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

The surface structure of submicron vapor grown carbon fibers has been investigated by means of scanning tunneling microscopy (STM) at the nanometer and atomic scale. At the nanometer scale the fibers were found to have a relatively smooth topography consisting of more or less rounded platelets just a few nm in diameter. Atomic scale imaging revealed the absence of long range graphitic order. Instead, the fiber surface was comprised for the most part of small structured regions, with lateral sizes typically between 1 and 4 nm. Within these structured regions, the observed atomic arrangement differed 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 proposed to account for these observations. The scanning tunneling microscopy characterization of the fibers is complemented with scanning electron microscopy, X-ray diffraction and nitrogen physical adsorption measurements. The results are discussed in terms of the specific structure and growth process of this type of fiber.