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Добірка наукової літератури з теми "SATURATED-ABSORPTION CAVITY RING-DOWN SPECTROSCOPY"

Автор: Grafiati
Опубліковано: 10 березня 2023

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Статті в журналах з теми "SATURATED-ABSORPTION CAVITY RING-DOWN SPECTROSCOPY"

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Lehmann, Kevin K. "Theoretical detection limit of saturated absorption cavity ring-down spectroscopy (SCAR) and two-photon absorption cavity ring-down spectroscopy." Applied Physics B 116, no. 1 (October 10, 2013): 147–55. http://dx.doi.org/10.1007/s00340-013-5663-3.

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Engeln, Richard, Gert von Helden, Giel Berden, and Gerard Meijer. "Phase shift cavity ring down absorption spectroscopy." Chemical Physics Letters 262, no. 1-2 (November 1996): 105–9. http://dx.doi.org/10.1016/0009-2614(96)01048-2.

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Ma, Tong-mei, Ling Li, Joanne Wing Har Leung, and Allan Shi Chung Cheung. "Cavity Ring Down Laser Absorption Spectroscopy of NiI." Chinese Journal of Chemical Physics 22, no. 6 (December 2009): 611–14. http://dx.doi.org/10.1088/1674-0068/22/06/611-614.

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Ma, Tongmei, J. W. H. Leung, and A. S. C. Cheung. "Cavity ring-down laser absorption spectroscopy of IrC." Chemical Physics Letters 385, no. 3-4 (February 2004): 259–62. http://dx.doi.org/10.1016/j.cplett.2003.12.096.

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Zalicki, Piotr, and Richard N. Zare. "Cavity ring‐down spectroscopy for quantitative absorption measurements." Journal of Chemical Physics 102, no. 7 (February 15, 1995): 2708–17. http://dx.doi.org/10.1063/1.468647.

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Fasci, E., S. Gravina, G. Porzio, A. Castrillo та L. Gianfrani. "Lamb-dip cavity ring-down spectroscopy of acetylene at 1.4 μm". New Journal of Physics 23, № 12 (1 грудня 2021): 123023. http://dx.doi.org/10.1088/1367-2630/ac3b6e.

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Abstract Doppler-free saturated-absorption Lamb dips are observed for weak vibration-rotation transitions of C2H2 between 7167 and 7217 cm−1, using a frequency-comb assisted cavity ring-down spectrometer based on the use of a pair of phase-locked diode lasers. We measured the absolute center frequency of sixteen lines belonging to the 2 ν 3 + ν 5 1 band, targeting ortho and para states of the molecule. Line pairs of the P and Q branches were selected so as to form a ‘V’-scheme, sharing the lower energy level. Such a choice made it possible to determine the rotational energy separations of the excited vibrational state for J-values from 11 to 20. Line-center frequencies are determined with an overall uncertainty between 3 and 13 kHz. This is over three orders of magnitude more accurate than previous experimental studies in the spectral region around the wavelength of 1.4 μm. The retrieved energy separations provide a stringent test of the so-called MARVEL method recently applied to acetylene.
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Loock, Hans-Peter, Jack A. Barnes, Gianluca Gagliardi, Runkai Li, Richard D. Oleschuk, and Helen Wächter. "Absorption detection using optical waveguide cavities." Canadian Journal of Chemistry 88, no. 5 (May 2010): 401–10. http://dx.doi.org/10.1139/v10-006.

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Cavity ring-down spectroscopy is a spectroscopic method that uses a high quality optical cavity to amplify the optical loss due to the light absorption by a sample. In this presentation we highlight two applications of phase-shift cavity ring-down spectroscopy that are suited for absorption measurements in the condensed phase and make use of waveguide cavities. In the first application, a fiber loop is used as an optical cavity and the sample is introduced in a gap in the loop to allow absorption measurements of nanoliters of solution at the micromolar level. A second application involves silica microspheres as high finesse cavities. Information on the refractive index and absorption of a thin film of ethylene diamine on the surface of the microresonator is obtained simultaneously by the measurements of the wavelength shift of the cavity mode spectrum and the change in optical decay time, respectively.
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Aiello, Roberto, Maria Giulia Delli Santi, Valentina Di Sarno, Maurizio De Rosa, Iolanda Ricciardi, Paolo De Natale, Luigi Santamaria, Giovanni Giusfredi, and Pasquale Maddaloni. "Lamb-dip ro-vibrational spectroscopy of buffer-gas-cooled acetylene." Journal of Physics: Conference Series 2439, no. 1 (January 1, 2023): 012002. http://dx.doi.org/10.1088/1742-6596/2439/1/012002.

