Dimer of parallel gold cylinders of diameter D = 10 nm. The cylinders are separated by a gap of dgap = 3 nm. The dimer is excited by a sub-cycle laser pulse with a Gaussian envelope characterized by a carrier frequency ω and a carrier envelope phase ϕ. Two examples of the laser electric field are shown for ϕ = 0 (blue line) and ϕ = π/2 (red line). We study the dynamics of the optical-field emitted electrons in the plasmonic gap and their dependence on ϕ and ω.

Project B08: Faraday Discussions 2019

Dynamics of electron-emission currents in plasmonic gaps induced by strong fields

The dynamics of ultrafast electron currents triggered by femtosecond laser pulse irradiation of narrow gaps in a plasmonic dimer is studied using quantum mechanical Time-Dependent Density Functional Theory (TDDFT). The electrons are injected into the gap due to the optical field emission from the surfaces of the metal nanoparticles across the junction. Further evolution of the electron currents in the gap is governed by the locally enhanced electric fields. The combination of TDDFT and classical modelling of the electron trajectories allows us to study the quiver motion of the electrons in the gap region as a function of the Carrier Envelope Phase (CEP) of the incident pulse. In particular, we demonstrate the role of the quiver motion in establishing the CEP-sensitive net electric transport between nanoparticles.

G. Aguirregabiria, D.-C. Marinica, M. Ludwig, D. Brida, A. Leitenstorfer, J. Aizpurua, A. G. Borisov 
Faraday Discussions 214, 147-157 (2019)
DOI: 10.1039/c8fd00158h