Kinetic energy and radial momentum distribution of hydrogen and oxygen atoms of water confined in silica hydrogel in the temperature interval 170–325 K

Water is an ubiquitous liquid and it is necessary for life;studies on water are therefore of obvious scientific andtechnological relevance. In view of its peculiar physicalproperties (the so-called water anomalies, particularly relevantat low temperatures [1]), studies on water structureand dynamics in ample temperature intervals, covering alsothe supercooling region, have attracted much interest in recent years. In particular, studies focused on the supercooledphase are important in order to test theories and hypotheses[2,3], including the liquid-liquid phase transition hypothesis[4-6] and the related fragile-to-strong crossover observed inwater confined in silica matrices and in the hydration waterof proteins [7,8]. In this context, water confined withinnanometer-sized porous hydrophilic/hydrophobic matriceshas been investigated both to extend the supercooling temperaturerange accessible to experiment and to mimic thecrowding/confined conditions experienced by water moleculesin biological systems relevant to biophysics, bio-preservation,and pharmaceutics. In view of the abovearguments, studies on the short-time dynamics of hydrogenand oxygen atoms of supercooled water (bulk or confined) are of great relevance.