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Aardema M, Fast M, Meas B, North SW. Rotational Distributions and Imaging of Singlet O 2 Following Spin-Forbidden Photodissociation of O 3. J Phys Chem A 2023; 127:7101-7114. [PMID: 37540577 PMCID: PMC10863062 DOI: 10.1021/acs.jpca.3c02736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 07/14/2023] [Indexed: 08/06/2023]
Abstract
We report REMPI spectra and velocity-mapped ion images of the O2(a1Δg) and (b1Σg+) fragments arising from the spin-forbidden photodissociation of O3 near 320 and 330 nm. The O2(a1Δg, v = 0) REMPI spectrum following a 320 nm dissociation shows enhanced peak intensity for the odd rotational states relative to the even states, which is the opposite of the trend observed by Gunthardt et al. ( J. Chem. Phys. 2019, 151, 224302) for spin-allowed dissociation at 266 nm but is consistent with the couplings between the B state and 3A' and 3A″ states calculated by Grebenshchikov and Rosenwaks ( J. Phys. Chem. A 2010, 114, 9809-9819). There are no significant differences between the ion image angular distributions of fragments in odd and even rotational states, which indicates a cold distribution of O3 and supports the explanation that the alternation in peak intensities results from a difference in the couplings. Quantitative analysis of the image angular distributions was limited due to the single laser polarization geometry accessible in one-color experiments. Radial distributions of the 320 nm images indicate a broad rotational distribution, evidenced in bimodal speed distributions with peaks corresponding to both high (j = 35-43) and low (j = 17-20) rotational states. The REMPI spectrum of O2(a1Δg) near 330 nm was collected, and while quantitative population analysis is difficult because of the perturbed resonant state, the spectrum clearly supports a broad rotational distribution as well, consistent with the images collected at 320 nm. A 2D-REMPI spectrum was collected following dissociation of O3 near 330 nm, which showed evidence of contributions from O2 fragments in both the a1Δg and b1Σg+ states. The rotational distribution for the O2(b1Σg+, v = 0) product peaks at j = 32 and is narrower than that of the O2(a1Δg) fragment, consistent with distributions reported by O'Keeffe et al. at longer dissociation wavelengths ( J. Chem. Phys. 2002, 117, 8705-8709). At smaller radii in the 2D-REMPI spectrum, there is additional signal assigned to v = 1-4 of O2(b1Σg+), with rotational distributions similar to v = 0. The vibrational distribution of the O2(b1Σg+) fragment peaks at v = 0, with populations monotonically decreasing with increasing vibrational state. Ion image angular distributions of the O2(b1Σg+) fragment and the corresponding anisotropy parameters are also reported.
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Affiliation(s)
- Megan
N. Aardema
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Megan Fast
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Benjamen Meas
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Simon W. North
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
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Aardema MN, McBane GC, North SW. Ozone Photodissociation in the Singlet Channel at 226 nm. J Phys Chem A 2022; 126:6898-6907. [PMID: 36129835 DOI: 10.1021/acs.jpca.2c04832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the rotational state distribution and vector correlations of the O2(a 1Δg, v = 0) fragments arising from the 226 nm photodissociation of jet-cooled O3. Consistent with previously reported trends, the rotational distribution is shifted to higher rotational states with decreasing wavelength. We observe highly suppressed odd rotational state populations due to a strong Λ-doublet propensity. The measured rotational distribution is in agreement with classical trajectory calculations for the v = 0 products, although the distribution is slightly narrower than predicted. The spatial anisotropy follows the previously observed trend of decreasing β with increasing photon energy with β = 0.72 ± 0.14 for v = 0, j = 38. As expected for a triatomic molecule, the v-j correlation is consistent with v perpendicular to j, but the measured correlation is nonlimiting due, in part, to rotational and translational depolarization. The j-dependent line width of the O2(a 1Δg) REMPI spectrum is also discussed in connection with the lifetime of the resonant O2(d 1Πg) state due to predissociation via the II 1Πg valence state.