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Abstract We present an original opto-mechanical scheme which, effectively coupling a Lamb-dip saturated-absorption cavity ring-down spectrometer to a buffer-gas-cooling (BGC) source, allows us to determine the absolute frequency of the acetylene (ν 1 + ν 3) R(1)e transition at 6561.0941 cm−1 with an overall (statistical + systematic) uncertainty as low as 1.2 kHz. By improving the previous record with buffer-gas-cooled molecules by one order of magnitude, our achievement opens the door to new kind of ultra-precise low-temperature spectroscopic studies.
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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 та 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, № 4 (2022): 0411001. http://dx.doi.org/10.3788/cjl202249.0411001.

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Tan, Zhongqi, and Xingwu Long. "A Developed Optical-Feedback Cavity Ring-Down Spectrometer and its Application." Applied Spectroscopy 66, no. 5 (May 2012): 492–95. http://dx.doi.org/10.1366/11-06291.

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A developed spectrometer based on optical-feedback cavity ring-down spectroscopy (OF-CRDS) has been demonstrated with a distributed feedback laser diode and a V-shaped glass ceramic cavity. The laser is coupled to the V-shaped cavity, which creates an absorption path length greater than 2.8 km, and resonance between the laser frequency and the cavity modes is realized by modulating the cavity length instead of tuning the laser wavelength to obtain a higher resolution. A noise-equivalent absorption coefficient of ∼2.6 × 10−8 cm−1Hz−1/2 (1σ) is determined with spectral resolution of ∼0.003 cm−1 and spectral range of 1.2 cm−1. As an application example, the absorption spectrum measurement of water vapor in the spectral range of 6590.3∼6591.5 cm−1 is demonstrated with this spectrometer.
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Більше джерел

Дисертації з теми "SATURATED-ABSORPTION CAVITY RING-DOWN SPECTROSCOPY"

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Burkart, Johannes. "Optical feedback frequency-stabilized cavity ring-down spectroscopy - Highly coherent near-infrared laser sources and metrological applications in molecular absorption spectroscopy." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAY045/document.

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La spectroscopie d'absorption moléculaire est un outil incontournable non seulement pour la physique fondamentale et la métrolgie mais aussi pour des domaines aussi divers que les sciences environnementales, la planétologie ou l'astrophysique. Ces dernières années, des techniques spectroscopiques qui exploitent l'amplification résonnante d'interaction entre lumière laser et molécules dans une cavité optique ont fourni des détectivités exceptionnelles sur l'axe d'absorption, tandis que l'axe de fréquence des spectromètres n'atteignait généralement pas le même niveau de précision.Dans cette thèse, nous avons répondu à ce défi en développant la spectroscopie en cavité par temps de déclin stabilisée en fréquence par rétroaction optique (OFFS-CRDS en anglais). Cette nouvelle technique présente une combinaison unique de stabilité et résolution fréquentielles sub-kHz, d'un niveau d'intensité lumineuse intra-cavité de l'ordre du kW/cm^2, d'une detectivite de 2 x 10^(−13) cm^(−1)Hz^(-1/2) limitée par le bruit de photons, et d'une limite de détection de 8.4 x 10^(−14) cm^(−1) sur une plage spectrale étroite. Ces performances inédites sont dues à l'asservissement de la cavité spectroscopique à un laser balayé en fréquence par modulation à bande latérale unique et stabilisé par rétroaction optique avec une cavité en V de réference ultrastable. Pour transférer la cohérence de ce laser sub-kHz à des lasers plus bruiteux dans d'autres gammes spectrales à travers un peigne de fréquence optique, nous avons exploré une nouvelle méthode de clonage de phase par une correction anticipative à large bande passante et démontré une erreur résiduelle de phase de 113 mrad. En appliquant l'OFFS-CRDS à la spectroscopie du CO2 à 1.6 μm, nous avons obtenu un spectre large bande avec une dynamique de 8 x 10^5, et nous avons déterminé douze fréquences de transition absolues avec une exactitude de l'ordre du kHz en mesurant des Lamb dips sub-Doppler en absorption saturée avec un dispositif équipé d'un peigne de fréquence. Par ailleurs, nous avons procédé à une analyse détaillée des sources d'erreurs systematiques en CRDS et nous avons déduit une formule analytique pour le déclin de cavité non-exponentiel dans un régime faiblement saturé qui est susceptible de contribuer à de futures mesures de moments de transition dipolaire indépendantes de la concentration. Nos résultats ouvrent des perspectives prometteuses pour des applications métrologiques de l'OFFS-CRDS, comme par exemple l'étude de profils de raie poussés, la mesures de rapports isotopiques et la spectroscopie d'absorption saturée extensive dans le proche infrarouge
High-precision molecular absorption spectroscopy is a powerful tool for fundamental physics and metrology, as well as for a broad range of applications in fields such as environmental sciences, planetology and astrophysics. In recent years, spectroscopic techniques based on the enhanced interaction of laser light with molecular samples in high-finesse optical cavities have provided outstanding detection sensitivities on the absorption axis, while the spectrometer frequency axis rarely met as high precision standards.In this thesis, we addressed this challenge by the development of Optical Feedback Frequency-Stabilized Cavity Ring-Down Spectroscopy (OFFS-CRDS). This novel technique features a unique combination of sub-kHz frequency resolution and stability, kW/cm^2-level intracavity light intensity, a shot-noise limited absorption detectivity down to 2 x 10^(−13) cm^(−1)Hz^(-1/2), as well as a detection limit of 8.4 x 10^(−14) cm^(−1) on a narrow spectral interval. This unprecedented performance is based on the tight Pound-Drever-Hall lock of the ring-down cavity to a single-sideband-tuned distributed-feedback diode laser which is optical-feedback-stabilized to a highly stable V-shaped reference cavity. To transfer the coherence of this sub-kHz laser source to noisier lasers in other spectral regions through an optical frequency comb, we have explored a novel high-bandwidth feed-forward phase cloning scheme and demonstrated a residual phase error as low as 113 mrad. Applying OFFS-CRDS to the spectroscopy of CO_2 near 1.6 μm, we obtained a broadband spectrum with a dynamic range of 8 x 10^5 and retrieved twelve absolute transition frequencies with kHz-accuracy by measuring sub-Doppler saturated absorption Lamb dips with a comb-assisted setup. Furthermore, we have performed a comprehensive analysis of systematic error sources in CRDS and derived an analytic formula for the non-exponential ring-down signal in a weakly saturated regime, which may contribute towards future concentration-independent transition dipole moment measurements. Our results open up promising perspectives for metrological applications of OFFS-CRDS, such as advanced absorption lineshape studies, isotopic ratio measurements and extensive saturated absorption spectroscopy in the near infrared
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NAKAEMA, WALTER M. "Espectroscopia de cavidade ressonante tipo ring-down supercontinuum resolvida no tempo para deteccao de multicomponentes gasosos." reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9590.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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CAVALCANTI, FABIO. "Desenvolvimento de um laser pulsado com emissão em 1053 nm para utilização na técnica de "Cavity Ring-Down Spectroscopy." reponame:Repositório Institucional do IPEN, 2014. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11790.

