Reaction pathways of water dimer following single ionization

Water dimer $\mathrm{(H_2O)_2}$ - a vital component of the earth's atmosphere - is an important prototypical hydrogen-bonded system. It provides direct insight into fundamental chemical and biochemical processes, e.g., proton transfer and ionic supramolecular dynamics occurring in astro- and atmospheric chemistry. Exploiting a purified molecular beam of water dimer and multi-mass ion imaging, we report the simultaneous detection of all generated ion products of $\mathrm{(H_2O)_2^+}$-fragmentation following single ionization. Detailed information about ion yields and reaction energetics of 13 ion-radical pathways, 6 of which are new, of $\mathrm{(H_2O)_2^+}$ are presented, including strong $\mathrm{{}^{18}O}$-isotope effects.