Inelastic Scattering of Broadband Electron Wave Packets Driven by an Intense Midinfrared Laser Field

Intense, 100 fs laser pulses at 3.2 and 3.6 mu m are used to generate, by multiphoton ionization, broadband wave packets with up to 400 eV of kinetic energy and charge states up to Xe+6. The multiple ionization pathways are well described by a white electron wave packet and field-free inelastic cross sections, averaged over the intensity-dependent energy distribution for (e, ne) electron impact ionization. The analysis also suggests a contribution from a 4d core excitation, or giant resonance, in xenon.