Slow photoelectron velocity-map imaging of cold tert-butyl peroxide

Photoelectron spectra of cryogenically cooled X∼¹A' tert-butyl peroxide anions are obtained using slow electron velocity-map imaging. The spectra show highly structured bands corresponding to detachment to the X∼²A″ and A∼²A^' electronic states of the neutral radical and represent a notable improvement in resolution over previous photoelectron spectra. We report an electron affinity of 1.1962(20) eV and a term energy T₀(A∼²A^') of 0.9602(24) eV for the tert-butyl peroxy radical. New vibrational structure is resolved, providing several frequencies for both neutral states. Additionally, the threshold behavior of the photodetachment cross section is investigated within the context of Dyson orbital calculations.