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Research paper : Innovative electron microscope for light-element atom visualization (Y. Sato et al.)−177−Synthesiology - English edition Vol.4 No.3 (2012) images. These results show the excellent spatial resolution of our microscope in TEM mode as well as in STEM mode. Comparing the TEM image of a SWCNT obtained at 30 kV (Fig. 9) with those of conventional microscopes (e.g. Fig. 1), we can easily recognize that the performance of our microscope is comparable to existing spherical aberration-corrected TEM systems operated at 120 kV.4.3 Performance of the second low-voltage microscope (TEM)Our second experimental microscope is a 30 kV-TEM equipped with a chromatic aberration corrector in tandem with a Delta spherical aberration corrector. As described in subchapter 3.3, its chromatic aberration corrector has an innovative optical system based on the combination concave-lens effect of superposed electrostatic and magnetic fields. We checked the fundamental operation of this microscope such as aberration correction in 2010, taking measures to reduce electric noise to improve its stability. We are currently verifying the effect of simultaneously correcting chromatic and spherical aberrations in TEM observation for various standard samples.Figure 10 shows a TEM image of Si<110> recorded by using this microscope temporarily equipped with a conventional electron gun. Even small lattice spacing of 125 pm was resolved, as shown by FFT, suggesting that the spatial resolution of this microscope is already comparable with that of our first microscope operated in TEM mode at the same voltage of 30 kV. We expect that the performance of this second microscope will be further improved to achieve higher resolutions by installing a new low-voltage CFEG (completed in September 2011) and by optimizing the alignment of the optical system including two aberration correctors.Fig. 8 Performance examination of the first low-voltage microscope in TEM modeRecorded at acceleration voltages of (a) 60 kV and (b) 30 kV Gold nanoparticles were used as test specimens. Fig. 9 TEM image of a SWCNT recorded at an acceleration voltage of 30 kVFig. 10 Performance examination of the second low-voltage microscope (TEM) Recorded at an acceleration voltage of 30 kV Si<110> was used as test specimen. (a)(b)60 kV30 kV2 nm2 nm118 pm79 pm94 pm204 pm236 pm118 pm102 pm91 pm204 pm2 nm2 nm125 pm

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