Two-channel dissociation of chemically and thermally activated n-butylbenzene cations (C10H14+)

The charge-transfer reaction O2+ + n-butylbenzene (C10H14) → O2 + C10H14+* was studied in a turbulent ion flow tube at temperatures between 423 and 548 K and pressures between 15 and 250 Torr in the buffer gases He and N2. Under chemical activation conditions stabilization vs dissociation ratios S/D of vibrationally highly excited C10H14+* as well as branching ratios of the fragments C7H7+ (m/z = 91) vs C7H8+ (m/z = 92) of the dissociation of C10H14+* were measured. Under thermal activation conditions, the rate constant of the dominating dissociation channel 92 was measured at 498 and 523 K. Employing information on the specific rate constants k(E) of the two channels 91 and 92 and on collisional energy transfer rates from the literature, the measured S/D curves and branching ratios 91/92 could be modeled well. It is demonstrated that the charge transfer occurs approximately equally through resonant transfer and complex-forming transfer. The thermal dissociation experiments provide a high precision value ...