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New and Innovative Methods to Characterize Materials Better

Low-Voltage SEM

Since the early 90s, low voltage scanning electron microscopy (LV-SEM) has been in the core of Prof. Gauvin's research. In 1995, he showed that Monte Carlo modeling was suitable to reproduce SEM experiments at low beam voltage and he predicted that later high-resolution FE-SEM would be able to discriminate nanometer scale precipitates in metallic alloys. Fifteen years later, LV-SEM is our trademark and we apply LV-SEM imaging and spectroscopy to a wide range of applications, from metallic alloys and coatings to mining ores and geological specimens and nanomaterials. With the advent of high quality SDD spectrometers, cutting edge LV X-ray microanalysis and spectroscopy is now a realistically applied technique. 


  1. R. Gauvin, P. Hovington and D. Drouin (1995), “Quantification of Spherical Inclusions in the Scanning Electron Microscope Using Monte Carlo Simulations”, Scanning, Vol. 17, Issue 4, pp. 202-219.

  2.  R. Gauvin and S. Yue (1997), “The observation of NbC precipitates in steel in the nanometer range using a field emission gun scanning electron microscope”, Microscopy & Microanalysis, Vol. 3, Supp. 2, pp. 1243-1244.

  3. N. Brodusch, M. L. Trudeau, P. Michaud, L. Rodrigue, J. Boselli, R. Gauvin (2012), “ Contribution of a New Generation FE-SEM in the Understanding of a 2099 Al-Li alloy”, Microscopy & Microanalysis, Vol. 18, No. 6, pp. 1393-1409.

  4. N. Brodusch, H. Demers, M. Trudeau and R. Gauvin (2014), “High-resolution imaging and X-ray microanalysis in the FE-SEM”, Surface and Interface Analysis, Vol. 46, pp. 1286-1290.

Monte Carlo Modeling

Professor Raynald Gauvin has been involved in the Monte Carlo modeling community for more than 35 years, and naturally this is a founding principle of the MEMRG. Through the years, he has improved the single scattering model and promoted Monte Carlo has a credible path to X-ray microanalysis. Recently, our collaboration with the Montréal based company ORS permitted to integrate MCXRay into the Dragonfly platform to benefit from a more powerful 3D environment combined with a simulation speed increase of 100 to 1000 times. Recently, we integrated the knock-on (KO) damage cross-sections in our program (not distributed) to account for KO damage in the propagation of electrons in beam-sensitive solids like Li compounds.

  1. A. Jaberi, N. Brodusch, J. Song and R. Gauvin (2023), “Prediction of primary knock-on damage during electron microscopy characterization of lithium-containing materials”, Ultramicroscopy , Vol. 256, p. 113884.

  2. Y. Yuan, H. Demers, S. Rudinsky and R. Gauvin (2019), “Secondary fluorescence correction for characteristic and bremsstrahlung X-rays using Monte Carlo X-ray depth distributions applied to bulk and multilayer materials”, Microscopy and Microanalysis, 25, (1), pp. 92-104.

  3. M. Attarian Shandiz, M. J.-F. Guinel, R. Gauvin (2016), “Monte Carlo simulation of the fine structure of the energy-loss near-edge structure (ELNES)”,  Microscopy & Microanalysis, Vol. 22(1), pp. 219-229


Towards Quantitative X-ray Microanalysis

The development of materials sustaining the transformation of today's society towards more greener and eco-friendly goods and services needs an appropriate and accurate measurement of the materials elemental distributions. Based on the long-standing experience of Professor Raynald Gauvin in X-ray microanalysis, MEMRG acts at improving existing methods as well as developing newer tools to extract composition/phase information from any sample. The advent of faster Monte Carlo simulation programs and of deep learning tools is revolutionizing quantitative X-ray microanalysis and through the impressive work of our students' team, MEMRG is at the front line to establish new tools to measure materials compositions.

  1. C. Teng, and R. Gauvin (2021), “The f-ratio model for quantitative X-ray microanalysis”, Talanta, 235, 122765.

  2. Y. Yuan, H. Demers, N. Brodusch, X. Wang and R. Gauvin (2020), “Inverse Modeling for quantitative X-ray microanalysis applied to 2D heterogeneous materials”, Ultramicroscopy, 219, 113117.

  3. R. Gauvin (2012), “What remains to be done to allow Quantitative X-Ray Microanalysis to become a Characterization Technique used with every EDS Spectra Acquired?”, Invited Paper, Microscopy & Microanalysis, Vol. 18, No. 5, pp. 915 - 940.

  4. Gauvin, N. Brodusch, P. Michaud (2012). "Determination of Diffusion Coefficients with Quantitative X-Ray Microanalysis at High - Spatial Resolution". Defect and Diffusion Forum. Vol - 323-325, pp. 61-67.


Low-Voltage STEM/EELS

Low voltage STEM electron energy-loss spectroscopy (LV-STEM-EELS) shows a cleaner low-loss spectrum which makes it the ideal solution for plasmon characterization and bandgap measurement. The three-windows detection system allows imaging quickly the intensity of the plasmon resonance peaks in space, and generates elemental maps from the higher energy core-loss region. The 0.55 eV energy resolution of the spectrometer allows the assessment of oxidation states and fingerprinting materials electronic structures. Recently, LV-STEM-EELS showed its potential use for elemental quantification.

