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Accelerating Voltage

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Raynald Gauvin – One of the best experts on this subject based on the ideXlab platform.

  • Investigation of the Effect of Magnification, Accelerating Voltage, and Working Distance on the 3D Digital Reconstruction Techniques.
    Scanning, 2020
    Co-Authors: S.m. Bayazid, Nicolas Brodusch, Raynald Gauvin

    Abstract:

    In this study, the effect of Scanning Electron Microscopy (SEM) parameters such as magnification ( ), Accelerating Voltage ( ), and working distance (WD) on the 3D digital reconstruction technique, as the first step of the quantitative characterization of fracture surfaces with SEM, was investigated. The 2D images were taken via a 4-Quadrant Backscattered Electron (4Q-BSE) detector. In this study, spherical particles of Ti-6Al-4V (15-45 μm) deposited on the silicon substrate were used. It was observed that the working distance has a significant influence on the 3D digital rebuilding method via SEM images. The results showed that the best range of the working distance for our system is 9 to 10 mm. It was shown that by increasing the magnification to 1000x, the 3D digital reconstruction results improved. However, there was no significant improvement by increasing the magnification beyond 1000x. In addition, results demonstrated that the lower the Accelerating Voltage, the higher the precision of the 3D reconstruction technique, as long as there are clean backscattered signals. The optimal condition was achieved when magnification, Accelerating Voltage, and working distance were chosen as 1000x, 3 kV, and 9 mm, respectively.

  • Electron energy-loss spectroscopy (EELS) with a cold-field emission scanning electron microscope at low Accelerating Voltage in transmission mode.
    Ultramicroscopy, 2018
    Co-Authors: Nicolas Brodusch, Hendrix Demers, Alexandra Gellé, Audrey Moores, Raynald Gauvin

    Abstract:

    Abstract A commercial electron energy-loss spectrometer (EELS) attached to a high-resolution cold-field emission scanning electron microscope in transmission mode (STEM) is evaluated and its potential for characterizing materials science thin specimens at low Accelerating Voltage is reviewed. Despite the increased beam radiation damage at SEM Voltages on sensitive compounds, we describe some potential applications which benefit from lowering the primary electrons Voltage on less-sensitive specimens. We report bandgap measurements on several dielectrics which were facilitated by the lack of Cherenkov radiation losses at 30 kV. The possibility of volume plasmon imaging to probe local composition changes in complex materials was demonstrated using energy-filtered STEM, either via spectrum imaging or elemental mapping using the “three-windows” method. As plasmonic materials are increasing used for energy, electronics or biomedical applications, the ability of reliably evaluate their properties at low Accelerating Voltage in a SEM is very appealing and is demonstrated. The energy resolution of the spectrometer, taken as the full width at half maximum of the zero-loss peak, was routinely measured at around 0.55 eV and it is demonstrated that t/λ ratios up to 1.5 allowed practical EEL spectroscopy at 30 kV.

  • about the contrast of δ precipitates in bulk al cu li alloys in reflection mode with a field emission scanning electron microscope at low Accelerating Voltage
    Journal of Microscopy, 2017
    Co-Authors: Nicolas Brodusch, Frederic Voisard, Raynald Gauvin

    Abstract:

    Summary
    Characterising the impact of lithium additions in the precipitation sequence in Al–Li–Cu alloys is important to control the strengthening of the final material. Since now, transmission electron microscopy (TEM) at high beam Voltage has been the technique of choice to monitor the size and spatial distribution of δ’ precipitates (Al3Li). Here we report on the imaging of the δ’ phase in such alloys using backscattered electrons (BSE) and low Accelerating Voltage in a high-resolution field-emission scanning electron microscope. By applying low-energy Ar+ ion milling to the surface after mechanical polishing (MP), the MP-induced corroded layers were efficiently removed and permitted the δ’s to be visible with a limited impact on the observed microstructure. The resulting BSE contrast between the δ’s and the Al matrix was compared with that obtained using Monte Carlo modelling. The artefacts possibly resulting from the sample preparation procedure were reviewed and discussed and permitted to confirm that these precipitates were effectively the metastable δ’s. The method described in this report necessitates less intensive sample preparation than that required for TEM and provides a much larger field of view and an easily interpretable contrast compared to the transmission techniques.

Nicolas Brodusch – One of the best experts on this subject based on the ideXlab platform.

  • Investigation of the Effect of Magnification, Accelerating Voltage, and Working Distance on the 3D Digital Reconstruction Techniques.
    Scanning, 2020
    Co-Authors: S.m. Bayazid, Nicolas Brodusch, Raynald Gauvin

    Abstract:

    In this study, the effect of Scanning Electron Microscopy (SEM) parameters such as magnification ( ), Accelerating Voltage ( ), and working distance (WD) on the 3D digital reconstruction technique, as the first step of the quantitative characterization of fracture surfaces with SEM, was investigated. The 2D images were taken via a 4-Quadrant Backscattered Electron (4Q-BSE) detector. In this study, spherical particles of Ti-6Al-4V (15-45 μm) deposited on the silicon substrate were used. It was observed that the working distance has a significant influence on the 3D digital rebuilding method via SEM images. The results showed that the best range of the working distance for our system is 9 to 10 mm. It was shown that by increasing the magnification to 1000x, the 3D digital reconstruction results improved. However, there was no significant improvement by increasing the magnification beyond 1000x. In addition, results demonstrated that the lower the Accelerating Voltage, the higher the precision of the 3D reconstruction technique, as long as there are clean backscattered signals. The optimal condition was achieved when magnification, Accelerating Voltage, and working distance were chosen as 1000x, 3 kV, and 9 mm, respectively.

