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Molecular dynamics of combustion reactions in supercritical carbon dioxide. Part 4: boxed MD study of formyl radical dissociation and recombination. J Mol Model 2019; 25:35. [PMID: 30631947 DOI: 10.1007/s00894-018-3912-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 12/18/2018] [Indexed: 10/27/2022]
Abstract
Fossil fuel oxy-combustion is an emergent technology where habitual nitrogen diluent is replaced by high pressure (supercritical) carbon dioxide. The supercritical state of CO2 increases the efficiency of the energy conversion and the absence of nitrogen from the reaction mixture reduces pollution by NOx. However, the effects of a supercritical environment on elementary reactions kinetics are not well understood at present. We used boxed molecular dynamics simulations at the QM/MM theory level to predict the kinetics of dissociation/recombination reaction HCO• + [M] ↔ H• + CO + [M], an important elementary step in many combustion processes. A wide range of temperatures (400-1600 K) and pressures (0.3-1000 atm) were studied. Potentials of mean force were plotted and used to predict activation free energies and rate constants. Based on the data obtained, extended Arrhenius equation parameters were fitted and tabulated. The apparent activation energy for the recombination reaction becomes negative above 30 atm. As the temperature increased, the pressure effect on the rate constant decreased. While at 400 K the pressure increase from 0.3 atm to 300 atm accelerated the dissociation reaction by a factor of 250, at 1600 K the same pressure increase accelerated this reaction by a factor of 100. Graphical abstract Formyl radical surrounded by carbon dioxide molecules.
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Abd Alrahman C, Khodabakhsh A, Schmidt FM, Qu Z, Foltynowicz A. Cavity-enhanced optical frequency comb spectroscopy of high-temperature H2O in a flame. OPTICS EXPRESS 2014; 22:13889-13895. [PMID: 24921580 DOI: 10.1364/oe.22.013889] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We demonstrate near-infrared cavity-enhanced optical frequency comb spectroscopy of water in a premixed methane/air flat flame. The detection system is based on an Er:fiber femtosecond laser, a high finesse optical cavity containing the flame, and a fast-scanning Fourier transform spectrometer (FTS). High absorption sensitivity is obtained by the combination of a high-bandwidth two-point comb-cavity lock and auto-balanced detection in the FTS. The system allows recording high-temperature water absorption spectra with a resolution of 1 GHz and a bandwidth of 50 nm in an acquisition time of 0.4 s, with absorption sensitivity of 4.2 × 10(-9) cm(-1) Hz(-1/2) per spectral element.
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Watt RS, Laurila T, Kaminski CF, Hult J. Cavity enhanced spectroscopy of high-temperature H(2)o in the near-infrared using a supercontinuum light source. APPLIED SPECTROSCOPY 2009; 63:1389-1395. [PMID: 20030985 DOI: 10.1366/000370209790108987] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In this paper we demonstrate how broadband cavity enhanced absorption spectroscopy (CEAS) with supercontinuum (SC) radiation in the near-infrared spectral range can be used as a sensitive, multiplexed, and simple tool to probe gas-phase species in high-temperature environments. Near-infrared SC radiation is generated by pumping a standard single-mode fiber with a picosecond fiber laser. Standard low reflectivity mirrors are used for the cavity and an optical spectrum analyzer is used for the detection of gas-phase species in combustion. The method is demonstrated by measuring flame generated H(2)O in the 1500 to 1550 nm region and room-temperature CO(2) between 1520 nm and 1660 nm. The broadband nature of the technique permits hundreds of rotational features to be recorded, giving good potential to unravel complex, convoluted spectra. We discuss practical issues concerning the implementation of the technique and present a straightforward method for calibration of the CEAS system via a cavity ringdown measurement. Despite the large spectral variation of SC radiation from pulse to pulse, it is shown that SC sources can offer good stability for CEAS where a large number of SC pulses are typically averaged.
