1
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Caracas Núñez M, Gonzalez MA, Núñez Portela M. Theoretical and experimental study of the 6S-8S two-photon absorption cross-section in cesium atoms. OPTICS EXPRESS 2023; 31:31749-31759. [PMID: 37858992 DOI: 10.1364/oe.496654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 08/08/2023] [Indexed: 10/21/2023]
Abstract
The probability of a two-photon absorption (TPA) process is quantified by means of the TPA cross-section. In this work the TPA cross-section for the 6S1/2 → 8S1/2 transition in cesium (Cs) atoms is obtained from a theoretical and experimental approach. It is calculated using second order perturbation theory including hyperfine structure and Doppler broadening for a thermal atomic vapor. The theoretical values for the TPA cross-sections of the two allowed hyperfine transitions are σ~3,3=3.10×10-24 cm4/W and σ~4,4=3.65×10-24 cm4/W. An experiment is set up to measure these cross-sections based on the quadratic dependence between the TPA transition rate and the intensity of the laser light. Values of σ~3,3=(3.6±1.1)×10-24 cm4/W and σ~4,4=(4.6±1.1)×10-24 cm4/W are obtained from the measurements. The results show an agreement between theory and experiment. To the best of our knowledge, this is the first time that these cross-sections are reported.
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2
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Wang G, Liu T, Zou M, Karsili TNV, Lester MI. UV photodissociation dynamics of the acetone oxide Criegee intermediate: experiment and theory. Phys Chem Chem Phys 2023; 25:7453-7465. [PMID: 36848133 DOI: 10.1039/d3cp00207a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
The photodissociation dynamics of the dimethyl-substituted acetone oxide Criegee intermediate [(CH3)2COO] is characterized following electronic excitation to the bright 1ππ* state, which leads to O (1D) + acetone [(CH3)2CO, S0] products. The UV action spectrum of (CH3)2COO recorded with O (1D) detection under jet-cooled conditions is broad, unstructured, and essentially unchanged from the corresponding electronic absorption spectrum obtained using a UV-induced depletion method. This indicates that UV excitation of (CH3)2COO leads predominantly to the O (1D) product channel. A higher energy O (3P) + (CH3)2CO (T1) product channel is not observed, although it is energetically accessible. In addition, complementary MS-CASPT2 trajectory surface-hopping (TSH) simulations indicate minimal population leading to the O (3P) channel and non-unity overall probability for dissociation (within 100 fs). Velocity map imaging of the O (1D) products is utilized to reveal the total kinetic energy release (TKER) distribution upon photodissociation of (CH3)2COO at various UV excitation energies. Simulation of the TKER distributions is performed using a hybrid model that combines an impulsive model with a statistical component, the latter reflecting the longer-lived (>100 fs) trajectories identified in the TSH calculations. The impulsive model accounts for vibrational activation of (CH3)2CO arising from geometrical changes between the Criegee intermediate and the carbonyl product, indicating the importance of CO stretch, CCO bend, and CC stretch along with activation of hindered rotation and rock of the methyl groups in the (CH3)2CO product. Detailed comparison is also made with the TKER distribution arising from photodissociation dynamics of CH2OO upon UV excitation.
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Affiliation(s)
- Guanghan Wang
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
| | - Tianlin Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
| | - Meijun Zou
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
| | - Tolga N V Karsili
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA 70504, USA.
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
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3
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Tendo S, Tanimoto Y, Daijogon T, Adaniya M, Kawabata D, Kobayashi K, Ogino Y, Kohguchi H, Yamasaki K. Overall and state-to-state quenching of atomic oxygen O(2p33p 3P ) by collisions with He and N2. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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4
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Wang XD, Parker DH, van de Meerakker SYT, Groenenboom GC, Onvlee J. Laser ionisation detection of O(3Pj) atoms in the VUV; application to photodissociation of O2. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1979264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- X.-D. Wang
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - D. H. Parker
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | | | - G. C. Groenenboom
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - J. Onvlee
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
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5
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Esposito VJ, Liu T, Wang G, Caracciolo A, Vansco MF, Marchetti B, Karsili TNV, Lester MI. Photodissociation Dynamics of CH 2OO on Multiple Potential Energy Surfaces: Experiment and Theory. J Phys Chem A 2021; 125:6571-6579. [PMID: 34314179 DOI: 10.1021/acs.jpca.1c03643] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
UV excitation of the CH2OO Criegee intermediate across most of the broad span of the (B 1A')-(X 1A') spectrum results in prompt dissociation to two energetically accessible asymptotes: O (1D) + H2CO (X 1A1) and O (3P) + H2CO (a 3A''). Dissociation proceeds on multiple singlet potential energy surfaces that are coupled by two regions of conical intersection (CoIn). Velocity map imaging (VMI) studies reveal a bimodal total kinetic energy release (TKER) distribution for the O (1D) + H2CO (X 1A1) products with the major and minor components accounting for ca. 40% and ca. 20% on average of the available energy (Eavl), respectively. The unexpected low TKER component corresponds to highly internally excited H2CO (X 1A1) products accommodating ca. 80% of Eavl. Full dimensional trajectory calculations suggest that the bimodal TKER distribution of the O (1D) + H2CO (X 1A1) products originates from two different dynamical pathways: a primary pathway (69%) evolving through one CoIn region to products and a smaller component (20%) sampling both CoIn regions enroute to products. Those that access both CoIn regions likely give rise to the more highly internally excited H2CO (X 1A1) products. The remaining trajectories (11%) dissociate to O (3P) + H2CO (a 3A'') products after traversing through both CoIn regions. The complementary experimental and theoretical investigation provides insight on the photodissociation of CH2OO via multiple dissociation pathways through two regions of CoIn that control the branching and energy distributions of products.
