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Artigos de revistas sobre o tema "Continuous–wave cavity ring-down spectroscopy"

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Publicado: 22 de junho de 2024

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1

Tan Zhongqi, 谭中奇, 龙兴武 Long Xingwu, 黄云 Huang Yun e 吴素勇 Wu Suyong. "Etaloning Effects in Continuous-Wave Cavity Ring down Spectroscopy". Chinese Journal of Lasers 35, n.º 10 (2008): 1563–66. http://dx.doi.org/10.3788/cjl20083510.1563.

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2

Huang, Haifeng, e Kevin K. Lehmann. "Sensitivity Limits of Continuous Wave Cavity Ring-Down Spectroscopy". Journal of Physical Chemistry A 117, n.º 50 (23 de setembro de 2013): 13399–411. http://dx.doi.org/10.1021/jp406691e.

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3

Dudek, John B., Peter B. Tarsa, Armando Velasquez, Mark Wladyslawski, Paul Rabinowitz e Kevin K. Lehmann. "Trace Moisture Detection Using Continuous-Wave Cavity Ring-Down Spectroscopy". Analytical Chemistry 75, n.º 17 (setembro de 2003): 4599–605. http://dx.doi.org/10.1021/ac0343073.

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4

Yan, W. B., Y. Chen, H. Chen, C. Krusen e P. T. Woods. "Development and Applications of Continuous-Wave Cavity Ring-Down Spectroscopy". International Journal of Thermophysics 29, n.º 5 (18 de junho de 2008): 1567–77. http://dx.doi.org/10.1007/s10765-008-0460-7.

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5

Li Zhe, 李哲, 张志荣 Zhang Zhirong, 夏滑 Xia Hua, 孙鹏帅 Sun Pengshuai, 余润罄 Yu Runqing, 王华东 Wang Huadong e 吴边 Wu Bian. "连续波腔衰荡吸收光谱技术中的模式匹配研究". Chinese Journal of Lasers 49, n.º 4 (2022): 0411001. http://dx.doi.org/10.3788/cjl202249.0411001.

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6

Santamaria, Luigi, Valentina Di Sarno, Paolo De Natale, Maurizio De Rosa, Massimo Inguscio, Simona Mosca, Iolanda Ricciardi, Davide Calonico, Filippo Levi e Pasquale Maddaloni. "Comb-assisted cavity ring-down spectroscopy of a buffer-gas-cooled molecular beam". Physical Chemistry Chemical Physics 18, n.º 25 (2016): 16715–20. http://dx.doi.org/10.1039/c6cp02163h.

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7

Huang, Haifeng, e Kevin K. Lehmann. "Sensitivity Limit of Rapidly Swept Continuous Wave Cavity Ring-Down Spectroscopy". Journal of Physical Chemistry A 115, n.º 34 (setembro de 2011): 9411–21. http://dx.doi.org/10.1021/jp111177c.

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8

Humphries, Gordon S., Iain S. Burns e Michael Lengden. "Application of Continuous-Wave Cavity Ring-Down Spectroscopy to Laminar Flames". IEEE Photonics Journal 8, n.º 1 (fevereiro de 2016): 1–10. http://dx.doi.org/10.1109/jphot.2016.2517575.

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9

Földes, T., P. Čermák, J. Rakovský, M. Macko, J. Krištof, P. Veis e P. Macko. "Electronic DFB laser switching for continuous wave cavity ring-down spectroscopy". Electronics Letters 46, n.º 7 (2010): 523. http://dx.doi.org/10.1049/el.2010.2360.

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10

Tan Zhongqi, 谭中奇, 冯先旺 Feng Xianwang e 龙兴武 Long Xingwu. "Electrocircuit design and application in continuous-wave cavity ring-down spectroscopy system". High Power Laser and Particle Beams 23, n.º 6 (2011): 1483–86. http://dx.doi.org/10.3788/hplpb20112306.1483.

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11

Wang, Jin-Duo, Jin Yu, Ze-Qiang Mo, Jian-Guo He, Shou-Jun Dai, Jing-Jing Meng, Xiao-Dong Wang e Yang Liu. "Numerical methods of mode selection in continuous-wave cavity ring-down spectroscopy". Acta Physica Sinica 68, n.º 24 (2019): 244201. http://dx.doi.org/10.7498/aps.68.20190844.