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Affiliation(s)
- Rosalynne S Watt
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, CB2 3RA Cambridge, UK
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Rahinov I, Goldman A, Cheskis S. Intracavity Laser Absorption Spectroscopy for flame diagnostics. Isr J Chem 2007. [DOI: 10.1560/ijc.47.2.131] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Sveum NE, Goncher SJ, Neumark DM. Determination of absolute photoionization cross sections of the phenyl radical. Phys Chem Chem Phys 2006; 8:592-8. [PMID: 16482301 DOI: 10.1039/b513960k] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Photoionization cross sections of the phenyl radical to form the phenyl cation were measured using tunable vacuum ultraviolet synchrotron radiation coupled with photofragment translational spectroscopy. The phenyl radical was produced via 193- or 248-nm dissociation of chlorobenzene. At 10.0 eV, the photoionization cross sections for the phenyl radical averaged over product channels were found to be 13.4 +/- 2.0 and 13.2 +/- 2.0 Mb, respectively, with very little effect seen from the range of internal excitation produced at the two photolysis wavelengths. Using the photoionization cross section values for each channel, photoionization efficiency curves for the phenyl radical were placed on an absolute scale from 7.8 to 10.8 eV.
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Affiliation(s)
- Niels E Sveum
- Department of Chemistry, University of California, Berkeley, 94720, USA
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Bulatov V, Chen Y, Khalmanov A, Schechter I. Absorption and scattering characterization of airborne microparticulates by a cavity ringdown technique. Anal Bioanal Chem 2005; 384:155-60. [PMID: 16328242 DOI: 10.1007/s00216-005-0173-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2005] [Revised: 10/03/2005] [Accepted: 10/12/2005] [Indexed: 11/29/2022]
Abstract
Nonresonant cavity ringdown laser absorption spectroscopy (CRLAS) was applied for detection and characterization of airborne particulates. Sensitive detection of a variety of aerosols under ambient conditions was achieved. The method provides, for the first time, time-resolved absolute aerosol concentration, with spatial resolution (along a line). The first report on absorption spectroscopy of monodispersed aerosols (in the size range 100-200 nm) is provided, and comparisons are made with the bulk data. The results indicate the possibility of applying CRLAS for selective analysis of aerosols. A new method for estimating the aerosol refraction index is also obtained from the ringdown data.
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Affiliation(s)
- Valery Bulatov
- Department of Chemistry, Technion-Israel Institute of Technology, 32000, Haifa, Israel
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Schocker A, Kohse-Höinghaus K, Brockhinke A. Quantitative determination of combustion intermediates with cavity ring-down spectroscopy: systematic study in propene flames near the soot-formation limit. APPLIED OPTICS 2005; 44:6660-72. [PMID: 16270555 DOI: 10.1364/ao.44.006660] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Cavity ring-down spectroscopy (CRDS) was applied in several fuel-rich, one-dimensional, premixed C3H6/O2/Ar flames at 50 mbars (37.5 torr) to measure absolute OH, HCO, and 1CH2 concentration as well as temperature as a function of stoichiometry. Although these flames near the sooting limit present a complex chemical environment, significant spectral interferences were found to be absent. Specific aspects of the CRDS technique for measurement of temperature and radical concentration profiles are discussed; and the results are analyzed in comparison with flame model simulations.
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Affiliation(s)
- Alexander Schocker
- Universität Bielefeld, Fakultät für Chemie, Physikalische Chemie I, Universitätsstrasse 25, D-33615 Bielefeld, Germany
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Krasnoperov LN, Chesnokov EN, Stark H, Ravishankara AR. Unimolecular Dissociation of Formyl Radical, HCO → H + CO, Studied over 1−100 Bar Pressure Range. J Phys Chem A 2004. [DOI: 10.1021/jp0403994] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Yang W, Joshi A, Xiao M. Enhancement of the cavity ringdown effect based on electromagnetically induced transparency. OPTICS LETTERS 2004; 29:2133-2135. [PMID: 15460880 DOI: 10.1364/ol.29.002133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We show that the unique absorption and dispersion properties of the electromagnetically induced transparency can be used effectively to relax the conditions for observing the cavity ringdown effect (CRE), which can be useful in applications of CRE in ultrasensitive detection of chemical species. A more straightforward and simple method is used to model the interesting CRE.
