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Mapping Metal Distributions In Thin Cryosections Without Scanning Transmission Electron Microscope With The Philips Electron Beam And Image Deflection (Ebid) Unit, A. J. Morgan, J. M. Brock, C. Winters, G. H. J. Lewis
Mapping Metal Distributions In Thin Cryosections Without Scanning Transmission Electron Microscope With The Philips Electron Beam And Image Deflection (Ebid) Unit, A. J. Morgan, J. M. Brock, C. Winters, G. H. J. Lewis
Scanning Microscopy
The purpose of the present paper was to describe the use of a commercially-available, and relatively inexpensive, beam and image deflection unit that can facilitate digital X-ray (element) mapping in a standard transmission electron microscope not furnished with a STEM attachment. The test specimen was a thin freeze-dried section of the metal-sequestering chloragogenous tissue from the earthworm, Lumbricus rubellus, inhabiting a soil naturally contaminated with Pb, Zn and Cd. Qualitative maps obtained from this material confirmed the efficacy of the deflection unit, and revealed the presence of three compositionally distinct metal-accumulating compartments within the chloragocytes: (i) ovoid, electron-dense, phosphate-bearing and …
Quantitative Dark-Field Mass Analysis Of Ultrathin Cryosections In The Field-Emission Scanning Transmission Electron Microscope, S. Brian Andrews, Roger A. Buchanan, Richard D. Leapman
Quantitative Dark-Field Mass Analysis Of Ultrathin Cryosections In The Field-Emission Scanning Transmission Electron Microscope, S. Brian Andrews, Roger A. Buchanan, Richard D. Leapman
Scanning Microscopy
The availability of a cryotransfer stage, highly efficient electron energy loss spectrometers, and ultrathin-window energy-dispersive x-ray spectrometers for the VG Microscopes HB501 field-emission scanning transmission electron microscope (STEM) provides this instrument with the potential for high resolution biological microanalysis. Recent technical advances offer cryosections that are thin enough to take advantage of the analytical capabilities of this microscope. This paper first discusses the quantitative characterization of freeze-dried, ultrathin cryosections of directly frozen liver and brain by low-dose dark-field STEM imaging. Such images reveal high-quality sections with good structural detail, mainly due to reduced preparation artifacts and electron beam damage. These …
Biological Electron Energy Loss Spectroscopy In The Field-Emission Scanning Transmission Electron Microscope, R. D. Leapman, S. Q. Sun, J. A. Hunt, S. B. Andrews
Biological Electron Energy Loss Spectroscopy In The Field-Emission Scanning Transmission Electron Microscope, R. D. Leapman, S. Q. Sun, J. A. Hunt, S. B. Andrews
Scanning Microscopy
The dedicated scanning transmission electron microscope (STEM) combined with parallel electron energy loss spectroscopy (EELS) provides a very sensitive means of detecting specific elements in small structures. EELS is more sensitive than optimized energy-dispersive X-ray spectroscopy by a factor of about three for calcium. Measurement of such low concentrations requires special processing methods such as difference-acquisition techniques and multiple least squares procedures for fitting reference spectra. By analyzing data recorded at each pixel in a spectrum-image it is possible to map quantitatively the elemental distributions in a specimen. It is possible to prepare cryosections that are sufficiently thin to avoid …