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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Mercier, Xavier. "Mesure de concentrations absolues d'espèces réactives minoritaires dans les flammes par la technique d'absorption Cavity Ring Down Spectroscopy (CRDS)." Lille 1, 2000. http://www.theses.fr/2000LIL10154.

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Анотація:
Les processus de combustion, qui representent aujourd'hui notre principal source d'energie, suscitent encore de nombreuses interrogations. Cela tient essentiellement a la complexite des mecanismes chimiques mis en jeu ainsi qu'a la difficulte inherente a l'etude d'un milieu qui est le sein de plusieurs milliers de reactions simultanees. Or, meme si des modeles performants permettent la simulation de systemes chimiques complexes, ils ne peuvent predire n'importe quels processus de combustion et l'approche experimentale de ceux-ci reste essentielle pour l'amelioration des modeles existant. En particulier, la mesure quantitative d'especes minoritaires dans les flammes constitue une etape fondamentale dans la validation des mecanismes chimiques a haute temperature. C'est dans cette optique que nous avons developpe une nouvelle technique pour l'etude de flamme, le cavity ring-down spectroscopy (crds). Cette technique, qui s'apparente a une methode d'absorption de tres haute sensibilite et dont le principe est base sur la mesure du temps de vie d'une impulsion laser injectee dans une cavite optique dans laquelle se trouve un echantillon absorbant, est apparue a la fin des annees 80 (o'keefe et deacon 1988) dans le cadre d'une etude spectroscopique
Dans ce memoire, nous montrons l'interet et les potentialites du crds pour l'etude de flammes homogenes. Pour ce faire, nous explicitons dans le detail le principe du crds et les precautions a prendre pour la mesure de concentrations absolues. Par ailleurs, une comparaison des profils de concentration absolue obtenus par crds (de cn et ch notamment) dans une flamme de ch 4/o 2 dopee en no, avec ceux issus de la modelisation au moyen du logiciel premix est egalement presentee. Le tres bon accord de cette comparaison montre que le crds, de part sa haute sensibilite et son caractere quantitatif direct, se revele etre une methode des plus efficaces pour la mesure de concentrations absolues d'especes dans des flammes homogenes
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Vasilchenko, Semen. "Development of an ultrasensitive cavity ring down spectrometer in the 2.10-2.35 µm region : application to water vapor and carbon dioxide." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY037/document.

