Time-resolved potodissociation (TRPD) of the naphthalene and azulene cations in an ion trap/reflectron

Dissociation rates have been measured by multiphoton ionization and time-re solved photodissociation for benzene-d(6)(.+), naphthalene-h(8)(.+), naphth alene-d(8)(.+), and azulene-h(8)(.+) employing a quadrupole ion trap/reflec tron mass spectrometer. Results compare favorably with available data from ICR cells and cylindrical ion traps. Azulene(.+) is photodissociated upon a bsorption of two 400 nm photons giving C2H2, H-., and H-2 eliminations. Dis sociation rate constants measured for naphthalene(.+) and azulene(.+) at id entical absolute energies are equal within experimental error. This experim ental result is in agreement with previous density functional theory (DFT) calculations that demonstrated the isomerization of azulene(.+) to naphthal ene(.+) below the dissociation limit of benzocyclobutadiene(.+) + acetylene .