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Verfahren und Anordnung zur abwechselnden Proben- und Untergrundmessung, insbesondere bei der hochempfindlichen absorptionsspektroskopischen, selektiven Spurengasanalyse

Process and arrangement for the alternating test and background measurement, in particular for the highly sensitive absorption spectroscopy selective trace gas analysis
 
: Werle, P.

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Frontpage ()

DE 1993-4338233 A: 19931109
DE 1993-4338233 A: 19931109
DE 4338233 C2: 19970206
G01N0021
Deutsch
Patent, Elektronische Publikation
Fraunhofer IFU; 2002 in Helmholtz-Gesellschaft integriert

Abstract
The invention relates to a process and an arrangement for alternating test and background measurement, in particular for highly sensitive absorption spectroscopy selective gas analysis. Instead of a previously usual exchange of sample air or sample gas in a measuring cell to receive a sample-free zero air, the invention foresees applying a magnetic and/or electrical field to the trace or test gas in the measuring cell for a predetermined period of time. As a result of the effect of the field, a shift in the energy level of the gas molecules takes place in the measuring cell acc. to the strong or Zeeman effect. Sensitivity-limiting background structures are not influenced by the field effect. In a viewed measuring window, sample and background measurements can then be performed in succession without any time delay by cyclically alternating the activation and deactivation of the field. By not physically replacing the gas in the measuring cell, as previously was the case, but shifting the position of the characteristic spectral signatures for the species under investigation, the background structure can be determined in the temporal signal-free spectral measuring window in the usual way. As a result of the invention, drift effects of the absorption-spectroscopy measuring instrument can be reduced, whereby at the same time an increase in measuring sensitivity can be obtained.

: http://publica.fraunhofer.de/dokumente/PX-38403.html