title: Ponderomotive shearing for spectral interferometry of extreme-ultraviolet pulses.
abstract: We propose a novel method for completely characterizing ultrashort pulses at extreme-ultraviolet (XUV) wavelengths by adapting the technique of spectral phase interferometry for direct electric-field reconstruction to this spectral region. Two-electron wave packets are coherently produced by photoionizing atoms with two time-delayed replicas of the XUV pulse. For one of the XUV pulses, photoionization occurs in the presence of a strong infrared pulse that ponderomotively shifts the binding energy, thereby providing the spectral shear needed for reconstruction of the spectral phase of the XUV pulse.
authors.affiliation: Department of Physics, Lund Institute of Technology, P.O. Box 118, SE-221 00 Lund, Sweden. johan.mauritsson@fysik.lth.se
authors.forename: Johan
authors.initials: J
authors.lastname: Mauritsson
authors.forename: Rodrigo
authors.initials: R
authors.lastname: López-Martens
authors.forename: Anne
authors.initials: A
authors.lastname: L'Huillier
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Schafer