Images of a photoelectron interfering with itself: the photodetachment microscope

An electron emitted from a pointlike source, when submitted to uniform acceleration by an electric field, can follow several trajectories to the point where it is detected. The corresponding interference pattern has been observed in a photodetachment experiment. Fitting the pattern with the squared Green function of the uniform acceleration problem makes it possible to perform electron spectrometry with a 1 µeV accuracy. This has been used for electron affinity measurements, both on atomic anions and with a molecular one.