Electron-ion coincidence momentum spectroscopy: Its application to Ar dimer interatomic decay

Electron-ion-ion coincidence momentum spectroscopy, a well-established tool to study the molecular-frame core-level photoelectron angular distribution, has been applied to investigate interatomic electronic decay processes in argon dimers Ar2 after the creation of a 2p inner-shell vacancy. Some interatomic Coulombic decay (ICD) processes from an Auger-final dicationic state are identified from the coincidence measurement between the kinetic energy of the ICD electron and the kinetic energy release between Ar+ and Ar2+. The interatomic character of the dissociation processes into Ar+-Ar+ is also discussed.