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Affiliation(s)
- Vincent J Esposito
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Tianlin Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Guanghan Wang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Adriana Caracciolo
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Michael F Vansco
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Barbara Marchetti
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - Tolga N V Karsili
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
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6
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Progresses on the Use of Two-Photon Absorption Laser Induced Fluorescence (TALIF) Diagnostics for Measuring Absolute Atomic Densities in Plasmas and Flames. PLASMA 2021. [DOI: 10.3390/plasma4010009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Recent developments in plasma science and technology have opened new areas of research both for fundamental purposes (e.g., description of key physical phenomena involved in laboratory plasmas) and novel applications (material synthesis, microelectronics, thin film deposition, biomedicine, environment, flow control, to name a few). With the increasing availability of advanced optical diagnostics (fast framing imaging, gas flow visualization, emission/absorption spectroscopy, etc.), a better understanding of the physicochemical processes taking place in different electrical discharges has been achieved. In this direction, the implementation of fast (ns) and ultrafast (ps and fs) lasers has been essential for the precise determination of the electron density and temperature, the axial and radial gradients of electric fields, the gas temperature, and the absolute density of ground-state reactive atoms and molecules in non-equilibrium plasmas. For those species, the use of laser-based spectroscopy has led to their in situ quantification with high temporal and spatial resolution, with excellent sensitivity. The present review is dedicated to the advances of two-photon absorption laser induced fluorescence (TALIF) techniques for the measurement of reactive species densities (particularly atoms such as N, H and O) in a wide range of pressures in plasmas and flames. The requirements for the appropriate implementation of TALIF techniques as well as their fundamental principles are presented based on representative published works. The limitations on the density determination imposed by different factors are also discussed. These may refer to the increasing pressure of the probed medium (leading to a significant collisional quenching of excited states), and other issues originating in the high instantaneous power density of the lasers used (such as photodissociation, amplified stimulated emission, and photoionization, resulting to the saturation of the optical transition of interest).
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7
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Rahman KA, Athmanathan V, Slipchenko MN, Roy S, Gord JR, Zhang Z, Meyer TR. Quantitative femtosecond, two-photon laser-induced fluorescence of atomic oxygen in high-pressure flames. APPLIED OPTICS 2019; 58:1984-1990. [PMID: 30874065 DOI: 10.1364/ao.58.001984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 02/06/2019] [Indexed: 06/09/2023]
Abstract
Quantitative femtosecond two-photon laser-induced fluorescence of atomic oxygen was demonstrated in an H2/air flame at pressures up to 10 atm. Femtosecond excitation at 226.1 nm was used to pump the 3pP3J'=0,1,2←←2pP3J''=0,1,2 electronic transition of atomic oxygen. Contributions from multiphoton de-excitation, production of atomic oxygen, and photolytic interferences were investigated and minimized by limiting the laser irradiance to ∼1011 W/cm2. Quantitative agreement was achieved with the theoretical equilibrium mole fraction of atomic oxygen over a wide range of fuel-air ratios and pressures in an H2/air laminar calibration burner.
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8
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Carrivain O, Orain M, Dorval N, Morin C, Legros G. Experimental Spectroscopic Studies of Carbon Monoxide (CO) Fluorescence at High Temperatures and Pressures. APPLIED SPECTROSCOPY 2017; 71:2353-2366. [PMID: 28523936 DOI: 10.1177/0003702817709439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Two-photon excitation laser-induced fluorescence of carbon monoxide (CO-LIF) is investigated experimentally in order to determine the applicability of this technique for imaging CO concentration in aeronautical combustors. Experiments are carried out in a high temperature, high-pressure test cell, and in a laminar premixed CH4/air flame. Influence of temperature and pressure on CO-LIF spectra intensity and shape is reported. The experimental results show that as pressure increases, the CO-LIF excitation spectrum becomes asymmetric. Additionally, the spectrum strongly shifts to the red with a quadratic dependence of the collisional shift upon pressure, which is different from the classical behavior where the collisional shift is proportional to pressure. Moreover, pressure line broadening cannot be reproduced by a Lorenztian profile in the temperature range investigated here (300-1750 K) and, therefore, an alternative line shape is suggested.
