Spectroscopic investigations of nanoporous SiO sub(2 impregnated with Ag [beta]-diketonates from supercritical solution of carbon dioxide)

Porous materials based on SiO sub(2 containing nanoparticles of silver (NP Ag) are perspective objects for different medico-biological and optoelectronic applications. In the present work nanoporous glasses Vycor (pore size [approx]4 nm) and synthetic opal matrices (OM, void size [approx]40 nm) impregnated with [beta]-diketonates of silver (Ag(hfac)COD) via solution of supercritical carbon dioxide were studied. Paramagnetic molecules Cu(hfac)) sub(2) were used as spectroscopic probes permitting to obtain the information about the incorporation of similar organometallic molecules into these matrices. Spectra of absorption and electronic paramagnetic resonance (EPR) in the samples of porous SiO sub(2 containing Ag(hfac)COD were studied before and after heat treatment in air atmosphere. In both materials impregnated at temperature above 50 degree C the absorption band at 420-430 nm (the plasmon resonance (PR) band)) typical for nanoparticles of metallic Ag is observed. This band increases in the intensity at heat treatment or at an increase in temperature of impregnation processing. Features of the formation of the PR band in each case depends on sizes and shape of voids in the samples as well as on conditions of heat treatment. The states of paramagnetic centers formed after Ag(hfac)COD introduction are analyzed.)