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12

McCarren, D., e E. Scime. "Continuous wave cavity ring-down spectroscopy for velocity distribution measurements in plasma". Review of Scientific Instruments 86, n.º 10 (outubro de 2015): 103505. http://dx.doi.org/10.1063/1.4932313.

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13

Tan, Zhongqi, Xingwu Long, Kaiyong Yang e Suyong Wu. "Spectral ripple effect in continuous-wave fold-type cavity ring down spectroscopy". Journal of the Optical Society of America B 27, n.º 12 (18 de novembro de 2010): 2727. http://dx.doi.org/10.1364/josab.27.002727.

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14

Rasheed, Abdur, e Daniel B. Curtis. "Note: A latched comparator circuit for triggering continuous-wave cavity ring-down spectroscopy". Review of Scientific Instruments 84, n.º 6 (junho de 2013): 066109. http://dx.doi.org/10.1063/1.4811846.

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15

Zhao, Dongfeng, Joseph Guss, Anton J. Walsh e Harold Linnartz. "Mid-infrared continuous wave cavity ring-down spectroscopy of a pulsed hydrocarbon plasma". Chemical Physics Letters 565 (abril de 2013): 132–37. http://dx.doi.org/10.1016/j.cplett.2013.02.025.

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16

Simpson, William R. "Continuous wave cavity ring-down spectroscopy applied toin situdetection of dinitrogen pentoxide (N2O5)". Review of Scientific Instruments 74, n.º 7 (julho de 2003): 3442–52. http://dx.doi.org/10.1063/1.1578705.

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17

Schmidt, F. M., O. Vaittinen, M. Metsälä, P. Kraus e L. Halonen. "Direct detection of acetylene in air by continuous wave cavity ring-down spectroscopy". Applied Physics B 101, n.º 3 (6 de maio de 2010): 671–82. http://dx.doi.org/10.1007/s00340-010-4027-5.

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18

Yang, Qing-Ying, Eamon K. Conway, Hui Liang, Iouli E. Gordon, Yan Tan e Shui-Ming Hu. "Cavity ring-down spectroscopy of water vapor in the deep-blue region". Atmospheric Measurement Techniques 15, n.º 15 (2 de agosto de 2022): 4463–72. http://dx.doi.org/10.5194/amt-15-4463-2022.

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Abstract. Water vapor absorption in the near-ultraviolet region is essential to describe the energy budget of Earth, but little spectroscopic information is available since it is a challenging spectral region for both experimental and theoretical studies. A continuous-wave cavity ring-down spectroscopic experiment was built to record absorption lines of water vapor around 415 nm. With a precision of 4×10-10 cm−1, 40 rovibrational transitions of H216O were observed in this work, and 27 of them were assigned to the (224), (205), (710), (304), (093), (125) and (531) vibrational bands. A comparison of line positions and intensities determined in this work to the most recent HITRAN database is presented. Water vapor absorption cross-sections near 415 nm were calculated based on our measurements, which vary between 1×10-26 and 5×10-26cm2 molec.−1. These data will also significantly impact the spectroscopy detection of trace gas species in the near-UV region.
19

Tan Zhongqi, 谭中奇, e 龙兴武 Long Xingwu. "Measurement of N2O Spectrum near 6590 cm-1with Continuous-Wave Cavity Ring-Down Spectroscopy". Acta Optica Sinica 29, n.º 4 (2009): 944–48. http://dx.doi.org/10.3788/aos20092904.0944.

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20

Wada, Ryuichi, e Andrew J. Orr-Ewing. "Continuous wave cavity ring-down spectroscopy measurement of NO2 mixing ratios in ambient air". Analyst 130, n.º 12 (2005): 1595. http://dx.doi.org/10.1039/b511115c.

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21

Fawcett, B. L., A. M. Parkes, D. E. Shallcross e A. J. Orr-Ewing. "Trace detection of methane using continuous wave cavity ring-down spectroscopy at 1.65 μm". Phys. Chem. Chem. Phys. 4, n.º 24 (2002): 5960–65. http://dx.doi.org/10.1039/b208486b.