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Affiliation(s)
| | - Mikael Orain
- 2 ONERA - The French Aerospace Lab, Mauzac, France
| | - Nelly Dorval
- 1 ONERA - The French Aerospace Lab, Palaiseau, France
| | - Celine Morin
- 3 LAMIH UMR CNRS 8201, UVHC, Valenciennes, France
| | - Guillaume Legros
- 4 Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 7190, Institut Jean Le Rond d'Alembert, Paris, France
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9
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Dvořák P, Mrkvičková M, Obrusník A, Kratzer J, Dědina J, Procházka V. Fluorescence measurement of atomic oxygen concentration in a dielectric barrier discharge. ACTA ACUST UNITED AC 2017. [DOI: 10.1088/1361-6595/aa70da] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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10
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Schmidt JB, Sands B, Scofield J, Gord JR, Roy S. Comparison of femtosecond- and nanosecond-two-photon-absorption laser-induced fluorescence (TALIF) of atomic oxygen in atmospheric-pressure plasmas. ACTA ACUST UNITED AC 2017. [DOI: 10.1088/1361-6595/aa61be] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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11
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Grubb MP, Dooley KS, Freeman CD, Peterson KA, North SW. Experimental and theoretical investigation of correlated fine structure branching ratios arising from state-selected predissociation of BrO (A2Π3/2). Phys Chem Chem Phys 2014; 16:607-15. [PMID: 24202006 DOI: 10.1039/c3cp53766h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present results for the v'-dependent predissociation dynamics of the BrO (A(2)Π3/2) state using velocity map ion imaging. Correlated fine structure branching ratios, Br((2)P(J)) + O((3)P(J)), have been measured for v' = 5-16 states. The experimental branching ratios are non-statistical and strongly dependent on the initial vibronic state. The current measurements represent an extensive dataset containing rich information about the predissociation dynamics of this system and should provide a stringent test for modern theory. New high level ab initio excited state potentials are presented and have been optimized using experimental v'-dependent predissociation lifetimes and calculated coupling constants. Comparisons between the experimental branching ratios and the predictions based on diabatic and adiabatic limiting models are presented. We find that the adiabatic model is most consistent with the observed trends in the correlated branching ratios, in contrast to previous studies on the related ClO system.
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Affiliation(s)
- Michael P Grubb
- Department of Chemistry, Texas A&M University, P. O. Box 30012, College Station, Texas 77842, USA.
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12
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Ulrich CK, Chen J, Tokel O, Houston PL, Grebenshchikov SY. Photodissociation of ozone from 321 to 329 nm: the relative yields of O(3P2) with O2(X 3Σg(-)), O2(a 1Δg) and O2(b 1Σg(+)). J Phys Chem A 2013; 117:12011-9. [PMID: 23795961 DOI: 10.1021/jp4041088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Product imaging of O((3)P2) following dissociation of ozone has been used to determine the relative yields of the product channels O((3)P2) + O2(X (3)Σg(-)) of ozone. All three channels are prominent at all wavelengths investigated. O2 vibrational distributions for each channel and each wavelength are also estimated assuming Boltzmann rotational distributions. Averaged over wavelength in the measured range, the yields of the O((3)P2) + O2(X (3)Σg(-)), O((3)P2) + O2(a (1)Δg), and O((3)P2) + O2(b (1)Σg(+)) channels are 0.36, 0.31,and 0.34, respectively. Photofragment distributions in the spin-allowed channel O((3)P) + O2(X (3)Σg(-)) are compared with the results of quantum mechanical calculations on the vibronically coupled PESs of the singlet states B (optically bright) and R (repulsive). The experiments suggest that considerably more vibrational excitation and less rotational excitation occur than predicted by the quantum calculations. The rotational distributions, adjusted to fit the experimental images, suggest that the dissociation takes place from a more linear configuration than the Franck-Condon bending angle of 117°. The dissociation at most wavelengths results in a positive value of the anisotropy parameter, β, both in the experiment and in the calculations. Calculations indicate that both nonadiabatic transitions and intersystem crossings substantially reduce β below the nominal value of 2.
