Partial rates in the high-frequency regime of intense-field photoionization of hydrogen

Complex rotation in the exterior scaling version is applied to the solution of the coupled equations of Floquet theory for ground state hydrogen submi tted to an external intense oscillating linearly polarized electric field. The calculations are done in the Kramers-Henneberger frame. The fluxes are calculated in the asymptotic real part of the integration axis. The total a nd 1-photon rates are used to reassess the performances of a high-frequency two-pole approximation previously developed (J Phys B 1999, 32, 3271). For overthreshold frequencies, the partial rates with definite values of n, th e number of absorbed photons, and l, the angular quantum number of the ejec ted electron, show oscillations which are erased when summing over l. (C) 2 001 John Wiley & Sons, Inc.