Fig. 3: Low-temperature water structuring and release.
From: Dehydration of a crystal hydrate at subglacial temperatures
a,b, Projections along the channel axis [001] of T1-R at 25 °C (a) and −173 °C (b), indicating that no thermally induced phase changes occur in this temperature range. The concentration and localization of diffuse difference electron density (0.5 e− Å−3) on cooling is shown. Colours: red, difference electron density contours; yellow, hydroxyl oxygen O9D; cyan, hydroxyl oxygen O9B; orange, remaining oxygen atoms; grey, carbon; blue, nitrogen; white, hydrogen. c, Photomicrographs of an initially hydrous red single crystal of T1 at −20 °C during chromogenic transition to yellow during dehydration. d,e, Difference axis lengths (d) and difference O(H)···ʘ; displacements (e) track differences between the hydrous and anhydrous crystals on cooling, referenced with respect to the latter. ʘ represents the centroid of symmetry-equivalent oxygen atoms.
