Influence of oxygen on the resonant photoacoustic signal from methane excited at the ν 3 mode

Barreiro, N. L.; Vallespi, Arturo; Santiago, Guillermo; Slezak, V.; Peuriot, A.

doi:10.1007/s00340-011-4546-8

Cited by 18 publications

(12 citation statements)

References 7 publications

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“…The use of various enhancement techniques also makes the setup more complex, since several resonance conditions have to be fulfilled at once, including the absorption transition (central lasing frequency), the optical resonator (central lasing frequency), and the acoustic resonator (modulation frequency). In any case, it remains a fundamental issue that acoustic resonators are subject to changes in their Q-factor and resonance frequency resulting from changes in environmental parameters, including temperature [103,104], humidity [105], and the gas matrix itself [106], since the speed of sound depends on all these factors. Additionally, the collisional partner influences the sensing behavior as well [107].…”

Section: Acoustic Resonator-enhanced Photoacoustic Spectroscopymentioning

confidence: 99%

Photoacoustic-Based Gas Sensing: A Review

Palzer

2020

Sensors

103

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The use of the photoacoustic effect to gauge the concentration of gases is an attractive alternative in the realm of optical detection methods. Even though the effect has been applied for gas sensing for almost a century, its potential for ultra-sensitive and miniaturized devices is still not fully explored. This review article revisits two fundamentally different setups commonly used to build photoacoustic-based gas sensors and presents some distinguished results in terms of sensitivity, ultra-low detection limits, and miniaturization. The review contrasts the two setups in terms of the respective possibilities to tune the selectivity, sensitivity, and potential for miniaturization.

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Section: Acoustic Resonator-enhanced Photoacoustic Spectroscopymentioning

confidence: 99%

Photoacoustic-Based Gas Sensing: A Review

Palzer

2020

Sensors

103

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“…The obtained NEDS is approximately one order of magnitude lower than state-of-art methane measurements conduct in the 3.3 µm wavelength region [9]. This is attributed to the QTF which has a slightly higher equivalent series resistance and lower Q-factor than the standard 32.7 kHz QTFs and the fact that the experiments were conducted in dry synthetic air which will lead to a strongly reduced PA signal [28]. However note that by applying 4W of average MIR power and better design (higher Q-factor) of the mR tubes we believe that the NEDS can easily be improved to 20-40 ppb for methane making the sensor as sensitive as state-of-art QEPAS sensors [9].…”

Section: Methane Measurementsmentioning

confidence: 78%

Off-axis quartz-enhanced photoacoustic spectroscopy using a pulsed nanosecond mid-infrared optical parametric oscillator

Lassen

Lamard²,

Feng³

et al. 2016

Opt. Lett.

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A trace-gas sensor, based on quartz-enhanced photoacoustic spectroscopy (QEPAS), consisting of two acoustically coupled micro-resonators (mR) with an off-axis 20 kHz quartz tuning fork (QTF) is demonstrated. The complete acoustically coupled mR system is optimized based on finite-element simulations and is experimentally verified. The QEPAS sensor is pumped resonantly by a nanosecond pulsed single-mode mid-infrared optical parametric oscillator. The sensor is used for spectroscopic measurements on methane in the 3.1-3.5 μm wavelength region with a resolution bandwidth of 1 cm^-1 and a detection limit of 0.8 ppm. An Allan deviation analysis shows that the detection limit at the optimum integration time for the QEPAS sensor is 32 ppbv at 190 s, and that the background noise is due solely to the thermal noise of the QTF.

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“…In both cases, only small effects (lower than 3 %) were observed. In particular, the strong decrease of PA signal when adding O 2 in the buffer gas described in [13,14] has not been observed.…”

Section: Flow Measurement and Calibrationmentioning

confidence: 74%

“…The effect of the CH 4 relaxation in O 2 has been presented in [13] in the case of near-infrared detection of methane with a line excitation of 2ν 3 band at 1.65 µm. The effect of CH 4 relaxation in O 2 [14] and the effect of water vapor [15] have also been presented in the case of an excitation in the ν 3 band at 3.3 µm. All the effects described therein are related to the coupling between ν 2 and ν 4 bands of methane and either the first vibrational state of oxygen or the ν 2 vibrational level of H 2 O.…”

Section: Flow Measurement and Calibrationmentioning

confidence: 97%

Optimization and complete characterization of a photoacoustic gas detector

et al. 2014

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periodically modulated in and out an absorption line of the studied molecule. During the relaxation process, energy is mainly transferred by collision to the surrounding molecules. A local change of temperature is then induced along the laser beam, and a standing wave is created inside the cell.Photoacoustic cells are often used in resonant mode in order to take advantage of the enhancement of the acoustical signal. The resonator shape directly affects the strength and the distribution of these pressure variations. To take full benefits of the sound wave amplification, the quality factor, the resonant frequency and the peak amplitude at resonance are the three main parameters to be determined. These three parameters are usually experimentally determined from the cell response:U is the measured voltage of the microphone (V), R M its sensitivity (V/Pa), W the optical power of the laser (W), c the gas concentration and K the absorption coefficient (cm −1 ). The maximum value of R c (ω) is often referred as the cell constant. This constant is used to determine the detection limit of the photoacoustic spectrometer. In order to enhance this detection limit, one must be able to predict the cell response.Positions of resonant frequencies and Q-factors can be calculated for simple resonant volume where analytic solution exists [2]. For more complex cells, electric analogy can also be used to investigate the cell response [3]. Finite element method (FEM) presents the ease of use of a computational calculation and has already demonstrated its capabilities for the simulation of the photoacoustic cell characteristics. Baumann et al. [4] predicted the resonant frequencies and Q-factors of a T-shaped cell with a goodAbstract We report the complete designing process and realization of a photoacoustic spectrometer. In a first step, the cell design is optimized in order to achieve maximum cell constant and working frequency using a finite element method. Technological and integration constraints are used to define dimensional constraints on the cell. In a second step, a dedicated optical bench is presented along with the photoacoustic cell. The resonator response is then measured using a quantum cascade laser for methane detection and condenser microphones as detectors. The system detection limit is also discussed as it depends not only on the cell response but is also a combination of parameters linked together: environmental noise, microphones characteristics and cell conception. The gas flow required in a dynamic operation of the sensor degrades the detection limit regardless of the microphones quality. Choices on cell conception to minimize gas flow noise are discussed.

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Influence of oxygen on the resonant photoacoustic signal from methane excited at the ν 3 mode

Cited by 18 publications

References 7 publications

Photoacoustic-Based Gas Sensing: A Review

Photoacoustic-Based Gas Sensing: A Review

Off-axis quartz-enhanced photoacoustic spectroscopy using a pulsed nanosecond mid-infrared optical parametric oscillator

Optimization and complete characterization of a photoacoustic gas detector

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