When to use electron microprobe?

Asked by: Cordia Heidenreich Sr.
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An electron microprobe (EMP), also known as an electron probe microanalyzer (EPMA) or electron micro probe analyzer (EMPA), is an analytical tool used to non-destructively determine the chemical composition of small volumes of solid materials.

What can an electron microprobe be used for?

An electron probe micro-analyzer is a microbeam instrument used primarily for the in situ non-destructive chemical analysis of minute solid samples. EPMA is also informally called an electron microprobe, or just probe. It is fundamentally the same as an SEM, with the added capability of chemical analysis.

What is the difference between SEM and EPMA?

Both instruments have the same basic principle of operation, and share many components. However, the SEM is optimized for imaging, especially when high resolution images are needed, whereas the EPMA is designed primarily for quantitative analysis.

Why is it so important to Polish and carbon coat the samples before electron microprobe analysis?

Coating the sample in carbon permits excess electrons to conduct away from the focussed electron beam during analysis, and reduces the effects of charging.

How does a microprobe work?

In an electron microprobe, a solid sample placed in vacuum is bombarded with a focused beam of high energy (accelerated) electrons (accelerating voltage 5 – 30 keV). This bombardment results in a variety of interactions between the beam electrons and the atoms and their electrons in the sample (Figure 1).

29 related questions found

What does microprobe mean?

: a device for microanalysis that operates by exciting radiation in a minute area of material so that the composition may be determined from the emission spectrum.

What is an electron probe microanalyzer?

Electron probe microanalyzer (EPMA) is a tool to determine the chemical composition of small volumes of solid materials. This technique is similar to scanning electron microscopy, where sample volumes of 10–30 μm3 can be investigated.

Which electron source is used in Epxma?

Electron- and proton-induced x-ray emission

EPXMA can be performed in (scanning) electron microscopes equipped with a semiconductor detector, or in electron microprobe analyzers featuring an ED detector and one or more WD detection systems.

What is the difference between EDS and WDS?

Energy dispersive spectrometers (EDS) sort the X-rays based on their energy; while wavelength dispersive spectrometers (WDS) sort the X-rays based on their wavelengths. WDS systems use X-ray diffraction as the means by which they separate X-rays of different wavelengths.

What is a SEM analysis?

Scanning Electron Microscopy, or SEM analysis, provides high-resolution imaging useful for evaluating various materials for surface fractures, flaws, contaminants or corrosion.

What is scanning electron microscope?

A scanning electron microscope (SEM) scans a focused electron beam over a surface to create an image. The electrons in the beam interact with the sample, producing various signals that can be used to obtain information about the surface topography and composition.

What type of microscope is a microprobe?

Because the electron microprobe is essentially a specialized scanning electron microscope, it can also be used to collect electron images. Secondary electron images (SEI) are used primarily to reveal surface features and morphology.

What does WDS measure?

Wavelength-dispersive X-ray spectroscopy (WDXS or WDS) is a non-destructive analysis technique used to obtain elemental information about a range of materials by measuring characteristic x-rays within a small wavelength range.

Why is WDS better than EDS?

For quantification purposes WDS is always better: much better energy/wavelength resolution, much better peak/background ratio. Energy shifts (chemical shifts) are determined by interaction of electrons with specimens, WDS is just better suited for their detection. So, both accuracy and precision are better for WDS.

Why is AES surface sensitive?

Surface sensitivity in AES arises from the fact that emitted electrons usually have energies ranging from 50 eV to 3 keV and at these values, electrons have a short mean free path in a solid. ... Because of the low energy of Auger electrons, most AES setups are run under ultra-high vacuum (UHV) conditions.

What is the function of TEM?

The transmission electron microscope is used to view thin specimens (tissue sections, molecules, etc) through which electrons can pass generating a projection image. The TEM is analogous in many ways to the conventional (compound) light microscope.

What is cathodoluminescence spectroscopy?

Cathodoluminescence is an optical and electromagnetic phenomenon in which electrons impacting on a luminescent material such as a phosphor, cause the emission of photons which may have wavelengths in the visible spectrum.

What is EDX used for?

Energy Dispersive X-Ray Analysis (EDX), referred to as EDS or EDAX, is an x-ray technique used to identify the elemental composition of materials.

What elements can XRF detect?

It can analyze elements from beryllium (Be) to americium (Am) in concentration ranges from 100 wt% to sub-ppm levels. XRF analysis is a robust technique, combining high precision and accuracy with straightforward, fast sample preparation.

What is XRF analysis?

XRF (X-ray fluorescence) is a non-destructive analytical technique used to determine the elemental composition of materials. ... XRF analyzers determine the chemistry of a sample by measuring the fluorescent (or secondary) X-ray emitted from a sample when it is excited by a primary X-ray source.

What are the components of SEM?

Components in a SEM

  • Electron Source. Tungsten (W) electron filament. Lanthanum hexaboride (LaB6) or Cerium hexaboride (CeB6) Field Emission Gun (FEG)
  • Lenses.
  • Scanning Coil.
  • Sample Chamber.
  • Detectors. Backscattered electron detector (BSD) Energy Dispersive Spectroscopy (EDS) Secondary Electron Detector (SED)

Why do petrographic microscopes have polarizers?

Petrographic microscopes are constructed with optical parts that do not add unwanted polarizing effects due to strained glass, or polarization by reflection in prisms and mirrors. ... Using one polarizer makes it possible to view the slide in plane polarized light; using two allows for analysis under cross polarized light.

What does TEM stand for?

Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image.

What are the advantages of scanning electron microscope?

Advantages of Scanning Electron Microscopy

  • Resolution. This test provides digital image resolution as low as 15 nanometers, providing instructive data for characterizing microstructures such as fracture, corrosion, grains, and grain boundaries.
  • Traceable standard for magnification. ...
  • Chemical analysis.

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