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Proceedings Paper

Fourier transform infrared spectroscopy of aqueous solutions using optical substraction
Author(s): Peter Snoer Jensen; Jimmy Bak; Peter E. Andersen; Stefan Andersson-Engels
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Paper Abstract

For the analysis of small concentrations of organics in aqueous solutions, a novel add-on accessory for dual- beam/optical subtraction spectroscopy has been built for a commercial Fourier transform infrared spectrometer. A standard FT-IR instrument requires a sample measurement and a separate reference measurement, whereas the optical subtraction instrument directly measures the difference between sample and reference. This has a number of advantages. The time delay between the two measurements is eliminated, and the effective measurement time is improved by a factor of two. Moreover, the optical subtraction provides a large reduction in dynamic range of the measured signal, which prevents detector saturation, and enables effective use of dynamic range of the analog to digital converter in the FT-IR spectrometer. This results in an increased signal to noise ratio, compared to the standard FT-IR instrument. By changing detector and light source the instrument may be used for both near- and mid-infrared spectroscopy. The increased sensitivity and stability of the optical subtraction instrument compared to the standard instrument is demonstrated by transmission measurements of aqueous urea solutions in the combination band region 4000 to 5999cm-1(2000 to 2500 nm).

Paper Details

Date Published: 23 May 2002
PDF: 10 pages
Proc. SPIE 4624, Optical Diagnostics and Sensing of Biological Fluids and Glucose and Cholesterol Monitoring II, (23 May 2002); doi: 10.1117/12.468319
Show Author Affiliations
Peter Snoer Jensen, Risoe National Lab. and Lund Institute of Technology (Denmark)
Jimmy Bak, Risoe National Lab. (Denmark)
Peter E. Andersen, Risoe National Lab. (Denmark)
Stefan Andersson-Engels, Lund Institute of Technology (Sweden)

Published in SPIE Proceedings Vol. 4624:
Optical Diagnostics and Sensing of Biological Fluids and Glucose and Cholesterol Monitoring II
Alexander V. Priezzhev; Gerard L. Cote, Editor(s)

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