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22

Hallock, A. J., E. S. F. Berman e R. N. Zare. "Use of Broadband, Continuous-Wave Diode Lasers in Cavity Ring-Down Spectroscopy for Liquid Samples". Applied Spectroscopy 57, n.º 5 (maio de 2003): 571–73. http://dx.doi.org/10.1366/000370203321666614.

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Cavity ring-down spectroscopy (CRDS) is an extremely sensitive absorption technique that has been applied primarily to gas samples, which are characterized by having narrow absorption features. Recently, CRDS has also been applied to liquid samples, which have broad absorption features. The use of small inexpensive diode lasers as light sources for liquid samples is demonstrated. The low cost coupled with the ease and technical straightforwardness of application gives this technique wide appeal.
23

Oh, Myoung-Kyu, Yong-Hoon Lee, Sung-Chul Choi, Do-Kyeong Ko e Jong-Min Lee. "Detection of Methane and Ethane by Continuous-Wave Cavity Ring-Down Spectroscopy Near 1.67 μm". Journal of the Optical Society of Korea 12, n.º 1 (25 de março de 2008): 1–6. http://dx.doi.org/10.3807/josk.2008.12.1.001.

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24

Tarsa, Peter B., Paul Rabinowitz e Kevin K. Lehmann. "Evanescent field absorption in a passive optical fiber resonator using continuous-wave cavity ring-down spectroscopy". Chemical Physics Letters 383, n.º 3-4 (janeiro de 2004): 297–303. http://dx.doi.org/10.1016/j.cplett.2003.11.043.

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25

Verbraak, H., A. K. Y. Ngai, S. T. Persijn, F. J. M. Harren e H. Linnartz. "Mid-infrared continuous wave cavity ring down spectroscopy of molecular ions using an optical parametric oscillator". Chemical Physics Letters 442, n.º 1-3 (julho de 2007): 145–49. http://dx.doi.org/10.1016/j.cplett.2007.05.051.

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26

Mellon, Daniel, Simon J. King, Jin Kim, Jonathan P. Reid e Andrew J. Orr-Ewing. "Measurements of Extinction by Aerosol Particles in the Near-Infrared Using Continuous Wave Cavity Ring-Down Spectroscopy". Journal of Physical Chemistry A 115, n.º 5 (10 de fevereiro de 2011): 774–83. http://dx.doi.org/10.1021/jp109894x.

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27

Földes, T. "Note: A very simple circuit for piezo actuator pseudo-tracking for continuous-wave cavity ring-down spectroscopy". Review of Scientific Instruments 84, n.º 1 (janeiro de 2013): 016102. http://dx.doi.org/10.1063/1.4774044.

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28

Nakayama, T., H. Fukuda, T. Kamikawa, A. Sugita, M. Kawasaki, I. Morino e G. Inoue. "Measurements of the 3ν 3 band of 14N15N16O and 15N14N16O using continuous-wave cavity ring-down spectroscopy". Applied Physics B 88, n.º 1 (22 de maio de 2007): 137–40. http://dx.doi.org/10.1007/s00340-007-2653-3.

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29

Peltola, J., M. Vainio, V. Ulvila, M. Siltanen, M. Metsälä e L. Halonen. "Off-axis re-entrant cavity ring-down spectroscopy with a mid-infrared continuous-wave optical parametric oscillator". Applied Physics B 107, n.º 3 (24 de maio de 2012): 839–47. http://dx.doi.org/10.1007/s00340-012-5074-x.

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30

Chakraborty Thakur, Saikat, Dustin McCarren, Jerry Carr e Earl E. Scime. "Continuous wave cavity ring down spectroscopy measurements of velocity distribution functions of argon ions in a helicon plasma". Review of Scientific Instruments 83, n.º 2 (fevereiro de 2012): 023508. http://dx.doi.org/10.1063/1.3687429.

