Experimental evidence of a liquid-liquid critical point in supercooled water
Preuve expérimentale de l'existence d'un point critique liquide-liquide dans l'eau surfondue
You, Seonju ; Ladd-Parada, Marjorie ; Nam, Kyeongmin ; Karina, Aigerim ; Lee, Seoyoung ; Shin, Myeongsik ; Yang, Cheolhee ; Han, Yeseul ; Jeong, Sangmin ; Park, Kichan ; Kim, Kyeongwon ; Ki, Minjeong ; Tyburski, Robin ; Andronis, Iason ; Ralf, Keely ; Lee, Jae Hyuk ; Eom, Intae ; Kim, Minseok ; Ma, Rory ; Jang, Dogeun ; Perakis, Fivos ; Poole, Peter H. ; Amann-Winkel, Katrin ; Kim, Kyung Hwan ; Nilsson, Anders
Année de publication
2026
The search for the liquid-liquid critical point in supercooled water is challenging owing to rapid crystallization. We studied supercooled water at timescales before ice formation by heating high- and low-density amorphous ices using infrared ultrafast laser pulses, followed by x-ray scattering. By varying the pump laser fluence, we accessed liquid states straddling the predicted critical point. We observed a crossover from a discontinuous to a continuous transition at which broad and slow structural variations occurred, consistent with critical fluctuations and slowing down. We also observed a rapid increase in the heat capacity indicating a critical divergence at 210 ± 8 K coincident with enhanced density fluctuations. These results suggest that our experiments have directly probed the vicinity of a critical point in supercooled water.</div>
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