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Affiliation(s)
- Megan N Aardema
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - George C McBane
- Department of Chemistry, Grand Valley State University, Allendale, Michigan 49401, United States
| | - Simon W North
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
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Gunthardt CE, Aardema MN, Hall GE, North SW. Evidence for lambda doublet propensity in the UV photodissociation of ozone. J Chem Phys 2019; 151:224302. [PMID: 31837678 DOI: 10.1063/1.5131504] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The photodissociation of O3 at 266 nm has been studied using velocity mapped ion imaging. We report temperature-dependent vector correlations for the O2(a1Δg, v = 0, j = 18-20) fragments at molecular beam temperatures of 70 K, 115 K, and 170 K. Both the fragment spatial anisotropy and the v-j correlations are found to be increasingly depolarized with increasing beam temperature. At all temperatures, the v-j correlations for the j = 19 state were shown to be reduced compared to those of j = 18 and 20, while no such odd/even rotational state difference was observed for the spatial anisotropy, consistent with previous measurements. We find that temperature-dependent differences in the populations and v-j correlations between the odd and even rotational states can be explained by a Λ-doublet propensity model. Although symmetry conservation should lead to formation of only the A' Λ-doublet component, and only even rotational states, out-of-plane rotation of the parent molecule breaks the planar symmetry and permits the formation of the A″ Λ-doublet component and odd rotational states. A simple classical model to treat the effect of parent rotation on the v-j correlation and the odd/even rotational population alternation reproduces both the current measurements and previously reported rotational distributions, suggesting that the "odd" behavior originates from a Λ-doublet propensity, and not from a mass independent curve crossing effect, as previously proposed.
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Affiliation(s)
- Carolyn E Gunthardt
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | - Megan N Aardema
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | - Gregory E Hall
- Chemistry Division, Brookhaven National Laboratory P.O. Box 5000 Upton, New York 11973-5000, USA
| | - Simon W North
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
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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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Horrocks SJ, Ritchie GAD, Sharples TR. Probing the O2 (a 1Delta g) photofragment following ozone dissociation within the long wavelength tail of the Hartley band. J Chem Phys 2007; 126:044308. [PMID: 17286471 DOI: 10.1063/1.2429656] [Citation(s) in RCA: 10] [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 technique of resonance enhanced multiphoton ionization (REMPI) has been used in conjunction with time-of-flight mass spectrometry (TOFMS), to investigate the dynamics of ozone photolysis in the long wavelength region of the Hartley band (301-311 nm). Specifically, both the translational anisotropy and the rotational angular momentum orientation of the O(2) (a (1)Delta(g); nu=0, J=16-20) fragments have been measured as a function of photolysis wavelength. Within this region, the thermodynamic thresholds for the formation of these products in combination with O ((1)D(2)) are approached and passed, and consequently these studies have allowed an investigation into the effects on the dynamics of slowing fragment recoil velocities and the increasing importance of vibrationally mediated photolysis. The determined beta parameters for all the J states probed follow a similar trend, decreasing from a value typical for the initial (1)B(2)<--(1)A(1) excitation responsible for the Hartley band [for example, beta=1.40+/-0.12 for the O(2) (a (1)Delta(g); J=18) fragment], to a much lower value beyond the thermodynamic threshold for the fragment's production (for example, beta=0.63+/-0.19 for the J=18 fragment following photolysis at 311 nm). This trend, similar to that observed when probing the atomic fragment in a previous set of experiments, [Horrocks et al., J. Chem. Phys. 125, 133313 (2006); Denzer et al., Phys. Chem. Chem. Phys. 16, 1954 (2006)] is consistent with the photodissociation of vibrationally excited ozone molecules beyond the threshold wavelengths and we estimate approximately 1/3 of this to be from excitation in the nu(3) asymmetric stretching mode. These observations are substantiated by the values of the beta(0) (2)(2,1) orientation moment measured, which for photolysis at 301 nm are negative, indicating that a bond opening mechanism provides the key torque for the departing O(2) fragment. The orientation moment becomes positive again for photolysis beyond threshold, however, as the increasing impulsive dissociation again begins to dominate the nature of the rotation of the departing molecular fragment. In addition, a (2+2) REMPI scheme has been utilized to probe the O(2) (a (1)Delta(g)) "low" J fragments, where the majority of the population resides following photolysis within this region. The REMPI-TOFMS technique has been used to confirm the rotational character of a spectral feature through examination of the signal line shapes obtained using different experimental geometries. The dynamical information subsequently obtained, probing the "low" J O(2) (a (1)Delta(g)) fragments on these rotational transitions, has unified previous translational anisotropy results obtained by detecting the O ((1)D(2)) atomic fragment with data for the O(2) (a (1)Delta(g); J=16-20) fragments.