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31

Nakayama, Tomoki, Hisato Fukuda, Akihiro Sugita, Satoshi Hashimoto, Masahiro Kawasaki, Simone Aloisio, Isamu Morino e Gen Inoue. "Buffer-gas pressure broadening for the (0003)←(0000) band of N2O measured with continuous-wave cavity ring-down spectroscopy". Chemical Physics 334, n.º 1-3 (abril de 2007): 196–203. http://dx.doi.org/10.1016/j.chemphys.2007.03.001.

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32

Sakamoto, Yosuke, Daisuke Yamano, Tomoki Nakayama, Masahiro Kawasaki, Isamu Morino e Gen Inoue. "Buffer-gas Pressure Broadening for the Third Overtone Band of NO Measured with Continuous-wave Cavity Ring-down Spectroscopy". Chemistry Letters 38, n.º 10 (5 de outubro de 2009): 1000–1001. http://dx.doi.org/10.1246/cl.2009.1000.

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33

Pradhan, M., R. E. Lindley, R. Grilli, I. R. White, D. Martin e A. J. Orr-Ewing. "Trace detection of C2H2 in ambient air using continuous wave cavity ring-down spectroscopy combined with sample pre-concentration". Applied Physics B 90, n.º 1 (27 de novembro de 2007): 1–9. http://dx.doi.org/10.1007/s00340-007-2833-1.

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34

Yamano, D., Y. Sakamoto, A. Yabushita, M. Kawasaki, I. Morino e G. Inoue. "Buffer-gas pressure broadening for the 2ν 3 band of methane measured with continuous-wave cavity ring-down spectroscopy". Applied Physics B 97, n.º 2 (12 de setembro de 2009): 523–28. http://dx.doi.org/10.1007/s00340-009-3720-8.

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35

Horstjann, M., M. D. Andrés Hernández, V. Nenakhov, A. Chrobry e J. P. Burrows. "Peroxy radical detection for airborne atmospheric measurements using cavity enhanced absorption spectroscopy of NO<sub>2</sub>". Atmospheric Measurement Techniques Discussions 6, n.º 6 (8 de novembro de 2013): 9655–88. http://dx.doi.org/10.5194/amtd-6-9655-2013.

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Abstract. Development of an airborne instrument for the determination of peroxy radicals (PeRCEAS – Peroxy Radical Cavity Enhanced Absorption Spectroscopy) is reported. Ambient peroxy radicals (HO2 and RO2, R being an organic chain) are converted to NO2 by adding NO, and are recycled through subsequent reaction with CO and O2, thus forming a chain reaction with an amplification factor called chain length. The concentration of NO2 is measured by continuous-wave cavity ring-down spectroscopy (CRDS) using an extended cavity diode laser at 409 nm. Optical feedback from a V-shaped cavity optimizes resonator transmission and allows for a simple detector set-up. CRDS directly yields absorption coefficients, thus providing NO2 concentrations without additional calibration. The optimum 1σ detection limit is 0.3 ppbv at an averaging time of 40 s and an inlet pressure of 300 mbar, corresponding to a concentration of 2 × 109 molecules cm−3. The calibration of the PeRCEAS chain length at an inlet pressure of 300 mbar yields a value of 120 ± 7. The peroxy radical 1σ detection limit for an averaging time of 120 s and a chain length of 120 is ~3 pptv.
36

Cheng, Chonghui, Sumei Liu, Haiyang Qi, Pengbing Hu, Pei Ye e Sunqiang Pan. "Optical-feedback cavity ring-down spectroscopy for NO2 extinction coefficient measurement using a continuous wave laser diode". Applied Optics 61, n.º 9 (14 de março de 2022): 2230. http://dx.doi.org/10.1364/ao.450874.

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37

Tang, Jing, Bincheng Li e Jing Wang. "High-precision measurements of nitrous oxide and methane in air with cavity ring-down spectroscopy at 7.6 µm". Atmospheric Measurement Techniques 12, n.º 5 (20 de maio de 2019): 2851–61. http://dx.doi.org/10.5194/amt-12-2851-2019.

