Measuring Principle
Belec spectrometers are spark emission spectrometers for rapid metal analyses. Stationary and mobile instruments have either a sparking stand or a sparking probe with a counter electrode, respectively. A sparking generator produces electric discharge between this electrode and the sample to be analysed. In the process, the material of the testing sample is converted into a gaseous state. The atoms of the elements in the materials are shifted into a higher state of energy. On return to normal state they emit light of the element-specific wavelengths.
3600 Lines per mm
The light reaches the entrance of the spectrometer either directly (stationary device) or via fiber optic (mobile device). At the entrance of the spectrometer there is a narrow slit of only 20 µm (1µm = 0,001mm). Through this slit the light hits the surface of an optical diffraction grating which is a concave aluminium disc of diameter 60 mm (stationary) or 30 mm (mobile) and 3600 groves per millimetre! Due to the large number of groves on the grating, the light diffracts so much, that it resolves into particular wavelengths.
On a focal plane spectral lines occur, which are illustrations of the light entering the entrance slit. This slit is displayed on the focal plane as often as the light of the different wavelengths entered the entrance slit. The result is a line spectrum.
Light hits Photomultiplier
The relevant lines which are suitable and also needed for a certain measuring program are selected by exit slits. A photomultiplier is situated behind it. Depending on the concentration of an element in a sample, the intensities of radiation which reach the photomultipliers are correspondingly high or low.
Exact Sample Configuration within Seconds
The measuring of material of well-known chemical compositions generates so-called calibration curves which are stored in the PC. For the further process these curves give information about the exact chemical composition of unknown material. The resulting values are displayed on a screen in percent or ppm, together with the corresponding chemical signs. The customer can store all analyses continuously on the PC or either print it out to have an analysis certificate in his hands, finally.
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May 08-11, 2012
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