Fig. 1: Representative diffraction data collected using MeV-UED.
A schematic of the ultrafast electron diffraction setup is shown in (a) for studies of thin Al targets pumped by 70 fs, 800 nm laser pulses. The inset shows the near flat-top profile of the pump pulse, and the shaded region is the 200 μm region probed by the electron beam. The false color diffraction pattern is the average of 20 single-shot measurements. Images in (b–e) show false color images of the radial diffraction pattern at selected time delays. Each image is the average of 20 measurements. Samples were irradiated with a fluence of ~200 mJ cm−2, corresponding to an absorbed energy density of 2.42 MJ kg−1. The patterns show clearly evidence of solid material at up to 2 ps delay, but by 5 ps the sharp peaks indicative of solid material are replaced by broad rings.
