LINEAR AND NONLINEAR-OPTICAL PROPERTIES SOL-GEL-DERIVED AU NANOMETER-PARTICLE-DOPED ALUMINA

The precursor Au-doped alumina gel film was prepared by a sol-gel meth od using HAuCl4 . 4H(2)O and alumina sol derived from AlCl3 . 6H(2)O. The precursor gel was heat treated in a H-2 gas flow at 300-800 degree s C. Average particle diameters of the Au particle of doped films were in the range of 4.6-12.7 nm. In the absorption spectra of the film, p lasmon resonance absorption was strongly dependent on the heat treatme nt temperature of the alumina matrix, showing more sharp spectra and s ignificant red shift with decreasing particle size. It was interpreted by a modified Mie-Drude equation by taking into consideration of a sp illing out of electrons from the Au particle to the alumina matrix. Th e measured values of chi(m)((3)) of the doped films are in the range o f 9.2X10(-6)-4.0X10(-5) esu in the neighborhood of plasmon resonance w avelength of 530-570 nm. These are larger than those reported for the other doped systems. A dominant nonlinear response on the 1-3 ps time scale was obtained, reflecting higher thermoconductivity of alumina co mpared to that of conventional matrix such as SiO2. (C) 1997 American Institute of Physics.