| The present work involves an investigation of the dissociation of H 2O, D2O and H2O2 by electron impact over an incident energy range from threshold to 300eV. A pulsed electron beam, a target vapor beam, and the axes of detector were arranged to be perpendicular to each of others. By using channeltron detector, the fragments following the electron impact were probed so that the time-of-flight (TOF) spectra were obtained. In the case of H2O/D2O, significant isotopic effect was observed through comparison between TOF spectra for two targets. This isotopic shift was adopted to identify the fragments produced by dissociation of H2O (D2O). The major peak, which was thought to be due to the fragment only containing hydrogen (deuterium) element, in the TOF spectra was extracted and translated to total released kinetic energy (RKE) spectra. The excitation function for that peak was measured as well. At least three dissociation processes showed up, whose threshold were about 12.5eV, 23eV, and 58eV, respectively. In the case of H2O2, the TOF spectra were obtained, which, unfortunately, proved to be the mixture of TOF spectra for H2O and for O2. The possible reason for that is the much low vapor pressure of H2O2 relative to the vapor pressure of H2O from the 30% water solution of H 2O2. Further experiments are required to investigate the dissociation of H2O2. |