  • Electron energy-loss spectroscopy (EELS) with a cold-field emission scanning electron microscope at low Accelerating Voltage in transmission mode.
    Ultramicroscopy, 2018
    Co-Authors: Nicolas Brodusch, Hendrix Demers, Alexandra Gellé, Audrey Moores, Raynald Gauvin

    Abstract:

    Abstract A commercial electron energy-loss spectrometer (EELS) attached to a high-resolution cold-field emission scanning electron microscope in transmission mode (STEM) is evaluated and its potential for characterizing materials science thin specimens at low Accelerating Voltage is reviewed. Despite the increased beam radiation damage at SEM Voltages on sensitive compounds, we describe some potential applications which benefit from lowering the primary electrons Voltage on less-sensitive specimens. We report bandgap measurements on several dielectrics which were facilitated by the lack of Cherenkov radiation losses at 30 kV. The possibility of volume plasmon imaging to probe local composition changes in complex materials was demonstrated using energy-filtered STEM, either via spectrum imaging or elemental mapping using the “three-windows” method. As plasmonic materials are increasing used for energy, electronics or biomedical applications, the ability of reliably evaluate their properties at low Accelerating Voltage in a SEM is very appealing and is demonstrated. The energy resolution of the spectrometer, taken as the full width at half maximum of the zero-loss peak, was routinely measured at around 0.55 eV and it is demonstrated that t/λ ratios up to 1.5 allowed practical EEL spectroscopy at 30 kV.

  • about the contrast of δ precipitates in bulk al cu li alloys in reflection mode with a field emission scanning electron microscope at low Accelerating Voltage
    Journal of Microscopy, 2017
    Co-Authors: Nicolas Brodusch, Frederic Voisard, Raynald Gauvin

    Abstract:

    Summary
    Characterising the impact of lithium additions in the precipitation sequence in Al–Li–Cu alloys is important to control the strengthening of the final material. Since now, transmission electron microscopy (TEM) at high beam Voltage has been the technique of choice to monitor the size and spatial distribution of δ’ precipitates (Al3Li). Here we report on the imaging of the δ’ phase in such alloys using backscattered electrons (BSE) and low Accelerating Voltage in a high-resolution field-emission scanning electron microscope. By applying low-energy Ar+ ion milling to the surface after mechanical polishing (MP), the MP-induced corroded layers were efficiently removed and permitted the δ’s to be visible with a limited impact on the observed microstructure. The resulting BSE contrast between the δ’s and the Al matrix was compared with that obtained using Monte Carlo modelling. The artefacts possibly resulting from the sample preparation procedure were reviewed and discussed and permitted to confirm that these precipitates were effectively the metastable δ’s. The method described in this report necessitates less intensive sample preparation than that required for TEM and provides a much larger field of view and an easily interpretable contrast compared to the transmission techniques.

Hidetaka Sawada – One of the best experts on this subject based on the ideXlab platform.

  • Atomic Resolution Imaging at an Ultralow Accelerating Voltage by a Monochromatic Transmission Electron Microscope.
    Physical review letters, 2016
    Co-Authors: Shigeyuki Morishita, Masaki Mukai, Kazu Suenaga, Hidetaka Sawada

    Abstract:

    Transmission electron microscopy using low-energy electrons would be very useful for atomic resolution imaging of specimens that would be damaged at higher energies. However, the resolution at low Voltages is degraded because of geometrical and chromatic aberrations. In the present study, we diminish the effect of these aberrations by using a delta-type corrector and a monochromator. The dominant residual aberration in a delta-type corrector, which is the sixth-order three-lobe aberration, is counterbalanced by other threefold aberrations. Defocus spread caused by chromatic aberration is reduced by using a monochromated beam with an energy spread of 0.05 eV. We obtain images of graphene and demonstrate atomic resolution at an ultralow Accelerating Voltage of 15 kV.

  • Resolution enhancement at a large convergence angle by a delta corrector with a CFEG in a low-AcceleratingVoltage STEM.
    Micron (Oxford England : 1993), 2014
    Co-Authors: Hidetaka Sawada, Takeo Sasaki, Fumio Hosokawa, Kazutomo Suenaga

    Abstract:

    Abstract Resolution reduction by a diffraction limit becomes severe with an increase in the wavelength of an electron at a relatively low Accelerating Voltage. For maintaining atomic resolution at a low Accelerating Voltage, a larger convergence angle with aberration correction is required. The developed aberration corrector, which compensates for higher-order aberration, can expand the uniform phase angle. Sub-angstrom imaging of a Ge [1 1 2] specimen with a narrow energy spread obtained by a cold field emission gun at 60 kV was performed using the aberration corrector. We achieved a resolution of 82 pm for a Ge–Ge dumbbell structure image by high angle annular dark-field imaging.

  • visualizing and identifying single atoms using electron energy loss spectroscopy with low Accelerating Voltage
    Nature Chemistry, 2009
    Co-Authors: Kazu Suenaga, Hidetaka Sawada, Takeo Sasaki, Yuta Sato, Zheng Liu, Hiromichi Kataura, Toshiya Okazaki, Koji Kimoto, K Omoto, Takeshi Tomita

    Abstract:

    Visualizing atoms and discriminating between those of different elements is a goal in many analytical techniques. The use of electron energy-loss spectroscopy (EELS) in such single-atom analyses is hampered by an inherent difficulty related to the damage caused to specimens by incident electrons. Here, we demonstrate the successful EELS single-atom spectroscopy of various metallofullerene-doped single-wall nanotubes (known as peapods) without massive structural destruction. This is achieved by using an incident electron probe with a low Accelerating Voltage (60 kV). Single calcium atoms inside the peapods were unambiguously identified for the first time using EELS. Elemental analyses of lanthanum, cerium and erbium atoms were also demonstrated, which shows that single atoms with adjacent atomic numbers can be successfully discriminated with this technique.