||Considering the widely recognized importance of hydrogen
bonding for the structure and properties of water,
there is surprisingly little experimental information
available on the temperature-dependent hydrogen-bond
geometry. Models of water structure usually invoke structural
motifs with well-defined hydrogen-bond geometry
[13–16], often inspired by high-pressure ice polymorphs.
If the distributions of hydrogen-bond length and angle in liquid water were available, preferably over a wide temperature
range, such models could be tested decisively. Researchers' aim is to provide this missing information. To
this end, they make use of the magnetic shielding tensor s,
which relates the applied magnetic field to the local field
experienced by the magnetic moment of a water proton.
The exquisite sensitivity of the shielding tensor to the
local electronic environment makes it a powerful probe of
hydrogen bonding .