title: Kinetic energy release of C70(+) and its endohedral cation N@C70(+): activation energy for N extrusion.
abstract: Unimolecular decomposition of C70(+) and its endohedral cation N@C70(+) were studied by high-resolution mass-analyzed ion kinetic energy (MIKE) spectrometry. Information on the energetics and dynamics of these reactions was extracted. C70(+) dissociates unimolecularly by loss of a C2 unit, whereas N@C70(+) expels the endohedral N atom. Kinetic energy release distributions (KERDs) in these reactions were measured. By use of finite heat bath theory (FHBT), the binding energy for C2 emission from C70(+) and the activation energy for N elimination from N@C70(+) were deduced from KERDs in the light of a recent finding that fragmentation of fullerene cations proceeds via a very loose transition state. The activation energy measured for N extrusion from N@C70(+) was found to be lower than that for C2 evaporation, higher than the value from its neutral molecule N@C70 obtained on the basis of thermal stability measurements, and coincident with the theoretical value. The results provide confirmation that the proposed extrusion mechanism in which the N atom escapes from the cage via formation of an aza-bridged intermediate is correct.
authors.affiliation: Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, IN 47404, USA. bcao@tara.tsukuba.ac.jp
authors.forename: Baopeng
authors.initials: B
authors.lastname: Cao
authors.forename: Tikva
authors.initials: T
authors.lastname: Peres
authors.forename: Chava
authors.initials: C
authors.lastname: Lifshitz
authors.forename: R James
authors.initials: RJ
authors.lastname: Cross
authors.forename: Martin
authors.initials: M
authors.lastname: Saunders