High Harmonic Generation in Laser-Assisted Radiative Attachment or Recombination Processes

Resonant enhancements are predicted in cross sections σ_n for laser-assisted radiative attachment or electron-ion recombination accompanied by absorption of n laser photons. These enhancements occur for incoming electron energies at which the electron can be attached or recombined by emitting μ laser photons followed by emission of a spontaneous photon upon absorbing n+μ laser photons. The close similarity between rescattering plateaus in spectra of resonant attachment/recombination and of high-order harmonic generation is shown based on a general parametrization for σ_n and on numerical results for e-H attachment.