Optical properties of low temperature prepared granular titanium dioxide on a silver substrate

Nanolayered systems composed of granular titanium dioxide layers coated on silver surfaces have been fabricated through a combined sputtering/sol–gel method. It has been demonstrated that, at a low temperature and in the absence of an additional heat treatment, nanocrystallites of titanium dioxide can be obtained without aggregation effects. The near-normal reflection spectrum showed a well-defined minimum at 314 nm corresponding to the silver bulk absorption properties and another structure beyond 400 nm that is due to surface plasma absorption. An effective medium theory is used to model the optical properties of the granular dielectric coated on a silver substrate, showing a good qualitative agreement with experiment.