Progress in cantilever enhanced photoacoustic spectroscopy

Koskinen, V.; Fonsen, J.; Roth, K.; Kauppinen, J.

doi:10.1016/j.vibspec.2008.01.013

Cited by 109 publications

(64 citation statements)

References 8 publications

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“…The optimum sensitivity achieved for the cantilever pressure transducer is superior to other cell designs using capacitive microphones, and the nonresonant operation of CEPAS cells can avoid the matrix influences on the PA signal [34,37]. A sensitive TDL-PAS setup based on cantilever-enhanced detection of oxygen (O 2 ) was demonstrated by Cattaneo et al [38] Such a high sensitivity suggests that reasonable detection limits for H 2 S could also be achieved using medium power light sources such NIR laser diodes around 1600 nm.…”

Section: Cantilever-enhanced Photoacoustic Spectroscopymentioning

confidence: 99%

“…However, PAS is a power scalable technique and therefore calls for excitation sources with high output powers [34]. Therefore, PAS applications usually utilize NIR distributed feedback (DFB) lasers, which typically provide output power between 10 and 40 mW.…”

Section: Cantilever-enhanced Photoacoustic Spectroscopymentioning

confidence: 99%

“…A novel detection approach, developed by Wilcken and Kauppinen [35], utilizes a silicon cantilever as an optical microphone with interferometric measurement of the sensor displacement and is termed cantilever-enhanced photoacoustic spectroscopy (CEPAS) [27,35,36]. The frequencydependent total system response combining the effects of the cantilever itself, gas heat transfer, relaxation pathways of the excited molecules and leakage through the gap and thermal diffusion to cell walls is discussed and derived in detail in [34,35] and is depicted in Fig. 3.…”

Section: Cantilever-enhanced Photoacoustic Spectroscopymentioning

confidence: 99%

“…The PA cell (yellow) is a polished and gold-coated cylindrical stainless steel tube (inner diameter of 6 mm and length of 100 mm) closed with a ZnSe window on the front end and a beam dump in the rear end of the tube. The balance cell is used for compensating the acceleration noise and reducing the effective spring constant due to the reduced gas spring effect [34,45]. The displacement of the silicon cantilever induced by the pressure wave from the dissipation of the absorbed infrared laser radiation is recorded by a compact Michelson interferometer.…”

Section: Cantilever-enhanced Photoacoustic Cellmentioning

confidence: 99%

“…The time-domain signal from the analog circuit module is digitized and subsequently Fourier-transformed, providing a frequency power spectrum. The magnitude of the peaks is directly proportional to the cantilever displacement, and hence, a linear dynamic range can be achieved for quantitative analysis [34].…”

Section: Cantilever-enhanced Photoacoustic Cellmentioning

confidence: 99%

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Cantilever-enhanced photoacoustic detection of hydrogen sulfide (H2S) using NIR telecom laser sources near 1.6 µm

Moser

Lendl

2016

Appl. Phys. B

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concentrations as low as 500 pptv manifesting in the characteristic odor of rotten eggs can already be detected by the human olfactory sense, the total loss of olfactory sensation starts at 150-200 ppmv [3]. Because of the wide occurrence of H 2 S in industrial processes and its often negative impact on process stabilities and product quality, its concentration needs to be tightly monitored. Furthermore, safety considerations and legal concentration limits also necessitate the accurate determination of H 2 S levels. In practice, concentrations ranging from sub-ppm levels at low pressures to several per cents at atmospheric conditions need to be monitored. Due to such diverse requirements, H 2 S analyzers based on different measurement technologies have been developed and are in industrial use. Apart from spectroscopic techniques based on absorption measurements, a range of other analytical techniques such as pulsed UV fluorescence [4], sulfur chemiluminescence [5], colorimetry employing a lead acetate tape [6], flame photometry as detector in gas chromatography [7] as well as electrochemical detection techniques ranging from potentiometric, galvanic, coulometric and amperometric detection [8] is frequently employed. It is interesting to note that in the petrochemical industry the lead acetate tape method is still in frequent use. Also, gas chromatographic methods are popular as they can be used to detect several components almost simultaneously, but this technique requires preparation and extraction of the sample gas leading to a time-consuming measurement. A general drawback of nonspectroscopic techniques is the fact that they do not allow for direct measurements. This, however, also applies to H 2 S detection based on UV fluorescence as this technique requires sample combustion as well as detection by chemoluminescence, where addition of reagents is required.Most of the spectroscopic techniques are based on the detection of the absorption spectrum of the molecules in Abstract Sensitive detection of hydrogen sulfide (H 2 S) at different pressure levels using a cantilever-enhanced photoacoustic detector in combination with a telecom NIR L-band laser source is reported. Amplitude and wavelength modulation schemes for photoacoustic signal generation are compared. A detection limit (3σ) of 8 ppmv was achieved for amplitude modulation mode with a 50-s averaging time for the H 2 S absorption near 1.6 µm. As compared to simulated spectra, the cantilever-enhanced photoacoustic detection approach in combination with the sufficiently stable and narrow bandwidth NIR laser is able to reproduce the rotationally resolved H 2 S spectrum at low pressures of 300 mbar.

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Section: Cantilever-enhanced Photoacoustic Spectroscopymentioning

confidence: 99%

Section: Cantilever-enhanced Photoacoustic Spectroscopymentioning

confidence: 99%