Most Significant Contributions to Research

 

 

  • Modelling of electron scattering in solids. A Monte Carlo (MC) program, CASINO, was developed to simulate electron scattering in solids for quantitative applications in electron microscopy. This program is presently used in more than 15 000 research centers in the world. The MC program WinX-ray, was developed to compute the total X-Ray spectrum for homogeneous specimen. Recently, the MC program MC X-Ray that simulates complete EDS spectra from heterogeneous materials was introduced. From the ISI Web of Science, the paper describing CASINO, Hovington P, Drouin D and Gauvin R (1997), Scanning, Vol. 19, No. 1, pp. 1-14, was cited 256 times. You can find more information about these MC Programs on the "Our Programs" page of this website. Learn more about this research application.

 

  • EELS simulation. A new MC program simulating Electron Energy Loss Spectroscopy (EELS) spectra was developed. This is the first MC program in the world that can simulate EELS spectra to determine the detection limit of elements as a function of specimen thickness, a fundamental limitation of EELS. 

 

  • Quantitative x-ray microanalysis in the scanning electron microscope (SEM) and in the transmission electron microscope (TEM) was unified for the first time through the f-ratio method, developed by the Gauvin group. Currently, the ZAF method is used in the SEM community and the Cliff and Lorimer method in the TEM community. The spread of the f-ratio method with the measurement of fundamental parameters for x-ray generation will make standardless analysis possible. Learn more about this research application.

 

  • A new method to measure the Koster-Kronig transition factors for the L and M lines was developed with accuracy better than 5%. Current accuracies are above 35 %. Their knowledge is vital for quantitative x-ray analysis involving L and M lines, which are used for rare earth elements that are critical in technology. Learn more about this research application.

 

  • STEM EBSD. Transmitted electrons in thin specimens were detected with the electron backscattered diffraction (EBSD) detector in the SU-8000 at 30 keV. 25 nm Al2Cu precipitates in an Al matrix were indexed as well as a 5.6 nm PdO2 particulates on a 40 nm carbon nanotube. So far, this is the best results obtained in a FE-SEM. Orientation maps in an Al alloy with grain as small as 10 nm were also acquired. Learn more about this research application.

 

  • Observation of nanometer precipitates in a Field Emission Scanning Electron Microscope. From simulations of Backscattered Electron images performed using CASINO, it was predicted in 1995 that 10 nm NbC precipitates embedded in an Iron matrix could be imaged at low electron beam energy using a Field Emission Scanning Electron Microscope (FE-SEM).  Such precipitates were imaged using a Field Emission Scanning Electron Microscope (FE-SEM) with beam energy of 2 keV in 1996. The microanalysis of these precipitates were also performed and a new era in electron microscopy just started. Learn more about this research application.

 

  • Quantitative X-Ray microanalysis in the VP-SEM. In the Variable Pressure Scanning Electron Microscope (VP-SEM), the incident electrons, which are scattered, can hit the specimen as far as millimeters, in extreme conditions, relative to the position of the incident beam. A new correction procedure to perform X-Ray microanalysis in the VP-SEM was proposed. This method that was proven recently to be the most accurate and valid among those developed by other researchers. Learn more about this research application.

     

  • Significant contribution on quantitative X-Ray microanalysis in the TEM. By simulating the number of X-Rays generated by Fast Secondary Electrons (FSE), using Monte Carlo simulations, It was showed that FSE significantly degrade the spatial resolution for the microanalysis of light elements. It was showed recently, by Monte Carlo simulations, that Auger might also have a similar effect to that of FSE. Learn more about this research application here and here.

 

  • Characterisation of electron diffusion in Solids using fractal geometry. Pr. Gauvin was the first researcher to use the concepts of fractal geometry to characterise the diffusion of incident electrons in solids.  Since  Electron Microscopy depends on the diffusion of electrons in solids, these results are of fundamental importance. 

 

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