The hydrogen bonding in water is dominated by pairwise dimer interactions, and the
predissociation of the water dimer following vibrational excitation is reported here. Velocity
map imaging was used for an experimental determination of the dissociation energy (D 0) of
(D2O) 2. The value obtained, 1244±10 cm–1 (14.88±0.12 kJ/mol), is in excellent agreement
with the calculated value of 1244±5 cm–1 (14.88±0.06 kJ/mol). This agreement between
theory and experiment is as good as the one obtained recently for (H2O) 2. In addition, pair …

Conspectus Water is one of the most pervasive molecules on earth and other planetary
bodies; it is the molecule that is searched for as the presumptive precursor to extraterrestrial
life. It is also the paradigm substance illustrating ubiquitous hydrogen bonding (H-bonding)
in the gas phase, liquids, crystals, and amorphous solids. Moreover, H-bonding with other
molecules and between different molecules is of the utmost importance in chemistry and
biology. It is no wonder, then, that for nearly a century theoreticians and experimentalists …