Fig. 3

Momentum exchange during electron–light interaction. a Direct electron beam measured in the diffraction plane as a function of transversal momentum (k_x, k_y) when no light is applied. b, c Same as a under illumination with 560 fs laser pulses of 11.1 × 10⁷ V/m peak field amplitude and α = α_C. The ϑ tilt angle is 0° in b and 35° in c. A clear streaking of the electron beam appears along the k_x direction in c as a result of momentum exchanges between light and electrons. d Electron-beam profile along k_x as a function of light polarization (sin ϕ = 0 for s-polarization and sin ϕ = ±1 for p-polarization). e Direct electron beam measured in the momentum-energy plane k_x − E in the absence of optical illumination. f, g Measured (f) and simulated (g) momentum-energy maps for illumination under the conditions of c