Zirconia covered silver clusters through functionalized monolayers

We report a method of synthesis for zirconia coated silver clusters using self-assembled monolayers as templates. Formation of the zirconia cover, as monitored with X-ray diffraction and absorption spectroscopy, suggests a continuous overlayer growth that can be inhibited at any stage. Surface plasmon resonance of the silver cluster undergoes a gradual shift and decreases in intensity upon systematic build-up of the dielectric cover. The zirconia overlayer is optically transparent for smaller coverages, but becomes opaque for thicker layers. Spectroscopic studies showed that the mercaptobenzoic acid monolayer is intact in the synthetic procedure and the surface thiolate binding is unaltered. Preliminary studies suggest that metal ions can be incorporated into the oxide layer leading to a shift in the plasmon resonance band implying the possible use of these materials as ion sensors.