Vibronic structure of alkoxy radicals via photoelectron spectroscopy

Ultraviolet photoelectron spectra of CH3O , CH3CH2O , (CH3)2CHO , (CH3)3CO , as well as CD3O 2 and CD3CD2O 2 are presented, providing improved electron affinities and new information on vibronic coupling in the corresponding neutral radicals. Jahn-Teller vibronic transitions are assigned to e vibrational modes of X̃ E CH3O. The excitation energy of the à A8 state of CH3CH2O with respect to the X̃ A9 state is observed directly at 355610 cm. Vibronic coupling between these low-lying electronic states perturbs the observed vibronic levels. Features of the (CH3)2CHO 2 photoelectron spectrum are assigned. The splitting between the X̃ A8 and à A9 states of (CH3)2CHO is determined to be 1225665 cm . Significant vibronic coupling is not observed in (CH3)2CHO. Vibrational assignments are made for the spectral features of (CH3)3CO and no Jahn-Teller effects are observed directly. Electron affinities ~EAs! for the neutrals ~RO! are ~in eV!; EA~CH3O!51.57260.004; EA~CD3O!51.55960.004; EA~CH3CH2O)51.71260.004; EA~CD3CD2O)51.69960.004; EA~~CH3)2CHO)51.84760.004; EA~~CH3)3CO)51.909 60.004. Bond dissociation energies of ROH, D300~RO–H!, along with D fH300~RO!, D fH300~RO ), and D fH300~RO ) are derived. © 2000 American Institute of Physics. @S0021-9606~00!00303-2#