Interferences in coherent electron emission from diatomic molecules

Recent studies of electron emission from molecular hydrogen by the impact of fast ions have shown the existence of interference effects. The interferences are manifested as oscillations in the velocity (or energy) distributions of the ejected electrons, and are analogous to the interference of light in Young’s two-slit experiment. The frequencies of the oscillatory structures depend strongly on the electron observation angle and to a lesser extent on the collision velocity. Additionally, secondary oscillations with ∼2-3 times higher frequencies attributed to scattering of the primary electron “wave” at the other atomic center are found to be superimposed on the primary oscillations. More recently, electron interference studies have focused on diatomic molecules more complex than H₂, including N₂ and O₂, for which only structures due to secondary interferences are apparently observed. Here, these various results are reviewed, outstanding questions identified, and future directions indicated.