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Affiliation(s)
- Wenge Yang
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
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Kim JW, Yoo YS, Lee JY, Lee JB, Hahn JW. Uncertainty analysis of absolute concentration measurement with continuous-wave cavity ringdown spectroscopy. APPLIED OPTICS 2001; 40:5509-5516. [PMID: 18364837 DOI: 10.1364/ao.40.005509] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
To evaluate the uncertainty of concentration measurement using cavity ringdown spectroscopy, we analytically derived expressions for uncertainty for parameters, such as temperature, laser frequency, and ringdown time deviation, from the model equation. The uncertainties that are due to systematic errors in a practical cavity ringdown system were assessed through an experimental study of the PQ(35) transition in an A band of molecular oxygen. We found that, except for the line strength that is regarded as a reference value independent of the measurement, the laser frequency jitter is the largest uncertainty source in the system. Some practical requirements for minimizing the uncertainty in concentration measurements are discussed. We also demonstrated determination of the line strength of the PQ(35) transition line of oxygen to be 8.63(3) x 10(-27) cm(-1) with a relative uncertainty of less than 0.4%.
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Thoman JW, McIlroy A. Absolute CH Radical Concentrations in Rich Low-Pressure Methane−Oxygen−Argon Flames via Cavity Ringdown Spectroscopy of the A2Δ−X2Π Transition. J Phys Chem A 2000. [DOI: 10.1021/jp0001687] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- John W. Thoman
- Chemistry Department, Williams College, 47 Lab Campus Drive, Williamstown, Massachusetts 01267
| | - Andrew McIlroy
- Combustion Research Facility, Sandia National Laboratories, MS 9055, P.O. Box 969, Livermore, California 94551-0969
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Min Z, Wong TH, Quandt R, Bersohn R. The Reactions of O(3P) with Alkenes: The Formyl Radical Channel. J Phys Chem A 1999. [DOI: 10.1021/jp992198j] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zhiyuan Min
- Department of Chemistry, Columbia University, New York, New York 10027
| | - Teh-Hwa Wong
- Department of Chemistry, Columbia University, New York, New York 10027
| | - Robert Quandt
- Department of Chemistry, Columbia University, New York, New York 10027
| | - Richard Bersohn
- Department of Chemistry, Columbia University, New York, New York 10027
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Derzy I, Lozovsky VA, Cheskis S. Absolute CH concentration in flames measured by cavity ring-down spectroscopy. Chem Phys Lett 1999. [DOI: 10.1016/s0009-2614(99)00462-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Mercier X, Jamette P, Pauwels J, Desgroux P. Absolute CH concentration measurements by cavity ring-down spectroscopy in an atmospheric diffusion flame. Chem Phys Lett 1999. [DOI: 10.1016/s0009-2614(99)00416-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Vander Wal RL, Ticich TM. Cavity ringdown and laser-induced incandescence measurements of soot. APPLIED OPTICS 1999; 38:1444-1451. [PMID: 18305765 DOI: 10.1364/ao.38.001444] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Currently laser-induced incandescence (LII) is widely used for the measurement of soot volume fraction. A particularly important aspect of the technique that has received less attention, however, is calibration. The applicability of cavity ringdown (CRD) for measurement of soot volume fraction f(v) is assessed, and the calibration of LII by means of CRD is demonstrated. The accuracy of CRD for f(v) determination is validated by comparison with traditional light extinction and path-integrated LII. By use of CRD, the quantification of LII for parts in 10(9) (ppb) f(v) levels is demonstrated. Results are presented that demonstrate the accuracy of CRD for a single laser pulse to be better than ?5% for measurement of ppb soot volume-fraction levels over a 1-cm path length. By use of CRD, spatially resolved LII signals from soot within methane-air diffusion flames are calibrated for ppb f(v) levels, thereby avoiding the extrapolation required of less sensitive methods in current use.
