The photodetachment microscope

Br- ions undergo photodetachment in the presence of an electric field. As a result of the photoexcitation process, the emitted electron's wave function extends to infinity, but inside a paraboloid elongated in the direction of the field. A position-sensitive detector set across the electron emission axis makes it possible to image the transverse factor of the atomic wave function. A ring pattern is observed, with a number of dark rings which is analogous to the first parabolic quantum number of the LoSurdo-Stark problem.