substrate and with diamond surface after H-treatment have been studied in situ by XPS and Auger spectroscopy. It was found the formation of a new chemical surface state of carbon atoms in the case of carbon atoms and radicals interaction with cleaned silicon. The same chemical state was revealed on the H-treated diamond surface. Graphite-like structure of carbon atoms was observed on the surface of unlearned silicon and H-treated diamond after interaction with carbon atoms and radicals. N(E) C KVV Auger spectrum for the new chemical state of carbon atoms significantly differs from typical spectra for sp(2) - and sp(3)-bonded carbon materials. The high energy part of this spectrum was interpreted under the hypothesis of sp(3)-bonded carbon atoms but with shifted fermi level position. (c) 2006 Elsevier B.V. All rights reserved.