Quantitative Analysis Of Bological Specimens by Spectrum-Imaging in the Energy Filtering Transmission Electron Microscope

Electron energy loss spectrum-imaging (EELSI) in the energy filtering transmission electron microscope (EFTEM) can provide more accurate analysis of elemental distributions than that obtainable by the standard two-window or three-window background subtraction techniques. Spectra containing many channels can be extracted from regions of interest and analyzed using established methods for quantitation. For example, the pre-edge background can be fitted by an inverse power law and subtracted from the post-edge spectrum. EELSI in the EFTEM is often superior to spectrum-imaging in the scanning transmission electron microscope for mapping specimen regions of size greater than 1 μm. This is due the much larger total beam current that is available at the specimen in a fixed-beam microscope relative to a scanned-beam microscope. Our aim here is demonstrate the advantages of such EELSI measurements for analysis of biological specimens. However, we also indicate some potential pitfalls in acquiring elemental maps in the EFTEM, which can be attributed to specimen instabilities during the acquisition.

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Recording transmitted beam current for X-ray microanalysis in a scanning transmission electron microscope

Journal of Microscopy ◽

10.1111/j.1365-2818.1980.tb04137.x ◽

1980 ◽

Vol 120 (2) ◽

pp. 207-211 ◽

Cited By ~ 2

Author(s):

A. T. Marshall

Keyword(s):

Electron Microscope ◽

Transmission Electron Microscope ◽

Beam Current ◽

Scanning Transmission Electron Microscope ◽

Transmitted Beam ◽

X Ray ◽

Scanning Transmission Electron ◽

Transmission Electron ◽

Scanning Transmission

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Measuring Polymer Microstructure using Spatially-Resolved Eels in the Stem

MRS Proceedings ◽

10.1557/proc-461-199 ◽

1996 ◽

Vol 461 ◽

Cited By ~ 1

Author(s):

K. Siangchaew ◽

D. Arayasantiparb ◽

M. Libera

Keyword(s):

Electron Microscope ◽

Transmission Electron Microscope ◽

Heavy Element ◽

Large Data ◽

Scanning Transmission Electron Microscope ◽

Differential Staining ◽

Spatially Resolved ◽

Transmission Electron ◽

Scanning Transmission ◽

Spectrum Imaging

ABSTRACTImage contrast for the examination of multiphase polymers in the transmission electron microscope (TEM) usually requires differential staining by a heavy element (Os, Ru, U). Staining methods have provided a wealth of microstructural information in polymers, but there are situations, particularly where high resolution is needed, where staining is undesirable or impossible. This research has collected microstructural information from multiphase polymers without heavy-element stains using spatially-resolved electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM). The technique is known as spectrum imaging. The principal problems facing spectrum imaging in polymer applications are: (1) the identification of spectral fingerprints distinguishing different polymer phases; and (2) the extraction of meaningful microstructural data from large data sets where the signal is weak due to instrumentation and materials constraints. This paper describes applications of spectrum imaging to PE/PS and HDPE/Nylon 6 blends. The aim is to identify adequate spectral features and establish data acquisition and extraction procedures for applications to general, unstained, multiphase polymers.

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Preliminary Results from the First Monochromated and Aberration Corrected 200-kV Field-Emission Scanning Transmission Electron Microscope

Microscopy and Microanalysis ◽

10.1017/s1431927606060697 ◽

2006 ◽

Vol 12 (6) ◽

pp. 498-505 ◽

Cited By ~ 19

Author(s):

Thomas Walther ◽

Heiko Stegmann

Keyword(s):

Electron Microscope ◽

Spatial Resolution ◽

Transmission Electron Microscope ◽

Chromatic Aberration ◽

Beam Current ◽

Scanning Transmission Electron Microscope ◽

Scanning Transmission Electron ◽

Transmission Electron ◽

Scanning Transmission ◽

Aberration Corrected

Experimental results from the first monochromated and aberration-corrected scanning transmission electron microscope operated at 200 kV are described. The formation of an electron probe with a diameter of less than 0.2 nm at an energy width significantly under 0.3 eV and its planned application to the chemical analysis of nanometer-scale structures in materials science are described. Both energy and spatial resolution will benefit from this: The monochromator improves the energy resolution for studies of energy loss near edge structures. The Cs corrector allows formation of either a smaller probe for a given beam current or yields, at fixed probe size, an enhanced beam current density using a larger condenser aperture. We also point out another advantage of the combination of both components: Increasing the convergence angle by using larger condenser apertures in an aberration-corrected instrument will enlarge the undesirable chromatic focus spread. This in turn influences spatial resolution. The effect of polychromatic probe tails is proportional to the product of convergence angle, chromatic aberration constant, and energy spread. It can thus be compensated for in our new instrument by decreasing the energy width by the same factor as the beam convergence is increased to form a more intense probe. An alternative in future developments might be hardware correction of the chromatic aberration, which could eliminate the chromatic probe spread completely.

