Vitrification of pure liquid water

SUMMARY The methods for vitrifying pure liquid water are reviewed: jet‐freezing of water/oil emulsions, vitrification of thin water layers on an electron‐microscope specimen grid, high‐pressure jet‐freezing and rapid cooling of aerosol droplets on a cryoplate. The first three need a liquid cryomedium for heat transfer in contrast to the last one. Small sample size in at least one dimension, with a diameter in the μm range or even less, is essential for vitrification. Vitrified liquid water has been characterized by electron and X‐ray diffraction, infrared spectroscopy and by differential thermal analysis warm‐up curves. These properties are compared with those of amorphous solid water prepared by deposition of the vapour.