The O2-2Πgresonance: theoretical analysis of electron scattering data

Parlant, Gérard; Fiquet-Fayard, F.

doi:10.1088/0022-3700/9/9/024

Cited by 58 publications

(29 citation statements)

References 23 publications

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“…Similar to that of FeO 4 , , MnO 4 has a peroxo isomer where two oxygen atoms are bound to Mn dissociatively, whereas the other two are bound associatively (n2, see Figure ). Note that the distance between peroxo oxygens is 1.41 Å, which can be compared with the bond lengths of 1.21 Å in the 3 ∑ - g ground state of O 2 , 1.23 Å in the excited 1 Δ g state of O 2 , and 1.36 Å in the 2 Π g ground state of O 2 - . The peroxo isomer is above the ground state of neutral MnO 4 by 0.2 eV.…”

Section: Resultsmentioning

confidence: 92%

Photodecomposition of MnO₄^-: A Theoretical Study

1999

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The electronic and geometrical structures of the ground states and low-lying isomers of MnO 4 and MnO 4 -have been calculated as a function of spin-multiplicities by using the molecular orbital theory based on generalized gradient approximation to the density functional formalism. Total energies of isomers are used for evaluating the energetics of the MnO 4 -decay through various fragmentation channels. Two primary channels were found depending on the energy of photons. The preferred photofragmentation channel, accessible with ≈2 eV photons, is found to involve an initial excitation of the ground-state MnO 4 -anion into its peroxo isomer followed by subsequent excitations into a superoxo form. Photodetachment of an extra electron from this superoxo isomer anion leads to the formation of a neutral superoxo isomer of MnO 4 , which, in turn, dissociates to MnO 2 + O 2 . Excitations of the anion peroxo isomer into biperoxo isomer are also possible with 3.7 eV, photons and the latter could dissociate spontaneously to MnO 2 -+ O 2 . A number of other decay channels are accessible with low-energy photons, but their intensities are expected to be low because these require flipping the spin of one or more electrons.

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Section: Resultsmentioning

confidence: 92%

Photodecomposition of MnO₄^-: A Theoretical Study

1999

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“…Due to spin−orbit coupling in the 2 Π O 2 •- , population of the first low-lying electronic state was accounted for in the calculation of its electronic partition function. An energy splitting of 160 cm -1 , obtained by Parlant and Fiquet-Fayard, with the ground and excited states both having a degeneracy of 2, was used. Pyrroline N -oxides with two equivalent 5-position substituents (i.e., DMPO) have TS structures that are enantiomeric.…”

Section: Methodsmentioning

confidence: 99%

Reactivity of Superoxide Radical Anion with Cyclic Nitrones: Role of Intramolecular H-Bond and Electrostatic Effects

et al. 2007

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Limitations exist among the commonly used cyclic nitrone spin traps for biological free radical detection using electron paramagnetic resonance (EPR) spectroscopy. The design of new spin traps for biological free radical detection and identification using EPR spectroscopy has been a major challenge due to the lack of systematic and rational approaches to their design. In this work, density functional theory (DFT) calculations and stopped-flow kinetics were employed to predict the reactivity of functionalized spin traps with superoxide radical anion (O 2•− ). Functional groups provide versatility and can potentially improve spin-trap reactivity, adduct stability, and target specificity. The effect of functional group substitution at the C-5 position of pyrroline N-oxides on spin-trap reactivity towards O 2•− was computationally rationalized at the PCM/B3LYP/ 6−31+G(d,p)//B3LYP/6−31G(d) and PCM/mPW1K/6−31+G(d,p) levels of theory. Calculated free energies and rate constants for the reactivity of O 2•− with model nitrones were found to correlate with the experimentally obtained rate constants using stopped-flow and EPR spectroscopic methods. New insights into the nucleophilic nature of O 2•− addition to nitrones as well as the role of intramolecular hydrogen bonding of O 2•− in facilitating this reaction are discussed. This study shows that using an N-monoalkylsubstituted amide or an ester as attached groups on the nitrone can be ideal in molecular tethering for improved spin-trapping properties and could pave the way for improved in vivo radical detection at the site of superoxide formation.

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“…Celotta et al [3] later measured the electron affinity of O 2 using molecular photodetachment spectroscopy. Those two complementary studies [2,3] provide a deeper understanding of the structure and dynamics of the 2 Π g state of O − 2 [4]. Several previously published theoretical treatments based on the R-matrix method deal with the 2 Π g resonance in the fixed-nuclei approximation [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Low-energy electron collisions with O2: Test of the molecularR-matrix method without diagonalization

Tarana

Greene

2013

Phys. Rev. A

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Electron collisions with O2 at scattering energies below 1 eV are studied in the fixed-nuclei approximation for a range of internuclear separations using the ab initio molecular R-matrix method. The 2 Πg scattering eigenphases and quantum defects are calculated. The parameters of the resonance and the energy of the bound negative ion are then extracted. Different models of the target that employ molecular orbitals calculated for the neutral target are compared with models based on anionic orbitals. A model using a basis of anionic molecular orbitals yields physically correct results in good agreement with experiment. An alternative method of calculation of the R-matrix is tested, where instead of performing a single complete diagonalization of the Hamiltonian matrix in the inner region, the system of linear equations is solved individually for every scattering energy. This approach is designed to handle problems where diagonalization of an extremely large Hamiltonian is numerically too demanding.

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The O₂^-2Π_gresonance: theoretical analysis of electron scattering data

Cited by 58 publications

References 23 publications

Photodecomposition of MnO₄^-: A Theoretical Study

Photodecomposition of MnO₄^-: A Theoretical Study

Reactivity of Superoxide Radical Anion with Cyclic Nitrones: Role of Intramolecular H-Bond and Electrostatic Effects

Low-energy electron collisions with O2: Test of the molecularR-matrix method without diagonalization

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The O2-2Πgresonance: theoretical analysis of electron scattering data

Cited by 58 publications

References 23 publications

Photodecomposition of MnO4-: A Theoretical Study

Photodecomposition of MnO4-: A Theoretical Study

Reactivity of Superoxide Radical Anion with Cyclic Nitrones: Role of Intramolecular H-Bond and Electrostatic Effects

Low-energy electron collisions with O2: Test of the molecularR-matrix method without diagonalization

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The O₂^-2Π_gresonance: theoretical analysis of electron scattering data

Photodecomposition of MnO₄^-: A Theoretical Study

Photodecomposition of MnO₄^-: A Theoretical Study