Non Franck-Condon Effects in Photoionization of Molecular Oxygen

Erman, P.; Karawajczyk, A.; Rachlew-Källne, E.; Riu, Jaume Rius i; Stankiewicz, Marek; Franzen, K. Y.; Moen, A Weider; Veseth, L.

doi:10.1238/physica.regular.062a00294

Cited by 8 publications

(3 citation statements)

References 23 publications

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“…Strong mixing between Rydberg and valence excited states also needs to be considered. Erman et al [56] have calculated the energies of several valence excited states but the predicted locations do not correlate particularly well with the features observed in the present study.…”

Section: Fluorescence Yield and Polarization For Thecontrasting

confidence: 78%

A fluorescence polarization study of the O₂⁺A²Π_u→ X²Π_gand the b⁴Σ_g⁻→ a⁴Π_utransitions in the excitation range 17–25 eV

Shaw

Holland

Rennie

et al. 2005

J. Phys. B: At. Mol. Opt. Phys.

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The fluorescence yields and polarizations of the O2+ A2Πu → X2Πg and the b4Σg− → a4Πu transitions have been measured between their thresholds and 25 eV using synchrotron radiation. The O2+ ions may be formed either through direct photoionization or through excitation into a Rydberg state followed by autoionization. The alignment of the resulting (A2Πu or b4Σg− state) ion has been determined by measuring the degree of linear polarization of the fluorescence emitted in the subsequent decay. The fluorescence yields and polarizations display prominent structure associated with autoionizing Rydberg states belonging to series converging onto the b4Σg−, B2Σg− or the c4Σu− ionization thresholds. The structure in the fluorescence polarization data has enabled the symmetry of the super-excited states to be deduced. Although the interpretation of this symmetry information has been straight-forward in regard to the Rydberg series converging onto the c4Σu− limit, the situation is less clear for the Rydberg series converging onto the b4Σg− or the B2Σg− limits. The measured polarizations have been compared with calculated values and, even for the A2Πu → X2Πg transition where the theoretical model incorporates resonant processes, the agreement is not particularly good.

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Section: Fluorescence Yield and Polarization For Thecontrasting

confidence: 78%

A fluorescence polarization study of the O₂⁺A²Π_u→ X²Π_gand the b⁴Σ_g⁻→ a⁴Π_utransitions in the excitation range 17–25 eV

Shaw

Holland

Rennie

et al. 2005

J. Phys. B: At. Mol. Opt. Phys.

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“…Computed excitation energies for the two lowest lying 3 ⌺ u Ϫ states that basically correspond to these configurations, are given in Table VII. 34 Computed results are given based on HF as well as KS orbitals, and in addition also results based on KS orbitals derived for the excited 3 g 1 u 4 1 g 3 , 3 ⌸ g state. Note that the double excitations under study are obtained as single excitations from this singly excited configuration.…”

Section: Similar Results Are Listed For O 2 Inmentioning

confidence: 99%

Molecular excitation energies computed with Kohn–Sham orbitals and exact exchange potentials

Veseth

2001

The Journal of Chemical Physics

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Articles you may be interested inDispersion energy evaluated by using locally projected occupied and excited molecular orbitals for molecular interaction J. Chem. Phys. 135, 094101 (2011); 10.1063/1.3629777Advantages and limitations of Kohn-Sham orbitals as single electron basis for multireference configuration interaction and multireference perturbation theory Physical interpretation and evaluation of the Kohn-Sham and Dyson components of the ε-I relations between the Kohn-Sham orbital energies and the ionization potentialsAb initio molecular orbital studies on the structure, energies, and photodissociation of the electronic excited states of C 2 H Exact local exchange potentials are computed for the diatomic molecules N 2 , O 2 , and CO, based on expansions in terms of molecular orbitals. Kohn-Sham orbitals and orbital energies are obtained for the exact exchange potentials, with correlation effects neglected. The ionization potential is in all cases found to be accurately predicted by the orbital energy of the highest occupied orbital. Limited configuration interaction calculations are performed based on the Kohn-Sham orbitals, and are found to yield accurate excitation energies for a series of singly excited states, in particular for N 2 and CO. Clearly inferior results are obtained from similar calculations by use of Hartree-Fock orbitals. Thus Kohn-Sham orbitals obtained with exact exchange potentials tend to have an interesting potential as basis for sophisticated many-body methods.

