Observation of molecular frame (e,2e) cross section using an electron–electron-fragment ion triple coincidence apparatus

Abstract

An apparatus for electron–electron-fragment ion triple coincidence experiments has been developed to examine binary (e,2e) scattering reaction in the molecular frame. In the axial recoil limit of fragmentation of the residual ion, measurements of vector correlations among the three charged particles are equivalent to (e,2e) experiments with fixed-in-space molecules. Details and performance of the apparatus are reported, together with preliminary result of collision dynamics study on ionisation–excitation processes of fixed-in-space H 2 molecules. We believe that this is the first observation of molecular frame (e,2e) cross sections.