A structural investigation of [C6H6]2+ and [C6H6]+˙ ions involved in charge exchange reactions

Autor: John H. Beynon, A.G. Brenton, M. Guilhaus, Robert Kingston
Rok vydání: 1985
Předmět:
Zdroj: Organic Mass Spectrometry. 20:565-571
ISSN: 1096-9888
0030-493X
DOI: 10.1002/oms.1210200907
Popis: Mass-analysed ion kinetic energy spectra for collisional activation (CA) of [C6H6]+˙ formed via electron capture by [C6H6]2+ ions in collision with neutral benzene molecules have been compared for the C6H6 isomers benzene, 1,5-hexadiyne and 2,4-hexadiyne. Comparisons of fragment abundance and total CA fragment yields were also made for [C6H6]+˙ ions generated by electron ionization (EI). CA conditions of ion velocity and collision gas pressure were identical in these comparisons. In general the fragment abundance patterns for the ions formed by charge exchange were very similar to those for singly charged benzene ions generated by EI. However, significant variations in CA fragment yield (the ratio of the total CA fragment ion abundance to the abundance of the incident unfragmented ions) were observed. It is not clear from the results whether these variations reflect structurally different ions or ions of different internal energies. The CA spectra of [C6H6]+˙ ions derived from charge exchange reactions between the benzene dication and the target gases He, Ne, Ar, Kr and Xe have also been recorded and, once again, very similar fragment abundance patterns were observed along with large variations in total CA fragment yields. Charge exchange efficiency measurements are reported for reactions between the benzene dication and the targets He, Ne, Ar, Kr, Xe and C6H6 (benzene) and also for the doubly charged ions derived from the linear C6H6 isomers. In the latter case Xe and benzene targets were used. The energetics and efficiency measurements for the former reactions suggest that for targets such as He and Ne the processes probably involve excited states of the doubly charged ions. The efficiencies measured for the latter reactions were distinctly different for the three C6H6 isomers and may indicate a strong dependence of charge exchange cross-section on doubly charged ion structure.
Databáze: OpenAIRE
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