Single-Molecule Study of a Plasmon-Induced Reaction for a Strongly Chemisorbed Molecule.

Chemical reactions induced by plasmons achieve effective solar-to-chemical energy conversion. However, the mechanism of the reactions induced by the plasmons, which generate a strong electric field, hot carriers and heat through the excitation and decay processes, is still controversial. In addition, what factor governs the mechanism is not fully understood. To obtain mechanistic knowledge, we investigated the plasmon-induced dissociation of a single-molecule strongly chemisorbed on a metal surface, two O 2 species chemisorbed on Ag(110) with different orientations and electronic structures, using a scanning tunnelling microscope (STM) combined with light irradiation at 5 K. A combination of quantitative analysis by the STM and density functional theory calculations revealed that the hot carriers are transferred to the antibonding (pi*) orbitals of O 2 strongly hybridized with the metal states and that the dominant pathway and reaction yield are determined by the electronic structures formed by the molecule-metal chemical interaction.