PHOTORESPONSIVE FORMATION OF GOLD PARTICLES IN SILICA TITANIA SOL-GELFILMS/

Fine gold (Au) particles were formed by photochemical and ther mal pro cesses in silica/titania glassy films. Photoreduction and/or thermal g elation of films dip-coated from silica/titania precursor solutions in cluding Au(III) ions yielded gold particles. Particle formation was ac companied by changes in the surface plasmon band. The size and morphol ogy of the particles were affected by the titania content of the mixtu re matrix films as well as by the gelation temperature. With higher ti tania contents and at higher temperatures the particle formation was a ccelerated and accompanied by a red shift of the absorption band. This particle formation occurred by diffusion and reduction of the doped A u(III) ions, both of which were promoted at higher titania contents. T he controllable photodeposition process enabled us to form micropatter ns of Au particles by using photomasks.