Self-Reactions in the HBr (DBr) + HBr System: A State-Selective Investigation of the Role of Rotation.

Self-reactions observed in the HBr (DBr) + HBr system have been investigated using a guided ion-beam experiment under single-collision conditions. The reaction channels observed are proton transfer/hydrogen abstraction (PT/HA) in the case of HBr and deuteron transfer/hydrogen abstraction (DT/HA) and charge transfer (CT) in the case of DBr. HBr/DBr ions have been formed with rotational energies selected using the resonance-enhanced multiphoton ionization (REMPI) formation process. Cross sections have been measured as a function of the rotational energy of the ion, , and of the center-of-mass collision energy, . In the region of low rotational energies, the cross section for both PT/HA and DT/HA decreases with increasing ion rotation. In this region, the cross section for CT increases with increasing ion rotation. For higher rotational energies, the cross section increases with increasing ion rotation for PT/HA and less pronounced for DT/HA. The cross section for CT becomes independent of ion rotation for high rotational energies. Since all reaction channels are exothermic, all cross sections decrease with increasing .