Since its early days electron microscopy has represented a splendid way to study the interactions between charged particles and electromagnetic fields. These efforts produced a flexible and powerful tool to investigate the properties of the matter at the highest spatial resolution. One of the main reason for the high resolution achievable in electron microscopy is related to the small wavelength, ?, associated to high-energy electrons, i.e. for 200 keV electrons ? = 2.5pm. Unfortunately, the quality of the electron lenses is relatively poor and the diffraction limit is still unreached. The proof of Otto Scherzer in 1936 that skilful lens design could never eliminate the spherical and chromatic aberration of rotationally symmetric lenses [1] promote the efforts of the scientific community to find a gateway. Since that time many attempts were made from one side to find a way to correct spherical and chromatic aberrations and from the other to find different approaches to recovery the information lost in TEM imaging. In the latter approaches it might be mentioned, for example, the invention of Gabor of the holography [2] or the through focal reconstruction of the exit phase wave in high resolution TEM (HRTEM) [3]. Very recently, electron optical devices capable of correcting spherical aberration are available and sub-ångström resolution have been achieved by HRTEM [4] and incoherent imaging in scanning transmission electron microscopy (STEM) by using high angle annular dark field detector [5]. Nevertheless, the diffraction limit in electron microscopy is still not reached. Coherent diffraction imaging (CDI) is an approach combining real and reciprocal space information to achieve images in principle limited only by diffraction limit [6]. Here we describe a new TEM-based CDI method to achieve sub-ångström resolution in lattice images of isolated as well as extended crystalline structures.

Electron diffractive imaging at sub-ångström resolution

E Carlino;L De Caro;C Giannini;
2011

Abstract

Since its early days electron microscopy has represented a splendid way to study the interactions between charged particles and electromagnetic fields. These efforts produced a flexible and powerful tool to investigate the properties of the matter at the highest spatial resolution. One of the main reason for the high resolution achievable in electron microscopy is related to the small wavelength, ?, associated to high-energy electrons, i.e. for 200 keV electrons ? = 2.5pm. Unfortunately, the quality of the electron lenses is relatively poor and the diffraction limit is still unreached. The proof of Otto Scherzer in 1936 that skilful lens design could never eliminate the spherical and chromatic aberration of rotationally symmetric lenses [1] promote the efforts of the scientific community to find a gateway. Since that time many attempts were made from one side to find a way to correct spherical and chromatic aberrations and from the other to find different approaches to recovery the information lost in TEM imaging. In the latter approaches it might be mentioned, for example, the invention of Gabor of the holography [2] or the through focal reconstruction of the exit phase wave in high resolution TEM (HRTEM) [3]. Very recently, electron optical devices capable of correcting spherical aberration are available and sub-ångström resolution have been achieved by HRTEM [4] and incoherent imaging in scanning transmission electron microscopy (STEM) by using high angle annular dark field detector [5]. Nevertheless, the diffraction limit in electron microscopy is still not reached. Coherent diffraction imaging (CDI) is an approach combining real and reciprocal space information to achieve images in principle limited only by diffraction limit [6]. Here we describe a new TEM-based CDI method to achieve sub-ångström resolution in lattice images of isolated as well as extended crystalline structures.
2011
Istituto di Cristallografia - IC
Istituto Officina dei Materiali - IOM -
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/238444
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