Mid-infrared laser spectroscopic determination of isotope ratios of N2O at trace levels using wavelength modulation and balanced path length detection

Waechter, H.; Sigrist, Markus W.

doi:10.1007/s00340-007-2576-z

Cited by 36 publications

(25 citation statements)

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“…Long path length multiple-pass cells can be rather susceptible to sinusoidal modulations of the spectrum baseline (fringes), induced by partial overlap of beam paths inside the cell. High finesse optical cavity based techniques too can suffer from unwanted reflections in the optical system, similarly leading to optical fringes, as well a a Note that the mixing ratios used in these two studies ( [86] and [87]) are a factor of, respectively, ∼ 2600 and ∼ 550 higher than natural.…”

Section: Discussionmentioning

confidence: 99%

Advances in laser-based isotope ratio measurements: selected applications

2008

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Advances in laser-based isotope ratio measurementsKerstel, E.; Gianfrani, L. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. ABSTRACT Small molecules exhibit characteristic ro-vibrational transitions in the near-and mid-infrared spectral regions, which are strongly influenced by isotopic substitution. This gift of nature has made it possible to use laser spectroscopy for the accurate analysis of the isotopic composition of gaseous samples. Nowadays, laser spectroscopy is clearly recognized as a valid alternative to isotope ratio mass spectrometry. Laserbased instruments are leaving the research laboratory stage and are being used by a growing number of isotope researchers for significant advances in their own field of research. In this review article, we discuss the current status and new frontiers of research on high-sensitivity and high-precision laser spectroscopy for isotope ratio analyses. Although many of our comments will be generally applicable to laser isotope ratio analyses in molecules of environmental importance, this paper concerns itself primarily with water and carbon dioxide, two molecules that were studied extensively in our respective laboratories. A complete coverage of the field is practically not feasible in the space constraints of this issue, and in any case doomed to fail, considering the large body of work that has appeared ever since the review by Kerstel in 2004 (Handbook of Stable Isotope Analytical Techniques, Chapt. 34, pp.

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Section: Discussionmentioning

confidence: 99%

Advances in laser-based isotope ratio measurements: selected applications

2008

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“…Nevertheless, it also has some disadvantages such as the large size of the instrument, which hinders in situ field measurements. Laser spectroscopy is a valuable alternative because it is inherently selective, even for molecules with the same mass (Janssen and Tuzson, 2006;Gagliardi et al, 2005;Nakayama et al, 2007;Uehara et al, 2001Uehara et al, , 2003Wächter and Sigrist, 2007), and field-deployable instruments for unattended measurements can be designed. A significant improvement was obtained in recent years by the implementation of quantum cascade laser absorption spectroscopy (QCLAS) to reach a precision of 0.5 ‰ for δ 15 N α and δ 15 N β at N 2 O mixing ratios of 90 ppm (Wächter et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Site selective real-time measurements of atmospheric N<sub>2</sub>O isotopomers by laser spectroscopy

et al. 2012

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Abstract. We describe the first high precision real-time analysis of the N 2 O site-specific isotopic composition at ambient mixing ratios. Our technique is based on mid-infrared quantum cascade laser absorption spectroscopy (QCLAS) combined with an automated preconcentration unit. The QCLAS allows for simultaneous and specific analysis of the three main stable N 2 O isotopic species, 14 N 15 N 16 O, 15 N 14 N 16 O, 14 N 14 N 16 O, and the respective site-specific relative isotope ratio differences δ 15 N α and δ 15 N β . Continuous, stand-alone operation is achieved by using liquid nitrogen free N 2 O preconcentration, a quasi-room-temperature quantum cascade laser (QCL), quantitative sample transfer to the QCLAS and an optimized calibration algorithm. The N 2 O site-specific isotopic composition (δ 15 N α and δ 15 N β ) can be analysed with a long-term precision of 0.2 ‰. The potential of this analytical tool is illustrated by continuous N 2 O isotopomer measurements above a grassland plot over a three week period, which allowed identification of microbial source and sink processes.

