Oxygen isotope ratio measurements in CO_2 by means of a continuous-wave quantum cascade laser at 4.3 μm (original) (raw)
Related papers
Optics Letters, 2007
A mid-infrared laser spectrometer was developed for simultaneous high-precision 18 O/ 16 O and 17 O/ 16 O isotope ratio measurements in carbon dioxide. A continuous-wave, liquid-nitrogen cooled, distributed feedback quantum cascade laser, working at a wavelength of 4.3 m, was used to probe 12 C 16 O 2 , 16 O 12 C 18 O, and 16 O 12 C 17 O lines at ϳ2311.8 cm −1 . High sensitivity was achieved by means of wavelength modulation spectroscopy with second-harmonic detection. The experimental reproducibility in the short and long terms was deeply investigated through the accurate analysis of a large number of spectra. In particular, we found a short term precision of 0.5‰ and 0.6‰, respectively, for 18 O/ 16 O and 17 O/ 16 O isotope ratios. The occurrence of systematic deviations is also discussed.
Journal of Modern Optics, 2005
We describe a prototype instrument using a Peltier cooled quantum cascade laser for precise measurement of stable carbon (13 C/ 12 C) isotopologue ratios in atmospheric CO 2. Using novel optics and signal processing techniques in a compact instrument, we are able to detect the difference between sample and reference with a precision of 0.1ø (2 standard error of mean of 11 samples) in 10 min of analysis time. The standard deviation of 0.18ø for individual 30 s measurements shows that this prototype instrument already approaches the best reported literature values using continuous wave lead alloy tunable diode lasers. The application of pulsed near room-temperature quantum cascade lasers to this demanding problem opens the possibility of field worthy rapid response isotopic instrumentation and attests to the maturity of these lasers as spectroscopic sources.
High Spectral-Purity Quantum Cascade Laser for Isotopic Analysis of Carbon Dioxide
Journal of Nanoscience and Nanotechnology, 2018
A distributed feedback quantum cascade laser with high side-mode suppression ratio (>25 dB), linear temperature and current tuning capability was fabricated and applied to CO 2 isotopic ratio measurements. Direct absorption spectroscopy was adopted to measure the CO 2 concentration and the isotope ratio simultaneously within a 40-cm-long gas cell. A 5000 ppmv standard CO 2 gas sample with ambient abundance and buffered by pure nitrogen was used to evaluate the performance of the system. After an average time of 5000 s, the mean value of the calculated concentration was 4958.8 ppmv with a standard deviation of 86 ppmv, showing a goodstability and small error. According to Allen deviation, the highest measurement precision of 1.37‰ was achieved after an integrating time of 95 s.
Applied Physics B, 2008
We present a new approach to the measurement of stable isotopic ratios of carbon dioxide using a near room temperature pulsed quantum cascade laser and a spectral ratio method based upon dual multiple pass absorption cells. The spectral ratio method improves precision and accuracy by reducing sensitivity to variations in the laser tuning rate, power and line width. The laser is scanned across three spectral lines (near 2310 cm -1 ) quantifying three CO 2 isotopologues: 12 C 16 O 2 , 13 C 16 O 2 and 12 C 16 O 18 O. Isotopic ratios are determined simultaneously with a precision of 0.2 δ for each ratio with a one second measurement. Signal averaging for 400 seconds improves the precision to better than 0.03 δ for both isotopic ratios ( 13 R and 18 R). Long term accuracy of 0.2 to 0.3 δ is demonstrated with replicate measurements of the same sample over a one month period. The fast time response of this instrument is suitable for eddy flux measurements.
