The frequency shifts in G, D and D* Raman modes in free-standing multi-wall carbon nanotube buckypapers were studied. Upon ion irradiation with 140keV He+ or 3MeV H+ ions, the intensity ratio of D-G modes increased linearly with fluence before amorphization. The ratio was used to measure quantitatively the level of disorder in the buckypaper. The study showed that, upon post-irradiation annealing, defect removal required little energy addition in lightly damaged buckypaper, which was evidenced by an activation energy of 0.36eV. Once amorphized, defect removal became very difficult. The D-G intensity ratio exhibited no reduction in heavily damage samples after annealing at up to 850C.

Defect Formation and Annealing Kinetics in Ion Irradiated Carbon Nanotube Buckypapers. A.Aitkaliyeva, M.C.McCarthy, M.Martin, E.G.Fu, D.Wijesundera, X.Wang, W.K.Chu, H.K.Jeong, L.Shao: Nuclear Instruments and Methods in Physics Research B, 2009, 267[20], 3443-6