Photoionization microscopy of the hydrogen atom in parallel electric and magnetic fields

In photoionization microscopy experiments, an atom is placed in static external elds, it is ionized by a laser, and the electron falls onto a position-sensitive detector. The current of electrons arriving at various points on the detector depends upon the initial state of the atom, upon the excited states to which the electron is resonantly or non-resonantly excited, and upon the various paths leading from the atom to the nal point on the detector. We report here the rst quantum-mechanical computations of photoionization microscopy in parallel electric and magnetic elds. We focus especially on the patterns resulting from resonant excited states. We show that the magnetic eld substantially modies some of these resonant states, conning them in the radial direction, and that it has a strong eect on the interference pattern at the detector.