title: Plasmon-Mediated Electron Transport in Tip-Enhanced Raman Spectroscopic Junctions.
abstract: We combine experiment, theory, and first-principles-based calculations to study the light-induced plasmon-mediated electron transport characteristics of a molecular-scale junction. The experimental data show a nonlinear increase in electronic current perturbation when the focus of a chopped laser beam moves laterally toward the tip-sample junction. To understand this behavior and generalize it, we apply a combined theory of the electronic nonequilibrium formed upon decoherence of an optically triggered plasmon and first-principles transport calculations. Our model illustrates that the current via an adsorbed molecular monolayer increases nonlinearly as more energy is pumped into the junction due to the increasing availability of virtual molecular orbital channels for transport with higher injection energies. Our results thus illustrate light-triggered, plasmon-enhanced tunneling current in the presence of a molecular linker.
authors.affiliation: Department of Chemistry, ‡Department of Materials Science and Engineering, and ⊥Applied Physics Graduate Program, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Partha Pratim
authors.initials: PP
authors.lastname: Pal
authors.affiliation: Department of Chemistry, ‡Department of Materials Science and Engineering, and ⊥Applied Physics Graduate Program, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Nan
authors.initials: N
authors.lastname: Jiang
authors.affiliation: Department of Chemistry, ‡Department of Materials Science and Engineering, and ⊥Applied Physics Graduate Program, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Sonntag
authors.affiliation: Department of Chemistry, ‡Department of Materials Science and Engineering, and ⊥Applied Physics Graduate Program, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Naihao
authors.initials: N
authors.lastname: Chiang
authors.affiliation: Department of Chemistry, ‡Department of Materials Science and Engineering, and ⊥Applied Physics Graduate Program, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Edward T
authors.initials: ET
authors.lastname: Foley
authors.affiliation: Department of Chemistry, ‡Department of Materials Science and Engineering, and ⊥Applied Physics Graduate Program, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Hersam
authors.affiliation: Department of Chemistry, ‡Department of Materials Science and Engineering, and ⊥Applied Physics Graduate Program, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Van Duyne
authors.affiliation: Department of Chemistry, ‡Department of Materials Science and Engineering, and ⊥Applied Physics Graduate Program, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Tamar
authors.initials: T
authors.lastname: Seideman
keywords: STM; electron; laser; molecular; nonthermal; plasmon