Dissociation Dynamics and Stability of Cyclic Alkoxy Radicals and Alkoxide Anions

Photodetachment and dissociative photodetachment processes of cyclopropoxide, c-C3H5O-, and cyclobutoxide have been studied at 532 nm. Photodetachment of c-C3H5O- produces both the ground X(2A‘ ‘) state and the first excited A(2A‘) state of cyclopropoxy radical, c-C3H5O. The X(2A‘ ‘) state is stable at lower levels of excitation, but with increasing internal energy, dissociation into HCO + C2H4 is observed. The A(2A‘) state completely dissociates into HCO + C2H4. Correlated measurements of photoelectron and photofragment kinetic energies provide dissociation energies c-C3H5O- and c-C3H5O into HCO- + C2H4 and HCO + C2H4 of 0.85 ± 0.07 and −0.26 ± 0.07 eV, respectively. Ab initio calculations have been performed to aid the interpretation of the dissociation mechanism. Cyclobutoxide, c-C4H7O-, undergoes only dissociative photodetachment to ground-state vinoxy radical and ethylene. The adiabatic electron affinity (AEA) of c-C4H7O is estimated to be 1.7 ± 0.1 eV. c-C4H7O- and c-C4H7O are both found to be therm...