The decomposition of C4H8+ complexes at controlled internal energies

Abstract

A coincidence technique is used to study the influence of the internal energy of the reactant ion on the cross section of the ion-molecule reactions in the C2H4+ + C2H4 system. The experiment is performed at thermal collision energies. In the ion-molecule reactions of C2H4+ + C2H4 our measurements indicate a barrier between the initially formed collision complex (C2H4)2+* and a tight complex (C4H8+)*. Using an extension of our earlier developed statistical model, now including a potential barrier between the initially formed loose complex (C2H4)2+* and the tight complex (C4H8+)*, our experimental data can be reproduced. For comparison also the internal energy dependence of the unimolecular decomposition of photoionised 1-C4H8+ is measured. Assuming that the photoionised 1-C4H8+ is identical with the tight (C4H8+)* complex, the model applied to the ion-molecule reactions describes also the unimolecular decay of 1-C4H8+ correctly, using the same set of parameters.