Photofragmentation of HCl near the chlorine L2,3 ionization 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) -> 6 sigma* excitation process, production of H+ is almost completely suppressed, which indicates a dominant ultrafast dissociation process leading to neutral H.