Study of electron-detachment and inelastic processes in Cl--rare-gas collisions

Cl--rare-gas collisions are investigated in the laboratory energy range 80-2000 eV. The main processes are identified by the characteristic energy losses undergone by the scattered particles. Relative differential cross sections for various processes have been measured. Basic similarities with other closed-shell systems (rare-gas-rare-gas and alkali-ion-rare-gas collisions) are underlined, and this gives confidence in the application of the molecular-orbital description to the halide negative-ion-rare-gas collisions. In particular, the use of this model suggests a new type of mechanism for the simple detachment process as an alternative to direct coupling between the incident state and a continuum. The simple detachment proceeds via a two-step mechanism: population of a resonant singly excited quasi-molecular state occurs at small internuclear distance; on the way out, this state autodetaches in the continuum associated with the 2 Sigma + ground state.