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Affiliation(s)
- C K Ulrich
- School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
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13
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Ion imaging studies of ClONO2 photodissociation: Primary branching ratios and secondary dissociation. Chem Phys 2009. [DOI: 10.1016/j.chemphys.2009.09.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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14
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Dooley KS, Grubb MP, Geidosch J, van Beek MA, Groenenboom GC, North SW. Correlated fine structure branching ratios arising from state-selected predissociation of ClO (A2Π3/2). Phys Chem Chem Phys 2009; 11:4770-6. [DOI: 10.1039/b823004h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Löhle S, Eichhorn C, Steinbeck A, Lein S, Herdrich G, Röser HP, Auweter-Kurtz M. Oxygen plasma flow properties deduced from laser-induced fluorescence and probe measurements. APPLIED OPTICS 2008; 47:1837-1845. [PMID: 18404183 DOI: 10.1364/ao.47.001837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Estimation of the local dissociation degree and the local mass-specific enthalpy of a pure oxygen plasma flow determined mainly from laser-induced fluorescence measurements are reported. Measurements have been conducted for several generator parameters in an inductively heated plasma wind tunnel. Additional probe measurements of total pressure together with the deduced translational temperature are used to estimate the local mass-specific enthalpy. For a reference condition, full dissociation has been measured. The measured translational temperature of atomic oxygen for this condition is T = 3500 K. Subsequently, the local mass-specific enthalpy has been derived using these local density and temperature measurements. For the reference condition the estimated value of h = 27 MJ/kg is in good agreement with the probe measurements and results from diode laser absorption spectroscopy.
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Affiliation(s)
- Stefan Löhle
- German Aerospace Center, Pfaffenwaldring 38-40, D-70569 Stuttgart, Germany.
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16
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Kim H, Dooley KS, North SW, Hall GE, Houston PL. Anisotropy of photofragment recoil as a function of dissociation lifetime, excitation frequency, rotational level, and rotational constant. J Chem Phys 2006; 125:133316. [PMID: 17029469 DOI: 10.1063/1.2216708] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Quantum mechanical calculations of photofragment angular distributions have been performed as a function of the frequency of excitation, the lifetime of the dissociative state, the rotational level, and the rotational constant. In the limit of high J values and white, incoherent excitation, the general results are found to agree exactly with both those of Mukamel and Jortner [J. Chem. Phys. 61, 5348 (1974)] and those of Jonah [J. Chem. Phys. 55, 1915 (1971)]. Example calculations describe how the anisotropy is dependent on the degree of broadening, the rotational constant, the initial rotational level, and the frequency of excitation. Applications are also made to interpret experimental results on the photodissociation of ClO via the 11-0, 10-0, and 6-0 bands of the A 2Pi3/2 -X 2Pi3/2 transition and on the photodissociation of O2 via the 0-0 band of the E 3Sigmau- -X 3Sigmag- transition.
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Affiliation(s)
- Hahkjoon Kim
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
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17
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Kim H, Dooley KS, Johnson ER, North SW. Photodissociation of the BrO radical using velocity map ion imaging: Excited state dynamics and accurate D00(BrO) evaluation. J Chem Phys 2006; 124:134304. [PMID: 16613452 DOI: 10.1063/1.2173265] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have studied the photodissociation dynamics of expansion-cooled BrO radical both above (278-281.5 nm) and below (355 nm) the A (2)Pi(3/2) state threshold using velocity map ion imaging. A recently developed late-mixing flash pyrolytic reactor source was utilized to generate an intense BrO radical molecular beam. The relative electronic product branching ratios at 355 nm and from 278 to 281.5 nm were determined. We have investigated the excited state dynamics based on both the product branching and the photofragment angular distributions. We find that above the O((1)D(2)) threshold the contribution of the direct excitation to states other than the A (2)Pi(3/2) state and the role of curve crossing is considerably larger in BrO compared to that observed for ClO, in agreement with recent theoretical studies. The measurement of low velocity photofragments resulting from photodissociation just above the O((1)D(2)) threshold provides an accurate and direct determination of the A (2)Pi(3/2) state dissociation threshold of 35418+/-35 cm(-1), leading to a ground state bond energy of D(0)(0)(BrO)=55.9+/-0.1 kcal/mol.
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Affiliation(s)
- Hahkjoon Kim
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
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18
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Kim H, Dooley KS, Groenenboom GC, North SW. Vibrational state-dependent predissociation dynamics of ClO (A2Π3/2): Insight from correlated fine structure branching ratios. Phys Chem Chem Phys 2006; 8:2964-71. [PMID: 16880909 DOI: 10.1039/b603353a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have studied the v'-dependent predissociation dynamics of the ClO A (2)Pi(3/2) state using velocity-map ion-imaging. Experimental final correlated state branching ratios, i.e. Cl((2)P(J=3/2,1/2)) + O((3)P(J=2,1,0)) channels, have been measured for v' = 6-11. We find that the branching ratios are highly variable and depend strongly on v', providing a window into the v'-dependent predissociation mechanism. A comparison of the experimental results with the recent model of Lane et al. (I. C. Lane, W. H. Howie and A. J. Orr-Ewing, Phys. Chem. Chem. Phys., 1999, 1, 3087) in both the diabatic and adiabatic limits suggests that the dynamics are closer to the diabatic limit. The overall Cl((2)P(J)) branching ratios are in good agreement with the diabatic model results. There are significant differences, however, between theory and experiment at the correlated state level, demonstrating the sensitivity of correlated measurements to the role of the exit channel coupling in the predissociation dynamics. The results highlight the need for more sophisticated quantum dynamical calculations to describe the correlated fine structure branching ratios in this system.
