H2O/D2O negative ion time-of-flight
mass
spectra from electron transfer processes at different collision energies
with neutral potassium yield OH–/OD–, O–, and H–/D–. The branching ratios show a relevant energy dependence with an
important isotope effect in D2O. Electronic state spectroscopy
of water has been further investigated by recording potassium cation
energy loss spectra in the forward scattering direction at an impact
energy of 205 eV (lab frame), with quantum chemical calculations for
the lowest-lying unoccupied molecular orbitals in the presence of
a potassium atom supporting most of the experimental findings. The
DO–D bond dissociation energy has been determined for the first
time to be 5.41 ± 0.10 eV. The collision dynamics revealed the
character of the singly excited (1b2–1) molecular orbital and doubly excited states in such K–H2O and K–D2O collisions.