| When running thermogravimetric tests in the high-temperature range, haven't you sometimes wished that, in addition to the mass change, you could achieve a quick, more exact mass-specific characterization of the decomposition gases of the material through on-line analysis? |
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| Only NETZSCH-Gerätebau can fulfill this wish for you with a progressive coupling of thermal analysis and mass spectrometry. |
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| The combination, which insiders call the Skimmer Coupling System, unites the simultaneous thermal analysis instruments (STA 409 and STA 429) with a furnace tailor-made for the particular application, a quadrupole mass spectrometer for detection and analysis of the reaction gases, and a two-stage pressure-reduction system, to make up an ideally-suited analysis system. |
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 Full advantage can be taken of the high level of detection sensitivity of the QMS only if a truly representative sample of the test atmosphere is transferred to the gas analyzer. Here, it is imperative that separation and loss of gas through condensation be prevented.
NETZSCH-Gerätebau has developed the perfect coupling system, made up of two orifices in tandem, which are held at the same temperature as the sample: the first orifice serves as a divergent nozzle and creates a compression zone, into which the second orifice, the so-called Skimmer, extends and creates a parallel molecular beam, which is directed at the ion source of the QMS.
The short transfer path (only a few millimeters) of the gas particles through the two orifices, which are located directly above the sample, guarantees a short response time and thus a perfect temperature-time correlation. Holding the sample and orifice system at the same temperature eliminates the disadvantageous condensation (for non-permanent gases) which usually occurs with capillary coupling systems and which is more or less dependent on the mass number. The result is a considerable increase in sensitivity (depending on the mass number, the intensity of the measurement signal is increased by up to over one hundred times). |
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| Pyrolysis of a polystyrene sample under an inert gas atmosphere |
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| Here, clearly stepped fragment packages can be observed. The mass number 208 represents the double monomer fragment. |
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| Quantification of MS signals is possible by PulseTA®. This technique is based on the injection of a specific amount of gas into the inert carrier gas stream and the monitoring of changes in mass and enthalpy, which result from the incremental reaction progress. |
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Different versions of the skimmer coupling system are available for different applications:
- Skimmer system of Al2O3 for use in oxidizing atmospheres to 1450°C
- Skimmer system of glassy carbon for use in inert gas atmospheres to 2000°C. |
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| The skimmer coupling system is a tool with high sensitivity, effectiveness and quality for material and process development as well as energy and environmental research. |