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Affiliation(s)
- Hahkjoon Kim
- Department of Chemistry, Texas A and University, P. O. Box 30012, College Station, Texas 77842, USA
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19
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Musgrave A, Bergeron DE, Wheatley RJ, Wright TG. Electronic spectroscopy of the deuterated isotopomers of the NO∙methane molecular complex. J Chem Phys 2005; 123:204305. [PMID: 16351254 DOI: 10.1063/1.2125748] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The molecular complexes formed between a nitric oxide molecule and the various deuterated isotopomers of the methane molecule have been studied in a supersonic jet expansion. The electronic spectrum arising from the transition corresponding to a 3s<--pi* excitation (approximately A (2)Sigma(+)<-- approximately X (2)Pi) located on the NO chromophore has been recorded employing resonance-enhanced multiphoton ionization spectroscopy, with each of CH(4), CH(3)D, CH(2)D(2), CHD(3), and CD(4) as the complexing partner. Rich spectra are obtained, whose appearance changes in a systematic way as the amount of deuteration increases. Unexpectedly, it was possible to record spectra not only in the parent mass channel, but also in various fragment channels; this also led to the identification of some O atom resonances; and their origin is discussed. Discussion is presented of the structure in the spectra, and its possible sources including hindered internal rotation of the methane and NO moieties, overall rotation of the complex, and tunneling. In addition, some guidance has been gleaned from ab initio calculations, and these are discussed in the light of the experimental results.
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Affiliation(s)
- Adam Musgrave
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
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20
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Kim H, Park J, Niday TC, North SW. The UV photodissociation dynamics of ClO radical using velocity map ion imaging. J Chem Phys 2005; 123:174303. [PMID: 16375524 DOI: 10.1063/1.2083487] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have studied the wavelength-dependent photodissociation dynamics of jet-cooled ClO radical from 235 to 291 nm using velocity map ion imaging. We find that Cl(2P(3/2))+O(1D(2)) is the dominant channel above the O(1D(2)) threshold with minor contributions from the Cl(2P(J))+O(3P(J)) and Cl(2P(1/2))+O(1D(2)) channels. We have measured the photofragment angular distributions for each dissociation channel and find that the A 2pi state reached via a parallel transition carries most of the oscillator strength above the O(1D(2)) threshold. The formation of O(3P(J)) fragments with positive anisotropy is evidence of curve crossing from the A 2pi state to one of several dissociative states. The curve crossing probability increases with wavelength in good agreement with previous theoretical calculations. We have directly determined the O(1D(2)) threshold to be 38,050+/-20 cm(-1) by measuring O(1D(2)) quantum yield in the wavelength range of 260-270 nm. We also report on the predissociation dynamics of ClO below the O(1D(2)) threshold. We find that the branching ratio of Cl(2P(3/2))/Cl(2P(1/2)) is 1.5+/-0.1 at both 266 and 291 nm. The rotational depolarization of the anisotropy parameters of the Cl(2P(3/2)) fragments provides predissociation lifetimes of 1.5+/-0.2 ps for the 9-0 band and 1.0+/-0.4 ps for the 8-0 band, in reasonable agreement with previous spectroscopic and theoretical studies.
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Affiliation(s)
- Hahkjoon Kim
- Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842, USA
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21
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Juchmann W, Luque J, Jeffries JB. Two-photon laser-induced fluorescence of atomic hydrogen in a diamond-depositing dc arcjet. APPLIED OPTICS 2005; 44:6644-52. [PMID: 16270553 DOI: 10.1364/ao.44.006644] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Atomic hydrogen in the plume of a dc-arcjet plasma is monitored by use of two-photon excited laser-induced fluorescence (LIF) during the deposition of diamond film. The effluent of a dc-arc discharge in hydrogen and argon forms a luminous plume as it flows through a converging-diverging nozzle into a reactor. When a trace of methane (< 2%) is added to the flow in the diverging part of the nozzle, diamond thin film grows on a water-cooled molybdenum substrate from the reactive mixture. LIF of atomic hydrogen in the arcjet plume is excited to the 3S and 3D levels with two photons near 205 nm, and the subsequent fluorescence is observed at Balmer-alpha near 656 nm. Spatially resolved LIF measurements of atomic hydrogen are made as a function of the ratio of hydrogen to argon feedstock gas, methane addition, and reactor pressure. At lower reactor pressures, time-resolved LIF measurements are used to verify our collisional quenching correction algorithm. The quenching rate coefficients for collisions with the major species in the arcjet (Ar, H, and H2) do not change with gas temperature variations in the plume (T < 2300 K). Corrections of the LIF intensity measurements for the spatial variation of collisional quenching are important to determine relative distributions of the atomic hydrogen concentration. The relative atomic hydrogen concentrations measured here are calibrated with an earlier calorimetric determination of the feedstock hydrogen dissociation to provide quantitative hydrogen-atom concentration distributions.
