The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform
Alfredo Tolley - One of the best experts on this subject based on the ideXlab platform.
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A method for thin Foil Thickness determination by transmission electron microscopy
Applied Surface Science, 2007Co-Authors: M.v. Castro Riglos, Alfredo TolleyAbstract:Abstract With the intention of determining the local Thickness within a crystalline thin Foil specimen, by means of transmission electron microscopy (TEM), a method previously proposed by Zuo and Shi [J.M. Zuo, Y.F. Shi, Microsc. Microanal. 7 (Suppl. 2) (2001) 224–225] was applied. Using the convergent beam technique, with the incident beam parallel to a zone axis with low indices, diffraction patterns were obtained for some aluminum alloys with low solute content. These patterns were contrasted with those obtained from simulations based on the dynamic theory with Bloch's waves formalism. The local Thickness of the thin Foil was then obtained by visually comparing the simulated patterns with the experimental one. Comparison of the proposed method with that based on the analysis of two-beam convergent beam patterns [P.M. Kelly, A. Jostsons, R.G. Blake, J.G. Napier, Phys. Stat. Solidi (a) 31 (1975) 771–780] and with that based on the ratio of intensity of the zero loss peak to the total intensity in an electron energy loss spectrum [R.F. Egerton, Electron Energy Loss Spectroscopy in the Electron Microscope, second ed., Plenum Press, New York, 1996] was carried out. A very good agreement between Thicknesses determined using the different methods was found. The sensitivity of the method of Zuo et al. was found to be about 1 or 2 nm. The advantages and limitations of the different methods are discussed. The method of Zuo et al. can provide fast and reliable results and can be applied in all modern instruments.
R. N. Stevens - One of the best experts on this subject based on the ideXlab platform.
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Measurement of Foil Thickness in transmission electron microscopy
Journal of Materials Science, 1994Co-Authors: Zhenpeng Pan, C. K. L. Davies, R. N. StevensAbstract:Methods for the measurement of the Thickness of thin-Foil specimens used in transmission electron microscopy are either difficult to carry out or have been subject to criticism. In particular, the contamination spot method is said to overestimate the Thickness because the region of rapidly changing contrast marking the apparent edge of the spot is not on the Foil surface but is on a broad contamination deposit whose Thickness is changing much more slowly. A new method for measuring Foil Thickness is proposed, based on contamination deposits on the Foil surfaces. The problems of the contamination spot method, in which the deposit is of circular form, are avoided by using one of the condenser lenses to focus the electron beam in a thin line on the Foil during deposition. Adequate contrast can be obtained with a line whose width is one-third to one-fifth of the Foil Thickness and having a height equal to or less than its width. The error, being a fraction of the line width, is then very small. After rotation of the Foil, the lines separate into two and the corresponding edges of the lines provide distinct features whose separation can be measured to determine Thickness. The axis of rotation, perpendicular to which the separation of the lines has to be measured to calculate Foil Thickness, is determined by depositing two contamination lines at right angles. The method allows a number of measurements of Thickness covering a relatively large area of Foil to be made per contamination experiment. Near the edge of the Foil, the upper and lower lines of contamination can join around the Foil edge to form a U shape which can be used to measure Thickness profile of the Foil right up to the edge.
M.v. Castro Riglos - One of the best experts on this subject based on the ideXlab platform.
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A method for thin Foil Thickness determination by transmission electron microscopy
Applied Surface Science, 2007Co-Authors: M.v. Castro Riglos, Alfredo TolleyAbstract:Abstract With the intention of determining the local Thickness within a crystalline thin Foil specimen, by means of transmission electron microscopy (TEM), a method previously proposed by Zuo and Shi [J.M. Zuo, Y.F. Shi, Microsc. Microanal. 7 (Suppl. 2) (2001) 224–225] was applied. Using the convergent beam technique, with the incident beam parallel to a zone axis with low indices, diffraction patterns were obtained for some aluminum alloys with low solute content. These patterns were contrasted with those obtained from simulations based on the dynamic theory with Bloch's waves formalism. The local Thickness of the thin Foil was then obtained by visually comparing the simulated patterns with the experimental one. Comparison of the proposed method with that based on the analysis of two-beam convergent beam patterns [P.M. Kelly, A. Jostsons, R.G. Blake, J.G. Napier, Phys. Stat. Solidi (a) 31 (1975) 771–780] and with that based on the ratio of intensity of the zero loss peak to the total intensity in an electron energy loss spectrum [R.F. Egerton, Electron Energy Loss Spectroscopy in the Electron Microscope, second ed., Plenum Press, New York, 1996] was carried out. A very good agreement between Thicknesses determined using the different methods was found. The sensitivity of the method of Zuo et al. was found to be about 1 or 2 nm. The advantages and limitations of the different methods are discussed. The method of Zuo et al. can provide fast and reliable results and can be applied in all modern instruments.
K.z. Botros - One of the best experts on this subject based on the ideXlab platform.
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A METHOD FOR DETERMINING Foil ThicknessES IN TEM BY USING CONVERGENT BEAM ELECTRON DIFFRACTION UNDER WEAK BEAM CONDITIONS
Micron, 1995Co-Authors: K.z. BotrosAbstract:Abstract In the present work, convergent beam electron diffraction was studied in zirconium (a material of intermediate atomic number) at 300 keV, under weak beam diffraction conditions. For a particular Thickness, the details in an observed low order disc were matched to those calculated using the multibeam dynamical theory. This presents the possibility of determining Foil Thickness over a wide range, with an estimated experimental accuracy of ≈7% or less. In contrast to other convergent beam techniques, the present method, which uses weak beam conditions, can employ commonly-occurring low order reflections to extract Thicknesses. A simple equation based on the two beam approximation, is derived to determine Foil Thickness (to within ≈ 10%) without resorting to detailed image matching. This equation can be used for a rough estimate of Foil Thickness while carrying out TEM observations.
Zhenpeng Pan - One of the best experts on this subject based on the ideXlab platform.
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Measurement of Foil Thickness in transmission electron microscopy
Journal of Materials Science, 1994Co-Authors: Zhenpeng Pan, C. K. L. Davies, R. N. StevensAbstract:Methods for the measurement of the Thickness of thin-Foil specimens used in transmission electron microscopy are either difficult to carry out or have been subject to criticism. In particular, the contamination spot method is said to overestimate the Thickness because the region of rapidly changing contrast marking the apparent edge of the spot is not on the Foil surface but is on a broad contamination deposit whose Thickness is changing much more slowly. A new method for measuring Foil Thickness is proposed, based on contamination deposits on the Foil surfaces. The problems of the contamination spot method, in which the deposit is of circular form, are avoided by using one of the condenser lenses to focus the electron beam in a thin line on the Foil during deposition. Adequate contrast can be obtained with a line whose width is one-third to one-fifth of the Foil Thickness and having a height equal to or less than its width. The error, being a fraction of the line width, is then very small. After rotation of the Foil, the lines separate into two and the corresponding edges of the lines provide distinct features whose separation can be measured to determine Thickness. The axis of rotation, perpendicular to which the separation of the lines has to be measured to calculate Foil Thickness, is determined by depositing two contamination lines at right angles. The method allows a number of measurements of Thickness covering a relatively large area of Foil to be made per contamination experiment. Near the edge of the Foil, the upper and lower lines of contamination can join around the Foil edge to form a U shape which can be used to measure Thickness profile of the Foil right up to the edge.