Time-Resolved Photodissociation (TRPD) of the Naphthalene and Azulene Cations in an Ion Trap/Reflectron

Dissociation rates have been measured by multiphoton ionization and time-resolved photodissociation for benzene- d 6 •+, naphthalene- h 8 •+, naphthalene- d 8 •+, and azulene- h 8 •+ employing a quadrupole ion trap/reflectron mass spectrometer. Results compare favorably with available data from ICR cells and cylindrical ion traps. Azulene •+ is photodissociated upon absorption of two 400 nm photons giving C 2 H 2, H ·, and H 2 eliminations. Dissociation rate constants measured for naphthalene •+ and azulene •+ at identical absolute energies are equal within experimental error. This experimental result is in agreement with previous density functional theory (DFT) calculations that demonstrated the isomerization of azulene •+ to naphthalene •+ below the dissociation limit of benzocyclobutadiene •+ + acetylene.