(a) A schematic of the experimental set-up. Light and electron pulses at a variable time delay are spatially overlapped on an isolated Ag nanowire suspended on a TEM grid with a few-layer graphene support layer. Probing electrons are detected using a CCD camera after passing through an electron imaging filter. (b) Map of the electron energy loss intensity versus the relative time delay Δt between the optical pump and electron probe pulses, taken on a single photoexcited nanowire (5.7 μm length, ≃67 nm radius). Excitation wavelength and polarization angle are 800 nm and ϕ=45°, respectively. Energy spectra at negative (Δt=−1.6 ps, black trace) and zero delay (Δt=0 ps, orange trace) are superimposed. The intensity in both the map and the spectra is plotted on a logarithmic scale. (c–g) Snapshots of an isolated nanowire at different time delays obtained using only the electrons that have gained energy, that is, those in the region indicated by the white arrow in b. Electron counts are on a linear scale. The vertical scale bar in c corresponds to 2 μm and holds for all images.