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The systematic study of quenching rate coefficients of NO(X2Π) colliding by NO(A2Σ+) and N2(A3Σ+u, B3Πg). Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.140031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Fletcher JD, Lanfri L, Ritchie GAD, Hancock G, Islam M, Richmond G. Time-resolved observations of vibrationally excited NO X 2Π ( v') formed from collisional quenching of NO A 2Σ + ( v = 0) by NO X 2Π: evidence for the participation of the NO a 4Π state. Phys Chem Chem Phys 2021; 23:20478-20488. [PMID: 34498634 DOI: 10.1039/d1cp03360c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Time-resolved observations have been made of the formation of vibrationally excited NO X 2Π (v') following collisional quenching of NO A 2Σ+ (v = 0) by NO X 2Π (v = 0). Two time scales are observed, namely a fast production rate consistent with direct formation from the quenching of the electronically excited NO A state, together with a slow component, the magnitude and rate of formation of which depend upon NO pressure. A reservoir state formed by quenching of NO A 2Σ+ (v = 0) is invoked to explain the observations, and the available evidence points to this state being the first electronically excited state of NO, a 4Π. The rate constant for quenching of the a 4Π state to levels v' = 11-16 by NO is measured as (8.80 ± 1.1) × 10-11 cm3 molecule-1 s-1 at 298 K where the error quoted is two standard deviations, and from measurements of the increased formation of high vibrational levels of NO(X) by the slow process we estimate a lower limit for the fraction of self-quenching collisions of NO A 2Σ+ (v = 0) which lead to NO a 4Π as 19%.
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Affiliation(s)
- James D Fletcher
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, UK.
| | - Lucia Lanfri
- Universidad Nacional de Córdoba, INFIQC CONICET, Córdoba, Argentina
| | - Grant A D Ritchie
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, UK.
| | - Gus Hancock
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, UK.
| | - Meez Islam
- School of Science and Engineering, Teesside University, Middlesbrough, TS1 3BA, UK
| | - Graham Richmond
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, UK.
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Winner JD, Pan F, McIlvoy MH, Bowersox RDW, North SW. Temperature perturbation related to the invisible ink vibrationally excited nitric oxide monitoring (VENOM) technique: a simulation study. APPLIED OPTICS 2019; 58:2702-2712. [PMID: 31045076 DOI: 10.1364/ao.58.002702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 02/27/2019] [Indexed: 06/09/2023]
Abstract
The limits of applicability of the invisible ink variant of the vibrationally excited nitric oxide monitoring (VENOM) technique for three distinct flow fields is reported in this work. This technique involves the generation of a grid of vibrationally excited NO (X,Π2) by exciting the NO A-X electronic transition at 226 nm, which subsequently relaxes via fluorescence and collisional quenching to produce vibrationally excited NO (X,Π2). This grid is then probed by two laser sheets tuned to distinct rotational states. The resulting images allow for the simultaneous measurement of temperature and velocity. The flow fields presented in this work provide a range of NO concentrations, vibrational lifetimes, pressures, temperatures, and collisional quenching, which explore the applicability of the invisible ink variant to a wide range of conditions. We have modelled the initial NO, O2, and N2 vibrational and rotational energy distribution resulting from the combination of fluorescence and quenching of electronically excited NO. The subsequent rethermalization of the sample, in particular the long-time vibrational relaxation, has been modelled using a forced harmonic oscillator model. The time-dependent temperature perturbation due to the invisible ink technique is evaluated for two distinct timescales: a short-timescale temperature rise resulting from collisional quenching and rotational/translational thermalization and a long-timescale temperature rise caused by vibrational thermalization. Under low pressures where fluorescence dominates quenching, there is minimal temperature perturbation of the flow field on the timescale of a VENOM measurement, and the short-timescale temperature perturbation only becomes significant at high NO seed concentrations. The predicted signal-to-noise ratio of the invisible ink method is unaffected for low-pressure, low-temperature flow fields. However, preserving signal-to-noise ratio for a high-temperature, high-pressure flow field could prove challenging due to the impact of quenching and self-absorption. Overall, we find that the invisible ink method is predicted to be a viable laser-based diagnostic for velocimetry and thermometry over a wide range of experimental conditions.
