An x-ray absorption and a normal Auger study of the fine structure in the S2p<sup>−1</sup>region of the CS<sub>2</sub>molecule

Hedin, Lage; Eland, J. H. D.; Karlsson, Lennart; Feifel, Raimund

doi:10.1088/0953-4075/42/8/085102

Cited by 5 publications

(2 citation statements)

References 15 publications

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“…23 It was initially hoped that stable triply charged ions might be unusually abundant at some particular resonance, but while no such enhancement was found, the spectra showed one interesting characteristic. The S 2 + fragment ion, whose formation requires a rearrangement, is formed with strongly enhanced abundance following excitation of most of the resonances.…”

Section: A Pepipico Experimentsmentioning

confidence: 99%

Spectra of the triply charged ion CS23+ and selectivity in molecular Auger effects

Eland

Rigby

Andersson

et al. 2010

The Journal of Chemical Physics

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Spectra of triply charged carbon disulphide have been obtained by measuring, in coincidence, all three electrons ejected in its formation by photoionization. Measurements of the CS 2 3+ ion in coincidence with the three electrons identify the energy range where stable trications are formed. A sharp peak in this energy range is identified as the 2 ⌸ ground state at 53.1Ϯ 0.1 eV, which is the lowest electronic state according to ab initio molecular orbital calculations. Triple ionization by the double Auger effect is provisionally divided, on the basis of the pattern of energy sharing between the two Auger electrons into contributions from direct and cascade Auger processes. The spectra from the direct double Auger effect via S 2p, S 2s, and C 1s hole states contain several resolved features and show selectivity based on the initial charge localization and on the identity of the initial state. Triple ionization spectra from single Auger decay of S 2p-based core-valence states CS 2 2+show retention of the valence holes in this Auger process. Related ion-electron coincidence measurements give the triple ionization yields and the breakdown patterns in triple photoionization at selected photon energies from 90 eV to above the inner shell edges.

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Section: A Pepipico Experimentsmentioning

confidence: 99%

Spectra of the triply charged ion CS23+ and selectivity in molecular Auger effects

Eland

Rigby

Andersson

et al. 2010

The Journal of Chemical Physics

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“…The energy scale for all spectra is calibrated using known core-to-valence transitions in argon, carbon disulfide, , and methyl iodide . The spectral resolution is determined to be 360 ± 20 meV by the Gaussian broadening of the 2p 3/2 → 4s transition in argon to match the observed spectra, assuming the core–hole lifetime broadening is 120 meV (Figure S2).…”

Section: Experimental Methodsmentioning

confidence: 99%

Electron-Withdrawing Effects in the Photodissociation of CH₂ICl To Form CH₂Cl Radical, Simultaneously Viewed Through the Carbon K and Chlorine L_2,3 X-ray Edges

et al. 2018

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A fundamental chlorine-containing radical, CH 2 Cl, is generated by the ultrafast photodissociation of CH 2 ICl at 266 nm and studied at both the carbon K edge (∼284 eV) and chlorine L 2,3 edge (∼200 eV) by femtosecond X-ray transient absorption spectroscopy. The electronic structure of CH 2 Cl radical is characterized by a prominent new carbon 1s X-ray absorption feature at lower energy, resulting from a transition to the half-filled frontier carbon 2p orbital (singly occupied molecular orbital of the radical; SOMO). Shifts of other core-to-valence absorption features upon photodissociation of CH 2 ICl to yield •CH 2 Cl indicate changes in the energies of core-level transitions of carbon and chlorine to the σ*(C−Cl) valence orbital. When the C−I bond breaks, loss of the electron-withdrawing iodine atom donates electron density back to carbon and shields the carbon 1s core level, resulting in a ∼0.8 eV red shift of the carbon 1s to σ*(C−Cl) transition. Meanwhile, the 2p inner shell of the chlorine atom in the radical is less impacted by the iodine atom removal, as demonstrated by the observation of a ∼0.6 eV blue shift of the transitions at the chlorine L 2,3 edges, mainly due to the stronger C−Cl bond and the increased energy of the σ*(C−Cl) orbital. The results suggest that the shift in the carbon 1s orbital is greater than the shift in the σ*(C−Cl) orbital upon going from the closed-shell molecule to the radical. Ab initio calculations using the equation of motion coupled-cluster theory establish rigorous assignment and positions of the X-ray spectral features in the parent molecule and the location of the SOMO in the CH 2 Cl radical.

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Highly Accurate and Robust Constraint-Based Orbital-Optimized Core Excitations

Lemke,

Kussmann,

Ochsenfeld

2024

J. Phys. Chem. A

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We adapt our recently developed constraint-based orbital-optimized excited-state method (COOX) for the computation of core excitations. COOX is a constrained density functional theory (cDFT) approach based on excitation amplitudes from linear-response time-dependent DFT (LR-TDDFT), and has been shown to provide accurate excitation energies and excited-state properties for valence excitations within a spin-restricted formalism.To extend COOX to core-excited states, we introduce a spinunrestricted variant which allows us to obtain orbital-optimized core excitations with a single constraint. Using a triplet purification scheme in combination with the constrained unrestricted Hartree− Fock formalism, scalar-relativistic zero-order regular approximation corrections, and a semiempirical treatment of spin−orbit coupling, COOX is shown to produce highly accurate results for K-and L-edge excitations of second-and third-period atoms with subelectronvolt errors despite being based on LR-TDDFT, for which core excitations pose a well-known challenge. L-and M-edge excitations of heavier atoms up to uranium are also computationally feasible and numerically stable, but may require more advanced treatment of relativistic effects. Furthermore, COOX is shown to perform on par with or better than the popular ΔSCF approach while exhibiting more robust convergence, highlighting it as a promising tool for inexpensive and accurate simulations of X-ray absorption spectra.

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An x-ray absorption and a normal Auger study of the fine structure in the S2p⁻¹region of the CS₂molecule

Cited by 5 publications

References 15 publications

Spectra of the triply charged ion CS23+ and selectivity in molecular Auger effects

Spectra of the triply charged ion CS23+ and selectivity in molecular Auger effects

Electron-Withdrawing Effects in the Photodissociation of CH₂ICl To Form CH₂Cl Radical, Simultaneously Viewed Through the Carbon K and Chlorine L_2,3 X-ray Edges

Highly Accurate and Robust Constraint-Based Orbital-Optimized Core Excitations

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An x-ray absorption and a normal Auger study of the fine structure in the S2p−1region of the CS2molecule

Cited by 5 publications

References 15 publications

Spectra of the triply charged ion CS23+ and selectivity in molecular Auger effects

Spectra of the triply charged ion CS23+ and selectivity in molecular Auger effects

Electron-Withdrawing Effects in the Photodissociation of CH2ICl To Form CH2Cl Radical, Simultaneously Viewed Through the Carbon K and Chlorine L2,3 X-ray Edges

Highly Accurate and Robust Constraint-Based Orbital-Optimized Core Excitations

Contact Info

Product

Resources

About

An x-ray absorption and a normal Auger study of the fine structure in the S2p⁻¹region of the CS₂molecule

Electron-Withdrawing Effects in the Photodissociation of CH₂ICl To Form CH₂Cl Radical, Simultaneously Viewed Through the Carbon K and Chlorine L_2,3 X-ray Edges