Role of resonances and quantum-mechanical interference in the generation of above-threshold-ionization spectra

A general technique for modeling the behavior of an atom in the presence of a laser field is described. This involves the integration of the time-dependent Schr\"odinger equation in the Kramers-Henneberger frame. Results are presented for a one-dimensional calculation for a model hydrogen atom across a range of frequencies and intensities. The resultant peaks in the photoelectron spectra produced are shown to be partly the result of Stark-shifted bound-state multiphoton resonances. The spectra also contain rainbow features due to interference between the electron amplitude generated on the rising and falling edge of the pulse. These rainbow features are a purely time-dependent effect that can only be easily reproduced in time-dependent calculations.