SiC bonding in (C-60)(n)Si-m clusters

This paper deals with a new type of SiC bonding where silicon atom seems to bridge C-60 molecules. We have studied Elms obtained by deposition of (C-6 0)(n)Si-m clusters prepared in a laser vaporization source. Prior depositio n, free ionized clusters were studied in a time-of-flight mass spectrometer . Mixed clusters (C-60)(n)Si-m were clearly observed. Abundance and photofr agmentation mass spectroscopies revealed the relatively high stability of t he (C-60)(n)Si-n(+), (C-60)(n)Si-n-1(+) and (C-60)(n)Si-n-2(+) species. Thi s observation is in favor of the, arrangement of these complexes as polymer s where the C60 cages may be bridged by a silicon atom. Free neutral cluste rs are then deposited onto substrate making up a nanogranular thin film (si milar or equal to 100 nm). The film is probed by Auger and X-ray photoemiss ion spectroscopies, but above all by surface enhanced Raman scattering. The results suggest an unusual chemical bonding between silicon and carbon and Cite environment of the silicon atom is expected to be totally different f rom the sp(3) latticed ten or twelve carbon neighbors might surround silico n atom. The bonding is discussed to the light of the so-called fullerene po lymerization as observed for pure fullerite upon laser irradiation. This op ens a new route for bridging C60 molecules together with an appreciable ene rgy bonding, since the usual van der Waals bonding in fullerite could be re placed by an ionocovalent bond. Such an assumption must be checked in the f uture by XAS and EXAFS experiments.