Development of a compact quantum cascade laser spectrometer for field measurements of CO2 isotopes
We report the development of a field-deployable, pulsed quantum cascade laser spectrometer. The instrument is designed to measure the 13 C/ 12 C isotopic ratio in the CO 2 released from volcanic vents. Specific 12 CO 2 and 13 CO 2 absorption lines were selected around 4.3 µm, where the P-branch of 12 CO 2 overlaps the R-branch of 13 CO 2 of the 00 0 1-00 0 0 vibrational transition. This particular selection makes the instrument insensitive to temperature variations. A dual-channel cell balances the two absorption signals. We provide details of the instrument design and a preliminary demonstration of its performance based on laboratory measurements of O 12 C 16 O and 16 O 12 C 18 O. PACS 42.55.Px; 42.62.Fi; 07.88.+y
Appl Phys B Lasers Opt, 2003
Applied Physics B g. gagliardi 1,u a. castrillo 1 r.q. iannone 1 e.r.t. kerstel 2 l. gianfrani 1 High-precision determination of the 13 CO 2 / 12 CO 2 isotope ratio using a portable 2.008-µm diode-laser spectrometer ABSTRACT A compact and portable diode-laser spectrometer is developed for high-precision measurements of the 13 CO 2 / 12 CO 2 isotope ratio. Ro-vibrational transitions belonging to different combination bands, around 2.008 µm, are detected for the two isotopomers, using wavelength-modulation spectroscopy with first-harmonic detection. The determination of the isotope ratio is performed through a comparison between the spectra, simultaneously acquired in two different multiple-reflection cells designed to contain the sample and reference gases. The reproducibility of our method is extensively investigated over different time scales. In particular, the shortterm precision of the isotope ratio determination is found to be 0.03%. We discuss the presence of possible systematic shifts in the δ-value and optimise the operating conditions to ensure accuracy within the precision level. A possible use for in-situ measurements in volcanic gases is also discussed. PACS 42.62.Fi; 42.55.Px; 33.20.Ea
Isotopes in Environmental and Health Studies, 2006
Recent measurements of carbon isotopes in carbon dioxide using near-infrared, diode-laser-based cavity ring-down spectroscopy (CRDS) are presented. The CRDS system achieved good precision, often better than 0.2 ‰, for 4 % CO 2 concentrations, and also achieved 0.15-0.25 ‰ precision in a 78 min measurement time with cryotrap-based pre-concentration of ambient CO 2 concentrations (360 ppmv). These results were obtained with a CRDS system possessing a data rate of 40 ring-downs per second and a loss measurement of 4.0 × 10 −11 cm −1 Hz −1/2 . Subsequently, the measurement time has been reduced to under 10 min. This standard of performance would enable a variety of high concentration (3-10 %) isotopic measurements, such as medical human breath analysis or animal breath experiments. The extension of this ring-down to the 2 µm region would enable isotopic analysis at ambient concentrations, which, combined with the small size, robust design, and potential for frequent measurements at a remote site, make CRDS technology attractive for remote atmospheric measurement applications.
Applied Physics B: Lasers and Optics, 2003
Applied Physics B g. gagliardi 1,u a. castrillo 1 r.q. iannone 1 e.r.t. kerstel 2 l. gianfrani 1 High-precision determination of the 13 CO 2 / 12 CO 2 isotope ratio using a portable 2.008-µm diode-laser spectrometer ABSTRACT A compact and portable diode-laser spectrometer is developed for high-precision measurements of the 13 CO 2 / 12 CO 2 isotope ratio. Ro-vibrational transitions belonging to different combination bands, around 2.008 µm, are detected for the two isotopomers, using wavelength-modulation spectroscopy with first-harmonic detection. The determination of the isotope ratio is performed through a comparison between the spectra, simultaneously acquired in two different multiple-reflection cells designed to contain the sample and reference gases. The reproducibility of our method is extensively investigated over different time scales. In particular, the shortterm precision of the isotope ratio determination is found to be 0.03%. We discuss the presence of possible systematic shifts in the δ-value and optimise the operating conditions to ensure accuracy within the precision level. A possible use for in-situ measurements in volcanic gases is also discussed. PACS 42.62.Fi; 42.55.Px; 33.20.Ea
Advances in laser-based isotope ratio measurements: selected applications
Applied Physics B, 2008
Appl. Phys. B (2008) Lasers and Optics Applied Physics B e. kerstel 1,u l. gianfrani 2 Advances in laser-based isotope ratio measurements: selected applications 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.