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Affiliation(s)
- Wolfgang Juchmann
- Molecular Physics Laboratory, SRI International, 333 Ravenswood Avenue, Menlo Park, California 94025, USA
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Greenslade ME, Lester MI, Radenović DC, van Roij AJA, Parker DH. (2+1) Resonance-enhanced ionization spectroscopy of a state-selected beam of OH radicals. J Chem Phys 2005; 123:074309. [PMID: 16229572 DOI: 10.1063/1.1997132] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A state-selected beam of hydroxyl radicals is generated using a pulsed discharge source and hexapole field. The OH radicals are characterized by resonance-enhanced multiphoton ionization (REMPI) spectroscopy via the nested D 2Sigma- and 3 2Sigma- Rydberg states. Simplified spectra are observed from the selected |MJ|=3/2 component of the upper Lambda-doublet level of the lowest rotational state (J=32) in ground (v"=0) and excited (v"=1-3) vibrational levels of the OH X 2Pi3/2 state. Two-photon transitions are observed to the D 2Sigma-(v'=0-3) and 3 2Sigma-(v'=0,1) vibronic levels, extending previous studies to higher vibrational levels of the Rydberg states. Spectroscopic constants are derived for the Rydberg states and compared with prior experimental studies. Complementary first-principle theoretical studies of the properties of the D 2Sigma- and 3 2Sigma- Rydberg states [see M. P. J. van der Loo and G. C. Groenenboom, J. Chem. Phys. 123, 074310 (2005), following paper] are used to interpret the experimental findings and examine the utility of the (2+1) REMPI scheme for sensitive detection of OH radicals.
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Affiliation(s)
- Margaret E Greenslade
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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23
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van der Loo MPJ, Groenenboom GC. Ab initiocalculation of (2+1) resonance enhanced multiphoton ionization spectra and lifetimes of the (D,3)Σ−2 states of OH and OD. J Chem Phys 2005; 123:074310. [PMID: 16229573 DOI: 10.1063/1.1997133] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
High-level ab initio potential-energy curves and transition dipole moments for the OH X 2Pi, 2 2Pi, 1 2Sigma-, D 2Sigma-, 3 2Sigma-, A 2Sigma+, B 2Sigma+, 1 2Delta, 1 4Sigma-, and 1 4Pi states are computed. The results are used to estimate the (2+1) resonance enhanced multiphoton ionization spectrum for the (D,3)2Sigma-(upsilon')<--2hnuX 2Piupsilon") transitions, which are compared with experiments by Greenslade et al. [see M. E. Greenslade, M. I. Lester, D. C. Radenovic, J. A. van Roij, and D. H. Parker, J. Chem. Phys. 123, 074309 (2005), preceeding paper]. We use the discrete variable representation-absorbing boundary condition method to incorporate the effect of the dissociative intermediate 1 2Sigma- state. We obtain qualitative agreement with experiment for the line strengths. Radiative and predissociative decay rates of the Rydberg (D,3)2Sigma- states of OH and OD were computed, including spin-orbit coupling effects and the effect of spin-electronic and gyroscopic coupling. We show that the lifetime of the Rydberg 2Sigma- states for rotationally cold molecules is limited mainly by predissociation caused by spin-orbit coupling.
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Affiliation(s)
- Mark P J van der Loo
- Institute of Theoretical Chemistry, University of Nijmegen, Toernooiveld 1, 6525ED, Nijmegen, The Netherlands
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25
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Teslja A, Dagdigian PJ. Determination of oxygen atom concentrations by cavity ring-down spectroscopy. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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26
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Roth M, Maul C, Gericke KH. Photodissociation Dynamics of Cl2O: Interpretation of Electronic Transitions. J Phys Chem A 2004. [DOI: 10.1021/jp049334r] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Melanie Roth
- Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, 38106 Braunschweig, Germany
| | - Christof Maul
- Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, 38106 Braunschweig, Germany
| | - Karl-Heinz Gericke
- Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, Hans-Sommer-Strasse 10, 38106 Braunschweig, Germany
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27
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Frank JH, Chen X, Patterson BD, Settersten TB. Comparison of nanosecond and picosecond excitation for two-photon laser-induced fluorescence imaging of atomic oxygen in flames. APPLIED OPTICS 2004; 43:2588-2597. [PMID: 15119630 DOI: 10.1364/ao.43.002588] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Two-photon laser-induced fluorescence (LIF) imaging of atomic oxygen is investigated in premixed hydrogen and methane flames with nanosecond and picosecond pulsed lasers at 226 nm. In the hydrogen flame, the interference from photolysis is negligible compared with the LIF signal from native atomic oxygen, and the major limitations on quantitative measurements are stimulated emission and photoionization. Excitation with a nanosecond laser is advantageous in the hydrogen flames, because it reduces the effects of stimulated emission and photoionization. In the methane flames, however, photolytic interference is the major complication for quantitative O-atom measurements. A comparison of methane and hydrogen flames indicates that vibrationally excited CO2 is the dominant precursor for laser-generated atomic oxygen. In the methane flames, picosecond excitation offers a significant advantage by dramatically reducing the photolytic interference. The prospects for improved O-atom imaging in hydrogen and hydrocarbon flames are presented.
