Two-Photon Activation Of O-Nitrobenzyl Ligands Bound To Gold Surfaces

We report on the use of two-photon absorption to photocleavage o-nitrobenzyl-based ligands bound to a gold surface with thiol groups. Ablation of ligands occurs at high power densities, but this can be largely avoided by reducing the optical power level, at which point two-photon mediated reactions still occur on a time scale of tens of seconds. This means that photoactive ligands can be activated at wavelengths where plasmon resonances in gold and silver nanoparticles can easily be achieved, which will allow the surface properties at the hot spots on plasmonic nanostructures to be chosen differently from the rest of the structure, with possible applications in high-efficiency Surface-Enhanced Raman Spectroscopy and bottom-up nanoassembly.