The double photoionization of HCl: An ion-electron coincidence study

The double photoionization of HCl molecules by synchrotron radiation has been studied in the energy range between 30 and 50 eV. The HCl2+ and Cl2+ product ions have been detected by a photoelectron-photoion-coincidence technique, while the H++Cl+ formation, which follows the double ionization of HCl, has been studied by photoelectron-photoion-photoion coincidence. The photon energy threshold for the production of HCl2+ ions has been found to be 35.4+/-0.6 eV, while for the dissociative channel leading to H++Cl+, it has been measured a threshold at 36.4+/-0.6 eV and a change in the slope of the cross-section energy dependence at 38.7+/-0.7 eV. The production of H+Cl2+ occurs with a threshold photon energy of 42.8+/-1.1 eV. These results appear to be in a good agreement with previous data by different experimental techniques and recent theoretical calculations performed by our laboratory. (C) 2004 American Institute of Physics.