NAPHTHALENE ION PHOTO-DISSOCIATION - 2-PHOTON AND 4-PHOTON PROCESSES

Multiphoton photodissociation processes in the naphthalene molecular ions have been studied both at visible (600-670 nm) and UV (240-350 nm) wavelengths. The optical spectrum obtained is similar to the one for 1-methyl-naphthalene. Based on energetics, the photodissociation in the UV requires sequential absorption of two photons, while that at visible wavelengths needs four photons. Kinetic equations for several mechanistic models are solved by either analytical methods or computer simulation. These simple models can explain the variable dependence of photodissociation rate on light intensity. Also, it is suggested that fast radiative cooling rates are responsible for the very weak pressure dependence of the observed dissociation rates. Finally, calculated results come close to quantitative agreement with observation with the further postulation that optically inert states or structures are in fast equilibrium with the excited ions. © 1980 American Institute of Physics.