Angular distributions, energy disposal, and branching studied by photoelectron–photoion coincidence spectroscopy: O2+, NO+, ICl+, IBr+, and I2+ fragmentation

It is shown that some levels of the A2Πu states of I2+, IBr+, and ICl+ are stable toward dissociation, and ought to decay by emission. The B2Σg+ state of I2+ is fully dissociated to ground state I++I, while the B2Σg+ states of IBr+ and ICl (probably) yield excited decay products. The c3Π and B1Π states of NO+ dissociate to ground state N++O fragments, while the c4Σg− and 2Πu states of O2+ near 24 eV dissociate to excited levels of O++O. The origin of anomalous time-of-flight peak shapes is discussed, and several examples are attributed to anisotropic fragment angular distributions.