  The investigation of ultrafast electronic and structural dynamics in
low-dimensional systems like nanowires and two-dimensional materials requires
femtosecond probes providing high spatial resolution and strong interaction
with small volume samples. Low-energy electrons exhibit large scattering cross
sections and high sensitivity to electric fields, but their pronounced
dispersion during propagation in vacuum so far prevented their use as
femtosecond probe pulses in time-resolved experiments. Employing a
laser-triggered point-like source of either divergent or collimated electron
wave packets, we developed a hybrid approach for femtosecond point projection
microscopy and femtosecond low-energy electron diffraction. We investigate
ultrafast electric currents in nanowires with sub-100 femtosecond temporal and
few 10 nm spatial resolutions and demonstrate the potential of our approach for
studying structural dynamics in crystalline single-layer materials.
