Image contrast in atomic resolution high-angle annular dark-field images

Abstract

Identification of individual C-C bonds is an ultimate goal of the carbon nanostructure characterization. We have been developping a high sensitivity transmission electron microscopy (TEM) which enables us to visualize a single C-C bond. A TEM equipped with an aberration corrector allows a higher spatial resolution without increasing its tension (the accelerating voltage). Then we have achieved the resolution of 0.14 nm, which corresponds to a typical C-C distance, at a moderate accelerating voltage (120kV). This merits a lot to realize the visualization of carbon atomic chain such as the alkyl chain without electron irradiation damage (1). Here we show some examples for atomic-level characterization of carbon nanostructures. The C60 fullerene molecule has been successfully identified its structure and orientation at a single-molecular basis (2). Also the active topological defects have been eventually caught redhanded (3). The technique can be widely applicable to visualize a biological activity, at an atomic level, for which any conformation change of the C-C bonds is responsible. The cis-/trans-isomerization of retinal molecules have been successfully visualized (4). (1) M. Koshino et al., Science 316 (2007) p853 (2) Z. Liu et al., J. Am. Chem. Soc., 129 (2007) pp.6666-6667 (3) K. Suenaga et al., Nature Nanotech. 2 (2007) pp.358-360 (4) Z. Liu et al., Nature Nanotech. 2 (2007) pp.422-425