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Research paper−172−Synthesiology - English edition Vol.4 No.3 pp.172-182 (Jan. 2012) dynamic behavior of single molecules and for detecting and identifying single light-element atoms.We recognize the advantage of using low acceleration voltages for observing light-element materials such as carbon nano-materials and have pioneered techniques for directly imaging their atomic-level structures using TEMs and STEMs with 120 kV operation. In 2004, single gadolinium (Ga) atoms incorporated into carbon nano-materials were identified by electron energy-loss spectroscopy (EELS) using a STEM[3], and hexagonal networks of carbon atoms in CNTs were unambiguously detected by a TEM[4]. In 2007, individual carbon atoms that formed six-member rings in CNTs were visualized using a TEM equipped with a spherical aberration corrector[5][6]. In 2008, carbon hexagonal networks in CNTs were imaged using an aberration-corrected TEM operated at an even lower acceleration voltage of 80 kV[7]. TEM images of single-walled CNTs (SWCNTs) observed under the conditions employed in these studies are shown in Fig. 1, where the effects of spherical aberration correction and different acceleration voltages on spatial resolution and image contrast are clearly found.Currently available TEM and STEM systems have contributed to the characterization of nano-materials, as mentioned above. However, if we presume that they will be applied to the high-resolution imaging of soft matter such as bio-molecules, they need to be further developed 1 IntroductionCurrently, electron microscopy plays an increasingly important role in the characterization of nano- and bio-materials amidst the acceleration of research and development in these fields. High-performance transmission electron microscope (TEM) and scanning TEM (STEM) are expected to enable the direct visualization of structures at the single-atom/molecule level, particularly for carbon nano-materials (carbon nanotubes (CNTs), graphenes, etc.) and so-called soft matter (e.g., organic molecules and bio-related materials). The technology employed in electron microscopy[1][2] has improved considerably since the 1970s. However, previous technological developments were generally aimed at achieving higher spatial resolution by employing ultra-high electron acceleration voltages. The use of electron microscopes that were once considered cutting-edge and operated at ultra-high voltages in the order of a million volts (MV) has become limited to the observation of thick crystalline materials that are generally stable under electron-beam irradiation, such as metals, alloys, and inorganic compounds. On the other hand, the observation of non-crystalline light element materials such as soft matter by using ultra-high voltage microscopes has often been hindered by serious irradiation-induced damage to the specimens and insufficient signal intensity. The development of innovative electron microscopes is essential for overcoming these technical difficulties as well as for directly observing the - Development of low-voltage electron microscopes in Triple-C project-Today, the demand for techniques to directly visualize the atomic-level structures of nano-materials and so-called soft matter (organic molecules, bio-materials, etc.) is rapidly increasing. Observing these objects using conventional transmission electron microscopes (TEM) and scanning TEM (STEM) often results in serious irradiation-induced structural damage, and the images produced have an unsuitable contrast due to the high electron-acceleration voltages. We believe that reducing the acceleration voltages to several tens of kilovolts will enable direct imaging with less damage and help produce images with a higher contrast. However, correcting various aberrations, such as spherical and chromatic aberrations (Cs and Cc, respectively) and high-order geometrical astigmatisms, is necessary to achieve atomic-level spatial resolution. In our Triple-C project, we have developed low-voltage TEM/STEM systems equipped with new Cs and Cc correctors for carbon-based nano-materials. Innovative electron microscope for light-element atom visualization Keywords : Structure characterization, electron microscopy, aberration correction, nano-material, soft matter, single molecule, single atom, electronic state [Translation from Synthesiology, Vol.4, No.3, p.166-175 (2011)]Yuta Sato1, Takeo Sasaki2, Hidetaka Sawada2, Fumio Hosokawa2, Takeshi Tomita2, Toshikatsu Kaneyama2, Yukihito Kondo2 and Kazutomo Suenaga1*1. Nanotube Research Center, AIST Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565, Japan *E-mail : , 2. JEOL Ltd. 3-1-2 Musashino, Akishima 196-8558, JapanOriginal manuscript received July 7, 2011, Revisions received August 22, 2011, Accepted August 23, 2011

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