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“…Non-Franck-Condon effects have been observed both theoretically and experimentally. 41,42,45 Early theoretical studies using multiple scattering model ͑MSM͒ 42 or STMT method 40,41 with multiplet-averaged potentials and statistic ratio of 2:1 did provide a qualitative picture of the resonance processes. The MSM calculations averaging over internuclear distances 42 achieved even better agreement with experiments.…”

Section: Cross Sections and Asymmetry Parameters For The Photoionimentioning

confidence: 99%

Theoretical studies of cross sections and photoelectron angular distributions in the valence photoionization of molecular oxygen

Lin

Lucchese

2002

The Journal of Chemical Physics

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Photoionization from ground state of molecular oxygen leading to a number of 1 g Ϫ1 , 1 u Ϫ1 , 3 g Ϫ1 , and 2 u Ϫ1 ion states have been investigated for photon energies up to 50 eV using the multichannel Schwinger method with configuration interaction. The use of a multichannel approach and correlated targets not only enables us to obtain results in good agreement with experimental data, but also leads to a better understanding of electron correlation effects in these photoionization processes. In addition to numerous Rydberg-type autoionization states that have been identified in the multichannel study, substantial effects of the open-channel coupling have also been found in almost every channel. These effects are evidences of the strong electron correlation in the photoionization dynamics of this system. The most significant interchannel coupling effect exists in the photoionization to the 3 g Ϫ1 channels, in which a complete failure of the single-channel photoionization description is found in the shape resonance process. In contrast to earlier theoretical studies, we found only one shape resonance in the photoionization to the 3 g Ϫ1 channels instead of two separated multiplet-specific shape resonances. A full description of the resonant state requires the inclusion of coupling to other valence photoionization channels. The photoelectron angular distributions have also been computed and compared to the existing experimental data. Good agreement between experiment and theory has been achieved. In this study, we also calculated molecular orientation parameters under the fixed-nuclei approximation, which contain symmetry information about the resonances and outgoing waves and which can be used to characterize the dynamics of the photoionization.

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Non Franck-Condon Effects in Photoionization of Molecular Oxygen

Cited by 8 publications

References 23 publications

A fluorescence polarization study of the O₂⁺A²Π_u→ X²Π_gand the b⁴Σ_g⁻→ a⁴Π_utransitions in the excitation range 17–25 eV

A fluorescence polarization study of the O₂⁺A²Π_u→ X²Π_gand the b⁴Σ_g⁻→ a⁴Π_utransitions in the excitation range 17–25 eV

Molecular excitation energies computed with Kohn–Sham orbitals and exact exchange potentials

Theoretical studies of cross sections and photoelectron angular distributions in the valence photoionization of molecular oxygen

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Non Franck-Condon Effects in Photoionization of Molecular Oxygen

Cited by 8 publications

References 23 publications

A fluorescence polarization study of the O2+A2Πu→ X2Πgand the b4Σg−→ a4Πutransitions in the excitation range 17–25 eV

A fluorescence polarization study of the O2+A2Πu→ X2Πgand the b4Σg−→ a4Πutransitions in the excitation range 17–25 eV

Molecular excitation energies computed with Kohn–Sham orbitals and exact exchange potentials

Theoretical studies of cross sections and photoelectron angular distributions in the valence photoionization of molecular oxygen

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Product

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A fluorescence polarization study of the O₂⁺A²Π_u→ X²Π_gand the b⁴Σ_g⁻→ a⁴Π_utransitions in the excitation range 17–25 eV

A fluorescence polarization study of the O₂⁺A²Π_u→ X²Π_gand the b⁴Σ_g⁻→ a⁴Π_utransitions in the excitation range 17–25 eV