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Affiliation(s)
- Jonathan H Frank
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551-0969, USA.
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Binetti M, Weiße O, Hasselbrink E, Katz G, Kosloff R, Zeiri Y. The role of nonadiabatic pathways and molecular rotations in the oxygen abstraction reaction on the Al(111) surface. Chem Phys Lett 2003. [DOI: 10.1016/s0009-2614(03)00586-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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29
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Buntin SA, Litorja M. Oxygen atom interactions with fused silica surfaces: 1D and 3P state-resolved energy transfer dynamics. J Chem Phys 2003. [DOI: 10.1063/1.1523898] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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30
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Cosofret BR, Lambert HM, Houston PL. Two-photon photodissociation of NO through Rydberg levels in the 265–278 nm region: Spectra and photofragment angular distributions. J Chem Phys 2002. [DOI: 10.1063/1.1513458] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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31
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Zou P, Kim H, North SW. The ultraviolet photodissociation of jet-cooled ClO and BrO radicals. J Chem Phys 2002. [DOI: 10.1063/1.1448282] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
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32
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Dylewski SM, Geiser JD, Houston PL. The energy distribution, angular distribution, and alignment of the O(1D2) fragment from the photodissociation of ozone between 235 and 305 nm. J Chem Phys 2001. [DOI: 10.1063/1.1405439] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Myhr FH, Driscoll JF. Oxygen-atom concentrations measured in flames: a method to improve the accuracy of laser-induced fluorescence diagnostics. APPLIED OPTICS 2001; 40:5388-5394. [PMID: 18364818 DOI: 10.1364/ao.40.005388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A procedure is proposed, denoted as the corrected laser-induced fluorescence (LIF) method, that reduces the error associated with the unavoidable photodissociation of O(2) molecules that has limited the measurement of oxygen-atom concentrations in the past. Two different laser intensities are employed, and the two signals that are obtained with two-photon LIF diagnostics are used to correct for the photolysis error. We measured oxygen-atom concentrations using this method at 33 locations in lean and rich flames. Results are compared with values determined by use of two independent techniques: the partial equilibrium method and equilibrium calculations. The measurements also quantify the shot noise, the photolysis errors, and the critical laser intensity required to avoid photolysis errors.
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Petrik NG, Knutsen K, Paparazzo E, Lea S, Camaioni DM, Orlando TM. Electron Beam Induced Damage of NaNO3 Single Crystals: An Energy, Temperature, and Quantum State Resolved Study. J Phys Chem B 2000. [DOI: 10.1021/jp993310g] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- N. G. Petrik
- W. R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352
| | - K. Knutsen
- W. R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352
| | - E. Paparazzo
- W. R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352
| | - S. Lea
- W. R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352
| | - D. M. Camaioni
- W. R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352
| | - T. M. Orlando
- W. R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352
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Geiser JD, Dylewski SM, Mueller JA, Wilson RJ, Toumi R, Houston PL. The vibrational distribution of O2(X 3Σg−) produced in the photodissociation of ozone between 226 and 240 and at 266 nm. J Chem Phys 2000. [DOI: 10.1063/1.480679] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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36
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Taniguchi N, Takahashi K, Matsumi Y, Dylewski SM, Geiser JD, Houston PL. Determination of the heat of formation of O3 using vacuum ultraviolet laser-induced fluorescence spectroscopy and two-dimensional product imaging techniques. J Chem Phys 1999. [DOI: 10.1063/1.479939] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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37
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Dodd JA, Lockwood RB, Hwang ES, Miller SM, Lipson SJ. Vibrational relaxation of NO(υ=1) by oxygen atoms. J Chem Phys 1999. [DOI: 10.1063/1.479671] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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Fletcher DG. Arcjet flow properties determined from laser-induced fluorescence of atomic nitrogen. APPLIED OPTICS 1999; 38:1850-1858. [PMID: 18305816 DOI: 10.1364/ao.38.001850] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Flow property measurements that were recently acquired in the Ames Research Center Aerodynamic Heating Facility arcjet using two-photon laser-induced fluorescence (LIF) of atomic nitrogen (N) are reported. The flow properties, which include velocity, translational temperature, and N concentration, were measured simultaneously over a range of facility operating conditions for N(2)-argon test gas flows in the 30-cm-diameter nozzle. A recent measurement of the two-photon excitation cross section for the 3p(4)D degrees <-- 2p(4)S degrees transition of atomic nitrogen is used to convert the relative nitrogen concentration measurements to absolute values, and a nitrogen flow reactor is used to provide a room-temperature, reference-wavelength calibration of the translational temperature and velocity measurements. When combined with information from facility measurements, an analysis of the flow properties obtained using two-photon LIF of N yields the total free-stream flow enthalpy.
