C-H BOND STRENGTH OF NAPHTHALENE ION - A REEVALUATION USING NEW TIME-RESOLVED PHOTODISSOCIATION RESULTS

摘要

The dissociation rates and branching ratios for naphthalene ion (naphthalene-d(8) ion) have been measured by time-resolved photodissociation at an internal energy of 7.10 (7.13) eV. Dissociation rate constants of 6450 (2360) s(-1) were observed, with acetylene loss being somewhat favored over hydrogen atom and hydrogen molecule losses. Using simple RRKM theory, these results were modeled along with prior information from time-resolved dissociative photoionization and from photoelectron photoion coincidence to give rate-energy curves. Extrapolated to threshold, bond energies of 4.48 eV for H atom loss and 4.41 eV for acetylene loss were derived, in agreement with predictions from independent thermochemical data. The C-H bond energy (4.48 eV) is discussed relative to those for neutral aromatic hydrocarbons (4.8 eV) and benzene ion (3.7 eV). [References: 23]