COULOMB EFFECT IN MULTIPHOTON IONIZATION OF RARE-GAS ATOMS

Using 200 fs, 800 nm Ti:sapphire laser pulses to ionize noble atom gas es, the ion versus intensity curves of these gases were obtained. By c omparing the experimental curves with those obtained using different t heoretical ionization rates, it was found that the inclusion of the ef fects on the ionization rate of the long-range Coulomb potential of th e parent ion through quasi-classical perturbation theory (as proposed by Perelomov et al and Krainov) gives a rather good overlap with the e xperimental results.