The17O nuclear magnetic shielding in H217O and D217O

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Abstract
The gas phase 17O isotope shift [σ(D2 17O)-σ(H2 17O)] has been measured experimentally and found to be 4·04 (±0·35) p.p.m. This supports an earlier theoretical prediction of 3·69 p.p.m. obtained from an ab initio calculation of the oxygen shielding surface. However, it contrasts with a value of 3·08 (±0·20) p.p.m. measured in the liquid phase. This, combined with the differing gas-to-liquid shifts of H2 17O and D2 17O, confirms the generally accepted belief that hydrogen bonding is stronger in liquid D2O than liquid H2O at the same temperature. Data are presented from which an absolute 17O shielding scale can be established once an atomic beam investigation of 17O hyperfine structure is made.