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A General Method for Spectrometer Design in the Scoff Approximation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092657 ◽

1976 ◽

Vol 34 ◽

pp. 538-539

Author(s):

J. R. Fields

Keyword(s):

Electron Microscope ◽

Transmission Electron Microscope ◽

Energy Analysis ◽

Incident Beam ◽

Scanning Transmission Electron Microscope ◽

Chemical Identification ◽

Scanning Transmission Electron ◽

Transmission Electron ◽

Scanning Transmission ◽

General Method

The energy analysis of electrons scattered by a specimen in a scanning transmission electron microscope can improve contrast as well as aid in chemical identification. In so far as energy analysis is useful, one would like to be able to design a spectrometer which is tailored to his particular needs. In our own case, we require a spectrometer which will accept a parallel incident beam and which will focus the electrons in both the median and perpendicular planes. In addition, since we intend to follow the spectrometer by a detector array rather than a single energy selecting slit, we need as great a dispersion as possible. Therefore, we would like to follow our spectrometer by a magnifying lens. Consequently, the line along which electrons of varying energy are dispersed must be normal to the direction of the central ray at the spectrometer exit.

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Resolution in the Scanning Transmission Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100095522 ◽

1972 ◽

Vol 30 ◽

pp. 454-455

Author(s):

M. G. R. Thomson

Keyword(s):

Electron Microscope ◽

Transmission Electron Microscope ◽

Spherical Aberration ◽

Signal To Noise Ratio ◽

Scanning Transmission Electron Microscope ◽

Dark Field ◽

Objective Lens ◽

Scanning Transmission Electron ◽

Transmission Electron ◽

Scanning Transmission

The variation of contrast and signal to noise ratio with change in detector solid angle in the high resolution scanning transmission electron microscope was discussed in an earlier paper. In that paper the conclusions were that the most favourable conditions for the imaging of isolated single heavy atoms were, using the notation in figure 1, either bright field phase contrast with β0⋍0.5 α0, or dark field with an annular detector subtending an angle between ao and effectively π/2.The microscope is represented simply by the model illustrated in figure 1, and the objective lens is characterised by its coefficient of spherical aberration Cs. All the results for the Scanning Transmission Electron Microscope (STEM) may with care be applied to the Conventional Electron Microscope (CEM). The object atom is represented as detailed in reference 2, except that ϕ(θ) is taken to be the constant ϕ(0) to simplify the integration. This is reasonable for θ ≤ 0.1 θ0, where 60 is the screening angle.

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Measurement of lattice parameter at the nanometer scale using convergent-beam microdiffraction from a thermal emission source

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100149283 ◽

1993 ◽

Vol 51 ◽

pp. 690-691

Author(s):

W. T. Pike

Keyword(s):

Electron Microscope ◽

Transmission Electron Microscope ◽

Thermal Emission ◽

Lattice Parameter ◽

Scanning Transmission Electron Microscope ◽

Emission Source ◽

Device Structure ◽

Transmission Electron ◽

Scanning Transmission ◽

Convergent Beam

With the advent of crystal growth techniques which enable device structure control at the atomic level has arrived a need to determine the crystal structure at a commensurate scale. In particular, in epitaxial lattice mismatched multilayers, it is of prime importance to know the lattice parameter, and hence strain, in individual layers in order to explain the novel electronic behavior of such structures. In this work higher order Laue zone (holz) lines in the convergent beam microdiffraction patterns from a thermal emission transmission electron microscope (TEM) have been used to measure lattice parameters to an accuracy of a few parts in a thousand from nanometer areas of material.Although the use of CBM to measure strain using a dedicated field emission scanning transmission electron microscope has already been demonstrated, the recording of the diffraction pattern at the required resolution involves specialized instrumentation. In this work, a Topcon 002B TEM with a thermal emission source with condenser-objective (CO) electron optics is used.

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Development of Line Analysis and Real-Time Elemental Mapping System in Stem Equipped with a Two-Window Energy Filter

Microscopy and Microanalysis ◽

10.1017/s1431927600031743 ◽

2001 ◽

Vol 7 (S2) ◽

pp. 1134-1135

Author(s):

K. Kaji ◽

T. Aoyama ◽

S. Taya ◽

S. Isakozawa

Keyword(s):

Electron Microscope ◽

Energy Loss ◽

Transmission Electron Microscope ◽

Scanning Transmission Electron Microscope ◽

Elemental Mapping ◽

Additional Function ◽

Edge Structure ◽

Transmission Electron ◽

Mapping System ◽

Scanning Transmission

The ability to obtain elemental maps processed by using inelastically scattered electrons in a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM) is extremely useful in the analysis of materials, and semiconductor devices such as ULSI’s and GMR heads. Electron energy loss spectra (EELS) also give useful information not only to identify unknown materials but also to study chemical bonding states of the objective atoms. Hitachi developed an elemental mapping system, consisting of a STEM (Hitachi, HD- 2000) equipped with a two-window energy filter (Hitachi, ELV-2000), and performed realtime conventional jump-ratio images with nanometer resolution by in-situ calculation of energy-filtered signals [1]. Additional function of acquiring EELS along any lines on specimen has been developed in this system to investigate the energy loss near edge structure (ELNES).Figure 1 shows a schematic figure of the two-window energy filter, consisting of two quadrupole lenses for focusing and zooming spectra, respectively, a magnetic prism spectrometer, a deflection coil and two kinds of electron beam detectors.

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