Full quantum state-to-state mapping of molecular ion collisions via electron-ion coincidence spectroscopy

Exothermic inelastic and reactive process with strong interactions usually lead to a large number of accessible quantum states in the product channels. The final quantum state distribution caries unique information about the microscopic collision mechanism. However, experimental measurement of a complete quantum state distribution in many channels remains challenging and rare.

We present a new method that allows us to measure state-to-state differential cross sections for both the inelastic and reactive scattering of molecular hydrogen ion upon collisions with neutral noble gas atoms. We are able to resolve rotational states for the final molecular ion in both cases. Our method is based on following the collisions using coincidence ion-electron velocity map imaging spectroscopy.