Pulsed and Coherent Electron Emission from Tungsten Nanotips

Pulsed coherent electron sources are highly demanded for the development of time-resolved electron diffraction and imaging techniques. Here, we report quantitative measurements of the pulse width and spatial coherence for electrons emitted from tungsten nanotips. The pulse width of 340 eV electrons from a homemade needle is determined to be about 7.3 ps using a pump (femtosecond optical pulse)−probe (electron pulse) method. DC-field emission from a commercial sharp tungsten needle tip achieves a transverse coherence length of about 70 nm. These results highlight the potential of tip-based electron sources for ultrafast electron diffraction and imaging applications.