Crossed-beam velocity map imaging of collisional autoionization processes

Applying the velocity map imaging technique Penning ion formation as well a s generation of associative ions is observed in autoionizing collisions of metastable neon atoms (Ne-* 2p(5) 3s P-3(2,0)) with ground state argon targ ets in a crossed molecular beam experiment. Metastable neon reactants are o btained by nozzle expansion through a dc discharge ring. The quality of the obtained results clearly demonstrates the suitability of this new, particu larly straightforward experimental approach with respect to angle and kinet ic energy resolved investigations of Penning processes in crossed-beam stud ies which are known to provide the highest level of detail. (C) 2000 Americ an Institute of Physics. [S0021-9606(00)01942-5].