Abstract
Few-photon multiple ionization of Ne and Ar atoms by strong vacuum ultraviolet laser pulses from the free-electron laser at Hamburg was investigated differentially with the Heidelberg reaction microscope. The light-intensity dependence of production reveals the dominance of nonsequential two-photon double ionization at intensities of and significant contributions of three-photon ionization as increases. recoil-ion-momentum distributions suggest that two electrons absorbing “instantaneously” two photons are ejected most likely into opposite hemispheres with similar energies.
- Received 5 February 2007
DOI:https://doi.org/10.1103/PhysRevLett.98.203001
©2007 American Physical Society