Twocolor ionization of hydrogen close to threshold with keV photons
Abstract
In a recent Letter [H. Bachau, M. Dondera, and V. Florescu, Phys. Rev. Lett. 112, 073001 (2014), 10.1103/PhysRevLett.112.073001] we considered the hydrogen atom in interaction with an electromagnetic field consisting in the coherent superposition of two keV pulses centered around two frequencies ω_{1} and ω_{2} that differ by a few atomic units. The analysis of the results obtained from the resolution of the timedependent Schrödinger equation focused on stimulated Compton scattering (SCS). We have developed in parallel an approach based on perturbation theory and it proved to be an appropriate and useful tool in complement to the nonperturbative approach. In this paper we present a detailed analysis of the electron spectra obtained for ℏω_{1}= 55 a.u. and two values of ℏω_{2}, 50 and 54 a.u. Emphasis is put on the case ℏω_{2}=54 a.u., where the electron emitted through SCS has the lowest energy, showing in particular that in the vicinity of the ionization threshold the cross section increases as ℏω_{1}ℏω_{2} decreases. We calculate photoelectron energy and angular distributions at various relative directions of propagation of the pulses. We discuss the limitations of the approximations underlying the numerical and analytical approaches used in this work.
 Publication:

Physical Review A
 Pub Date:
 September 2014
 DOI:
 10.1103/PhysRevA.90.033423
 Bibcode:
 2014PhRvA..90c3423D
 Keywords:

 32.80.Wr;
 12.20.Ds;
 Other multiphoton processes;
 Specific calculations