Interlayer spacing anomaly of single-wall carbon nanohorn aggregate

Newly found single-wall carbon nanohorns (SWNH) are synthesized by a CO2 laser vaporization of a pure carbon target in an Ar gas. Purification method using centrifugal separation and structural features of aggregated form of SWNHs (SWNH aggregate) are studied in this Letter. Although the X-ray diffraction profile taken for highly purified SWNH aggregates does not show any sharp 002 diffraction corresponding to that of the ordinary graphite, a huge broad diffraction comes to be observed. This huge broad diffraction is well explained by the double layer diffraction model associated with two graphene sheets apart from 0.40 nm. (C) 2000 Elsevier Science B.V. All rights reserved.