Dynamical crossover and breakdown of the Stokes-Einstein relation in confined water and in methanol-diluted bulk water.
Using nuclear magnetic resonance and quasi-elastic neutron scattering spectroscopic techniques, we obtain experimental evidence of a well-defined dynamic crossover temperature T(L) in supercooled water. We consider three different geometrical environments: (i) water confined in a nanotube (quasi-one-dimensional water), (ii) water in the first hydration layer of the lysozyme protein (quasi-two-dimensional water), and (iii) water in a mixture with methanol at a methanol molar fraction of x = 0.22 (quasi-three-dimensional water). The temperature predicted using a power law approach to analyze the bulk water viscosity in the super-Arrhenius regime defines the fragile-to-strong transition and the Stokes-Einstein relation breakdown recently observed in confined water. Our experiments show that these observed processes are independent of the system dimension d and are instead caused by the onset of an extended hydrogen-bond network that governs the dynamical properties of water as it approaches dynamic arrest.
Mallamace
Francesco
F
Dipartimento di Fisica, Università di Messina and IRCCS Neurolesi Bonino-Pulejo, I-98166, Messina, Italy. francesco.mallamace@unime.it
Branca
Caterina
C
Corsaro
Carmelo
C
Leone
Nancy
N
Spooren
Jeroen
J
Stanley
H Eugene
HE
Chen
Sow-Hsin
SH
D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D000432:Methanol / Q000737:chemistry*; D009113:Muramidase / Q000737:chemistry; D043942:Nanotubes / Q000737:chemistry; D013696:Temperature; D014783:Viscosity; D014867:Water / Q000737:chemistry*
D014867:Water; D009113:Muramidase; D000432:Methanol