Energy-filtering transmission electron microscopy in materials science

Reimer, Ludwig; Fromm, I.; Hülk, Christoph; Rennekamp, R.

doi:10.1051/mmm:0199200302-3014100

Cited by 29 publications

(8 citation statements)

References 62 publications

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“…EFTEM imaging is performed at Gaussian focus, as the image contrast results from the intrinsic differences in chemistry or electronic structure between the phases. 10 In recent years, chemical imaging of organic materials via EFTEM imaging has become increasingly popular. For example, the microstructure of multiphase systems has been probed via core-loss elemental mapping, [11][12][13][14][15] and the spatial distribution of carbon bonding states in a triphase polymer composite has also been mapped.…”

Section: Introductionmentioning

confidence: 99%

3D Nanoscale Characterization of Thin-Film Organic Photovoltaic Device Structures via Spectroscopic Contrast in the TEM 1

2010

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The three-dimensional characterization of third generation photovoltaic device structures at the nanometer scale is essential to the development of efficient, reliable, and inexpensive solar cell technologies. Electron tomography is a powerful method for three-dimensional characterization; however, the application of this method to the organic materials systems that comprise typical high-efficiency devices is complicated by the difficulty in generating contrast from the compositionally similar materials. Herein we report the application of low-loss energy-filtered transmission electron microscopy as a method of generating spectroscopic contrast from a common organic bulk-heterojunction thin film consisting of a polymer donor and a fullerene-derivative acceptor. Spectral imaging methods combined with principal component analysis are used to characterize the contrast generation mechanism and to determine the optimum data acquisition parameters for this particular combination of organic phases. A proof of method for using the low-loss spectral signal as a basis for electron tomography is presented, and the advantages and drawbacks of the technique as applied to multiphase organic systems relative to the more commonly employed bright-field imaging approach are outlined.

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Section: Introductionmentioning

confidence: 99%

3D Nanoscale Characterization of Thin-Film Organic Photovoltaic Device Structures via Spectroscopic Contrast in the TEM 1

2010

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“…Energy filtering transmission electron microscopes allow one to record images that are formed exclusively by electrons that have undergone a specific energy loss. Selecting only those electrons that have caused an element‐specific inner‐shell excitation and after removing a background, one may quickly obtain so‐called elemental maps, which contain the two‐dimensional distribution of a single element in the specimen ( Craven et al ., 1978 ; Reimer et al ., 1992 ; Hofer et al ., 1995 ; Reimer, 1995). While this description might suggest a straightforward interpretation, Kohl & Rose (1985) showed that one has to consider the quantum mechanical nature of the scattering process as well as the influence of the microscope to understand the intensity distribution in highly resolved (< 10 nm) elemental maps ( Golla & Kohl, 1997).…”

Section: Introductionmentioning

confidence: 99%

Relativistic calculations of intensity distributions in elemental maps using contrast transfer functions

Knippelmeyer

Kohl

1999

Journal of Microscopy

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The interpretation of highly resolved elemental maps is not straightforward: one has to consider the quantum mechanical nature of the scattering process as well as the influence of the microscope. Existing calculations of the contrast in elemental maps are based on a non-relativistic approach, while in most of the currently installed electron microscopes, the electrons penetrate the specimen with relativistic energies >/= 200 keV. Therefore, we have recalculated the intensity distribution in elemental maps based on a fully relativistic theory. Using the concept of contrast transfer functions, the simulations account for lens aberrations as well as the defocus. Surprisingly, the results exhibit considerable deviations between the relativistic and non-relativistic calculations even in the region of low acceleration voltages such as 100 kV. These differences increase with increasing acceleration voltage and are strongly dependent on aperture and energy loss. Quantitative simulations and evaluations of highly resolved elemental maps should therefore make use of a fully relativistic theory.

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“…Energy-filtering transmission electron microscopy (EFTEM) is now a well-established tool for imaging elemental distributions complementing standard analytical techniques such as energy-dispersive X-ray spectrometry (EDXS) or electron energy-loss spectrometry (EELS) (Leapman and Hunt, 1992;Krahl, 1990;Mayer et al, 1994;Hofer et al, 1995a;Reimer et al, 1992). In particular, EFTEM explores the rich information provided by the EEL-spectrum in a spatial resolved manner.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Energy-filtering Transmission Electron Microscopy in Materials Science

et al. 2000

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Energy-filtered transmission electron microscopy (EFTEM) can be used to acquire elemental distribution images at high lateral resolution within short acquisition times. In this article, we present an overview of typical problems from materials science which can be preferentially solved by means of EFTEM. In the first example, we show how secondary phases in a steel specimen can be easily detected by recording jump ratio images of the matrix element under rocking beam illumination. Secondly, we describe how elemental maps can be converted into concentration maps. A Ba-Nd-titanate ceramics serves as a typical materials science example exhibiting three different compounds with varying composition.

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Energy-filtering transmission electron microscopy in materials science

Cited by 29 publications

References 62 publications

3D Nanoscale Characterization of Thin-Film Organic Photovoltaic Device Structures via Spectroscopic Contrast in the TEM 1

3D Nanoscale Characterization of Thin-Film Organic Photovoltaic Device Structures via Spectroscopic Contrast in the TEM 1

Relativistic calculations of intensity distributions in elemental maps using contrast transfer functions

Quantitative Energy-filtering Transmission Electron Microscopy in Materials Science

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