State-Specific Nonresonant and Resonant Plasmon-Driven Electron Transfer into Single Molecules

Harnessing plasmonic energy to drive selective chemical transformations is central to photocatalysis, solar energy conversion, and molecular optoelectronics. Plasmon-driven chemistry proceeds through nonresonant plasmonic hot electron transfer or more efficient resonant charge transfer, yet cleanly disentangling these channels has remained a long-standing challenge, especially in synthetic nanoparticle systems with heterogeneous molecular environments. Here, using the nanocavity plasmon generated between an Ag tip and individual pentacene molecules on Ag(110) in a scanning tunneling microscopy (STM) junction, we directly unveil both channels with submolecular resolution. Combining chopper-modulated laser excitation with lock-in detection enables plasmon-induced current mapping at 0.3 nm resolution, allowing real-space correlation with frontier molecular orbitals. By tuning photon energy and bias voltage, we identify nonresonant hot-electron transfer via the lowest unoccupied molecular orbital (LUMO) and resonant charge transfer via LUMO + 1, where the resonant pathway markedly accelerates C-H bond breaking.