Plasmonic Properties of Copper Nanoparticles Fabricated by Nanosphere Lithography

The localized surface plasmon resonance (LSPR) of oxide-free Cu nanoparticles fabricated by nanosphere lithography is examined by UV−vis extinction spectroscopy and electrodynamics theory. The LSPR of the Cu nanoparticles is significantly affected by the presence of copper oxides and the removal of the oxide species yields a dramatic difference in the observed LSPR. From a comparison of the LSPR of Cu, Ag, and Au nanoparticles of similar geometry, we conclude that Cu displays an intense and narrow LSPR peak that is comparable to Ag and Au.