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Abstract. A high-sensitivity methane (CH4) and nitrous oxide (N2O) sensor based on mid-infrared continuous-wave (CW) cavity ring-down spectroscopy (CRDS) techniques was developed for environmental and biomedical trace-gas measurements. A tunable external-cavity mode-hop-free (EC-MHF) quantum cascade laser (QCL) operating at 7.4 to 7.8 µm was used as the light source. The effect of temperature fluctuation on the measurement sensitivity of the CRDS experimental setup was analyzed and corrected, and a sensitivity limit of absorption coefficient measurement of 7.2×10-10 cm−1 was achieved at 1330.50 cm−1 with an average of 139 measurements or 21 s averaging time and further improved to 2.3×10-10 cm−1 with an average of 3460 measurements, or 519 s averaging time. For the targeted CH4 and N2O, absorption lines located at 1298.60 and 1327.07 cm−1 with temperature effect correction detection limits of 13 and 11 pptv were experimentally achieved with 10.4 and 10.2 s averaging times and could be further improved to 5 and 9 pptv with 482.5 and 311 s averaging times, respectively. Four spectral bands (1298.4 to 1298.9 cm−1, 1310.1 to 1312.3 cm−1, 1326.5 to 1328 cm−1, and 1331.5 to 1333 cm−1) in the spectral range from 1295 to 1335 cm−1 were selected for the separate and simultaneous measurements of CH4 and N2O under normal atmospheric pressure, and all were in good agreements. The concentrations of CH4 and N2O of atmospheric air collected at different locations and of exhaled breath were measured and analyzed. Continuous measurements of CH4 and N2O concentrations of indoor laboratory air over 45 h were also taken. It was found that anaerobic bacteria in the water and soil of wetlands might significantly increase the CH4 concentration in the air. The measured N2O concentration in the central city area was somewhat lower than the reported normal level in open air. Our results demonstrated the temporal and spatial variations of CH4 and N2O in the air.
38

Yamano, Daisuke, Akihiro Yabushita, Masahiro Kawasaki e Agnes Perrin. "Absorption spectrum of nitrous acid for the ν1+2ν3 band studied with continuous-wave cavity ring-down spectroscopy and theoretical calculations". Journal of Quantitative Spectroscopy and Radiative Transfer 111, n.º 1 (janeiro de 2010): 45–51. http://dx.doi.org/10.1016/j.jqsrt.2009.07.009.

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39

Thiebaud, Jérôme, Sabine Crunaire e Christa Fittschen. "Measurements of Line Strengths in the 2ν1Band of the HO2Radical Using Laser Photolysis/Continuous Wave Cavity Ring-Down Spectroscopy (cw-CRDS)". Journal of Physical Chemistry A 111, n.º 30 (agosto de 2007): 6959–66. http://dx.doi.org/10.1021/jp0703307.

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40

Frunder, H., R. Angstl, D. Illig, H. W. Schrötter, L. Lechuga-Fossat, J. M. Flaud, C. Camy-Peyret e W. F. Murphy. "The coherent anti-Stokes Raman spectroscopy spectrum of the Q-branch of the ν1 band of hydrogen sulfide". Canadian Journal of Physics 63, n.º 9 (1 de setembro de 1985): 1189–94. http://dx.doi.org/10.1139/p85-193.

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The coherent anti-Stokes Raman spectroscopy (CARS) spectrum of the Q-branch of the ν1 band of natural H2S has been measured at a pressure of 1.3 kPa with continuous-wave excitation in the cavity of an argon-ion ring laser. For comparison with the experimental spectrum, Raman line positions and intensities were calculated from energy levels and wave functions that were previously obtained from the study of the pure rotation spectrum and the 2ν2, ν1, and ν3 bands by Fourier transform infrared spectroscopy. These Raman line positions and intensities formed the basis for the simulation of the theoretical CARS spectrum, which is in excellent agreement with the experimental one.
41

Nakamichi, Shinji, Yoshimitsu Kawaguchi, Hisato Fukuda, Shinichi Enami, Satoshi Hashimoto, Masahiro Kawasaki, Toyofumi Umekawa, Isamu Morino, Hiroshi Suto e Gen Inoue. "Buffer-gas pressure broadening for the (3 001)III← (0 0 0) band of CO2measured with continuous-wave cavity ring-down spectroscopy". Phys. Chem. Chem. Phys. 8, n.º 3 (2006): 364–68. http://dx.doi.org/10.1039/b511772k.

