Tracking ultrafast hot-electron diffusion in space and time by ultrafast thermo-modulation microscopy

Abstract

The ultrafast response of metals to light is governed by intriguing non-equilibrium dynamics involving the interplay of excited electrons and phonons. The coupling between them gives rise to nonlinear diffusion behavior on ultrashort timescales. Here, we use scanning ultrafast thermo-modulation microscopy to image the spatio-temporal hot-electron diffusion in a thin gold film. By tracking local transient reflectivity with 20 nm and 0.25 ps resolution, we reveal two distinct diffusion regimes, consisting of an initial rapid diffusion during the first few picoseconds after optical excitation, followed by about 100-fold slower diffusion at longer times. We simulate the thermo-optical response of the gold film with a comprehensive three-dimensional model, and identify the two regimes as hot-electron and phonon-limited thermal diffusion, respectively.

20 pages, 8 figures

References in corpus (5)

• Temperature-dependent optical properties of gold thin films
• Temperature effects on the surface plasmon resonance in copper nanoparticles
• An analytic model of the Gruneisen parameter at all densities
• Ambipolar diffusion of photo-excited carriers in bulk GaAs
• Temperature-dependent permittivity of annealed and unannealed gold films

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