High Resolution Imaging and Spectroscopy Using CS-corrected TEM with Cold FEG JEM-ARM200F

  • 概要

JEOLnews Volume 47, Number 1, 2012 C. Ricolleau†, J. Nelayah†, T. Oikawa†, ††, Y. Kohno††, N. Braidy†, †††,
G. Wang†, F. Hue† and D. Alloyeau†

† Laboratoire Matériaux et Phénomènes Quantiques,
Université Paris Diderot/CNRS
†† JEOL Ltd.
††† Laboratoire d’Etude des Microstructures, ONERA-CNRS

Recently, at the University Paris Diderot (France), a unique in the world electron microscope configuration was installed. It consists of a JEOL JEM-ARM200F spherical aberration corrected electron microscope (TEM) equipped with a cold field emission gun (CFEG). In this paper, we report on the performances of this newly developed 80 - 200 kV microscope. Firstly, we show that the stability of both emission and probe currents makes the use of this new cold-FEG much friendlier. Energy spread of electrons emitted from the CFEG has been measured as a function of emission current and shows a very last 0.26 eV energy resolution at 200 kV and even 0.23 eV at 80 kV. The combination of the cold FEG and the CEOS aberration corrector of the objective lens, associated to enhanced mechanical and electrical stabilities of this new TEM, allows reaching a point resolution of 75 pm at 200 kV and 80 pm at 80 kV. This unseen point resolution at 200 kV has allowed us to study the structure of CoPt nanoparticles by observing direct images of their atomic arrangement along high indexes zone axis, as well as carbon graphite along the [0001] zone axis orientation. The high sensitivity of this microscope allows us to image and to analyze the chemical specie of single atoms diffusing on an amorphous carbon substrate. Finally, we used the small energy spread of the CFEG to study the surface plasmon resonance modes characteristic of bimetallic nanoparticles in close electromagnetic interaction.

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