Probing the warm dense copper nano-foil with ultrafast electron shadow imaging and deflectometry

We conducted ultrafast electron shadow imaging and deflection measurements of the optical laser-produced warm dense copper nano-foil. The results show that a significant amount of charge is ejected from the foil, forming electron clouds of hundreds of microns on both sides of the pumped foil. Furthermore, even for a thin 30-nm copper film, we found that the electron clouds develop asymmetry between the pumped front side and the rear side at the pump fluence of 4.5 J/cm2. The possible mechanism leading to this ejected charge asymmetry and its implication are discussed.