Spin-contrast-variation
(SCV) small-angle neutron scattering
(SANS)
is a technique to determine the nanostructure of composite materials
from the scattering of polarized neutrons that changes with proton
polarization of samples. The SCV-SANS enabled us to determine structure
of nanoice crystals that were generated in rapidly frozen sugar solutions
by separating the overlapped signals from the nanoice crystals and
frozen amorphous solutions. In the frozen glucose solution, we found
that the nanoice crystals formed a planar structure with a radius
larger than several tens of nanometers and a thickness of 2.5 ±
0.5 nm, which was close to the critical nucleation size of ice crystals
in supercooled water. This result suggests that the glucose molecules
were preferentially bound to a specific face of nanoice crystals and
then blocked the crystal growth perpendicular to that face.