Specific Process Knowledge/Characterization/Element analysis: Difference between revisions
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== Energy Dispersive X-ray analysis == | == Energy Dispersive X-ray analysis (EDX) == | ||
The technique of extracting information from the X-rays generated in a sample that is irradiated with electrons is called energy dispersive X-ray analysis or EDX. (Other acronyms are Energy Dispersive x-ray Spectroscopy, EDS, or Electron Probe Microanalysis, EPMA). The energetic electrons in the incident beam create core level vacancies as they collide with sample atoms electrons in a multiple scattering process. This leaves the atoms in the sample in an excited state. In the process of decaying from this state photons may be emitted. The energy of these photons is determined by the difference in energy of the shells involved. Since atomic shells are unique for every element so will be the transitions between them. Thus, every element has its own characteristic X-ray spectrum that can be used to determine the elemental composition. | The technique of extracting information from the X-rays generated in a sample that is irradiated with electrons is called energy dispersive X-ray analysis or EDX. (Other acronyms are Energy Dispersive x-ray Spectroscopy, EDS, or Electron Probe Microanalysis, EPMA). The energetic electrons in the incident beam create core level vacancies as they collide with sample atoms electrons in a multiple scattering process. This leaves the atoms in the sample in an excited state. In the process of decaying from this state photons may be emitted. The energy of these photons is determined by the difference in energy of the shells involved. Since atomic shells are unique for every element so will be the transitions between them. Thus, every element has its own characteristic X-ray spectrum that can be used to determine the elemental composition. | ||
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image:SIMScascade.gif|A beam of high energy ions is rastered on the surface of the sample. Some of the atoms that used to make up the surface are sputtered off and emitted as secondary ions. The mass of the these ions is measured with a mass spectrometer. | image:SIMScascade.gif|A beam of high energy ions is rastered on the surface of the sample. Some of the atoms that used to make up the surface are sputtered off and emitted as secondary ions. The mass of the these ions is measured with a mass spectrometer. | ||
image:Schematic XPS.JPG|The atoms in the sample is irradiated with X-rays and the energy of the incoming photons are adsorbed. Photoelectrons are ejected, and the energy of these electrons can be measured. Since the energy of the incoming photon is known, the binding energy of the electrons in the atom can be determined. The binding energy is characteristic for the element, and therefore the composition of the sample can be determined. | image:Schematic XPS.JPG|The atoms in the sample is irradiated with X-rays and the energy of the incoming photons are adsorbed. Photoelectrons are ejected, and the energy of these electrons can be measured. Since the energy of the incoming photon is known, the binding energy of the electrons in the atom can be determined. The binding energy is characteristic for the element, and therefore the composition of the sample can be determined. | ||
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== Secondary Ion Mass Spectrometry == | == Secondary Ion Mass Spectrometry == | ||