Recoil Ion Momentum Spectroscopy A ’momentum microscope ’ to view atomic collision dynamics

Abstract. Recoil ion momentum spectroscopy is a powerful tool for investigating the dynamics of ion, electron or photon impact reactions with atoms or molecules. It allows to measure the three dimensional momentum vector of the ion from those reactions with high resolution and 4 pi solid angle. It can be easily combined with novel 4 pi electron momentum analysers and for coincident detection of the projectile. This technique gives a complete image of the square of the correlated many body final state wave function in momentum space (i.e. fully differential cross sections) for the various reactions. The application to photo double ionization of helium by linear and circular polarized light is discussed.