Rare-gas clusters in intense extreme-ultraviolet pulses from a high-order harmonic source

Phys Rev Lett. 2014 Feb 21;112(7):073003. doi: 10.1103/PhysRevLett.112.073003. Epub 2014 Feb 20.

Abstract

We report evidence for two previously unidentified effects in the ionization of rare-gas clusters by intense extreme-ultraviolet pulses. First, electron spectra indicate multistep photoemission with increasing isotropy for larger clusters due to electron-atom collisions. Second, very slow (meV) electrons are interpreted as the first experimental evidence for Rydberg-like atomic state formation in the nanoplasma expansion. Only small fractions of Xe2+ ions were found, in sharp contrast to previous results recorded under comparable conditions [Murphy et al., Phys. Rev. Lett. 101, 203401 (2008).