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Issue 4, 2011
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Trace species detection in the near infrared using Fourier transform broadband cavity enhanced absorption spectroscopy: initial studies on potential breath analytes

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Abstract

Cavity enhanced absorption measurements have been made of several species that absorb light between 1.5 and 1.7 µm using both a supercontinuum source and superluminescent light emitting diodes. A system based upon an optical enhancement cavity of relatively high finesse, consisting of mirrors of reflectivity ∼99.98%, and a Fourier transform spectrometer, is demonstrated. Spectra are recorded of isoprene, butadiene, acetone and methane, highlighting problems with spectral interference and unambiguous concentration determinations. Initial results are presented of acetone within a breath-like matrix indicating ppm precision at <∼10 ppm acetone levels. Instrument sensitivities are sufficiently enhanced to enable the detection of atmospheric levels of methane. Higher detection sensitivities are achieved using the supercontinuum source, with a minimum detectable absorption coefficient of ∼4 × 10−9 cm−1 reported within a 4 min acquisition time. Finally, two superluminescent light emitting diodes are coupled together to increase the wavelength coverage, and measurements are made simultaneously on acetylene, CO2, and butadiene. The absorption cross-sections for acetone and isoprene have been measured with an instrumental resolution of 4 cm−1 and are found to be 1.3 ± 0.1 × 10−21 cm2 at a wavelength of 1671.9 nm and 3.6 ± 0.2 × 10−21 cm2 at 1624.7 nm, respectively.

Graphical abstract: Trace species detection in the near infrared using Fourier transform broadband cavity enhanced absorption spectroscopy: initial studies on potential breath analytes

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Publication details

The article was received on 01 Jul 2010, accepted on 18 Nov 2010 and first published on 13 Dec 2010


Article type: Paper
DOI: 10.1039/C0AN00462F
Citation: Analyst, 2011,136, 801-806
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    Trace species detection in the near infrared using Fourier transform broadband cavity enhanced absorption spectroscopy: initial studies on potential breath analytes

    W. Denzer, G. Hancock, M. Islam, C. E. Langley, R. Peverall, G. A. D. Ritchie and D. Taylor, Analyst, 2011, 136, 801
    DOI: 10.1039/C0AN00462F

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