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Un spectromètre utilisant la technique CRDS a été développé entre 2.00 et 2.35 µm afin de réaliser la spectroscopie en absorption de molécules d’intérêt atmosphérique et planétologique avec une très grande sensibilité et à haute résolution spectrale. Cette région du spectre correspond à une fenêtre de transparence de la vapeur d’eau et du dioxyde de carbone. Ces fenêtres sont des zones de très faible absorption utilisées pour le sondage des atmosphères terrestre et vénusienne dans lesquelles la vapeur d’eau et le dioxyde de carbone représentent respectivement les absorbants gazeux principaux dans l’infrarouge.La technique CRDS consiste à injecter des photons dans une cavité optique de haute finesse et à mesurer la durée de vie des photons dans cette cavité. Celle-ci est mesurée en interrompant l’injection des photons dans la cavité optique lors du passage en résonance du laser avec l’un des modes longitudinaux. Cette durée de vie dépend de la réflectivité des miroirs et des pertes intra-cavité comme celles induites par un gaz qui absorbe. Mesurer ces pertes en fonction de la longueur d’onde permet d’obtenir le spectre d’absorption du gaz en question. L’extrême réflectivité des miroirs permet d’atteindre dans une cavité d’un peu plus d’1 m de longueur une sensibilité équivalente à celle qui serait obtenue classiquement avec une cellule d’absorption longue de plusieurs milliers de kilomètres.Trois diodes laser DFB émettant autour de 2.35, 2.26 et 2.21 µm ont été utilisées avec ce spectromètre. Grâce à une rétro-action optique provenant d’une cavité externe, certaines de ces diodes ont pu être affinées, ce qui a permis de mieux injecter la cavité haute finesse et ainsi de réduire le niveau de bruit du spectromètre. Parallèlement grâce à une collaboration avec l’Institut d’Electronique (IES, UMR 5214) à Montpellier et la société Innoptics nous avons pu tester le prototype d’un VECSEL (Vertical-External-Cavity Surface-Emitting-Laser). Ce laser a permis de couvrir une gamme spectrale de 80 cm-1, entre 4300 et 4380 cm-1, équivalente à quatre diodes laser DFB. La sensibilité obtenue en routine avec ce spectromètre, correspondant au coefficient minimum détectable, est typiquement de 1×10-10 cm-1. Le chapitre introductif (Chapitre 1) fait le point sur les différentes techniques permettant d’acquérir des spectres en absorption dans la gamme spectrale étudiée et sur les sensibilités atteintes. A notre connaissance l’instrument développé ici est le plus sensible dans cette région du spectre. Le fonctionnement de ce spectromètre CRDS est détaillé dans le chapitre 2.Pour démontrer les performances obtenues avec notre instrument celui-ci a été utilisé pour enregistrer des transitions quadrupolaires donc de très faible intensité. Ainsi la transition S(3) de la bande 1–0 de HD a été enregistrée pour la première fois et son intensité mesurée (S=2.5×10-27 cm/molecule). La sensibilité obtenue en routine a encore pu être améliorée en réalisant une moyenne d’une centaine de spectres sur une gamme spectrale réduite pour atteindre 1×10-11 cm-1. Grâce à cela nous avons pu mesurer la position et l’intensité de la raie quadrupolaire électrique O(14) de la bande 2–0 de N2 qui est très fortement interdite avec une intensité de 1.5×10-30 cm/molecule. Ces mesures font l’objet du chapitre 3 de cette thèse.Les deux derniers chapitres sont dédiés à la caractérisation de l’absorption du CO2, au centre de la fenêtre de transparence, et à celle de la vapeur d’eau. Dans les deux cas, les transitions permises du monomère et la contribution du continuum ont été étudiées. Ce dernier correspond à une absorption variant lentement avec la longueur d’onde. Les sections efficaces du « self-continuum » de la vapeur d’eau ont notamment été mesurées en plusieurs points de la fenêtre de transparence avec une incertitude beaucoup plus faible que les mesures existantes. Elles représentent un jeu de données décisif pour tester les modèles décrivant ce continuum
A cavity ring down spectrometer has been developed in the 2.00-2.35 µm spectral range to achieve highly sensitive absorption spectroscopy of molecules of atmospheric and planetologic interest and at high spectral resolution. This spectral region corresponds to a transparency window for water vapor and carbon dioxide. Atmospheric windows, where absorption is weak, are used to sound the Earth’s and Venus’ atmospheres where water vapor and carbon dioxide represent the main gaseous absorbers in the infrared, respectively.The CRDS technique consists of injecting photons inside a high finesse optical cavity and measuring the photon’s life time of this cavity. This life-time depends on the mirror reflectivity and on the intra-cavity losses due to the absorbing gas in the cavity. Measuring these losses versus the wavelength allow obtaining the absorption spectrum of the gas. The extreme reflectivity of the mirrors allows reaching, for a 1-meter long cavity, a sensitivity equivalent to the one obtained classically with absorption cells of several thousands of kilometers.Three DFB laser diodes emitting around 2.35, 2.26, 2.21 µm were used with this spectrometer giving access to the 4249-4257, 4422-4442 and 4516-4534 cm-1 interval, respectively. Thanks to optical feedback from an external cavity, two of these diodes were spectrally narrowed leading to a better injection of the high finesse cavity thus reducing the noise level of the spectrometer. In parallel, we tested a VECSEL (Vertical-external-Cavity, Surface Emitting laser) through a collaboration with the Institu d’Electronique (IES, UMR 5214) in Montpellier and the Innoptics firm. This laser source is able to cover a 80 cm-1 spectral range centered at 4340 cm-1, equivalent to four DFB laser diodes. In routine the achieved sensitivity with this spectrometer, corresponding to the minimum detectable coefficient is typically of 1×10-10 cm-1. The introductive chapter (Chapter 1) makes the point on the different techniques allowing absorption spectra recordings in the studied spectral region and on their sensitivity. The experimental set-up, the characteristics and performances by the CRD spectrometer developed in this work are detailed in Chapter 2. To our knowledge this instrument is the most sensitive in the considered spectral region.In Chapter 3, detection of quadrupolar electric transitions of HD and N2 illustrate the level of sensitivity reached: (i) the S(3) transition in the 1-0 band of HD has been recorded for the first time and its intensity measured (S=2.5×10-27 cm/molecule), (ii) the position and intensity of the highly forbidden O(14) quadrupolar electric transition of the 2-0 band of N2 have also been newly determined.The two last chapters are devoted to the characterization of the CO2 absorption, in the centre of the transparency window, and of the water vapor absorption. In both cases, we not only studied the allowed transitions of the monomer, but also the continuum absorption. This latter correspond to a weak background absorption varying slowly with the wave length. The self-continuum cross-sections of the water vapor continuum were measured in many spectral points through the transparency window with a much better accuracy compared to existing measurements. These CRDS data constitute a valuable data set to validate the reference model (MT_CKD) for the continuum which is implemented in most of the atmospheric radiative transfer codes
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Kiwanuka, Ssegawa-Ssekintu. "Supercontinuum radiation for ultra-high sensitivity liquid-phase sensing." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/245137.

