Langmuir 1991, 7, 3046-3051
3046
A Comparison of Iron Oxides Photodeposited in Porous Vycor Glass and Tetramethoxysilane/Methanol/Water Xerogels Edgar A. Mendoza,? Eugene Wolkow,t D. Suni1,t Peter Wong,? Jonathon Sokolov,t Miriam H. Rafailovich,t Marten den Boer,$ and Harry D. Gafney*pt Departments of Chemistry and Physics, City University of New York, Queens College, Flushing, New York 11367, and Department of Physics, City University of New York, Hunter College, New York, New York 10021 Received April 22, 1991. In Final Form: October 3, 1991 The iron oxides obtained by photolysis of Fe(C0)5 physisorbed onto porous Vycor glass (PVG) are compared to those obtained in tetramethoxysilane/methanol/water xerogels. Mossbauer and X-ray absorptionfine structure, extended,data indicatethe formation of surface-bound, octahedrally coordinated Fe3+species in both materials. Although photoimagingexperiments showthat iron oxide images of equivalent resolution can be deposited in both glasses, consolidation of the PVG samples, but not the xerogel samples, yields magnetically ordered materials exhibitingmagnetic hyperfine fields of 370 and 425 kG, respectively. Formation of a magnetically ordered material depends on initial Fe(C0)5 loading, and its occurrence in one glass, but not the other, is thought to reflect differences in the morphologies of the two materials. Introduction New optical technologies rest not only on the development of nonlinear optical materials, but also on the means to incorporate these materials in optically transparent media such as glass.'-* The refractory nature of glass precludes simple coupling techniques, and one avenue of investigation is to develop a means to create the optical elements in glass. Photolysis of organometallic precursors adsorbed onto porous Vycor glass (PVG) followed by thermal consolidation, for example, yields highly resolved (
