Plasmonic Interfaces for Electro-Optic Characterization of Molecular Junctions

Metallic nanowires have interesting optical applications that make them promising platforms for sensing applications. The optical properties originate from the excitation of surface plasmon polaritons with light. We use this phenomenon to develop new spectroscopic tools to characterize the nature and details of the molecular structures within active regions of nanometer-scale devices. To achieve optical excitation at the nanometer-scale, we use a far field plasmon launching and emission technique based on nanowires coupled to molecular junctions. It is shown that plasmons can couple efficiently across small interfaces and can propagate along crossed nanowires. Furthermore, the light emitted as elastic scattered photons can be used to selectively couple light into the region of molecules for optical excitation. The possibility of doing local optical excitation of molecules simultaneously with their current-voltage measurements could lead to a new sensing platform for molecules based on plasmonic interfaces.