Surface characterization of submicron vapor grown carbon fibers by scanning tunneling microscopy

The surface structure of submicron vapor grown carbon fibers has been inves tigated by means of scanning tunneling microscopy (STM) at the nanometer an d atomic scale. At the nanometer scale the fibers were found to have a rela tively smooth topography consisting of more or less rounded platelets just a few nm in diameter. Atomic scale imaging revealed the absence of long ran ge graphitic order. Instead, the fiber surface was comprised for the most p art of small structured regions, with lateral sizes typically between 1 and 4 nm. Within these structured regions, the observed atomic arrangement dif fered in most of the cases from that of perfect graphite. Likewise, linear structures and ring-like superstructures were also observed on the surface of the fibers at;the atomic scale. Some possible interpretations are propos ed to account for these observations. The scanning tunneling microscopy cha racterization of the fibers is complemented with scanning electron microsco py, X-ray diffraction and nitrogen physical adsorption measurements. The re sults are discussed in terms of the specific structure and growth process o f this type of fiber. (C) 2001 Elsevier Science Ltd. All rights reserved.