  1. N. Dumaresq, N. Brodusch, S. Bessette and R. Gauvin (2023), “Elemental quantification using electron energy-loss spectroscopy with a low accelerating voltage  ”, Under Preparation.

  2. A. Gellé, G. D. Price, F. Voisard, N. Brodusch, R. Gauvin, Z. Amara, and A. Moores (2021), “Enhancing Singlet Oxygen Photocatalysis with Plasmonic Nanoparticles”, ACS Applied Materials & Interfaces, 13, 30, pp. 35606 - 35616.

  3. N. Brodusch, H. Demers, A. Gellé, A. Moores and R. Gauvin (2019), “Electron energy-loss spectroscopy (EELS) with a cold-field emission scanning electron microscope at low accelerating voltage in transmission mode”, Ultramicroscopy, 203, pp.1-36.


Electron Channeling Contrast

Characterizing the microstructure of crystalline materials is essential to understand and predict their mechanical properties. As a companion technique to EBSD, electron channeling contrast (ECCI) is a fast BSE imaging technique to reveal the crystal orientations of a finely polished sample. Since it is more sensitive to local orientation variations, ECCI is ideal to image subgrain boundaries and crystal defects like dislocations, staking faults and nanotwins. Combined to the high spatial resolution of BSE imaging in cold-field emission SEMs, ECCI is now a reliable and mature technique to characterize crystalline materials down to the nanometer level and MEMRG has a strong expertise in using this technique at McGill University.

  1. N. Brodusch, S. V. Brahimi, E. Barbosa De Melo, J. Song, S. Yue, N. Piché and R. Gauvin (2021), “Scanning Electron Microscopy versus Transmission Electron Microscopy for Material Characterization: A Comparative Study on High-Strength Steels”, Scanning, 5511618.

  2. M. Dorri, S. Turgeon, N. Brodusch, M. Cloutier, P. Chevallier, R. Gauvin and D. Mantovani (2016), “Characterization of Amorphous Oxide Nano-Thick Layers on 316L Stainless Steel by Electron Channeling Contrast Imaging and Electron Backscatter Diffraction”, Microscopy and Microanalysis, 22, (5), pp. 997-1006.

  3. S. Kaboli, H. Demers, N. Brodusch and R. Gauvin (2015), “Rotation Contour Contrast Reconstruction using EBSD in a Scanning Electron Microscope”, Journal of Applied Crystallography, Vol. 48, pp. 776-785. 


Advanced Imaging Techniques

Over the years, MEMRG has developed a strong experience of making use of conventional tools to expend the capabilities of imaging materials with SEMs and STEMs. The fore scattered electron detector of an EBSD camera provides impressive imaging of magnetic domains in ferromagnetic materials and at the same time, the EBSD screen can be used as a BSE/STEM detector in which precise imaging conditions reveal different contrasts from a single set of EBSD scan points. Thanks to the combination of the FIB and SEM columns in our NX-5000, 3D volume datasets are now routinely produced from Li-ion battery electrodes, complex alloys or bone fragments.

  1. N. Brodusch, H. Demers and R. Gauvin (2018), “Imaging with a Commercial Electron Backscatter Diffraction (EBSD) Camera in a SEM: A Review”, Journal of Imaging, 4, (7), 88.

  2. N. Brodusch, H. Demers and R. Gauvin (2015), “Dark-Field Imaging Based on Post-Processed Electron Backscatter Diffraction Patterns of Bulk Crystalline Materials in a Scanning Electron Microscope”,  Ultramicroscopy, 148, pp. 123-131.

  3. M. Gallaugher, N. Brodusch, R. Gauvin and R. Chromik (2014), “Magnetic domain structure and crystallographic orientation of electrical steels revealed by a forescatter detector and electron backscatter diffraction”, Ultramicroscopy, Vol. 42, pp. 40-49


Sample Preparation / Charging

Even with high-end characterization equipment, a good and relevant sample preparation is a prerequisite to extract high quality data and ensure reproducibility. At MEMRG, we acquired a strong expertise in sample preparation of various materials through the years, especially using ion beam techniques. In addition, we have developed special preparation techniques and sequences to allows high resolution imaging and spectroscopy of difficult materials like polymers or charging ceramics. As an example, we reported in 2015 an ion beam milling sequence that permitted to record EBSD maps from pure lithium sheets without other preparation steps.

  1. N. Brodusch, M. Yourdkhani, P. Hubert and R. Gauvin (2015), “Efficient cross-section preparation method for high-resolution imaging of hard polymer composites with a scanning electron microscope”, Journal of Microscopy, 260, 117-124 .

  2. N. Brodusch, K. Waters, H. Demers and R. Gauvin (2014), “Ionic Liquid-Based Observation Technique for Nonconductive Materials in the Scanning Electron Microscope: Application to the Characterization of a Rare Earth Ore”, Microscopy Research and Technique, Vol. 77,  No. 3,  pp.  225 - 235.

  3. N. Brodusch, S. Boisvert and R. Gauvin (2013), “Flat ion milling: a powerful tool for preparation of cross-sections of lead-silver alloys”, Microscopy, Vol. 62, No. 3, pp. 411-418.

  4. Brochu, M.; Demers, H.; Gauvin, R.; Pugh, M. D. & Drew, R. A. L. (2005), "Determination of E2 for Nitride Ceramics Using FE-SEM and the Duane-Hunt Limit Procedure" 
    Microscopy and Microanalysis, 11, pp. 56-65


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