Ar+3 photodissociation and its mechanisms

The photodissociation spectrum of Ar+3 between 520 and 620 nm is reported. A broadband peaking near 520 nm is observed with a cross section of ∼1.8×10−16 cm2 at the peak, in agreement with the findings of Levinger et al. [J. Chem. Phys. 89, 71 (1988)]. However, in the present work, a shoulder whose prominence is highly temperature dependent is observed between 545 and 555 nm. The new results are discussed in terms of various electronic transitions and pathways to dissociation. The photodissociation mechanisms are studied by translational energy analysis of photofragmentation. Three photodissociation mechanisms that involve two electronic energy surfaces are proposed which account for the experimental findings.