Time-Dependent Mass Spectra and Breakdown Graphs. 6. Slow Unimolecular Dissociation of Bromobenzene ions at Near Threshold Energies

Article abstract of DOI:10.1021/j100257a021

Time-resolved photoionization mass spectrometry (TPIMS) in the millisecond range has been employed to study the reaction C6H5Br(1+) radical -> C6H5(1+) + Br radical in bromobenzene.Experimental photoionization efficiency curves were fitted with a QET model calculation by assuming a critical energy E_o = 2.76 eV and an activation entropy ΔS(excit.) = 8.07 eu.The activation entropy coresponds to the totally loose (orbiting) transititon state.Ultraslow unimolecular dissociations having microcanonical rate coefficients k(E)