SLIDE 1 Spectroscopy
MENA3100,OBK, 24.01.18
An introduction
SLIDE 2 Spectroscopy
The art of using the spectroscope; that branch of science which involves the use of the spectroscope. In mod. use, the investigation of spectra by any of various instruments.
spectrum, n.
3 a. The coloured band into which a beam of light is decomposed by means of a prism or diffraction grating. Also, a dark band containing bright lines produced similarly; such a (coloured or dark) band, or the pattern of lines in it, as characteristic of the light source; hence, the pattern of absorption or emission of light or other electromagnetic radiation over any range of wavelengths exhibited by a body or substance.
- 3b. The entire range of wavelengths (or
frequencies) of electromagnetic radiation, from the longest radio waves to the shortest gamma rays of which the range
- f visible light is only a small part; any
- ne part of this larger range.
- 3c. An actual or notional arrangement
- f the component parts of any
phenomenon according to frequency, energy, mass, or the like. Cf. mass spectrum n., power n.1
spectroscopy, n.
SLIDE 3 a formative element < Greek -σκοπία observation ( < σκοπεῖν to examine, look at: see -y suffix3), used to form
- ns. denoting: (a) (formerly) divination by inspection of
something (ooscopy, ornithoscopy); (b) scientific examination by means of some instrument (stethoscopy, telescopy); (c) medical examination of some part of the body (gastroscopy, peritoneoscopy).
A terminal element of nouns with the general sense ‘action, process, or art of measuring (something specified by the initial element)’.
Spectroscopy vs. spectrometry
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Must disperse the colours
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Refractive index is a function of colour
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Diffraction from a grating (gitter)
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Interference
SLIDE 9 Electromagnetic radiation X-rays most interesting for us
Diffraction from crystal lattices
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SLIDE 11 Wave-particel duality
Louis de Broglie
The wave nature of electrons Electrons
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Charged particles can be manipulated by magnets
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The detector may discriminate between energies
SLIDE 14 Why spectroscopy?
We typically want information about Composition Energy of chemical bonds, bandgap …
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(For us) it may be useful to separate into Absorpsjon and emission spectroscopy
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Absorpsjon spectroscopy From the sun Fraunhofer lines
(Helium: Pierre-Jules-César Janssen, 1868, 587.49 nanometers)
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X-rays: Electrons Electrons: Electric field (electrons and protons) Neutrons: Atomic nucleus (almost true) Interactions
SLIDE 18 Most relevant absorpsion for us:
Electron energy loss spectroscopy (EELS)
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Quantitative vs. qualitative analysis
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Exitation: Can give absorpsjon De-exitation (relaxation): Can give us interesting signals Heat Electromagnetic radiation Electron "beams"
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Ultraviolet light Fluorescence Phosphorescence X-rays Electrons Exitation by: De-exitation by: Light X-rays Electrons X-rays Electrons
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Spectroscopy with incident x-rays and with incident electrons Read By Johan Taftø
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X-ray induced Transfer its energy to an electron If it leaves the sample we get a photoelectron The energy is Ep = hn – EB1 – W X-ray photoelectron spectroscopy (XPS)
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X-ray induced X-ray absorpsjon as function of wavelength/energy X-ray absorpsjon spectroscopy (XAS)
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Electron induced Electron energy loss spectroscopy (EELS) Ineleastic scattering
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X-ray emission Energy dispersive spectroscopy (EDS) Wavelength dispersive spectroscopy
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Auger electron emission
