Single-file diffusion of confined water inside SWNTs: an NMR study.
We report a nuclear magnetic resonance (NMR) study of confined water inside approximately 1.4 nm diameter single-walled carbon nanotubes (SWNTs). We show that the confined water does not freeze even up to 223 K. A pulse field gradient (PFG) NMR method is used to determine the mean squared displacement (MSD) of the water molecules inside the nanotubes at temperatures below 273 K, where the bulk water outside the nanotubes freezes and hence does not contribute to the proton NMR signal. We show that the mean squared displacement varies as the square root of time, predicted for single-file diffusion in a one-dimensional channel. We propose a qualitative understanding of our results based on available molecular dynamics simulations.
Das
Anindya
A
Department of Physics, Indian Institute of Science, Bangalore 560012, India.
Jayanthi
Sundaresan
S
Deepak
Handiganadu Srinivasa Murthy Vinay
HS
Ramanathan
Krishna Venkatachala
KV
Kumar
Anil
A
Dasgupta
Chandan
C
Sood
Ajay K
AK
D004058:Diffusion; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D037742:Nanotubes, Carbon; D014867:Water