捕捉水的隐藏转变

Rapid measurements capture structural transition in a short-lived liquid state of supercooled water Francesco Paesani1,2,3,4 W ater behaves in unusual ways when it is cooled below its normal freezing point (0°C) without turning into ice, a phenomenon known as supercooling. In this regime, its density decreases after passing through a maximum, the amount of energy required to raise water’s temperature (heat capacity) rises sharply, and water be- comes markedly more compressible (1). These phenomena hint at a hidden reorganization of water molecules. However, probing these structural transformations has long been difficult because deeply supercooled water (liquid water cooled well below its freezing point without crystallizing) solidifies on microsecond timescales, which is too short for observations using conventional experimental tech- niques. …