Knowledge Bank

Microwave and radio frequency transitions of $(H2O)2$ and $(D2O)2$ have been observed by the molecular beam electric resonance method. Rf transitions across the K = 2 asymmetry doublets for J = 5 - 11 have been assigned. The microwave spectrum is considerably enriched by hydrogen tunneling motions, and has not yet been assigned. The theory of these motions will be briefly described.