title: Measurement of the dielectric function of α-Al2O3 by transmission electron microscopy - Electron energy-loss spectroscopy without Cerenkov radiation effects.
abstract: The dielectric function of α-Al2O3 was measured by electron energy-loss spectroscopy (EELS) coupled with the difference method. The influence of Cerenkov radiation was significant in measurements using a 200kV transmission electron microscope (TEM) and the correct dielectric function could not be obtained using the conventional EELS procedure. However, a good agreement between the optical data and EELS for the dielectric functions was obtained via a 60kV TEM. Combining EELS and the difference method, however, provided an accurate measurement of the dielectric function for α-Al2O3 even at an accelerating voltage of 200kV. The combination of EELS and the difference method in the nano-beam diffraction mode could derive an accurate dielectric function with superior spatial resolution regardless of the occurrence of Cerenkov radiation.
authors.affiliation: Laboratory of Integrated Function Materials, Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan. Electronic address: sakaguchi@eng.hokudai.ac.jp.
authors.forename: Norihito
authors.initials: N
authors.lastname: Sakaguchi
authors.affiliation: Laboratory of Integrated Function Materials, Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
authors.forename: Luka
authors.initials: L
authors.lastname: Tanda
authors.affiliation: Laboratory of Integrated Function Materials, Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kunisada
keywords: Dielectric function; Difference method; Electron energy-loss spectroscopy; Kramers–Kronig analysis