Structures of D5d-C80 and Ih-Er3N@C80 Fullerenes and Their Rotation Inside Carbon Nanotubes Demonstrated by Aberration-Corrected Electron Microscopy

Abstract

Time-dependent orientational changes of D5d-C80 and Ih-Er3N@C80 fullerenes inside single-walled carbon nanotubes (SWNTs) were demonstrated by aberration-corrected transmission electron microscopy (TEM) at real atomic-level resolution. Detailed structure of the ellipsoidal D5d-C80 fullerene, e.g., the pyrene-like tetracyclic component in its cylindrical body, was unambiguously identified by the TEM images. The Er−Er distances in Ih-Er3N@C80 were estimated to be 0.35 ± 0.03 nm, and the C3 symmetry axis of the Er3N cluster was suggested to agree with one of the S6 axes of the spherical Ih-C80 cage. Our results indicate that atomic-resolution TEM enables the investigation of the orientations of individual molecules inside SWNTs in relation to the interactions of the molecules with the outer graphene walls.