Jc. Williamson et Ah. Zewail, ULTRAFAST ELECTRON-DIFFRACTION - VELOCITY MISMATCH AND TEMPORAL RESOLUTION IN CROSSED-BEAM EXPERIMENTS, Chemical physics letters, 209(1-2), 1993, pp. 10-16
The time resolution of crossed-beam experiments is explicitly related
to velocity mismatch and other beam parameters. Application of this ge
neral treatment to ultrafast electron diffraction reveals that a time
resolution of approximately 1.4 picoseconds can be achieved under conv
entional conditions. It is possible to reduce this value by increasing
the electron energy, varying the angle between the electron and laser
pulses, and reducing the focal width of the laser and the size of the
molecular beam.