Isotope effects in the electron impact break-up of water

Total fragmentation of H2O and D2O has been studied as a function of incide nt energy over the range from threshold to 325 eV. A small subset of possib le dissociation channels has been selected by making use of a novel solid x enon matrix detector which is selectively sensitive to O(S-1) metastable at oms. O-fragment kinetic energies and appearance potentials have been measur ed and significant isotopic effects are observed. Within the errors of the measurements the cross-section for O(S-1) production from H2O is the same a s that from D2O. The cross sections reach a maximum value of 1.5 x 10(-18) cm(2) at 100 eV incident electron energy.