A sub-50meV spectrometer and energy filter for use in combination with 200kV monochromated (S)TEMs

Brink, H.A.; Barfels, M; Burgner, R.P.; Edwards, Byard

doi:10.1016/s0304-3991(03)00102-5

Cited by 61 publications

(41 citation statements)

References 24 publications

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“…In fact, some TEMs can even resolve better than 50 meV (Bink et al, 2003), which is close to the energy of phonon excitations. An example of monochromated EELS with 100 meV energy resolution as compared to synchrotron XAS is shown in Fig.…”

Section: Electron Energy-loss Spectroscopymentioning

confidence: 89%

“…23. The experimental bulk modulus as a function of actinide element for Th at 50-72 GPa (Bellussi et al, 1981;Benedict, 1987;Benedict and Holzapfal 1993), Pa at 100-157 GPa (Birch, 1947;Benedict et al, 1982;Benedict, 1987;Haire et al, 2003), U at 100-152 GPa (Yoo et al, 1998;Benedict and Dufour, 1985;Akella et al, 1990), Np at 74-118 GPa (Dabos et al, 1987;Benedict, 1987;Benedict and Holzapfal 1993), Pu at 40-55 (Roof, 1981;Benedict, 1987;Benedict and Holzapfal 1993), Am at 30 GPa (Heathman et al, 2000), Cm at 37 GPa (Heathman et al, 2005), Bk at 35 , and Cf at 50 GPa (Peterson et al, 1983). Notice the striking similarity between bulk modulus and the melting temperature in the pseudo-binary phase diagram in Fig.…”

Section: Fig 6 (A) (Color Online) Rearranged Periodicmentioning

confidence: 99%

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Nature of the5fstates in actinide metals

2009

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Actinide elements produce a plethora of interesting physical behaviors due to the 5f states. This review compiles and analyzes progress in understanding of the electronic and magnetic structure of the 5f states in actinide metals. Particular interest is given to electron energy-loss spectroscopy and many-electron atomic spectral calculations, since there is now an appreciable library of core d → valence f transitions for Th, U, Np, Pu, Am, and Cm. These results are interwoven and discussed against published experimental data, such as x-ray photoemission and absorption spectroscopy, transport measurements, and electron, x-ray, and neutron diffraction, as well as theoretical results, such as density-functional theory and dynamical mean-field theory.

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Section: Electron Energy-loss Spectroscopymentioning

confidence: 89%

Section: Fig 6 (A) (Color Online) Rearranged Periodicmentioning

confidence: 99%

Nature of the5fstates in actinide metals

2009

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“…However, the factors influencing energy resolution not only depend on the microscope, like energy spread of the electron beam, acceleration voltage stability, and monochromator and spectrometer performance [20], but also on the environment of the microscope in terms of magnetic fields [21]. Simultaneously with the improvement in energy resolution of the monochromated (S)TEMs, their sensitivity to external stray fields has increased, too.…”

Section: Instrumental Developmentsmentioning

confidence: 99%

An Introduction to High-resolution EELS in Transmission Electron Microscopy

et al. 2008

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The practical advantages of an electron monochromator for electron energy-loss spectroscopy (EELS) in transmission electron microscopy are described. Typical examples from materials and nanoparticle research demonstrate the use of EELS with high energy and spatial resolution. Recent instrumental developments are also reviewed with a discussion of how the technique could be used to study catalyst structures of the future.

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The filter's electron optical energy resolution is a function of 1.)

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confidence: 99%

“…This permits the use of a larger pre-filter camera length, reducing the effect of image-spectrum coupling for the same collection angle and consequently allowing for a smaller energy window for an energy filtered CBED image. Such a filter has been designed for monochromated TEMs [4].…”

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confidence: 99%

The Effect of Cs-Correction on Filtered Imaging and Spectral Energy Resolution for a Post-Column Imaging Energy Filter

Barfels¹,

Kundmann²,

Trevor³

et al. 2005

MAM

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The emergence of commercially available Cs aberration corrected transmission electron microscopes [1] in combination with monochromators [2,3] raises the question how spherical aberration correction may affect the energy resolution of a high resolution sub-50 meV electron energy loss spectrometer [4]. Spherical aberrations of the objective lens are not only detrimental to spatial resolution, but can also significantly degrade the spectral energy resolution of an electron energy loss spectrum or limit the slit width used for energy-filtered diffraction imaging.The filter's electron optical energy resolution is a function of 1.) filter aberrations and 2.) the optical coupling of the specimen with the spectrometer, called image-spectrum mixing. An energy filter can be coupled to the microscope optics either in diffraction mode or in image mode. A postcolumn filter focuses the projector lens crossover into an energy dispersed spectrum. In diffraction mode the projector crossover contains an image of the specimen. Conversely in image mode the projector crossover contains a diffraction pattern of the specimen. Most electron energy loss spectroscopy (EELS) measurements, STEM spectrum imaging and energy filtered diffraction patterns are acquired in the image-coupled filter mode. In comparison to diffraction-spectrum mixing much less is known about image-spectrum mixing. The effect of diffraction-spectrum mixing has been shown for both in-column [5,6] and post-column filters [7,8]. It has also been mathematically presented in terms of transmissivity [9], which is the imaged area as a function of solid scattering angle that can be passed through the filter for a given energy resolution defined by the filter aberrations. Calculating the size of the image in the projector crossover using the approach in [9], then for a camera length of 15 mm and a probe size of 5 nm the image size in the spectrum of the post-column filter is only 0.08 eV. However, this analysis neglects the effect of spherical aberrations of the objective lens. Accounting for spherical aberrations, it can be shown that the size of the projector crossover in the spectrum at the disc of minimum confusion with an objective lens Cs of 1.1 mm and a 100 mrad collection angle amounts to 9.3 eV. This is a much more realistic value of the projector crossover size in the spectrum of an image-coupled filtered mode. If most of the image magnification is obtained with the objective lens, the aberrations of all the other electron microscope lenses are expected to be far less in shaping the projector crossover waist. This condition may vary for different microscopes.A post-column filter with partial 3 rd order aberration correction and a 5 mm entrance aperture was used to acquire an energy filtered CBED pattern of Si <111> at 200 kV on a conventional TEM with a LaB6 emitter. The filter aberrations are shown in FIG 1. The non-isochromaticity is 1.5 eV. The Cs of the objective lens is 1.1 mm. FIG 2 shows an energy filtered diffraction pattern, which is an image-coupled filt...

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A sub-50meV spectrometer and energy filter for use in combination with 200kV monochromated (S)TEMs

Cited by 61 publications

References 24 publications

Nature of the5fstates in actinide metals

Nature of the5fstates in actinide metals

An Introduction to High-resolution EELS in Transmission Electron Microscopy

The Effect of Cs-Correction on Filtered Imaging and Spectral Energy Resolution for a Post-Column Imaging Energy Filter

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