We report detailed studies of the distribution of pentagons on carbon nanot
ube tips. For a conical tube end, five pentagons are clustered to form a sh
arp tip. By examining the process of initial oxidation, we can identify the
most strained pentagons on the tip. The pentagon distribution, which deter
mines the pattern of oxidation, can be deduced with reasonable confidence f
rom high-resolution transmission electron microscopy and computer-image sim
ulation. (C) 1999 Elsevier Science B.V. All rights reserved.