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Affiliation(s)
- S J Horrocks
- Physical and Theoretical Chemistry Laboratory, The University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK
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Matsumi Y, Kawasaki M. Photolysis of Atmospheric Ozone in the Ultraviolet Region. Chem Rev 2003; 103:4767-82. [PMID: 14664632 DOI: 10.1021/cr0205255] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yutaka Matsumi
- Solar Terrestrial Environment Laboratory and Graduate School of Science, Nagoya University, Toyokawa 442-8505, Japan.
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Affiliation(s)
- H Sato
- Laser Photochemistry Research Group, Department of Chemistry for Materials, Faculty of Engineering, Mi'e University, 1515 Kamihamacho, Tsu 514-8507, Japan.
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Lin SY, Han KL, He GZ. Exact three-dimensional quantum mechanical calculation of ozone photodissociation in the Hartley band. J Chem Phys 2001. [DOI: 10.1063/1.1374580] [Citation(s) in RCA: 21] [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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O’Keeffe P, Ridley T, Lawley KP, Maier RRJ, Donovan RJ. Kinetic energy analysis of O(3P0) and O2(b 1Σg+) fragments produced by photolysis of ozone in the Huggins bands. J Chem Phys 1999. [DOI: 10.1063/1.479023] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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O'Keeffe P, Ridley T, Wang S, Lawley KP, Donovan RJ. Photodissociation of ozone between 335 and 352 nm to give O2(b1Σ+g)+O(3PJ). Chem Phys Lett 1998. [DOI: 10.1016/s0009-2614(98)01190-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Denzer W, Hancock G, Pinot de Moira JC, Tyley PL. Spin-forbidden dissociation of ozone in the Huggins bands. Chem Phys 1998. [DOI: 10.1016/s0301-0104(97)00328-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Takahashi K, Taniguchi N, Matsumi Y, Kawasaki M, Ashfold MNR. Wavelength and temperature dependence of the absolute O(1D) production yield from the 305–329 nm photodissociation of ozone. J Chem Phys 1998. [DOI: 10.1063/1.476133] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Denzer W, Hancock G, Pinot de Moira JC, Tyley PL. Direct observation of spin-forbidden formation of O(1D) in the near-UV photolysis of ozone. Chem Phys Lett 1997. [DOI: 10.1016/s0009-2614(97)01187-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Role of spin-orbit coupling in processes of synthesis and photodegradation of ozone. THEOR EXP CHEM+ 1997. [DOI: 10.1007/bf02764766] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Takahashi K, Kishigami M, Taniguchi N, Matsumi Y, Kawasaki M. Photofragment excitation spectrum for O(1D)from the photodissociation of jet-cooled ozone in the wavelength range 305–329 nm. J Chem Phys 1997. [DOI: 10.1063/1.473629] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Relative quantum yields for O1D production in the photolysis of ozone between 301 and 336 nm: evidence for the participation of a spin-forbidden channel. Chem Phys Lett 1997. [DOI: 10.1016/s0009-2614(96)01342-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Ball SM, Hancock G, Martin SE, Pinot de Moira JC. A direct measurement of the O(1D) quantum yields from the photodissociation of ozone between 300 and 328 nm. Chem Phys Lett 1997. [DOI: 10.1016/s0009-2614(96)01363-2] [Citation(s) in RCA: 26] [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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Takahashi K, Kishigami M, Matsumi Y, Kawasaki M, Orr‐Ewing AJ. Observation of the spin‐forbidden O(1D)+O2(X 3Σg−) channel in the 317–327 nm photolysis of ozone. J Chem Phys 1996. [DOI: 10.1063/1.472370] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Takahashi K, Matsumi Y, Kawasaki M. Photodissociation Processes of Ozone in the Huggins Band at 308−326 nm: Direct Observation of O(1D2) and O(3Pj) Products. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp9528065] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kenshi Takahashi
- Institute for Electronic Science, and Graduate School of Environmental Science, Hokkaido University, Sapporo 060, Japan
| | - Yutaka Matsumi
- Institute for Electronic Science, and Graduate School of Environmental Science, Hokkaido University, Sapporo 060, Japan
| | - Masahiro Kawasaki
- Institute for Electronic Science, and Graduate School of Environmental Science, Hokkaido University, Sapporo 060, Japan
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