Photofragmentation of HCl near the chlorine L2,3ionization threshold: new evidence of a strong ultrafast dissociation channel

We report a study using partial-ion-yield spectroscopy around the Cl 2p ionization threshold of HCl. All cation channels have been measured, while no evidence for anion production was obtained. The absence of any detectable H − can be related to the electronegativity difference between the two atoms and the observed low probability of directly creating Cl ++ and Cl +++ . In the photon-energy region around the Cl 2p 3/2,1/2 → 6σ* excitation process, production of H + is almost completely suppressed, which indicates a dominant ultrafast dissociation process leading to neutral H.