Filling carbon nanotubes with metals by the arc-discharge method: the key role of sulfur N. Demoncy, O. Stéphan, N. Brun, C. Colliex, A. Loiseau and H. Pascard Eur. Phys. J. B, 4 2 (1998) 147-157 Published online: 15 July 1998 DOI: 10.1007/s100510050363