On the role of inelastic scattering in phase-plate transmission electron microscopy

Hettler, Simon; Wagner, Jochen; Dries, Manuel; Oster, Marco; Wacker, Christian; Schröder, Rasmus R.; Gerthsen, D.

doi:10.1016/j.ultramic.2015.04.001

Cited by 15 publications

(12 citation statements)

References 26 publications

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“…The phase shift φ PP and defocus ∆ f of the images are determined by a Matlab-based (Math-Works, Natick, MA, USA) pattern recognition software [20] under the assumption that the phase shift is only induced on the unscattered electrons. A time series of HFPP TEM images allows to trace the PCTF evolution and thus the phase shift induced by an electron-beam induced modification of the thin film.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Charging of carbon thin films in scanning and phase-plate transmission electron microscopy

et al. 2018

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A systematic study on charging of carbon thin films under intense electron-beam irradiation was performed in a transmission electron microscope to identify the underlying physics for the functionality of hole-free phase plates. Thin amorphous carbon films fabricated by different deposition techniques and single-layer graphene were studied. Clean thin films at moderate temperatures show small negative charging while thin films kept at an elevated temperature are stable and not prone to beam-generated charging. The charging is attributed to electron-stimulated desorption (ESD) of chemisorbed water molecules from the thin-film surfaces and an accompanying change of work function. The ESD interpretation is supported by experimental results obtained by electron-energy loss spectroscopy, hole-free phase plate imaging, secondary electron detection and x-ray photoelectron spectroscopy as well as simulations of the electrostatic potential distribution. The described ESD-based model explains previous experimental findings and is of general interest to any phase-related technique in a transmission electron microscope.

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Section: Accepted Manuscriptmentioning

confidence: 99%

Charging of carbon thin films in scanning and phase-plate transmission electron microscopy

et al. 2018

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“…Including an amorphous part in the illuminated sample area leads to the presence of Thon rings which are exploited to determine j PP by a pattern recognition process [19] adapted to PP TEM [20].…”

Section: Resultsmentioning

confidence: 99%

High-resolution transmission electron microscopy with an electrostatic Zach phase plate

et al. 2016

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A new method to control lattice-fringe contrast in high-resolution transmission electron microscopy (HRTEM) images by the implementation of a physical phase plate (PP) is proposed. PPs are commonly used in analogy to Zernike PPs in light microscopy to enhance the phase contrast of weak-phase objects with nm-sized features, which often occur in life science applications. Such objects otherwise require strong defocusing, which leads to a degradation of the instrumental resolution and impedes intuitive image interpretation. The successful application of an electrostatic Zach PP in HRTEM is demonstrated by the investigation of single crystalline Si and Ge samples. The influence of the Zach PP on the image formation process is assessed by analyzing the amplitudes of (111) reflections in power spectra which show a cosine-type dependence on the induced phase shift under certain conditions as predicted by theory.

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“…The short elastic mean free path in the ZAC-alloy is not fully compensated by the reduced film thickness because P elastic in the ZAC-alloy is increased by a factor of angles. Phonon-scattered electrons in the object can be excluded from image formation by an appropriately sized objective aperture [31]. The inelastic mean free path λ inelastic can be measured from lowloss EELS spectra if the film thickness t is known [32] λ inelastic = t ln I ZL +I LL I ZL…”

Section: Discussionmentioning

confidence: 99%

“…The probability for inner-shell ionization is small compared with phonon and plasmon scattering, which are the dominating processes with energy losses of up to 30 eV. Electrons which are phonon scattered in the object can be excluded from image formation by an appropriately sized objective aperture because phonon scattering predominantly occurs in large scattering angles (Hettler et al, 2015). However, inelastic scattering in the PP material remains a limiting factor in the application of thin-film PPs in HRTEM.…”

Section: Discussionmentioning

confidence: 99%

Thin-Film Phase Plates for Transmission Electron Microscopy Fabricated from Metallic Glasses

et al. 2016

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(M. Dries). AbstractThin-film based phase plates are meanwhile a widespread tool to enhance the contrast of weak-phase objects in transmission electron microscopy (TEM). The thin film usually consists of amorphous carbon, which suffers from quick degeneration under the intense electron-beam illumination. Recent investigations have focused on the search for alternative materials with an improved material stability.This work presents thin-film based phase plates fabricated from metallic glass alloys, which are characterized by a high electrical conductivity and an amorphous structure. Thin films of the zirconiumbased alloy Zr 65.0 Al 7.5 Cu 27.5 (ZAC) are prepared and their phase-shifting properties are tested. The ZAC-alloy film is investigated by different TEM techniques, which reveal a range of beneficial characteristics. Particularly favorable is the small probability for inelastic plasmon scattering, which is promising to improve the performance of thin-film based phase plates in phase-contrast TEM.

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On the role of inelastic scattering in phase-plate transmission electron microscopy

Cited by 15 publications

References 26 publications

Charging of carbon thin films in scanning and phase-plate transmission electron microscopy

Charging of carbon thin films in scanning and phase-plate transmission electron microscopy

High-resolution transmission electron microscopy with an electrostatic Zach phase plate

Thin-Film Phase Plates for Transmission Electron Microscopy Fabricated from Metallic Glasses

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