Hollow Waveguide Infrared Spectroscopy and Sensing

Charlton, Christy; Thompson, Bruce T.; Mizaikoff, Boris

doi:10.1007/5346_004

Cited by 3 publications

(3 citation statements)

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“…Guo and Sun reviewed the progress in modified MPCs and CMR cells and compared them in terms of optical pathlength (OPL), volume, and path-to-volume ratio (PVR) [116]. HWG-based gas cells have been discussed in detail in books and reviews [129][130][131]. We compared the main features among the modified MPCs, CMR cells and HWG, as shown in Table 1.…”

Section: New Types Of Gas Cellsmentioning

confidence: 99%

Mid-Infrared Tunable Laser-Based Broadband Fingerprint Absorption Spectroscopy for Trace Gas Sensing: A Review

Zhang

et al. 2019

Applied Sciences

130

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The vast majority of gaseous chemical substances exhibit fundamental rovibrational absorption bands in the mid-infrared spectral region (2.5–25 μm), and the absorption of light by these fundamental bands provides a nearly universal means for their detection. A main feature of optical techniques is the non-intrusive in situ detection of trace gases. We reviewed primarily mid-infrared tunable laser-based broadband absorption spectroscopy for trace gas detection, focusing on 2008–2018. The scope of this paper is to discuss recent developments of system configuration, tunable lasers, detectors, broadband spectroscopic techniques, and their applications for sensitive, selective, and quantitative trace gas detection.

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Section: New Types Of Gas Cellsmentioning

confidence: 99%

Mid-Infrared Tunable Laser-Based Broadband Fingerprint Absorption Spectroscopy for Trace Gas Sensing: A Review

Zhang

et al. 2019

Applied Sciences

130

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“…The use of hollow silica waveguides (HSWs) for the construction of low-volume gas cells has become better established over recent years [12] but has yet to fully develop into a mature technology. HSWs were initially developed for guiding high-power infrared light from sources such as CO 2 (10.6 μm) or Er:YAG lasers (2.94 μm) [13].…”

Section: Introductionmentioning

confidence: 99%

Low-volume, fast response-time hollow silica waveguide gas cells for mid-IR spectroscopy

et al. 2016

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Hollow silica waveguides (HSWs) are used to produce long path length, low-volume gas cells, and are demonstrated with quantum cascade laser spectroscopy. Absorption measurements are made using the intrapulse technique, which allows measurements to be made across a single laser pulse. Simultaneous laser light and gas coupling is achieved through the modification of commercially available gas fittings with low dead volume. Three HSW gas cell configurations with different path lengths and internal diameters are analyzed and compared with a 30 m path length astigmatic Herriott cell. Limit of detection measurements are made for the gas cells using methane at a wavelength 7.82 μm. The lowest limit of detection was provided by HSW with a bore diameter of 1000 μm and a path length of 5 m and was measured to be 0.26 ppm, with a noise equivalent absorbance of 4.1×10^-4. The long-term stability of the HSW and Herriott cells is compared through analysis of the Allan-Werle variance of data collected over a 24 h period. The response times of the HSW and Herriott cells are measured to be 0.8 s and 36 s, respectively.

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“…To enhance the effective optical path length, a hollow waveguide was utilized to propagate mid-infrared radiation from the light source to the detector simultaneously serving as a low-volume, miniaturized gas cell. FTIR spectroscopy taking advantage of hollow waveguides (FTIR-HWG) has previously been demonstrated as a powerful analytical method for gas phase chemical detection with detection limits generally in the low ppm concentration range without preconcentration. − A preconcentration step based on thermal desorption was used here to further lower the detection limits into the ppb range complying with EPA and OSHA guidelines for measuring BTX in ambient air. Solid phase microextraction (SPME) via graphitized carbon black sorbent tubes has been applied to preconcentrate gas standards or field samples, which were then thermally desorbed as a concentrated gas plume into the HWG.…”

Section: Introductionmentioning

confidence: 99%

Infrared Hollow Waveguide Sensors for Simultaneous Gas Phase Detection of Benzene, Toluene, and Xylenes in Field Environments

Young

Menegazzo

Riley³

et al. 2011

Anal. Chem.

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Simultaneous and molecularly selective parts-per-billion detection of benzene, toluene, and xylenes (BTX) using a thermal desorption (TD)-FTIR hollow waveguide (HWG) trace gas sensor is demonstrated here for the first time combining laboratory calibration with real-world sample analysis in field. A calibration range of 100-1000 ppb analyte/N(2) was developed and applied for predicting the concentration of blinded environmental air samples within the same concentration range, and demonstrate close agreement with the validation method used here, GC-FID. The analyte concentration prediction capability of the TD-FTIR-HWG trace gas sensor also compares well with the industrial standard and other experimental techniques including GC-PID, ultrafast GC-FID, and GC-DMS, which were simultaneously operated in the field. With the advent of a quantum cascade laser with emission frequencies specifically tailored to efficiently overlap benzene absorption as the most relevant analyte, the overall sensor footprint could be considerably reduced to ultimately yield hand-held trace gas sensors facilitating direct and real-time detection of BTX in air down to low ppb levels.

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Hollow Waveguide Infrared Spectroscopy and Sensing

Cited by 3 publications

References 0 publications

Mid-Infrared Tunable Laser-Based Broadband Fingerprint Absorption Spectroscopy for Trace Gas Sensing: A Review

Mid-Infrared Tunable Laser-Based Broadband Fingerprint Absorption Spectroscopy for Trace Gas Sensing: A Review

Low-volume, fast response-time hollow silica waveguide gas cells for mid-IR spectroscopy

Infrared Hollow Waveguide Sensors for Simultaneous Gas Phase Detection of Benzene, Toluene, and Xylenes in Field Environments

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