A study of Cs intercalation in multi-walled carbon nanotubes was carried out using cross-sectional scanning photo-emission microscopy. It was found that Cs atoms initially deposited on the tips of aligned nanotubes diffused towards their roots. The Cs diffusion constant for the nanotubes at room temperature was deduced from the Cs distribution measured along the axis of the tube.

Extremely Small Diffusion Constant of Cs in Multiwalled Carbon Nanotubes. S.Suzuki, Y.Watanabe, T.Ogino, S.Heun, L.Gregoratti, A.Barinov, B.Kaulich, M.Kiskinova, W.Zhu, C.Bower, O.Zhou: Journal of Applied Physics, 2002, 92[12], 7527-31