Quasielastic neutron scattering study of water confined in carbon nanopores

¹ Neutron Scattering Science Division, Oak Ridge National Laboratory - Oak Ridge, TN 37830, USA
² Department of Materials Science and Engineering, Drexel University - 3141 Chestnut Street, Philadelphia, PA 19104, USA
³ Chemical Science Division, Oak Ridge National Laboratory - Oak Ridge, TN 37830, USA

^a mavilachaths@ornl.gov

Received: 16 June 2011
Accepted: 11 July 2011

Abstract

Microscopic dynamics of water confined in nanometer and sub-nanometer pores of carbide-derived carbon (CDC) were investigated using quasielastic neutron scattering (QENS). The temperature dependence of the average relaxation time, ⟨τ⟩, exhibits super-Arrhenius behavior that could be described by Vogel-Fulcher-Tammann (VFT) law in the range from 250 K to 190 K; below this temperature, ⟨τ⟩ follows Arrhenius temperature dependence. The temperature of the dynamic crossover between the two regimes in water confined in the CDC pores is similar to that observed for water in hydrophobic confinement of the larger size, such as 14 Å ordered mesoporous carbon (CMK) and 16 Å double-wall carbon nanotubes. Thus, the dynamical behavior of water remains qualitatively unchanged even in the very small hydrophobic pores.