Production of C2H4Cl+ by dissociative photoionization of weak molecular complexes in C2H4+HCl mixtures

Abstract

The photoionization efficiency (PIE) spectrum from 600 to 1200 A for the production of the ion C2H4C1 + by dissociative photoionization of the products of roomtemperature jet expansions of a 1:4 mixture of CzH4 and HC1 was measured at several nozzle pressures. The results were resolved into the PIE yield curve for the heterodimer process CzH4.HCI+hv--*C2H4C1 + + H + e. This reaction is necessarily characterized by a large change in geometry between neutral complex and ionic product. The observed spectrum exhibits an unusual and conspicuous peak at 15.2 eV that is characterized by a sharp cutoff to the high energy side. This feature points to the onset of strongly nonstatistical channels for the production of C2H4C1 + at this energy such that product formation proceeds through very few states. The observed onset of C2H4C1 + at 11.92+0.24eV is 17 _+ 6 kcal tool-~ above the true threshold. An important conclusion is that at all energies above the onset the yield of dissociative ionization of the heterodimer to the cation CzH,,C1 + is determined by dynamical factors.

Photoionization-Induced Intracluster Reactions of Chlorobenzene/Ammonia Mixed Complexes

“…Dissociative reactions in small mixed dimer ions usually proceed with barrier energies (£b) of the order of tenths of an electronvolt to several electronvolts. For example (1,3-C4H6-S02)+ -C4H6SO+ + 0 (£b = 2.3 eV)1 (C2H4-HC1)+ -C2H4C1+ + H (£b = 0.7 eV)2 (2) Analogous reactions that do not occur in dimers often take place in trimers, but still with high barriers. 3 -1-297 North Illinois Avenue, Apt.…”