title: Photoemission and ionization of He+ under simultaneous irradiation of fundamental laser and high-order harmonic pulses.
abstract: We theoretically study the response of He+ exposed simultaneously to an intense Ti:sapphire laser and its 27th or 13th harmonic pulses. High-order harmonic emission from He+ is enhanced by many orders of magnitude compared with the case of the fundamental pulse alone. Moreover, while an individual 10 fs laser (wavelength lambda(F)=800 nm) or its 27th harmonic pulse with a peak intensity of 3 x 10(14) and 10(13) W/cm(2), respectively, ionizes no more than 5 x 10(-6) of He+, their combined pulse leads to a surprisingly high He2+ yield of 17%.
authors.affiliation: Department of Quantum Engineering and Systems Science, Graduate School of Engineering, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656, Japan. ishiken@q.t.u-tokyo.ac.jp
authors.forename: Kenichi
authors.initials: K
authors.lastname: Ishikawa