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42

Horstjann, M., M. D. Andrés Hernández, V. Nenakhov, A. Chrobry e J. P. Burrows. "Peroxy radical detection for airborne atmospheric measurements using absorption spectroscopy of NO<sub>2</sub>". Atmospheric Measurement Techniques 7, n.º 5 (13 de maio de 2014): 1245–57. http://dx.doi.org/10.5194/amt-7-1245-2014.

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Abstract. Development of an airborne instrument for the determination of peroxy radicals (PeRCEAS – peroxy radical chemical enhancement and absorption spectroscopy) is reported. Ambient peroxy radicals (HO2 and RO2, R being an organic chain) are converted to NO2 in a reactor using a chain reaction involving NO and CO. Provided that the amplification factor, called effective chain length (eCL), is known, the concentration of NO2 can be used as a proxy for the peroxy radical concentration in the sampled air. The eCL depends on radical surface losses and must thus be determined experimentally for each individual setup. NO2 is detected by continuous-wave cavity ring-down spectroscopy (cw-CRDS) using an extended cavity diode laser (ECDL) at 408.9 nm. Optical feedback from a V-shaped resonator maximizes transmission and allows for a simple detector setup. CRDS directly yields absorption coefficients, thus providing NO2 concentrations without additional calibration. The optimum 1σ detection limit is 0.3 ppbv at an averaging time of 40 s and an inlet pressure of 300 hPa. Effective chain lengths were determined for HO2 and CH3O2 at different inlet pressures. The 1σ detection limit at an inlet pressure of 300 hPa for HO2 is 3 pptv for an averaging time of 120 s.
43

Tang, Yongxin, Shaoyue L. Yang e Kevin K. Lehmann. "Measurements of CH3D line strengths, foreign pressure-broadening, and pressure-shift coefficients at near-IR region using continuous-wave cavity ring-down spectroscopy". Journal of Molecular Spectroscopy 291 (setembro de 2013): 48–56. http://dx.doi.org/10.1016/j.jms.2013.03.004.

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44

Nwaboh, Javis Anyangwe, Stefan Persijn, Kathrin Heinrich, Marcus Sowa, Peter Hering e Olav Werhahn. "QCLAS and CRDS-Based CO Quantification as Aimed at in Breath Measurements". International Journal of Spectroscopy 2012 (18 de janeiro de 2012): 1–10. http://dx.doi.org/10.1155/2012/894841.

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Laser-spectrometric methods to derive absolute and traceable carbon monoxide (CO) amount fractions in exhaled human breath could be of advantage for early disease detection as well as for treatment monitoring. As proof-of-principle laboratory experiment, we employed intra-pulse and continuous wave (cw) quantum cascade laser spectroscopy (QCLAS), both at 4.6 μm. Additional experiments were carried out applying cw cavity ring-down spectroscopy (CRDS) with a CO sideband laser and a QCL. We emphasize metrological data quality objectives, thatis, traceability and uncertainty, which could serve as essential benefits to exhaled breath measurements. The results were evaluated and compared on a 100 μmol/mol CO level using the two QCLAS spectrometers, and the cw CO sideband laser CRDS setup. The relative standard uncertainties of the pulsed and the cw QCLAS CO amount fraction results were ±4.8 and ±2.8%, respectively, that from the CO sideband laser CRDS was ±2.7%. Sensitivities down to a 3 nmol/mol CO level were finally demonstrated and quantified by means of cw CRDS equipped with a QCL yielding standard uncertainties of about ±2.5 that are exclusively limited by the available line strength figure quality. With this study we demonstrate the achieved comparability of CO quantifications, adhering metrological principles.
45

Washenfelder, R. A., A. R. Attwood, J. M. Flores, K. J. Zarzana, Y. Rudich e S. S. Brown. "Broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region for measurements of nitrogen dioxide and formaldehyde". Atmospheric Measurement Techniques 9, n.º 1 (15 de janeiro de 2016): 41–52. http://dx.doi.org/10.5194/amt-9-41-2016.

