Two molecules of water have been trapped inside a fullerene cage allowing the formation of a hydrogen bond between the two molecules to be observed. It is the first time that the elusive dimer of water has been isolated and could open the way to fundamental studies of hydrogen bonding in water.

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Two molecules of water have been trapped inside a fullerene cage allowing the formation of a hydrogen bond between the two molecules to be observed. It is the first time that the elusive dimer of water has been isolated and could open the way to fundamental studies of hydrogen bonding in water.