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Affiliation(s)
- R L Vander Wal
- National Center for Microgravity Research, NASA Lewis Research Center, MS 110-3, 21000 Brookpark Road, Cleveland, Ohio 44135, USA.
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Hahn JW, Yoo YS, Lee JY, Kim JW, Lee HW. Cavity ringdown spectroscopy with a continuous-wave laser: calculation of coupling efficiency and a new spectrometer design. APPLIED OPTICS 1999; 38:1859-1866. [PMID: 18305817 DOI: 10.1364/ao.38.001859] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
For the efficient operation of a cavity ringdown spectroscopy (CRDS) system utilized with a continuous-wave (cw) laser, we numerically analyze the coupling efficiency of a cw laser to a ringdown cavity in terms of changes in the scanning rate, the laser linewidth, and the mirror reflectivity. We also demonstrate a new simple design for a CRDS system that can produce a CRDS signal with only a piezoelectric transducer (PZT), without the acousto-optic modulator that is usually adopted to switch off the cw laser beam that enters the cavity. Furthermore, we investigate the feasibility of the cw CRDS technique with a fast-scanning PZT by recording a CRDS spectrum of acetylene overtones. The detection sensitivity that corresponds to the noise-equivalent absorption is found to be approximately 3 x 10(-9)/cm.
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Affiliation(s)
- J W Hahn
- Optical High Temperature Measurement Group, Korea Research Institute of Standards and Science, PO Box 102, Yusong, Taejon 305-600, Korea
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Delve PA, Whitaker BJ. Saturation and lifetime effects on degenerate four-wave mixing spectroscopy. J Chem Phys 1999. [DOI: 10.1063/1.478328] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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21
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Mercier X, Therssen E, Pauwels J, Desgroux P. Cavity ring-down measurements of OH radical in atmospheric premixed and diffusion flames. Chem Phys Lett 1999. [DOI: 10.1016/s0009-2614(98)01233-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Lozovsky V, Derzy I, Cheskis S. Nonequilibrium concentrations of the vibrationally excited OH radical in a methane flame measured by cavity ring-down spectroscopy. Chem Phys Lett 1998. [DOI: 10.1016/s0009-2614(97)01443-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Quandt R, Min Z, Wang X, Bersohn R. Reactions of O(3P) with Alkenes: H, CH2CHO, CO, and OH Channels. J Phys Chem A 1998. [DOI: 10.1021/jp9730611] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Robert Quandt
- Department of Chemistry, Columbia University, New York, New York 10027
| | - Zhiyuan Min
- Department of Chemistry, Columbia University, New York, New York 10027
| | - Xuebin Wang
- Department of Chemistry, Columbia University, New York, New York 10027
| | - Richard Bersohn
- Department of Chemistry, Columbia University, New York, New York 10027
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Diau EWG, Smith GP, Jeffries JB, Crosley DR. HCO concentration in flames via quantitative laser-induced fluorescence. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s0082-0784(98)80434-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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27
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Lozovsky VA, Derzy I, Cheskis S. Radical concentration profiles in a low-pressure methane-air flame measured by intracavity laser absorption and cavity ring-down spectroscopy. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s0082-0784(98)80433-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Wright SA, Dagdigian PJ. Fluorescence excitation spectroscopy of the Ar–HCO(X̃ 2A′,B̃ 2A′) van der Waals complex. J Chem Phys 1997. [DOI: 10.1063/1.474469] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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30
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Lozovsky VA, Cheskis S, Kachanov A, Stoeckel F. Absolute HCO concentration measurements in methane/air flame using intracavity laser spectroscopy. J Chem Phys 1997. [DOI: 10.1063/1.473900] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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