Partial oscillator strengths (25-40 eV) for repulsive states of D₂(H₂)

Abstract

In the range of excitation energies from 26 to 40 eV there is evidence for the existence of resonant autoionising Rydberg states in D2(H2). In a 'photoionisation' experiment, using fast electron scattering at zero degrees, the authors have studied the dissociative decay of these states, leading to energetic D+(H+) fragments. After extraction by a strong field a time-of-flight analysis was made of all fragments emitted over 4 pi , in a photon energy range between 18 and 40 eV. This enabled them to determine partial oscillator strengths for contributions from the 1s sigma g, 2p sigma u and Rydberg states. The absence of an isotope effect between D2 and H2 for the repulsive states under study shows that for these states there is no competition with decay modes other than autoionisation. As a function of photon energy, they find contributions from different Rydberg states leading to fragments with a kinetic energy distribution centred around 3 eV at 28 eV, and around 1 eV at 35 eV photon energy.