Nanoscale Optical and Mechanical Manipulation of Molecular Alignment in Metal–Molecule–Metal Structures

Abstract

Equilibrium molecular orientations, monitored using surface enhanced Raman scattering, are controlled by both optical and mechanical means in metal–molecule–metal nanogap structures, formed on an atomically planar Au(111) surface. The spatially confined optical near-fields exert a torque on the molecules in the nanogaps and align the molecular orientations along the field vector. The mechanical compression from the metal nanogaps not only disturbs the molecular alignments but also perturbs the electronic structures at metal–molecule interfaces. The implications of such interactions are discussed with respect to control and detection of local electronic properties in molecular nanodevices.