Incoherent broadband cavity enhanced absorption spectroscopy for in situ measurements of NO2 with a blue light emitting diode

Wu, Tao; Zhao, Weixiong; Chen, W.; Zhang, W.; Gao, Xiaoming

doi:10.1007/s00340-008-3308-8

Cited by 67 publications

(40 citation statements)

References 37 publications

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“…99.8% at 365 nm and a 5 m radius of curvature. Focusing the beam into the cavity centre improved the cavity quality and minimised dispersion losses (Fiedler et al, 2007;Wu et al, 2008). Light exiting the cavity was focussed into a Czerny-Turner spectrograph (Andor SR-163) with a 163 cm focal length and a 1200 l mm −1 , 300 nm blaze grating.…”

Section: Spectrometer Setupmentioning

confidence: 99%

A broadband optical cavity spectrometer for measuring weak near-ultraviolet absorption spectra of gases

Chen

Venables

2011

Atmos. Meas. Tech.

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Abstract. Accurate absorption spectra of gases in the nearultraviolet (300 to 400 nm) are essential in atmospheric observations and laboratory studies. This paper describes a novel incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for measuring very weak absorption spectra from 335 to 375 nm. The instrument performance was validated against the 3 B 1 -X 1 A 1 transition of SO 2 . The measured absorption varied linearly with SO 2 column density and the resulting spectrum agrees well with published spectra. Using the instrument, we report new absorption cross-sections of O 3 , acetone, 2-butanone, and 2-pentanone in this spectral region, where literature data diverge considerably. In the absorption minimum between the Huggins and Chappuis bands, our absorption spectra fall at the lower range of reported ozone absorption crosssections. The spectra of the ketones agree with prior spectra at moderate absorptions, but differ significantly at the limits of other instruments' sensitivity. The collision-induced absorption of the O 4 dimer at 360.5 nm was also measured and found to have a maximum cross-section of ca. 4.0 × 10 −46 cm 5 molecule −2 . We demonstrate the application of the instrument to quantifying low concentrations of the shortlived radical, BrO, in the presence of stronger absorptions from Br 2 and O 3 .

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Section: Spectrometer Setupmentioning

confidence: 99%

A broadband optical cavity spectrometer for measuring weak near-ultraviolet absorption spectra of gases

Chen

Venables

2011

Atmos. Meas. Tech.

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“…[5]). Since its advent, CEAS has found numerous applications in detecting trace species [5][6][7][8][9][10][11][12][13][14][15], studies of gas phase kinetics [16][17][18][19][20][21], capturing weak molecular transitions [22][23][24][25][26] and probing interfacial interactions [27][28][29] and molecular dynamics [30].…”

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confidence: 99%

Understanding the sensitivity of cavity-enhanced absorption spectroscopy: pathlength enhancement versus noise suppression

Ouyang

Jones

2012

Appl. Phys. B

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Cavity-enhanced absorption spectroscopy is now widely used as an ultrasensitive technique in observing weak spectroscopic absorptions. Photons inside the cavity are reflected back and forth between the mirrors with reflectivities R close to one and thus (on average) exploit an absorption pathlength L that is 1/(1 -R) longer than a single pass measurement. As suggested by the Beer-Lambert law, this increase in L results in enhanced absorbance A (given by aL with a being the absorption coefficient) which in turn favours the detection of weak absorptions. At the same time, however, only (1 -R) of the incident light can enter the cavity [assuming that mirror transmission T is equal to (1 -R)], so that the reduction in transmitted light intensity DI caused by molecular absorption equates to that would be obtained if in fact no cavity were present. The enhancement in A = DI/I, where

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“…This allows for real time and simultaneous measurement of NO 2 and NO 3 concentrations with detection limits of respectively 600 pptv and 2 pptv, for an optimal 400 s acquisition time. Relatively compact IBB-CEAS setups based on a LED have been previously reported [16,18,19,21]. The lower detection limit reported for NO 3 is 2.5 pptv measured around 662 nm for a 516 s acquisition time [16].…”

Section: Introductionmentioning

confidence: 99%

“…Different analyzers based on Light Induced Fluorescence (LIF) [11], Cavity Ring Down Spectroscopy (CRDS) [12], Optical Feedback Cavity Enhanced Absorption Spectroscopy (OF-CEAS) [13], cavity-attenuated phase shift spectroscopy [14], Incoherent Broad-Band Cavity-Enhanced Absorption Spectroscopy (IBB-CEAS) [15][16][17][18][19][20][21] have been developed. The instrument described here is in the continuity of our previous work [20], based on the IBB-CEAS technique.…”

Section: Introductionmentioning

confidence: 99%

Incoherent broad-band cavity-enhanced absorption spectroscopy for simultaneous trace measurements of NO2 and NO3 with a LED source

Ventrillard-Courtillot

O'Brien

Kassi

et al. 2010

Appl. Phys. B

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In the past decade, due to a growing awareness of the importance of air quality and air pollution control, many diagnostic tools and techniques have been developed to detect and quantify the concentration of pollutants such as NO x , SO x , CO, and CO 2 . We present here an Incoherent Broad-Band Cavity-Enhanced Spectroscopy (IBB-CEAS) setup which uses a LED emitting around 625 nm for the simultaneous detection of NO 2 and NO 3 . The LED light transmitted through a high finesse optical cavity filled with a gas sample is detected by a low resolution spectrometer. After calibration of the spectrometer with a NO 2 reference sample, a linear multicomponent fit analysis of the absorption spectra allows for simultaneous measurements of NO 2 and NO 3 concentrations in a flow of ambient air. The optimal averaging time is found to be on the order of 400 s and appears to be limited by the drift of the spectrometer. At this averaging time the smallest detectable absorption is 2×10−10 cm −1 , which corresponds to detection limits of 600 pptv for NO 2 and 2 pptv for NO 3 . This compact and low cost instrument is a promising diagnostic tool for air quality control in urban environments.

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Incoherent broadband cavity enhanced absorption spectroscopy for in situ measurements of NO2 with a blue light emitting diode

Cited by 67 publications

References 37 publications

A broadband optical cavity spectrometer for measuring weak near-ultraviolet absorption spectra of gases

A broadband optical cavity spectrometer for measuring weak near-ultraviolet absorption spectra of gases

Understanding the sensitivity of cavity-enhanced absorption spectroscopy: pathlength enhancement versus noise suppression

Incoherent broad-band cavity-enhanced absorption spectroscopy for simultaneous trace measurements of NO2 and NO3 with a LED source

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