No abstract

ArF and KrF laser-induced decomposition of gaseous toluene adjacent to silica leads to silica etching and chemical vapor deposition of fluffy, amorphous, and nanosized carbon-polyoxocarbosilane composites that were analyzed by Fourier tranform infrared, Raman, X-ray photoelectron, Auger and electron paramagnetic resonance spectra, and electron microscopy and were diagnosed for magnetic and thermal properties. It is shown that the composite composition, structure, and properties are remarkably affected by the laser source. The diamagnetic, high-surface area and Si/O-rich composite produced with ArF laser radiation is a blend of nanosized bodies of polyoxocarbosilane and carbon, merged into agglomerates and spheres. The very rare ferromagnetic, lower-surface area and Si/O-poor composite produced with KrF laser radiation is composed of less than 10 nm sized carbonaceous bodies. The formation of polyoxocarbosilane is judged to be a sequence of reactions of carbonaceous fragments with silica (carbothermal reduction) and with intermediary silicon monoxide. The reported laser-backside gas-phase etching has potential for fabrication of novel nanocomposite materials.