On the unimolecular loss of acetylene from metastable C11H9]+ ions

Extensive ¹³C labelling experiments demonstrate that loss of acetylene from metastable [C₁₁H₉]⁺ ions is a complex process, which can be described quantitatively in terms of a four-parameter model. The major reaction path (77.8%) involves scrambling of all 11 carbon atoms. Insight into the reaction details is provided neither by the kinetic energy release associated with the reaction [C₁₁H₉]⁺ → [C₉H₇]⁺ + C₂H₂ nor by the analysis of the collisional activation mass spectra of the resulting [C₉H₇]⁺ ions.