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“…It should also be mentioned that isotope ratios like 14 N 15 NO/ 15 N 14 NO can be determined in a straightforward manner in contrast to IRMS, which does not enable a direct determination due to identical masses of these two isotopes. It is the first time that N 2 O isotope ratios have been measured with laser spectroscopic methods at these trace levels [46]. A more detailed report on the CO measurements will be published elsewhere.…”

Section: 3mentioning

confidence: 99%

Trace gas monitoring with infrared laser-based detection schemes

et al. 2007

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The success of laser-based trace gas sensing techniques crucially depends on the availability and performance of tunable laser sources combined with appropriate detection schemes. Besides near-infrared diode lasers, continuously tunable midinfrared quantum cascade lasers and nonlinear optical laser sources are preferentially employed today. Detection schemes are based on sensitive absorption measurements and comprise direct absorption in multi-pass cells as well as photoacoustic and cavity ringdown techniques in various configurations. We illustrate the performance of several systems implemented in our laboratory. These include time-resolved multicomponent traffic emission measurements with a mobile CO 2 -laser photoacoustic system, a diode-laser based cavity ringdown device for measurements of impurities in industrial process control, isotope ratio measurements with a difference frequency (DFG) laser source combined with balanced path length detection, detection of methylamines for breath analysis with both a near-IR diode laser and a DFG source, and finally, acetone measurements with a heatable multipass cell intended for vapor phase studies on doping agents in urine samples.PACS 33.20.Ea; 42.62.Fi; 42.72.Ai; 87.64.km; 92.60 Trace gases play a key role in various areas such as air pollution, climate research, industrial process control, agriculture, food industry, volcanology, workplace safety and medical diagnostics. There exist numerous gas sensing devices based on different detection principles like gas chromatography (GC), mass spectrometry (MS) or combinations of the two (GC-MS), chemiluminescence, Fourier transform infrared spectroscopy (FTIR), electrochemical sensors, colorimetry, etc. In recent years, laser-spectroscopic sensing devices have attracted a lot of interest (see e.g., [1]) as they enable high detection sensitivity (down to sub-ppb concentrations) and selectivity (including differentiation between isotopomers and isomers), multicomponent capabil- Trace gas sensor requirements with corresponding approach for laser-based detection system ity and large dynamic range (several orders of magnitude in concentration), and generally neither sample-preparation nor -preconcentration are required. However, the laser source characteristics in terms of available wavelengths, tunability, linewidth, power, operation temperature, etc., as well as the combination with appropriate sensitive detection schemes are crucial for the success of laser-based sensing. Table 1 lists the main sensing requirements and the corresponding approaches using laser-based methods. Ideally, one system can fulfill all requirements. The combination of broad continuous tuning with a narrow linewidth and a certain power level favors laserbased systems. Laser sourcesTunable near-infrared (near-IR) lasers are readily available, notably diode lasers equipped with an external cavity. These external cavity III-V diode lasers (ECDLs) represent excellent sources in terms of availability, compactness, robustness and tuning characteri...

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Mid-infrared laser spectroscopic determination of isotope ratios of N2O at trace levels using wavelength modulation and balanced path length detection

Cited by 36 publications

References 30 publications

Advances in laser-based isotope ratio measurements: selected applications

Advances in laser-based isotope ratio measurements: selected applications

Site selective real-time measurements of atmospheric N<sub>2</sub>O isotopomers by laser spectroscopy

Trace gas monitoring with infrared laser-based detection schemes

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Mid-infrared laser spectroscopic determination of isotope ratios of N2O at trace levels using wavelength modulation and balanced path length detection

Cited by 36 publications

References 30 publications

Advances in laser-based isotope ratio measurements: selected applications

Advances in laser-based isotope ratio measurements: selected applications

Site selective real-time measurements of atmospheric N&lt;sub&gt;2&lt;/sub&gt;O isotopomers by laser spectroscopy

Trace gas monitoring with infrared laser-based detection schemes

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Site selective real-time measurements of atmospheric N<sub>2</sub>O isotopomers by laser spectroscopy