Ionizing collisions of cesium and potassium atoms with water

Crossed beam studies of K and Cs collisions with H2O and D2O have been made for laboratory alkali beam energies from 10 to 200 eV. The only ionic products observed were K+, Cs+, OH−, and OD−. The positive and negative ion thresholds are equal to within ∼0.1 eV and correspond to the H(2S)+OH−(1Σ) limit of H2O−. The positive and negative ion energy and angular distributions are discussed including the observation of an OD− ’’pickup’’ reaction.