Photoelectron spectroscopy of ClH2− and ClD2−: A probe of the Cl+H2 van der Waals well and spin–orbit excited states

Photoelectron (PE) spectra of ClH2− and ClD2− were measured at 299 nm (4.154 eV). Photodetachment of these anions accesses the prereactive van der Waals well on the ground state Cl+H2 potential energy surface, as well as the low-lying spin–orbit excited states resulting from the interaction of Cl and Cl* with H2. The PE spectra are dominated by two relatively narrow peaks corresponding to transitions to the neutral Cl⋅H2 and Cl*⋅H2 complexes. The energetics and widths of these features are interpreted in terms of the properties of the anion and neutral potential energy surfaces.