Electron affinity measurement of hydrogen negative ion

Abstract

Photodetachment Microscopy experiment was first carried out in the presence of an electric field by Blondel et al in 1996 for Bromine negative ion. It measures the spatial distribution of ejected electrons on the detector screen which is a direct view of the spatial structure of the wave function of an atomic electron in the form of a ring pattern. From a semi-classical point of view, this ring pattern is formed because of the interference between two electron waves; one is direct while the other is reflected from an electric field. Following Blondel's photodetachment microscopy experiment, a formula that displays the Newton Rings is derived using a theoretical imaging technique or hydrogen negative ion near a plane interface. The interface means an elastic plane in the vicinity of the source of photoelectrons. The direct and reflected electron waves in this formula generate quantum interference in the form of Newton Rings. It is found that the number of rings increases as we increase the photon energy of the laser light. This finding is in accordance with the very well-known Einstein photoelectric effect which finally provides help to find the electron affinity of the hydrogen negative ion very accurately.