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Abstract. Formaldehyde (CH2O) is the most abundant aldehyde in the atmosphere, and it strongly affects photochemistry through its photolysis. We describe simultaneous measurements of CH2O and nitrogen dioxide (NO2) using broadband cavity-enhanced absorption spectroscopy in the ultraviolet spectral region. The light source consists of a continuous-wave diode laser focused into a Xenon bulb to produce a plasma that emits high-intensity, broadband light. The plasma discharge is optically filtered and coupled into a 1 m optical cavity. The reflectivity of the cavity mirrors is 0.99930 ± 0.00003 (1− reflectivity = 700 ppm loss) at 338 nm, as determined from the known Rayleigh scattering of He and zero air. This mirror reflectivity corresponds to an effective path length of 1.43 km within the 1 m cell. We measure the cavity output over the 315–350 nm spectral region using a grating monochromator and charge-coupled device array detector. We use published reference spectra with spectral fitting software to simultaneously retrieve CH2O and NO2 concentrations. Independent measurements of NO2 standard additions by broadband cavity-enhanced absorption spectroscopy and cavity ring-down spectroscopy agree within 2 % (slope for linear fit = 1.02 ± 0.03 with r2 = 0.998). Standard additions of CH2O measured by broadband cavity-enhanced absorption spectroscopy and calculated based on flow dilution are also well correlated, with r2 = 0.9998. During constant mixed additions of NO2 and CH2O, the 30 s measurement precisions (1σ) of the current configuration were 140 and 210 pptv, respectively. The current 1 min detection limit for extinction measurements at 315–350 nm provides sufficient sensitivity for measurement of trace gases in laboratory experiments and ground-based field experiments. Additionally, the instrument provides highly accurate, spectroscopically based trace gas detection that may complement higher precision techniques based on non-absolute detection methods. In addition to trace gases, this approach will be appropriate for measurements of aerosol extinction in ambient air, and this spectral region is important for characterizing the strong ultraviolet absorption by brown carbon aerosol.
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Wei, Qianhe, Bincheng Li, Jing Wang, Binxing Zhao e Ping Yang. "Impact of Residual Water Vapor on the Simultaneous Measurements of Trace CH4 and N2O in Air with Cavity Ring-Down Spectroscopy". Atmosphere 12, n.º 2 (6 de fevereiro de 2021): 221. http://dx.doi.org/10.3390/atmos12020221.

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Methane (CH4) and nitrous oxide (N2O) are among the most important atmospheric greenhouse gases. A gas sensor based on a tunable 7.6 μm continuous-wave external-cavity mode-hop-free (EC-MHF) quantum cascade laser (from 1290 to 1350 cm−1) cavity ring-down spectroscopy (CRDS) technique was developed for the simultaneous detection of CH4 and N2O in ambient air with water vapor (H2O) mostly removed via molecular sieve drying to minimize the impact of H2O on the simultaneous measurements. Still, due to the broad and strong absorption spectrum of H2O in the entire mid-infrared (mid-IR) spectral range, residual H2O in the dried ambient air due to incomplete drying and leakage, if not properly accounted for, could cause a significant influence on the measurement accuracy of the simultaneous CH4 and N2O detection. In this paper, the impact of residual H2O on the simultaneous CH4 and N2O measurements were analyzed by comparing the CH4 and N2O concentrations determined from the measured spectrum in the spectral range from 1311 to 1312.1 cm−1 via simultaneous CH4 and N2O measurements and that determined from the measured spectrum in the spectral range from 1311 to 1313 cm−1 via simultaneous CH4, N2O, and H2O measurements. The measured dependence of CH4 and N2O concentration errors on the simultaneously determined H2O concentration indicated that the residual H2O caused an under-estimation of CH4 concentration and over-estimation of N2O concentration. The H2O induced CH4 and N2O concentration errors were approximately linearly proportional to the residual H2O concentration. For the measurement of air flowing at 3 L per min, the residual H2O concentration was stabilized to approximately 14 ppmv, and the corresponding H2O induced errors were −1.3 ppbv for CH4 and 3.7 ppbv for N2O, respectively.
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Wu, Tao, Renzhi Hu, Pinhua Xie, Lijie Zhang, Changjin Hu, Xiaoyan Liu, Jiawei Wang, Liujun Zhong, Jinzhao Tong e Wenqing Liu. "A Mid-Infrared Quantum Cascade Laser Ultra-Sensitive Trace Formaldehyde Detection System Based on Improved Dual-Incidence Multipass Gas Cell". Sensors 23, n.º 12 (16 de junho de 2023): 5643. http://dx.doi.org/10.3390/s23125643.