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Few J, Fletcher JD, Hancock G, Redmond JL, Ritchie GAD. An FTIR emission study of the products of NO A 2Σ + (v = 0, 1) + O 2 collisions. Phys Chem Chem Phys 2017; 19:11289-11298. [PMID: 28418047 DOI: 10.1039/c7cp00904f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Collisional quenching of NO A2Σ+ (v = 0, 1) by O2 has been studied through the detection of vibrationally excited products by time-resolved Fourier transform infrared emission spectroscopy. Non-reactive quenching of NO A2Σ+ (v = 0) produces a vibrational distribution in NO X2Π which has been quantified for v = 2-22, and is found to be bimodal. The results are consistent with two quenching channels. The first forms the ground X3Σ or low-lying a 1Δg electronic state of O2 with a distribution including high vibrational levels of NO X2Π which is slightly hotter than statistical. Two possibilities are identified for the second channel. The first, with a similar quantum yield to that producing higher vibrational levels, forms a highly electronically excited state, such as O2 c1Σ, with low vibrational levels in NO X2Π which are inverted with a distribution resembling that resulting from a sudden or harpoon mechanism. The second is that ground state oxygen is formed with low vibrational energy partitioned into NO X2Π. In addition, vibrationally excited NO2 is observed, but at intensities which indicate that it is formed in low quantum yield. Quantitatively unobservable processes (defined as those which do not form ground state NO (v ≥ 2)) are found to have a branching ratio of at most 25 ± 5%. The results are compared with those of previous studies and the most consistent interpretation suggests that dissociation of O2 to form ground state O(3P) atoms and ground vibrational state NO X2Π (v = 0) is the main reactive process rather than NO2 formation. Qualitatively similar results are seen for the quenching of NO A2Σ+ (v = 1).
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Affiliation(s)
- Julian Few
- Department of Chemistry, University of Oxford, Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford, OX1 3QZ, UK.
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Few J, Hancock G. Rate constants for collisional quenching of NO (A(2)Σ(+), v = 0) by He, Ne, Ar, Kr, and Xe, and infrared emission accompanying rare gas and impurity quenching. Phys Chem Chem Phys 2014; 16:11047-53. [PMID: 24777304 DOI: 10.1039/c4cp00740a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The quenching rates of NO (A(2)Σ(+), v = 0) with He, Ne, Ar, Kr and Xe have been studied at room temperature by measurements of the time dependence of the fluorescence decay following laser excitation. The rates are slow, with upper limits of rate constants determined as between 1.2 and 2.0 × 10(-14) cm(3) molecule(-1) s(-1), considerably lower than those reported before in the literature. Such slow rates can be markedly influenced by impurities such as O2 and H2O which have quenching rate constants close to gas kinetic values. Time resolved Fourier transform infrared emission has been used to observe the products of the quenching processes with the rare gases and with impurities. For He, Ne Ar and Kr there is no difference within experimental error of the populations in NO (X(2)Π v ≥ 2) produced with and without rare gas present, but the low quantum yields of such quenching (of the order of 5% for an atmosphere of rare gas) preclude quantitative information on the quantum states being obtained. For quenching by Xe the collisional formation of electronically excited Xe atoms dominates the emission at early times. Vibrationally excited NO (X(2)Π, v) and products of reactive quenching are observed in the presence of O2 and H2O.
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Affiliation(s)
- Julian Few
- Department of Chemistry, University of Oxford, Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford, OX1 3QZ, UK.
