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Electron probe micro-analyzer (EPMA) CAMECA SX-100
Quantitative chemical analysis at the micrometer scale
The CAMECA SX-100 electron microprobe enables the precise determination of the chemical composition (B–U) of solid materials at the micrometer scale. Its focused electron beam can reach a diameter of approximately 0.5 µm , allowing for the targeting of very small areas. It enables the quantitative analysis of major and minor elements and, under optimized analytical conditions, certain trace elements , with detection limits reaching approximately 30 to 40 ppm . Quantification is based on comparing the measured intensities with those of certified reference materials , supplemented by the application of matrix corrections. Particularly well-suited to minerals, glasses, metals, ceramics, and many synthetic materials, the microprobe allows for spot analyses, profiling, and elemental mapping to characterize the composition and spatial distribution of elements within the sample.
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Availability and contact
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User Fees
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Sample types
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Technique and applications
The electron microprobe quantitatively determines the composition of micrometre-scale volumes at the surface of a solid. A beam of accelerated electrons excites the sample, and the characteristic X-rays are analyzed mainly by wavelength-dispersive spectrometry. The analytical process includes beam generation, electron–matter interactions, WDS analysis and quantitative acquisition.
1 | Electron Source
A heated tungsten filament emits electrons by thermionic emission. A potential difference between the cathode and anode accelerates them. Electromagnetic lenses condense and focus the beam. The accelerating voltage, beam current, probe size and working distance are adapted to the nature and stability of the phase being analyzed. A high current density increases the X-ray signal but can heat, volatilize or alter sensitive materials.
Technique and applications
Sample types
The electron microprobe is equipped with several sample holders allowing the analysis of substrates of different sizes and shapes.
Solid samples
Solid, compact and massive materials, such as rocks, metals, concrete, etc., are normally prepared as thin sections in standard format (46x27mm), or as polished sections (D25 x H25 mm or D30 x H30 mm).
Mirror polishing
The analysis surface must be perfectly flat, mirror-polished, clean, and free from any surface irregularities, deep scratches, open pores, or grain detachments. These defects alter the X-ray emission geometry and can render quantitative analysis invalid.
Carbon coating - service offered by MicroLab
All insulating surfaces intended for EPMA must receive a uniform conductive carbon coating. MicroLab routinely offers carbon coating services prior to analysis. The laboratory oversees the preparation and application of the conductive thin film to ensure adequate dissipation of electrical charges and maintain comparable analytical conditions between samples and standards. Samples previously coated with a conductive layer must be reported to the MicroLab manager. An old, contaminated, metallic, or unknown-thickness coating may need to be removed and replaced to ensure the quality of the analyses.
Irregular samples
Some fragments can be evaluated individually. However, a flat and polished analysis area, stable fixation, a sample height compatible with the analysis chamber, and vacuum stability are essential.
Impact of preparation on quality and repeatability
Quantitative EPMA assumes a known geometry between the beam, the surface, and the spectrometers. Any topography or inclination alters the emergence angle and absorption of X-rays, sometimes producing significant biases. Electrical charge deflects the beam and makes the current unstable. Carbon coating dissipates electrical charges without generating interference with the analyzed sample. However, the thickness must be uniform: a film that is too thick or different between the sample and the standard can attenuate low-energy X-rays and affect the accuracy of measurements, particularly for light elements. Sample preparation and carbon coating, both critical procedures, are performed in a controlled manner by MicroLab.
COMPATIBLE SAMPLES
Sample types
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User Fees
MicroLab rates are set according to the type of user, the instrument usage mode and, depending on the service, the analysis time or the number of samples. Some services, particularly sample preparation, may be billed per sample, while instrument use and data processing are generally billed on an hourly or daily basis.
User Categories
Université Laval
This category includes users whose projects are funded, in whole or in part, by Université Laval, regardless of their faculty or affiliated unit. In particular, it includes undergraduate, master’s and doctoral students carrying out work as part of a research project supervised by a Université Laval professor or researcher.
Research / Public Funding
This category includes students, professors, researchers and professionals from other Canadian universities, CEGEPs or research centres, when the work is carried out as part of projects or within institutions funded primarily by public funds. These funds may come, for example, from government or para-governmental organizations, federal or provincial research programs, or other public funding sources.
Industry
This category applies to private companies and to work carried out in an industrial or commercial context.
Usage Modes
When several usage modes are offered for an instrument, rates distinguish between assisted and unassisted use.
Assisted
The instrument is operated by the lead operator or the technical manager, who is responsible for starting the analysis, changing samples when necessary and assisting the user through the various stages of the measurement. This mode is particularly suited to analyses requiring specific instrumental expertise and to occasional users.
Unassisted
After completing appropriate training, users can carry out their own analyses and, when necessary, change samples themselves. Use nevertheless remains under the supervision of the instrument manager. Initial training is billed according to the time required and includes both staff time and instrument use.
Unassisted use is restricted to Université Laval users and depends on the instrument, the type of analysis and the user's level of experience. For the conditions of access to this mode, please contact the manager of the relevant instrument.
Pricing Based on Analysis Duration
For services with hourly and daily rates, billing is based on the total instrument usage time, including the time required to prepare and configure the instrument for the analysis.
For periods under 6 hours, the hourly rate applies. From 6 hours up to 24 hours, a daily flat rate applies. Beyond 24 hours, billing continues in daily increments at the applicable daily rate.
The daily flat rate is particularly advantageous for long analyses: its cost generally corresponds to that of six hours of use, while allowing the instrument to be used for up to 24 hours. For example, an analysis lasting 12, 18 or 24 hours is billed at the same daily flat rate rather than as the sum of the individual hours.
Services listed “per sample” are billed according to the number of samples processed, regardless of this hourly/daily structure.