The ionization dynamics of a xenon cluster with 40 atoms is analyzed under a pump-probe scenario of laser pulses where an infrared laser pulse of 50-fs length follows with a well-defined time delay a vuv pulse of the same length and peak intensity. The mechanism of resonant energy absorption due to the coincidence of the ir laser frequency with the frequency of collective motion of quasifree electrons in the cluster is mapped out by varying the time delay between the pulses.
Phys. Rev. A

Siedschlag, C., & Rost, J. M. (2005). Surface-plasma resonance in small rare-gas clusters by mixing ir and vuv laser pulses. Phys. Rev. A, 71(Article number: 31401), 1–4. doi:10.1103/physreva.71.031401