Rotationally resolved threshold photoelectron spectra of OH and OD

The results of combined experimental and theoretical studies of the rotationally resolved photoelectron spectra of OH and OD following single-photon ionization are presented. The measured zero-kinetic-energy (ZEKE) spectra were obtained using pulsed field ionization in conjunction with a vacuum ultraviolet laser source. The OH⁺ and OD⁺ (X ³Σ^-, v⁺=0) rotational distributions were studied over the range 95.0-95.4 nm. Agreement between the observed and calculated spectra is very encouraging. Improved values for the ionization potentials of OH and OD (104 989 and 105 085±2 cm^-1, respectively) are reported and the unusual dynamics favoring ΔN<0 transitions are discussed.