Cavity ring-down spectroscopy: recent technological advances and applications

Maity, Abhijit; Maithani, Sanchi; Pradhan, Manik

doi:10.1016/b978-0-12-818870-5.00003-4

Cited by 8 publications

(6 citation statements)

References 138 publications

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“…At each reflection, a small fraction of the incident light is lost via transmission, leading to an intensity decay. This light-intensity decay is known for presenting an exponential behavior [53,54].…”

Section: Vocs Identification Through Ir Spectroscopymentioning

confidence: 99%

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Ion Mobility Spectrometry Towards Environmental Volatile Organic Compounds Identification and Quantification: a Comparative Overview over Infrared Spectroscopy

Moura

Vassilenko

Ribeiro

2023

Emiss. Control Sci. Technol.

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Volatile organic compounds (VOCs) can be extremely toxic and hazardous to expose humans in both indoor and outdoor environments; thus, their detection, correct identification, and accurate quantification are relevant and demanding tasks that need to be addressed. Fortunately, several known analytical techniques allow the qualitative and quantitative assessment of these compounds. This review paper stresses on two independent spectroscopic techniques, infrared spectroscopy and ion mobility spectrometry, both suitable for the detection of very small concentration levels of VOCs in gaseous samples. Infrared spectroscopy is a well-known technique that has been largely applied per se or combined with additional methodologies, to study VOCs at both high and low concentration levels. On the other hand, ion mobility spectrometry gained relevance in this field, due to its capability to measure trace concentration levels, namely ppbv and even pptv. For this review paper, several scientific papers were analyzed, and the most relevant were addressed throughout the text. The working principles of both techniques are carefully addressed, and updated data is provided for highlighting the advantages and disadvantages of both techniques for the environmental VOCs assessment in air quality control.

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Section: Vocs Identification Through Ir Spectroscopymentioning

confidence: 99%

“…During the analysis, the decay of light intensity is measured as a function of time. From this feature, the cavity ring-down time or decay time can be calculated, which basically is the time required for the light intensity to reach 1 e of its initial intensity [53,55]. It can be represented as t:…”

Section: Vocs Identification Through Ir Spectroscopymentioning

confidence: 99%

Ion Mobility Spectrometry Towards Environmental Volatile Organic Compounds Identification and Quantification: a Comparative Overview over Infrared Spectroscopy

Moura

Vassilenko

Ribeiro

2023

Emiss. Control Sci. Technol.

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“…If the cavity contains an absorbing medium such as a chemical vapor or even an aerosol, the additional absorption of that medium is then indirectly observed through seeing the change in the RDT. [6][7][8] The decay of light leaking out of the cavity as a function of time is expressed in the equation: eq. 2…”

Section: Cavity Ring-down Spectroscopymentioning

confidence: 99%

Pushing the limits of vibrational spectroscopy-based detection: the potential of cavity ring-down spectroscopy for trace threat vapor detection

Pardoe

Languirand

2023

Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XXIV

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Traditional vapor sensing based on vibrational spectroscopy methods employs Fourier-transform infrared (FTIR) spectroscopy, which can produce reliable identification of ppm-level chemical vapors; however, chemical warfare agent poses a threat down to ppb and lower levels. Novel cavity ring-down spectroscopy-based sensors offer a possible path toward combining the high amount of spectral fingerprint data available from traditional IR methods, and the sensitivity of higher-sensitivity technologies, such as nanomaterial arrays and ion-mobility spectroscopy (IMS) which lack high amounts of data which can be used to uniquely identify molecules and are still plagued by high false-alarm rates and low selectivity. Cavity ring-down expands the effective path length of a gas analyzer by orders of magnitude by reflecting the IR light back and forth across an analyzer cavity. By characterizing the loss of light with each bounce by understanding the reflectivity of the mirrors employed at each end of the cavity, a characteristic "ring-down" time of the reflected light through a gas medium can be measured. Then, as analyte is introduced into the cavity, the ring-down times at each wavelength are shifted as a function of the absorbance of the analyte. Comparison of the measured vs. expected ringdown times can be interpreted to produce an IR absorption spectrum of the analyte. The effective pathlength of on order of kilometers allows for extremely high sensitivity beyond the capability of modern FTIR-based analyzers; however, this sensitivity comes at the expense of easier-to-saturate detectors as well. Additionally, cavity ring-down systems have already demonstrated the ability to measure absorption of aerosols both solid and liquid, filling a major gap left by FTIR vapor analyzers and opening the possibility of bioaerosol detection. We present a comparison of the two technologies and where they complement as well as fill in gaps in detection capabilities and offer a path forward for future generations of CB detection.

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“…The light is reflected back and forth as it passes through, leading to the exponential decay of the light. By measuring the decay time (ring-down time), CRDS analyses the light intensity variations resulting from cavity loss due to absorption by target molecules [136,137]. CRDS is a direct quantitative gas sensing technique that is more sensitive than conventional absorption spectroscopy and GC techniques and relatively resistant to power fluctuations.…”

Section: Optical Gas Sensingmentioning

confidence: 99%

Greenhouse Gas Emissions and Life Cycle Assessment on the Black Soldier Fly (Hermetia illucens L.)

2022

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The black soldier fly (BSF) is recognised as a valuable insect for mitigating feed and organic waste management challenges. Thus, concerted efforts are being directed toward the promotion of the BSF. Despite the numerous advantages of BSF larvae, there are several critical environmental aspects, particularly its global warming potential, that need to be considered before large-scale adoption due to the complexity of the insect’s value chain. The direct assessment of greenhouse gas (GHG) and ammonia emissions from BSF larvae biotreatment is crucial for conducting a life cycle assessment (LCA) to evaluate the insect products’ environmental performance. This article reviews the emissions of GHG from BSF larvae bioconversion activities based on different gas sensing techniques while highlighting the factors that influence these emissions. Generally, low gas emissions were reported. However, the influence of various factors influencing emissions remains unclear, especially for nitrous oxide. We also analysed LCA studies on BSFL products while emphasising the uncertainties and variabilities among the studies. The wide variation of impact scores reported in the studies suggests that standardised guidelines should be developed to streamline methodical approaches for impact assessments pertaining to system boundaries, functional units, allocation, and system expansion assumptions. We identified several aspects for future improvements to harmonise studies in order to enhance the comparative assessment of the BSFL products.

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Cavity ring-down spectroscopy: recent technological advances and applications

Cited by 8 publications

References 138 publications

Ion Mobility Spectrometry Towards Environmental Volatile Organic Compounds Identification and Quantification: a Comparative Overview over Infrared Spectroscopy

Ion Mobility Spectrometry Towards Environmental Volatile Organic Compounds Identification and Quantification: a Comparative Overview over Infrared Spectroscopy

Pushing the limits of vibrational spectroscopy-based detection: the potential of cavity ring-down spectroscopy for trace threat vapor detection

Greenhouse Gas Emissions and Life Cycle Assessment on the Black Soldier Fly (Hermetia illucens L.)

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