title: Dynamics of water confined in single- and double-wall carbon nanotubes.
abstract: Using high-resolution quasielastic neutron scattering, we investigated the temperature dependence of single-particle dynamics of water confined in single- and double-wall carbon nanotubes with the inner diameters of 14+/-1 and 16+/-3 A, respectively. The temperature dependence of the alpha relaxation time for water in the 14 A nanotubes measured on cooling down from 260 to 190 K exhibits a crossover at 218 K from a Vogel-Fulcher-Tammann law behavior to an Arrhenius law behavior, indicating a fragile-to-strong dynamic transition in the confined water. This transition may be associated with a structural transition from a high-temperature, low-density (<1.02 gcm(3)) liquid to a low-temperature, high-density (>1.14 gcm(3)) liquid found in molecular dynamics simulation at about 200 K. However, no such dynamic transition in the investigated temperature range of 240-195 K was detected for water in the 16 A nanotubes. In the latter case, the dynamics of water simply follows a Vogel-Fulcher-Tammann law. This suggests that the fragile-to-strong crossover for water in the 16 A nanotubes may be shifted to a lower temperature.
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-8562, USA. mamontove@ornl.gov
authors.forename: E
authors.initials: E
authors.lastname: Mamontov
authors.forename: C J
authors.initials: CJ
authors.lastname: Burnham
authors.forename: S-H
authors.initials: SH
authors.lastname: Chen
authors.forename: A P
authors.initials: AP
authors.lastname: Moravsky
authors.forename: C-K
authors.initials: CK
authors.lastname: Loong
authors.forename: N R
authors.initials: NR
authors.lastname: de Souza
authors.forename: A I
authors.initials: AI
authors.lastname: Kolesnikov