Incoherent broad-band cavity-enhanced absorption spectroscopy (IBB-CEAS) based on arc lamps has been around for a few years, but only two reports exist using light-emitting diodes (LEDs). We present a setup based on a 643-nm LED which is of interest for the simultaneous detection of NO3 and NO2. The latter is chosen for testing as it is stable and available in calibrated diluted samples. A detection limit in the ppbv range is obtained with 2-min averaging (5x10(-9)/cm rms baseline noise level), comparable to the best performance of chemiluminescence devices used for pollution monitoring. At 1-s acquisition time, the detection limit is below 10 ppbv. Extrapolation to NO3 yields a detection limit of a few pptv for a few minutes averaging. We also test the retrieval of absolute sample absorption (and concentration) using the cavity mirror reflectivity obtained with a commercial spectrophotometer, and we conclude that a calibration based on a reference sample of known concentration is preferable for accurate concentration measurements with IBB-CEAS. Finally, we present a rigorous frequency-domain derivation of cavity transmission as a function of wavelength for a broad-band spectrally smooth source, which complements the time-domain derivation by Fiedler et al. This derivation exposes an issue with multiple transverse mode excitation inherent to this technique, which may result in slightly distorted spectral profiles.
%0 Journal Article
%1 Triki:2008p3431
%A Triki, M
%A Cermak, P
%A Mejean, G
%A Romanini, D
%D 2008
%J Applied Physics B-Lasers and Optics
%K Dependence, Laser, Light-Emitting-Diodes, Ring-Down Spectroscopy Temperature,
%N 1
%P 195--201
%R 10.1007/s00340-008-2958-x
%T Cavity-enhanced absorption spectroscopy with a red LED source for NOx trace analysis
%U http://www.springerlink.com/content/e070g143283g6k75/
%V 91
%X Incoherent broad-band cavity-enhanced absorption spectroscopy (IBB-CEAS) based on arc lamps has been around for a few years, but only two reports exist using light-emitting diodes (LEDs). We present a setup based on a 643-nm LED which is of interest for the simultaneous detection of NO3 and NO2. The latter is chosen for testing as it is stable and available in calibrated diluted samples. A detection limit in the ppbv range is obtained with 2-min averaging (5x10(-9)/cm rms baseline noise level), comparable to the best performance of chemiluminescence devices used for pollution monitoring. At 1-s acquisition time, the detection limit is below 10 ppbv. Extrapolation to NO3 yields a detection limit of a few pptv for a few minutes averaging. We also test the retrieval of absolute sample absorption (and concentration) using the cavity mirror reflectivity obtained with a commercial spectrophotometer, and we conclude that a calibration based on a reference sample of known concentration is preferable for accurate concentration measurements with IBB-CEAS. Finally, we present a rigorous frequency-domain derivation of cavity transmission as a function of wavelength for a broad-band spectrally smooth source, which complements the time-domain derivation by Fiedler et al. This derivation exposes an issue with multiple transverse mode excitation inherent to this technique, which may result in slightly distorted spectral profiles.
@article{Triki:2008p3431,
abstract = {Incoherent broad-band cavity-enhanced absorption spectroscopy (IBB-CEAS) based on arc lamps has been around for a few years, but only two reports exist using light-emitting diodes (LEDs). We present a setup based on a 643-nm LED which is of interest for the simultaneous detection of NO3 and NO2. The latter is chosen for testing as it is stable and available in calibrated diluted samples. A detection limit in the ppbv range is obtained with 2-min averaging (5x10(-9)/cm rms baseline noise level), comparable to the best performance of chemiluminescence devices used for pollution monitoring. At 1-s acquisition time, the detection limit is below 10 ppbv. Extrapolation to NO3 yields a detection limit of a few pptv for a few minutes averaging. We also test the retrieval of absolute sample absorption (and concentration) using the cavity mirror reflectivity obtained with a commercial spectrophotometer, and we conclude that a calibration based on a reference sample of known concentration is preferable for accurate concentration measurements with IBB-CEAS. Finally, we present a rigorous frequency-domain derivation of cavity transmission as a function of wavelength for a broad-band spectrally smooth source, which complements the time-domain derivation by Fiedler et al. This derivation exposes an issue with multiple transverse mode excitation inherent to this technique, which may result in slightly distorted spectral profiles.},
added-at = {2010-06-22T19:38:37.000+0200},
affiliation = {Univ J Fourier Grenoble, CNRS, UMR 5588, Spectrometrie Phys Lab, F-38402 St Martin Dheres, France},
author = {Triki, M and Cermak, P and Mejean, G and Romanini, D},
biburl = {https://www.bibsonomy.org/bibtex/2e563ecc41775ce71ec77936cfcd849ff/gsmith},
date-added = {2010-05-05 15:39:38 -0400},
date-modified = {2010-05-05 15:39:52 -0400},
doi = {10.1007/s00340-008-2958-x},
interhash = {b45aa3fb63428de964984627d4cd582f},
intrahash = {e563ecc41775ce71ec77936cfcd849ff},
journal = {Applied Physics B-Lasers and Optics},
keywords = {Dependence, Laser, Light-Emitting-Diodes, Ring-Down Spectroscopy Temperature,},
language = {English},
local-url = {file://localhost/Users/geoffreysmith/Documents/Papers/Applied%20Physics%20B-Lasers%20and%20Optics/2008/Applied%20Physics%20B-Lasers%20and%20Optics,%2091,%20195-201%202008.pdf},
month = Jan,
number = 1,
pages = {195--201},
pmid = {000254247100035},
rating = {0},
timestamp = {2010-06-22T19:39:02.000+0200},
title = {Cavity-enhanced absorption spectroscopy with a red LED source for NOx trace analysis},
uri = {papers://E88B624E-D406-46FF-9D95-BB9C1AAE3FDC/Paper/p3431},
url = {http://www.springerlink.com/content/e070g143283g6k75/},
volume = 91,
year = 2008
}