Plasmon manipulation by post-transition metal alloying

The design of new plasmonic materials is essential for continued progress in light manipulation at nanometer length scales. Often, multimetallic nanoparticles exhibit superior catalytic, mechanical, or corrosion-resistant behavior compared with their unary counterparts. Despite these advantages, designing multimetallic plasmonic materials remains challenging because, except for Au, Ag, and Al, most metallic elements exhibit poor plasmonic behavior. Here, we describe a strategy for manipulating the plasmon resonances of noble metal nanoparticles by post-transition metal alloying. We show how the metallic properties of post-transition metals—Bi, Ga, In, and Sn—can be imparted onto noble metals, enabling tunable higher-energy plasmon resonances that maintain high extinction coefficients and enter the UV. Theoretical modeling of simulated metallic mixtures and idealized Drude free-electron materials shows how this tunability is generalizable. Consequently, post-transition metal alloying provides a powerful strategy for realizing a new chemically diverse class of tunable plasmonic materials.