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Formaldehyde (HCHO) is a tracer of volatile organic compounds (VOCs), and its concentration has gradually decreased with the reduction in VOC emissions in recent years, which puts forward higher requirements for the detection of trace HCHO. Therefore, a quantum cascade laser (QCL) with a central excitation wavelength of 5.68 μm was applied to detect the trace HCHO under an effective absorption optical pathlength of 67 m. An improved, dual-incidence multi-pass cell, with a simple structure and easy adjustment, was designed to further improve the absorption optical pathlength of the gas. The instrument detection sensitivity of 28 pptv (1σ) was achieved within a 40 s response time. The experimental results show that the developed HCHO detection system is almost unaffected by the cross interference of common atmospheric gases and the change of ambient humidity. Additionally, the instrument was successfully deployed in a field campaign, and it delivered results that correlated well with those of a commercial instrument based on continuous wave cavity ring-down spectroscopy (R2 = 0.967), which indicates that the instrument has a good ability to monitor ambient trace HCHO in unattended continuous operation for long periods of time.
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Zhang, Cuihong, Mirna Shamas, Mohamed Assali, Xiaofeng Tang, Weijun Zhang, Laure Pillier, Coralie Schoemaecker e Christa Fittschen. "Absolute Absorption Cross-Section of the Ã←X˜ Electronic Transition of the Ethyl Peroxy Radical and Rate Constant of Its Cross Reaction with HO2". Photonics 8, n.º 8 (24 de julho de 2021): 296. http://dx.doi.org/10.3390/photonics8080296.

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The absolute absorption cross-section of the ethyl peroxy radical C2H5O2 in the Ã←X˜ electronic transition with the peak wavelength at 7596 cm−1 has been determined by the method of dual wavelengths time resolved continuous wave cavity ring down spectroscopy. C2H5O2 radicals were generated from pulsed 351 nm photolysis of C2H6/Cl2 mixture in presence of 100 Torr O2 at T = 295 K. C2H5O2 radicals were detected on one of the CRDS paths. Two methods have been applied for the determination of the C2H5O2 absorption cross-section: (i) based on Cl-atoms being converted alternatively to either C2H5O2 by adding C2H6 or to hydro peroxy radicals, HO2, by adding CH3OH to the mixture, whereby HO2 was reliably quantified on the second CRDS path in the 2ν1 vibrational overtone at 6638.2 cm−1 (ii) based on the reaction of C2H5O2 with HO2, measured under either excess HO2 or under excess C2H5O2 concentration. Both methods lead to the same peak absorption cross-section for C2H5O2 at 7596 cm−1 of σ = (1.0 ± 0.2) × 10−20 cm2. The rate constant for the cross reaction between of C2H5O2 and HO2 has been measured to be (6.2 ± 1.5) × 10−12 cm3 molecule−1 s−1.
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Fiadzomor, Phyllis A. Y., Derek M. Baker, Anthony M. Keen, Robert B. Grant e Andrew J. Orr-Ewing. "Pressure Broadening of H2O Absorption Lines in the 1.3 μm Region Measured by Continuous Wave-Cavity Ring-Down Spectroscopy: Application in the Trace Detection of Water Vapor in N2, SiH4, CF4, and PH3". Applied Spectroscopy 62, n.º 12 (dezembro de 2008): 1354–62. http://dx.doi.org/10.1366/000370208786822142.

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Jain, Chaithanya, Pranay Morajkar, Coralie Schoemaecker, Bela Viskolcz e Christa Fittschen. "Measurement of Absolute Absorption Cross Sections for Nitrous Acid (HONO) in the Near-Infrared Region by the Continuous Wave Cavity Ring-Down Spectroscopy (cw-CRDS) Technique Coupled to Laser Photolysis". Journal of Physical Chemistry A 115, n.º 39 (6 de outubro de 2011): 10720–28. http://dx.doi.org/10.1021/jp203001y.

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