Proton mobility and stability of water clusters containing alkali metal ions

► Abundance mass spectra of M+(H2O)n (M = Li, Na, K, Rb and Cs) have been recorded. ► Magic number peaks in abundance spectra and in evaporation spectra are identical. ► Reactions with D2O show that proton mobility is insignificant in all M+(H2O)n. ► Quantum chemical calculations show that activation energies for H/D exchange are high. ► These clusters will be useful for benchmarking in future studies of H/D exchange.