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The real-time detection of trace species is key to a wide range of applications such as on-line chemical process analysis, medical diagnostics, identification of environmentally toxic species and atmospheric pollutant sensing. There is a growing demand for suitable techniques that are not only sensitive, but also simple to operate, fast and versatile. Most currently available techniques, such as spectrophotometry, are neither sensitive enough nor fast enough for kinetic studies, whilst other techniques are too complex to be operated by the non-specialist. This thesis presents two techniques that have been developed for and applied to liquid-phase analysis, with supercontinuum (SC) radiation used for liquid-phase absorption for the first time. Firstly, supercontinuum cavity enhanced absorption spectroscopy (SC-CEAS) was used for the kinetic measurement of chemical species in the liquid phase using a linear optical cavity. This technique is simple to implement, robust and achieves a sensitivity of 9.1 × 10−7 cm−1 Hz−1/2 at a wavelength of 550nm for dye species dissolved in water. SC-CEAS is not calibration-free and for this purpose a second technique, a time-resolved variant called broadband cavity ring-down spectroscopy (BB-CRDS), was successfully developed. Use of a novel single-photon avalanche diode (SPAD) array enabled the simultaneous detection of ring-down events at multiple spectral positions for BB-CRDS measurements. The performance of both techniques is demonstrated through a number of applications that included the monitoring of an oscillating (Belousov-Zhabotinsky) reaction, detection of commercially important photoluminescent metal complexes (europium(III)) at trace level concentration, and the analysis of biomedical species (whole and lysed blood) and proteins (amyloids). Absorption spectra covering the entire visible wavelength range can be acquired in fractions of a second using sample volumes measuring only 1.0mL. Most alternative devices capable of achieving similar sensitivity have, up until now, been restricted to single wavelength measurements. This has limited speed and number of species that can be measured at once. The work presented here exemplifies the potential of these techniques as analytical tools for research scientists, healthcare practitioners and process engineers alike.
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Chase, Tanya. "Greenhouse gas detection using cavity enhanced absorption spectroscopy and cavity ring-down spectroscopy : trace detection of CH₄, CO₂ and N₂0 in ambient air, standard gas samples and in the headspace of soils." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.686246.

