The boson peak of deeply cooled confined water reveals the existence of a low-temperature liquid-liquid crossover.
The Boson peak of deeply cooled water confined in the pores of a silica xerogel is studied by inelastic neutron scattering at different hydration levels to separate the contributions from matrix, water on the pore surfaces and "internal" water. Our results reveal that at high hydration level, where the contribution from internal water is dominant, the temperature dependence of the Boson peak intensity shows an inflection point at about 225 K. The complementary use of differential scanning calorimetry to describe the thermodynamics of the system allows identifying the inflection point as the signature of a water liquid-liquid crossover.
Department of Physics and Chemistry, University of Palermo, via Archirafi 36, 90123 Palermo, Italy.
Antonio
A
Cupane
Department of Physics and Chemistry, University of Palermo, via Archirafi 36, 90123 Palermo, Italy.
Margarita
M
Fomina
CNRS - Institut de Biologie Structurale, 71 avenue des Martyrs, 38000 Grenoble, France.
Giorgio
G
Schirò
D002152:Calorimetry, Differential Scanning; D003080:Cold Temperature; D005782:Gels; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
D005782:Gels; D014867:Water; D012822:Silicon Dioxide