Knowledge Bank

The lowest lying electronic state of $H3O$ Rydberg radical is determined to lie 2.3 eV above the ground state. This result has been obtained by studying the reaction $H3O++OH-$ in the gas phase as a function of center-of mass collision energy using electrostatically merged ion beams. The rate constant of this reaction was measured as a function of center of mass collision energy and put onto an absolute sale by calibrating it to the reaction $O++O-$ and using Landau-Zener (LOZ) absorbing sphere theory. When applying LZ absorbing sphere theory to ion-ion recombination reactions, one important parameter is the location of electronically excited states of the neutral products. It is this dependence that has allowed an experimental determination of the location of the lowest lying electronic state of $H3O$ Rydberg radical.