One-photon infrared photodissociation of polyatomic ions in a fast beam

Article abstract of DOI:10.1021/j100295a030

Photodissociation of 22 vibrationally excited polyatomic ions, ranging in size from four to thirteen atoms, has been observed following absorption of a single CO₂-laser photon. In a number of cases the infrared wavelength dependence of the process shows well-defined peaking, which can be interpreted as absorption at the normal-mode frequencies of the ion. Kinetic energy release and order-of-magnitude fragmentation rate information have also been obtained for both photon-induced and metastable decomposition of a number of the ions. RRKM theory modeling indicates that these data are compatible with a quasi-equilibrium theory description of the unimolecular decomposition of highly vibrationally excited molecular ions. Considered as resulting from the last photon absorption of a multiphoton dissociation process, these results are relevant to understanding infrared multiphoton photochemistry of polyatomic molecules.