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Affiliation(s)
- D G Fletcher
- Reacting Flow Environments Branch, NASA Ames Research Center, MS 230-2, Moffett Field, California 94035, USA
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39
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Adams SF, Miller TA. Two-photon absorption laser-induced fluorescence of atomic nitrogen by an alternative excitation scheme. Chem Phys Lett 1998. [DOI: 10.1016/s0009-2614(98)00972-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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40
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Goehlich A, Kawetzki T, Döbele HF. On absolute calibration with xenon of laser diagnostic methods based on two-photon absorption. J Chem Phys 1998. [DOI: 10.1063/1.476388] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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41
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Buijsse B, van der Zande WJ, Eppink ATJB, Parker DH, Lewis BR, Gibson ST. Angular distributions for photodissociation of O2 in the Herzberg continuum. J Chem Phys 1998. [DOI: 10.1063/1.476141] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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43
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Becker S, Braatz C, Lindner J, Tiemann E. Investigation of the predissociation of SO2: state selective detection of the SO and O fragments. Chem Phys 1995. [DOI: 10.1016/0301-0104(95)00114-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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44
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Brown MS, Jeffries JB. Measurement of atomic concentrations in reacting flows through the use of stimulated gain or loss. APPLIED OPTICS 1995; 34:1127-1132. [PMID: 21037642 DOI: 10.1364/ao.34.001127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Apump laser at 226 nm was used to generate a population inversion between the 3p (3)P(2) and 3s (3)S(1) states of the oxygen atom in the postflame gases of a 7-torr H(2)/O(2) flame by means of resonant two-photon absorption from the ground state. The inversion produced an amplified spontaneous emission (ASE) signal at 845 nm. A probe laser tuned to this transition was crossed at a small angle with the pump beam. The probe beam experienced gain at the expense of theASE signal. By analyzing the gain on the probe beam and the loss on the ASE signal, we have determined the density of oxygen atoms in the flame environment.
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Dux R, Grützmacher K, Wende B. Absolute determination of local ground-state densities of atomic hydrogen in nonlocal-thermodynamic-equilibrium environments by two-photon polarization spectroscopy. PHYSICAL REVIEW. E, STATISTICAL PHYSICS, PLASMAS, FLUIDS, AND RELATED INTERDISCIPLINARY TOPICS 1995; 51:1416-1427. [PMID: 9962785 DOI: 10.1103/physreve.51.1416] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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46
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Fein A, Bernstein JS, Song XM, Cool TA. Experiments concerning resonance-enhanced multiphoton ionization probe measurements of flame-species profiles. APPLIED OPTICS 1994; 33:4889-4898. [PMID: 20935865 DOI: 10.1364/ao.33.004889] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Resonance-enhanced multiphoton ionization (REMPI) detection of radical species in low-pressure laboratory flames is a promising tool for the development and refinement of combustion models. For accurate REMPI species concentration measurements in flame zones with inherently high background ionization levels, an understanding of the influence of plasma sheaths on REMPI probe response is required. Proper probe response is found to depend on careful control of probe-biasing and laserfocusing conditions. Only negatively biased probes are suitable, because of the influences of secondary ionization on the response of positively biased probes. In situ probe calibration procedures with the (2 + 2) REMPI of N(2) at 270.6 nm are described. Detection of O atoms in a stoichiometric 20-Torr methane-oxygen flame permits a precise comparison of both laser-induced fluorescence and REMPI measurements with flame-modeling results.
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47
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Park H, Slanger TG. O2(X,v=8–22) 300 K quenching rate coefficients for O2 and N2, and O2(x) vibrational distribution from 248 nm O3 photodissociation. J Chem Phys 1994. [DOI: 10.1063/1.466997] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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48
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Huang Y, Gordon RJ. The effect of amplified spontaneous emission on the measurement of the multiplet state distribution of ground state oxygen atoms. J Chem Phys 1992. [DOI: 10.1063/1.463697] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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49
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Smith AV, Raymond TD, Riley ME. Measurement of select transition strengths and autoionizing lifetimes in atomic oxygen. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1992; 45:4688-4696. [PMID: 9907550 DOI: 10.1103/physreva.45.4688] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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50
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Matsumi Y, Shafer N, Tonokura K, Kawasaki M, Huang Y, Gordon RJ. Doppler profiles and fine‐structure branching ratios of O(3Pj) from photodissociation of carbon dioxide at 157 nm. J Chem Phys 1991. [DOI: 10.1063/1.461408] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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