Solid analysis techniques
The analysis of materials structure and composition is an extremely vast subject which concerns scientific and industrial fields as various as chemistry, geology, life sciences, semiconductors ... The specific needs of each one of these fields led to the rise of a broad range of analysis techniques. Some examples are presented in the following page table.
These techniques are mostly based on the sending of a probe (particles beam) on the sample to be analyzed. The interaction of the probe with the material generates diffraction or particles emission phenomena which are analyzed and make it possible to determine its characteristics. Analysis methods can be distinguished according to:
- The type of provided information: atomic, chemical or isotopic composition, crystallographic structure, ...
- the sensitivity to the presence of an element or a chemical compound (detection limit),
- the dimension of analyzed area,
- the localization of analyzed area: at the surface or in the volume,
X-rays probes can provide information on the sample crystallographic structure (by diffraction) or on its composition thanks to transitions between deep electronic levels of atoms (by spectroscopy), whereas the visible or infra-red spectroscopy generates a signature of chemical bonds or molecular states, which have a much weaker energy. Various methods also use electronic or ionic probes (electronic microscopy, Rutherford backscattering, etc.) mainly for imagery or atomic composition applications.
A non exhausitve summary of the different solid analysis techniques is given in the following table:
|Probe||Detection||Analysis technique name||Typical application||Detection limit|
|X-ray photons||X-ray photons||XRD (X-Ray Diffraction)||Spatial structure of crystals unit cells or molecules.|
|XRF (X-Ray Fluorescence)||Atomic composition in volume.||0.1%|
|TXRF (Total Reflection X-Ray Fluorescence)||Atomic composition of plane surfaces.||109 at/cm2|
|Electrons||XPS (X-ray Photoelectron Spectroscopy)||Atomic composition near from surface (a few nm).||~0.1%|
|Visible or near IR photons||Visible or near IR photons||Raman spectroscopy||Molecular imagery and structures of biological tissues, chemical composition.||~1%|
|IR photons||IR photons||Infra-red spectroscopy||Chemical composition.||1-10ppm|
|Electrons||Electrons||SEM (Scanning Electron Microscopy)||High resolution imagery.|
|TEM (Transmission Electron Microscopy)||High resolution imagery, electron diffraction.|
|AES (Auger Electron Spectrometry)||Atomic composition close to surface (a few nm).||~0.1%|
|Ions (beam)||Ions (beam)||SIMS (Secondary Ion Mass Spectrometry)||Depth profiles of doping elements concentration in semiconductors, mass spectra.||0.1ppm|
|Light ions (beam)||Ions (beam)||RBS (Rutherford Backscattering Spectrometry)||Atomic composition of intermediate or heavy elements in a material made up of light elements.||100ppm|
|Gamma photons, particles||NRA (Nuclear Reaction Analysis)||Atomic composition of light elements, detection of isotopic markers.||~0.5%|
|Ar ions (plasma)||Visible photons||GD-OES (Glow Discharge - Optical Emission Spectrometry)||Depth profiles for surface treatments, coatings, paintings and semiconductors.||~0.5%|
|Acid solution||Metals||VDP-ICP-MS ((Vapour Phase Decomposition – Inductively Coupled Plasma – Mass Spectrometry)||Atomic composition of plane surfaces.||109 at/cm2|