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Sánchez-González R, Bowersox RDW, North SW. Vibrationally excited NO tagging by NO(A²∑⁺) fluorescence and quenching for simultaneous velocimetry and thermometry in gaseous flows. OPTICS LETTERS 2014; 39:2771-2774. [PMID: 24784099 DOI: 10.1364/ol.39.002771] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present measurements demonstrating simultaneous determination of velocity and temperature using a variant of the Vibrationally Excited Nitric Oxide Monitoring (VENOM) technique that does not employ NO2. The variant is based on tagging by electronic excitation of NO in the A²∑(1/2)⁺ (v'=0)←X2Π1/2(v''=0) band and subsequent formation of vibrationally excited NO(X2Π) by spontaneous emission and collisional quenching. Sequential planar laser-induced fluorescence imaging of the nascent NO(X2Π, v''=1) was used to obtain spatially resolved average streamwise velocity and rotational/translational temperature. The temperature determination using this approach extends the applicability of the VENOM technique to low-density, high-speed flows, where slow thermalization of the tagged molecules represents a limiting factor.
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Abstract
This review focuses on experimental studies of the dynamical outcomes following collisional quenching of electronically excited OH A2Σ+ radicals by molecular partners. The experimental observables include the branching between reactive and nonreactive decay channels, kinetic energy release, and quantum state distributions of the products. Complementary theoretical investigations reveal regions of strong nonadiabatic coupling, known as conical intersections, which facilitate the quenching process. The dynamical outcomes observed experimentally are connected to the local forces and geometric properties of the nuclei in the conical intersection region. Dynamical calculations for the benchmark OH-H2 system are in good accord with experimental observations, demonstrating that the outcomes reflect the strong coupling in the conical intersection region as the system evolves from the excited electronic state to quenched products.
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Affiliation(s)
- Julia H. Lehman
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
| | - Marsha I. Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
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Burgos Paci MA, Few J, Gowrie S, Hancock G. Products of the quenching of NO A 2Σ+ (v = 0) by N2O and CO2. Phys Chem Chem Phys 2013; 15:2554-64. [PMID: 23296078 DOI: 10.1039/c2cp43878j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Collisional quenching of NO A (2)Σ(+) (v = 0) by N(2)O and CO(2) has been studied through measurements of vibrationally excited products by time resolved Fourier transform infrared emission. In both cases vibrationally excited NO X (2)Π (v) is seen and quantified in levels v≥ 2 with distributions which are close to statistical. However the quantum yields to produce these levels are markedly different for the two quenchers. For CO(2) such quenching accounts for only ca. 26% of the total: for N(2)O it is ca. 85%. Far more energy is seen in the internal modes of the CO(2) product than those of N(2)O. The results are rationalised in terms of cleavage of the N(2)-O bond being dominant in the latter case, with either a similar O atom production or a specific channel producing almost exclusively NO in low vibrational levels (v = 0,1) for quenching by CO(2). Minor reactive channels yielding NO(2) are seen in both cases, and O((1)D) is observed with low quantum yield in the reaction with N(2)O. The results are discussed in terms of previous models of the quenching processes, and are consistent with the very high yield of NO X (2)Π (v = 0) previously observed by laser induced fluorescence for quenching of NO A (2)Σ(+) (v = 0) by CO(2).
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Dempsey LP, Sechler TD, Murray C, Lester MI. Quantum State Distribution of the OH X2Π Products from Collisional Quenching of OH A2Σ+ by O2 and CO2. J Phys Chem A 2009; 113:6851-8. [DOI: 10.1021/jp902935c] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Logan P. Dempsey
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
| | - Timothy D. Sechler
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
| | - Craig Murray
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
| | - Marsha I. Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
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Dempsey LP, Sechler TD, Murray C, Lester MI, Matsika S. State-resolved distribution of OH X Π2 products arising from electronic quenching of OH A Σ2+ by N2. J Chem Phys 2009; 130:104307. [DOI: 10.1063/1.3077027] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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