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The work presented in this thesis is predicated upon the environmental applications of cavity enhanced absorption spectroscopy and cavity ring-down spectroscopy. These are related techniques that are highly useful for sensitive gas detection which is important in terms of anthropologically induced climate change and the detection of the changing levels of greenhouse gases. Sensitive gas detection techniques, specifically isotope ratio analysis, are useful for determining the sources and sinks of greenhouse gases and for distinguishing whether sources and sinks are natural or anthropogenic. The research involved gas detection using commercial near-infrared cavity ring-down spectrometers, made by Picarro, and highlights how well and to what environmental uses these instruments can be applied. Various gas mixtures containing methane and carbon dioxide were analysed by the CRDS instruments to try to determine the detection limits, and the effect that varying the concentrations would have upon the precision and accuracy of the measurements made. Headspace soil measurements of CH4 and C02 were also demonstrated to be made easily without processing of the gas stream.The main work described in this Thesis involved the implementation of a home-built optical feedback cavity enhanced absorption spectroscopy /cavity ring-down spectroscopy experiment which made use of a V-shaped optical cavity and a 7.8 υm quantum cascade laser for the detection of greenhouse gases in the mid-infrared. This comprised of the detection and analyses of spectral lines of methane and nitrous oxide isotopologues. Measurement in the mid-IR took advantage of the excitation of the stronger fundamental vibrational transitions occurring in this region and increased optical path lengths from the optical cavity and signal amplification from optical feedback are features that gave high signal to noise measurements. These techniques have the potential to be further developed for field usage by overcoming many of the limitations of alternative greenhouse gas detection techniques, such as instrument sensitivity and portability.
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8

Lu, Jessica Weidgin. "Dynamics of Atmospherically Important Triatomics in Collisions with Model Organic Surfaces." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77045.

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Detailed investigations of molecular collisions at the gas-surface interface provide insight into the dynamics and mechanisms of important interfacial reactions. A thorough understanding of the fundamental interactions between a gas and surface is crucial to the study of heterogeneous chemistry of atmospheric organic aerosols. In addition to changing the chemical and physical properties of the particle, reactions with oxidizing gases may alter aerosol optical properties, with implications for the regional radiation budget and climate. Molecular beams of CO₂, NO₂ and O₃ were scattered from long-chain methyl (CH₃-), hydroxyl (OH-), vinyl (H₂C=CH-) and perfluorinated (CF₃(CF₂)₈-, or F-) ω-functionalized alkanethiol self-assembled monolayers (SAMs) on gold, to explore the reaction dynamics of atmospherically important triatomics on proxies for organic aerosols. Energy exchange and thermal accommodation during the gas-surface collision, the first step of most interfacial reactions, was probed by time-of-flight techniques. The final energy distribution of the scattered molecules was measured under specular scattering conditions (θi = θf = 30°). Overall, extent of energy transfer and accommodation was found to depend on the terminal functional group of the SAM, incident energy of the triatomics, and gas-surface intermolecular forces. Reaction dynamics studies of O3 scattering from H2C=CH-SAMs revealed that oxidation of the double bond depend significantly on O₃ translational energy. Our results indicate that the room-temperature reaction follows the Langmuir-Hinshelwood mechanism, requiring accommodation prior to reaction. The measurements also show that the dynamics transition to a direct reaction for higher translational energies. Possible environmental impacts of heterogeneous reactions were probed by evaluating the change in the optical properties of laboratory-generated benzo[a]pyrene (BaP)-coated aerosols, after exposure to NO₃ and NO₂, at 532 nm and 355 nm by three aerosol analysis techniques: cavity ring-down aerosol spectroscopy (CRD-AS) at 355 nm and 532 nm, photoacoustic spectroscopy (PAS) at 532 nm, and an aerosol mass spectrometer (AMS). Heterogeneous reactions may lead to the nitration of organic-coated aerosols, which may account for atmospheric absorbance over urban areas. Developing a detailed understanding of heterogeneous reactions on atmospheric organic aerosols will help researchers to predict the fate, lifetime, and environmental impact of atmospherically important triatomics and the particles with which they collide.
Ph. D.
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9

Li, Jing. "Applications of optical-cavity-based spectroscopic techniques in the condensed phase." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:d6a0c476-e67f-4390-a63a-e3cb9e60bf2c.

