EN
A high-resolution VUV laser absorption spectroscopy is used to investigate the photon-induced ion-pair formation in D2 in the spectral region from 140117.4 to 140732.0 cm−1. We report determination of photoionization efficiency in ortho-para D2 in supersonic molecular beam with energy resolution of 0.1 cm−1. The assignment of the superexcited D2 Rydberg states is done based on the quantum defect theory.