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.