Dynamics of charge clouds ejected from laser-induced warm dense gold nanofilms

Abstract

We report a systematic study of the ejected charge dynamics surrounding laser-produced 30-nm warm dense gold films using single-shot femtosecond electron shadow imaging and deflectometry. The results reveal a two-step dynamical process of the ejected electrons under high pump fluence conditions: an initial emission and accumulation of a large amount of electrons near the pumped surface region, followed by the formation of hemispherical clouds of electrons on both sides of the film, which escape into the vacuum at a nearly isotropic and constant velocity with an unusually high kinetic energy of more than 300 eV. We also developed a model of the escaping charge distribution that not only reproduces the main features of the observed charge expansion dynamics but also allows us to extract the number of ejected electrons remaining in the cloud.

Electron cascades and secondary electron emission in graphene under energetic ion irradiation

“…Similar electrostatic approaches have been used previously to model the barrier for electron emission in charged metallic clusters [37][38][39][40] and to study the dynamics of the emitted electrons in metals during laser irradiation. 41 In the following, we describe these techniques in detail. Throughout this work, we use a 0 for the hydrogen Bohr radius and atomic units (a.u.)…”