Kinetic energy release of C70(+) and its endohedral cation N@C70(+): activation energy for N extrusion.
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.
Cao
Baopeng
B
Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, IN 47404, USA. bcao@tara.tsukuba.ac.jp
Peres
Tikva
T
Lifshitz
Chava
C
Cross
R James
RJ
Saunders
Martin
M