Bilinear Jahn–Teller coupling effects in the methoxy radical: impact on photoelectron spectra and spin–orbit splittings

A previous theoretical investigation of the multimode dynamical Jahn–Teller effect in the methoxy radical is extended to calculate the vibrational structure of the first bands of the photoelectron spectra of CH3O− and CD3O− and to include the effects of spin–orbit coupling. Bilinear coupling terms between the e and a1 vibrational modes are shown to be of major importance for the spectral intensities; they also lead to a marked dependence of the spin–orbit splittings on the quantum numbers of the a1 modes in the electronic ground state of the radical.