Strongly Anisotropic Orientational Relaxation of Water Molecules in Narrow Carbon Nanotubes and

onfinement leads to dramatic changes in the structure and dy-namics of water.1 At the structural level, confinement may lead to new types of molecular order that are not present in the bulk. Confinement of water molecules in a space of a few molecular diameters in ex-tent, such as narrow carbon nanotubes, leads to solidlike ordering2–5 even at room temperature. Water near surfaces also tends to order in layers, as has been probed by X-ray diffraction.6 Several experimental and simulation studies have demonstrated that the dynamic behavior of confined water molecules is markedly different from tha