INVESTIGATION OF THE PENNING IONIZATION M ECHANISM OF H2O BY HE-ASTERISK (2(1)S, 2(3)S) AND NE-ASTERISK (3PO, 3P2)

Experimental observations of Penning ionisation of H2O by the helium m etastables 2(1)S and 2(3)S and by the neon metastables P(3)0 and P(3)2 are reported. The kinetic energies of the ions created during the col lision process (both parent and fragment) are analysed. Certain partic ularities of the experimental results are explained by involving the h ypothesis of transfers of vibrational energy to kinetic energy. Furthe rmore, the forms of the energy distributions of the fragment ions are explained by the predissociation of the B(2)2 state of H2O+.