Fourier transform infrared spectroscopy of aqueous solutions using optical subtraction

PS Jensen, J Bak, PE Andersen, Stefan Andersson-Engels

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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 5000cm(-1) (2000 to 2500nm).
Original languageEnglish
Title of host publicationOPTICAL DIAGNOSTICS AND SENSING OF BIOLOGICAL FLUIDS AND GLUCOSE AND CHOLESTEROL MONITORING II
EditorsAV Priezzhev, GL Cote
PublisherSPIE
Pages150-159
Volume4624
ISBN (Print)0-8194-4363-8
DOIs
Publication statusPublished - 2002
EventConference on Optical Diagnostics and Sensing of Biological Fluids and Glucose and Cholesterol Monitoring II, SAN JOSE, CA, JAN 23-24, 2002 -
Duration: 0001 Jan 2 → …

Publication series

Name
Volume4624
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceConference on Optical Diagnostics and Sensing of Biological Fluids and Glucose and Cholesterol Monitoring II, SAN JOSE, CA, JAN 23-24, 2002
Period0001/01/02 → …

Subject classification (UKÄ)

  • Atom and Molecular Physics and Optics

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