QEPAS based detection of broadband absorbing molecules using a widely tunable, cw quantum cascade laser at 8.4 μm

Lewicki, R.; Wysocki, Gerard; Kosterev, Anatoliy A.; Tittel, Frank K.

doi:10.1364/oe.15.007357

Cited by 110 publications

(59 citation statements)

References 18 publications

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“…Like conventional photoacoustic spectroscopy, QEPAS does not require optical detectors. With little or no modification to the spectrophone, this technique can be used in different spectral regions to detect broadband absorbing molecules [18,19], as well as small molecules with narrow linewidth [20]. This feature is especially attractive for gas sensing in the 5-20 µm region, where the availability of high-performance optical detectors is limited, and cryogenic cooling is often required.…”

Section: Introductionmentioning

confidence: 99%

QEPAS based ppb-level detection of CO and N_2O using a high power CW DFB-QCL

Ma¹,

Lewicki²,

Razeghi³

et al. 2013

Opt. Express

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344

209

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An ultra-sensitive and selective quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor platform was demonstrated for detection of carbon monoxide (CO) and nitrous oxide (N 2 O). This sensor used a stateof-the art 4.61 µm high power, continuous wave (CW), distributed feedback quantum cascade laser (DFB-QCL) operating at 10°C as the excitation source. For the R(6) CO absorption line, located at 2169.2 cm −1 , a minimum detection limit (MDL) of 1.5 parts per billion by volume (ppbv) at atmospheric pressure was achieved with a 1 sec acquisition time and the addition of 2.6% water vapor concentration in the analyzed gas mixture. For the N 2 O detection, a MDL of 23 ppbv was obtained at an optimum gas pressure of 100 Torr and with the same water vapor content of 2.6%. In both cases the presence of water vapor increases the detected CO and N 2 O QEPAS signal levels as a result of enhancing the vibrational-translational relaxation rate of both target gases. Allan deviation analyses were performed to investigate the long term performance of the CO and N 2 O QEPAS sensor systems. For the optimum data acquisition time of 500 sec a MDL of 340 pptv and 4 ppbv was obtained for CO and N 2 O detection, respectively. To demonstrate reliable and robust operation of the QEPAS sensor a continuous monitoring of atmospheric CO and N 2 O concentration levels for a period of 5 hours were performed. 6728-6738 (2003). 27. X. Chao, J. B. Jeffries, and R. K. Hanson, "Wavelength-modulation-spectroscopy for real-time, in situ NO detection in combustion gases with a 5.2 µm quantum-cascade laser," Appl. Phys. B 106(4), 987-997 (2012). 28. L. Dong, R. Lewicki, K. Liu, P. R. Buerki, M. J. Weida, and F. K. Tittel, "Ultra-sensitive carbon monoxide detection by using EC-QCL based quartz-enhanced photoacoustic spectroscopy," Appl. Phys. B 107(2), 275-283 (2012). 29. L. ©2013 Optical Society of America

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Section: Introductionmentioning

confidence: 99%

QEPAS based ppb-level detection of CO and N_2O using a high power CW DFB-QCL

Ma¹,

Lewicki²,

Razeghi³

et al. 2013

Opt. Express

Self Cite

344

209

View full text Add to dashboard Cite

show abstract

“…While the tuning range of a single EC-QCL is much smaller than a Fourier transform infrared (FT-IR) spectrometer, it is still sufficient to capture enough detail in the absorption spectra for reliable identification of large molecules in the gas-phase or many condensed-phase materials. Examples of EC-QCLs measuring broadband absorption spectra include the detection of ethane using wavelength modulation spectroscopy with a sensitivity of 100 ppbv [22], Freon 125 with quartz enhanced photoacoustic spectroscopy (QEPAS) [23] and fluorocarbons at low ppbv levels in real-time [24].…”

Section: Introductionmentioning

confidence: 99%

Influence of Ethanol on Breath Acetone Measurements Using an External Cavity Quantum Cascade Laser

et al. 2016

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Broadly tunable external cavity quantum cascade lasers (EC-QCLs) in combination with off-axis integrated cavity enhanced spectroscopy (OA-ICOS) provide high molecular gas sensitivity and selectivity. We used an EC-QCL in the region of 1150-1300 cm´1 in both broadband scan mode, as well as narrow scanning mode around 1216 cm´1, respectively, for detection of acetone in exhaled breath. This wavelength region is essential for accurate determination of breath acetone due to the relative low spectral influence of other endogenous molecules like water, carbon dioxide or methane. We demonstrated that ethanol has a strong spectroscopic influence on the acetone concentration in exhaled breath, an important detail that has been overlooked so far. An ethanol correction is proposed and validated with the reference measurements from a proton-transfer reaction mass spectrometer (PTR-MS) for the same breath samples from ten persons. With the ethanol correction, both broadband and narrowband molecular spectroscopy represent an attractive way to accurately assess the exhaled breath acetone. The importance of considering spectroscopic ethanol influence is essential, especially for the narrowband scans, (e.g., 1216 cm´1), for which the error in determining the acetone concentrations can rise up to 39% if it is not considered.

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“…More recently, QEPAS has also been implemented with larger molecules with broad, unresolved absorption spectra, such as acetone and freons [8][9][10]. The main difference in the implementation of QEPAS with narrow-line molecules and broadband absorbers is that wavelength modulation (WM) at half the QTF resonance frequency with second-harmonic (2f ) detection and reduced pressure operation is applicable for target analytes with well-resolved absorption lines, whereas amplitude modulation (AM) at the QTF frequency and detection at the same frequency is necessary for molecular species with unresolved congested spectra.…”

Section: Introductionmentioning

confidence: 99%

Performance evaluation of a near infrared QEPAS based ethylene sensor

Schilt¹,

Kosterev

Tittel

2008

Appl. Phys. B

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A sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS) was evaluated for the detection of trace levels of ethylene at atmospheric pressure using a fiber coupled DFB diode laser emitting in the 1.62 μm spectral range. A noise-equivalent QEPAS signal of ∼4 ppm C 2 H 4 was achieved for a 0.7 s data acquisition time using wavelength-modulation with a second-harmonic detection scheme on the strongest C 2 H 4 absorption peak at 6177.14 cm −1 with an average optical power of ∼15 mW. Improved detection sensitivity of 0.5 and 0.3 ppm C 2 H 4 (1σ ) was demonstrated using longer averaging time of 70 and 700 s, respectively. Important characteristics for the QEPAS based sensor operation in real-world conditions are presented, particularly the influence of external temperature variations. Furthermore, the response time of the ethylene sensor was measured in different configurations and it is shown that the QEPAS technique can provide a response time in a few seconds range even without active gas flow.

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QEPAS based detection of broadband absorbing molecules using a widely tunable, cw quantum cascade laser at 8.4 μm

Cited by 110 publications

References 18 publications

QEPAS based ppb-level detection of CO and N_2O using a high power CW DFB-QCL

QEPAS based ppb-level detection of CO and N_2O using a high power CW DFB-QCL

Influence of Ethanol on Breath Acetone Measurements Using an External Cavity Quantum Cascade Laser

Performance evaluation of a near infrared QEPAS based ethylene sensor

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