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Cavity ring-down spectroscopy (CRDS) and cavity enhanced absorption spectroscopy (CEAS) are two well-established absorption spectroscopic techniques originally developed for gas-phase samples. Condensed-phase applications of these techniques still remain rare, complicated as they are by additional background losses induced by condensed-phase samples as well as the intracavity components in which the sample is constrained. This thesis is concerned with the development and application of optical-cavity-based techniques in the condensed phase. Polarization-dependent evanescent wave CRDS (EW-CRDS) has been used to study the molecular orientation at the solid/air and solid/liquid interfaces. An increase in average orientation angle with respect to the surface normal has been observed for both methylene blue and coumarin molecules as a function of coverage at the fused silica/air interface. An orientation-angle-dependent photobleaching of pyridin molecules at the fused silica/methanol interface have also been observed. EW-CRDS has also been used to monitor slow in situ photobleaching of thin dye films deposited on the prism surface. The photobleaching dynamics is interpreted as a combination of first- and second-order processes. A significant fraction of this thesis has been devoted to studying magnetic field effects (MFEs) on the kinetics of the radical pair (RP) reactions in solution, in an effort to understand the ability of animals to sense the geomagnetic field. Two novel optical-cavity-based techniques – broadband CEAS (BBCEAS) and CRDS have been developed for this purpose. BBCEAS uses a supercontinuum (SC) source as the cavity light source and a CCD camera as photodetector, enabling simultaneous acquisition of absorption spectrum across the whole visible region (400 – 800 nm). In CRDS, a tunable optical parametric oscillator has been used as the cavity light source. Combined with the switching of external magnetic field (SEMF) method, this technique allows the decay kinetics of the geminate RPs to be monitored, with nanosecond resolution. Both BBCEAS and CRDS provide sensitivity superior to single-pass transient absorption (TA), a technique traditionally used in the MFE studies. A series of photochemical systems have been studied by BBCEAS and CRDS, respectively, among which, the MFEs of drosophila melanogaster cryptochrome has been observed. Importantly, this is the first time an MFE has been observed in an animal cryptochrome, and provides key supporting evidence for the cryptochrome hypothesis of magnetoreception in animals. Besides the optical-cavity-based techniques, a novel fluorescence detection method of MFEs has also been demonstrated. This technique proved ultrahigh sensitivity when applicable.
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10

Davies, Nicholas William. "The climate impacts of atmospheric aerosols using in-situ measurements, satellite retrievals and global climate model simulations." Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/34544.

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Aerosols contribute the largest uncertainty to estimates of radiative forcing of the Earth’s atmosphere, which are thought to exert a net negative radiative forcing, offsetting a potentially significant but poorly constrained fraction of the positive radiative forcing associated with greenhouse gases. Aerosols perturb the Earth’s radiative balance directly by absorbing and scattering radiation and indirectly by acting as cloud condensation nuclei, altering cloud albedo and potentially cloud lifetime. One of the major factors governing the uncertainty in estimates of aerosol direct radiative forcing is the poorly constrained aerosol single scattering albedo, which is the ratio of the aerosol scattering to extinction. In this thesis, I describe a new instrument for the measurement of aerosol optical properties using photoacoustic and cavity ring-down spectroscopy. Characterisation is performed by assessing the instrument minimum sensitivity and accuracy as well as verifying the accuracy of its calibration procedure. The instrument and calibration accuracies are assessed by comparing modelled to measured optical properties of well-characterised laboratory-generated aerosol. I then examine biases in traditional, filter-based absorption measurements by comparing to photoacoustic spectrometer absorption measurements for a range of aerosol sources at multiple wavelengths. Filter-based measurements consistently overestimate absorption although the bias magnitude is strongly source-dependent. Biases are consistently lowest when an advanced correction scheme is applied, irrespective of wavelength or aerosol source. Lastly, I assess the sensitivity of the direct radiative effect of biomass burning aerosols to aerosol and cloud optical properties over the Southeast Atlantic Ocean using a combination of offline radiative transfer modelling, satellite observations and global climate model simulations. Although the direct radiative effect depends on aerosol and cloud optical properties in a non-linear way, it appears to be only weakly dependent on sub-grid variability.
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Частини книг з теми "SATURATED-ABSORPTION CAVITY RING-DOWN SPECTROSCOPY"

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Sneep, M., and W. Ubachs. "Cavity Ring-Down Spectroscopy of O2–O2 Collisional Induced Absorption." In Weakly Interacting Molecular Pairs: Unconventional Absorbers of Radiation in the Atmosphere, 203–11. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-010-0025-3_17.

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2

Cancio, P., I. Galli, S. Bartalini, G. Giusfredi, D. Mazzotti, and P. De Natale. "Saturated-Absorption Cavity Ring-Down (SCAR) for High-Sensitivity and High-Resolution Molecular Spectroscopy in the Mid IR." In Springer Series in Optical Sciences, 143–62. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-40003-2_4.

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3

Hamilton, D. J., M. G. D. Nix, S. G. Baran, G. Hancock, and A. J. Orr-Ewing. "Optical feedback cavity-enhanced absorption spectroscopy (OF-CEAS) in a ring cavity." In TDLS 2009, 1–10. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-02292-0_1.

