Yuta Sato, Kazu Suenaga, Shingo Okubo, Toshiya Okazaki, and Sumio Iijima

Transcription

1 The Structures of D 5d -C 80 and I h -Er 3 N@C 80 Fullerenes and their Rotation inside Carbon Nanotubes demonstrated by Aberration-Corrected Electron Microscopy Yuta Sato, Kazu Suenaga, Shingo Okubo, Toshiya Okazaki, and Sumio Iijima Research Center for Advanced Carbon Materials, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba , Japan Supporting Information - Methods - Figure S1 Procedure to reduce the contrast of the SWNT walls in a TEM image - Figure S2 D 5d -C 80 fullerene cages inside (18,1) SWNTs - Figure S3 D 5d -C 80 fullerene cages inside SWNTs 1

2 Methods Preparation of materials The soot containing D 5d -C 80 and I h -Er 3 N@C 80 were produced by direct current (DC) arc discharge in the same manners as reported previously. 14,15 The D 5d -C 80 and I h -Er 3 N@C 80 fullerenes were isolated by high-performance liquid chromatography (HPLC). HiPco SWNTs (Carbon Nanotechnologies, Inc.) were heat-treated at 2273 K in vacuum for 3 h, in order to enlarge their diameters by heat-induced coalescence. 28,29 The SWNTs with enlarged diameters were then maintained at 813 K in dry air with a flow rate of 0.1 l/min for 3 h, in order to open small windows in their closed ends and on their sidewalls. D 5d -C 80 or I h -Er 3 N@C 80 fullerenes dissolved in toluene were dropped on these SWNTs for encapsulation. The SWNTs thus filled with D 5d -C 80 or I h -Er 3 N@C 80 were dispersed in n-hexane by sonication, and then dropped on a copper TEM grid coated with a holey carbon film. TEM experiments An electron microscope (JEOL Co. Ltd., JEM-2010F) equipped with a post-specimen spherical aberration corrector (CEOS GmbH) was used at an accelerating voltage of 120 kv. TEM observations of fullerene molecules were performed at ambient temperature with C s and C c values of about 1 µm and 1.1 mm, respectively, and f of around -5 nm. A typical beam current used for the observations was electrons/nm 2 s. A charge-coupled device (CCD) camera (Gatan Inc., model 894) attached to the microscope was used to capture TEM images. Sequential TEM images were obtained at a rate of 2.5 s/frame (1.0 s for exposure, and 1.5 s subsequently for 2

3 readout with the electron beam blanked). For simulation of the TEM images, the D 5d and I h structures of C 80 fullerene cages were optimized by density functional theory (DFT) calculations using the PC GAMESS program package. 30 References (28) Nikolaev, P.; Thess, A.; Rinzler, A. G.; Colbet, D. T.; Smalley, R. E. Chem. Phys. Lett. 1997, 266, 422. (29) Yudasaka, M.; Ichihashi, T.; Kasuya, D.; Kataura, H.; Iijima, S. Carbon 2003, 41, (30) Granovsky, A. A. PC GAMESS version 7.0, see the web site 3

4 Figure S1. Procedure to reduce the contrast of the SWNT walls in a TEM image. (a) Original TEM image of the D 5d -C 80 fullerene cages inside the (18,1) SWNT. (b) FFT image of a before masking the bright spots from the nanotube walls (indicated by yellow and red hexagons). (c) FFT image after masking. (d) IFFT image of (c). 4

5 Figure S2. D 5d -C 80 fullerene cages inside (18,1) SWNTs. (a)-(c) Schematic illustrations of the D 5d -C 80 cages in the (18,1) SWNT (top panels) and their TEM images simulated with C s of 1 µm (bottom panels). The center frames in (a), (b) and (c) best agree with the experimentally observed images at 0, 45 and 79 s, respectively, in Fig. 2. A pair of five-membered rings penetrated by the five-fold axis in each D 5d -C 80 cage is colored red. 5

6 Figure S3. D 5d -C 80 fullerene cages inside SWNTs. (a)-(e) TEM images experimentally observed for the D 5d -C 80 cages in SWNTs by aberration-corrected microscopy (left panels), schematic illustrations for suggested orientations of the fullerene cages (center panels), and simulated TEM images (right panels). A pair of five-membered rings penetrated by the five-fold axis in each D 5d -C 80 cage is colored red, and chiral indices of outer SWNTs are given in center panels. 6