Enhanced hot electron rise time published in Nature Commun.
O. Lozan, R. Sundararaman, B. Ea-Kim, J.-M. Rampnoux, P. Narang, S. Dilhaire and P. Lalanne, “Increased rise time of electron temperature during adiabatic plasmon focusing”, Nature Commun. 8, 1656 (2017)
The Dilhaire and Lalanne groups at Bordeaux show that when plasmons are adiabatically focused to the tip of a tapered plasmonic waveguide, the time taken for electrons to reach their maximum temperature near the tip appears to increase. This is exactly opposite to the expected result: near the tip, the focused high-intensity plasmon creates more hot carriers, which require fewer collisions to thermalize and should hence reach their maximum temperature quicker. Using calculations of hot carrier transport in this structure, we show that, in fact, the increase in rise time is due to rapid flow of energy from the hotter tip to the cooler regions near it. This heat flow delays the rise of the temperature by about a picosecond, roughly hundred nanometers from the tip, and it is this delayed region that contributes to the averaged signal obtained from the tip region. Plasmonic hot carrier systems require careful simulations of carrier dynamics and transport!