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Тези доповідей конференцій з теми "SATURATED-ABSORPTION CAVITY RING-DOWN SPECTROSCOPY"

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Pastor, P. Cancio, I. Galli, G. Giusfredi, D. Mazzotti, and P. De Natale. "Saturated-Absorption Cavity Ring-Down Spectroscopy." In Frontiers in Optics. Washington, D.C.: OSA, 2010. http://dx.doi.org/10.1364/fio.2010.ftul4.

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2

Mazzotti, Davide, Saverio Bartalini, Pablo Cancio, Iacopo Galli, Giovanni Giusfredi, and Paolo De Natale. "Saturated-Absorption Cavity Ring-Down Spectroscopy for Radiocarbon Measurements." In Optics and Photonics for Energy and the Environment. Washington, D.C.: OSA, 2017. http://dx.doi.org/10.1364/ee.2017.em2b.1.

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3

Andrews, Nicholas L. P., Jessica Litman, Klaus Bescherer, Jack A. Barnes, and Hans-Peter Loock. "Fiber-Loop Cavity Ring-Down Absorption Spectroscopy." In Applied Industrial Optics: Spectroscopy, Imaging and Metrology. Washington, D.C.: OSA, 2014. http://dx.doi.org/10.1364/aio.2014.am4a.4.

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4

Engeln, Richard, and Gerard Meijer. "A Fourier Transform Cavity Ring Down Spectrometer." In Fourier Transform Spectroscopy. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/fts.1997.ftua.1.

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5

Memovich, Madeline, and Kevin Lehmann. "SATURATED ABSORPTION SPECTROSCOPY AND TWO-PHOTON CAVITY RING-DOWN ABSORPTION SPECTROSCOPY FOR TRACE GAS DETECTION OF NITROUS OXIDE." In 2022 International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2022. http://dx.doi.org/10.15278/isms.2022.ff09.

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6

Cone, Michael, Edward S. Fry, and Joseph A. Musser. "Ring-Down Absorption Spectroscopy in an Integrating Cavity." In Frontiers in Optics. Washington, D.C.: OSA, 2009. http://dx.doi.org/10.1364/fio.2009.fwr5.

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7

Kassi, Samir, Alain Campargue, Amaelle Landais, Mathieu Casado, Mathieu Daëron, and Tim Stoltmann. "OPTICAL FEEDBACK STABILIZED LASER CAVITY RING DOWN SPECTROSCOPY: FROM SATURATED SPECTROSCOPY TO ISOTOPIC RATIO." In 73rd International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2018. http://dx.doi.org/10.15278/isms.2018.tg06.

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Manzanares, Carlos, and Parashu Nyaupane. "CAVITY RING DOWN ABSORPTION OF OXYGEN IN AIR AS A TEMPERATURE SENSOR." In 71st International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2016. http://dx.doi.org/10.15278/isms.2016.wk08.

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9

Gianfrani, L., R. W. Fox, and L. Hollberg. "High sensitivity detection of molecular oxygen using cavity-enhanced frequency modulation spectroscopy." In Laser Applications to Chemical and Environmental Analysis. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/lacea.1998.lmc.23.

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In recent years, high finesse optical cavities have been used for high sensitivity spectroscopy by exploiting the very long absorption path lengths, 10 to 100 times greater than in traditional multipass cells. Cavity Ring Down Spectroscopy applications have been widely performed with both pulsed [1] and CW laser sources [2]. Direct absorption spectroscopy with an optical cavity has also been demonstrated by recording the peak transmitted power around an absorption line [3]. Another relevant application is represented by saturated absorption spectroscopy of overtone molecular transitions. In this case, high finesse and high build-up provide enough intracavity power for saturation of the absorbing gas [4]. More recently, the “NICE-OHMS” method, using frequency modulation techniques, has been used to detect extremely weak saturated signals in a high finesse cavity [5]. In this novel method, the laser beam is frequency modulated at exactly the cavity free-spectral-range (FSR) frequency. Using heterodyne detection of the transmitted power, the phase shift of the central carrier produced by optical dispersion gives rise to the signal. The NICE-OHMS method has reported detection sensitivities for absorption of 10−12 cm−1 [5]. In this work, we demonstrate how the cavity enhanced frequency modulation technique can be used to perform high sensitivity measurements of small absorption signals, corresponding to weak absorption lines in molecular oxygen.
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Hodges, Joseph, Kevin Lehmann, D. Bailey, Adam Fleisher, and Gang Zhao. "CAVITY RING-DOWN SPECTROSCOPY MEASUREMENTS OF RESONANCE-ENHANCED TWO-PHOTON ABSORPTION BY N2O." In 2020 International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2020. http://dx.doi.org/10.15278/isms.2020.wd05.

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