Qualitatively different theoretical predictions for strong-field photoionization rates

Abstract

We give examples showing that two well-known versions of the -matrix theory, which describes a nonresonant multiphoton ionization of atoms and ions in intense laser fields, lead to qualitatively different results. The latter refer not only to total ionization rates, but also to energy distributions of photoelectrons, for instance in a polarization plane of the laser field. It should be possible to make an experiment testing predictions of both theories in the near future.S ________________ *bauer@uni.lodz.pl

Multipeak envelope of the above-threshold-ionization energy spectrum in a strong circularly polarized laser field

“…This is probably a typical situation for most of the excited states (with the principal quantum number n > 1), although we have verified this statement only for n = 2. A similar existence of a multipeak envelope was found previously in the 3D case (both in the full solid angle [8] and in the polarization plane [17,23]). On the whole, we connect 063417-8 this phenomena with a nontrivial functional dependence (on r or p) of the initial-state wave function (respectively, in the spatial or the momentum representation).…”

“…In fact, we found such behavior for the states 2p ± in Ref. [17] and for the 2s state [23]. Figures 5-10 show generally that when the electron initially rotates against the laser field one should expect a smaller final kinetic energy than for the corotated electrons.…”

“…The latter may be applied in the length gauge (LG) [4,8] or in the velocity gauge (VG) [7]. Extensive studies of gauge aspects by others [9][10][11][12][13] as well as by us [8,[14][15][16][17] has led us to a present belief of superiority of the LG in the context of S-matrix and strong laser fields. Our present results amplify this conviction.…”

Numerical tests of theoretical models describing ionization of H(1s) atom by linearly polarized flat pulse of laser radiation

“…( 10) is used. [49][50][51] This is true both for the linear [49] and circular polarization [50] of incident radiation. However, the limit ω → 0 (when the field amplitude F = const and γ → 0) does not mean that there is no electric field.…”

Simple formula for the ionization rate of diatomic molecules in an intense laser field using the velocity gauge

“…[16] In the meantime, many authors have performed studies, attempting to theoretically prove that the gauge invariant is still valid for photoionization amplitude. [17][18][19][20][21][22] However, all of them are achievable within any gauge as long as a proper partition of the Hamiltonian is performed. The case is not so optimistic in that as long as one expands the SFA to molecular systems [23,24] in any gauge, similar or even more pronounced gauge dependencies will appear.…”