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Oxford Instruments Analytical GmbH Wellesweg 31 D- 47589 Uedem (Germany). Jochen Meurs Senior Product Manager OES. OPTICAL EMISSION SPECTROMETRY. It is all about light, wavelength and peaks.
D- 47589 Uedem (Germany)
Senior Product Manager OES
In 1666 Isaac Newton collected sunlight with a magnifying glass, sent these beams of light through a prism and observed the passing light on a screen. He noticed a separation into colours. This colour ribbon is called a spectrum.
General definition: light is what we can see
But light is a wave (energy) where different colours have different wavelengths (energy)
Is a continuous range or sequence defined in a particular order.
The colours available in a rainbow and visible by the human eye define a spectrum in which the individual colours has a defined appearance order and going from lower to higher wavelength (blue to red)
Beside the visible part of the spectrum, the light spectrum has areas of „waves“ the human eye can not determine.
Only spectrometers are able to observe the entire range.
The Light Spectrum
Violet 380 nm
Blue 460 nm
Green 510 nm
Yellow 560 nm
Orange 610 nm
Red 660 nm
n = c / l
Conversion Frequency / Wavelength (c = speed of light)
Source and Ignition
Readout of the CCD, calculation of the results, steering of the source and printout/storage of the data
The light is reflected and
separated by the diffraction
grating. The spectra appears on
the Rowland Circle.
Readout of the Intensity, calculation of the results
Steering of the source
Diffraction Grating, works similar like a prism
CCD for the readout of the light-intensity
Printout or storage of data
Polychrome light, emitted during spark process, passes through the entrance slit and falls on the grating. The light is reflected and dispersed into individual spectral lines. The separated light is corresponding to particular wavelength of elements. The light than falls simultaneously on the CCD sensors.
Is like a concave mirror, but with rules on it. Modern Gratings have up to 4000 rules/mm. The incoming light is reflected and diffracted. The spectra appears.
130 – 800 nm
Why do all elements have many different spectral lines?
....simply - each transition of an electron corresponds to a spectral line of a different wavelength
The intensity relates to the probability of a transition
Example: Aluminium about 400 lines
Ferrum about 4500 lines
Uranium about 5000 lines
Chromium about 2000 lines
RE12: approx. 120 ppm C
BAS 406: 0.173 % C
BAS 407: 0.49 % C
BAS 408: 0.289 % C
BAS 409: 0.086 % C
C – 193.1 nm
1. Steel plant laboratories
2. Foundry laboratories
3. semi-finished products (e.g. tube manufacturers)
4. Fabricators (incoming inspection)
Fields of use for spark-OES
5. PMI-testing (refineries, power plants, ship yards)
6. Scrap sorting