Tracing non-equilibrium plasma dynamics on the attosecond timescale in small clusters

TL;DR

This paper demonstrates a method to trace the ultrafast non-equilibrium plasma dynamics in small rare-gas clusters on the attosecond timescale using time-delayed XUV pulses to measure electron detachment energies, revealing plasma formation during femtosecond laser pulses.

Contribution

It introduces a novel attosecond pump-probe scheme to monitor nano-plasma formation and dynamics in clusters with high temporal resolution.

Findings

Charge buildup occurs during femtosecond pulse irradiation.

The proposed scheme is experimentally feasible with current harmonic generation techniques.

Attosecond pulses can induce and observe non-equilibrium plasma dynamics.

Abstract

It is shown that the energy absorption of a rare-gas cluster from a vacuum-ultraviolet (VUV) pulse can be traced with time-delayed extreme-ultraviolet (XUV) attosecond probe pulses by measuring the kinetic energy of the electrons detached by the probe pulse. By means of this scheme we demonstrate, that for pump pulses as short as one femtosecond, the charging of the cluster proceeds during the formation of an electronic nano-plasma inside the cluster. Using moderate harmonics for the VUV and high harmonics for the XUV pulse from the same near-infrared laser source, this scheme with well defined time delays between pump and probe pulses should be experimentally realizable. Going to even shorter pulse durations we predict that pump and probe pulses of about 250 attoseconds can induce and monitor non-equilibrium dynamics of the nano-plasma.