| 1. |
- Kiselev, M. D., et al.
(författare)
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An experimental and theoretical study of the Kr 3d correlation satellites
- 2022
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 55:5
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Tidskriftsartikel (refereegranskat)abstract
- The Kr 3d correlation satellites have been studied experimentally by using plane polarized synchrotron radiation to record polarization dependent photoelectron spectra (PES), and theoretically by employing the R-matrix method to calculate photoionization cross sections, PES and angular distributions. The experimental spectra have allowed the photoelectron anisotropy parameters characterizing the angular distributions, and the intensity branching ratios, related to the photoionization partial cross sections, to be evaluated. The results are discussed in terms of normal and conjugate shake-up processes. The experimental and calculated photoelectron angular distributions associated with those correlation satellites that arise predominantly through conjugate shake-up mechanisms are shown to be isotropic. In contrast, the anisotropy parameters associated with satellites due to normal shake-up processes exhibit a dependence on electron kinetic energy similar to that of the anisotropy parameters corresponding to the Kr 3d main lines. The theoretical results include an analysis of the partial waves representing the emitted photoelectron and, for certain correlation satellites, show that a particular ionization continuum dominates. This, in turn, may allow the dominant normal or conjugate shake-up mechanism forming the satellite to be identified.
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| 2. |
- Mailhiot, M., et al.
(författare)
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Multielectron coincidence spectroscopy of the Ar2+(2p-2) double-core-hole decay
- 2023
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Ingår i: Physical Review A. - 2469-9926. ; 107:6
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Tidskriftsartikel (refereegranskat)abstract
- The dominant decay pathways of argon 2p-2 double-core-hole states have been investigated using synchrotron radiation and a magnetic-bottle-type spectrometer coupled with an ion time-of-flight spectrometer. This experiment allows for efficient multi-electron-ion coincidence measurements, and thus for following the Auger cascade step by step in detail. Dominant decay pathways leading to Ar4+ final states via Ar3+ intermediate states have been assigned with the help of theoretical ab initio calculations. The weak correlated decay of the two core holes by emission of a single Auger electron, leading to Ar3+ final states, has been observed at 458.5-eV kinetic energy. Compared to the total decay of the 2p-2 double core vacancies, this two-electron-one-electron process was measured to have a branching ratio of 1.9 x 10-3 & PLUSMN; 1.0 x 10-3. Furthermore, the remaining decay paths of the Ar1+ (1s-1) core hole to higher charge states and their respective contributions to the total yield have been analyzed and show very good agreement with theoretical results.
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| 3. |
- Boudjemia, N., et al.
(författare)
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Electron spectroscopy and dynamics of HBr around the Br 1s(-1) threshold
- 2020
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 22:46, s. 26806-26818
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Tidskriftsartikel (refereegranskat)abstract
- A comprehensive electron spectroscopic study combined with partial electron yield measurements around the Br 1s ionization threshold of HBr at approximately equal to 13.482 keV is reported. In detail, the Br 1s(-1) X-ray absorption spectrum, the 1s(-1) photoelectron spectrum as well as the normal and resonant KLL Auger spectra are presented. Moreover, the L-shell Auger spectra measured with photon energies below and above the Br 1s(-1) ionization energy as well as on top of the Br 1s(-1)sigma* resonance are shown. The latter two Auger spectra represent the second step of the decay cascade subsequent to producing a Br 1s(-1) core hole. The measurements provide information on the electron and nuclear dynamics of deep core-excited states of HBr on the femtosecond timescale. From the different spectra the lifetime broadening of the Br 1s(-1) single core-hole state as well as of the Br(2s(-2),2s(-1)2p(-1),2p(-2)) double core-hole states are extracted and discussed. The slope of the strongly dissociative HBr 2p(-2)sigma* potential energy curve is found to be about -13.60 eV angstrom(-1). The interpretation of the experimental data, and in particular the assignment of the spectral features in the KLL and L-shell Auger spectra, is supported by relativistic calculations for HBr molecule and atomic Br.
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| 4. |
- Mailhiot, M., et al.
(författare)
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Search for the interatomic Auger effect in Nitrous Oxide
- 2023
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 265
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Tidskriftsartikel (refereegranskat)abstract
- The interatomic Auger effect following O 1s ionization in N2O has been experimentally investigated using multi-electron coincidence spectroscopy. The expected transition energies have been established by comparison to the measured N 1s−1v−1 core-valence double ionization energies. We describe a procedure to eliminate the background of two competing processes contributing spectroscopic signatures to the same energy range, namely double Auger decay of the O 1s vacancy and direct single-photon double ionization into the N 1s−1v−1 states. While the interatomic Auger transitions could not be successfully isolated, we provide an upper boundary of the transition probability of 0.07% with respect to the dominant single Auger decay after O 1s ionization.
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| 5. |
- Holappa, M., et al.
(författare)
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Atom-solid binding energy shifts for K 2p and Rb 3d sublevels
- 2011
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 184:7, s. 371-374
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Tidskriftsartikel (refereegranskat)abstract
- Binding energy shifts between free and solid state atoms for K 2p and Rb 3d photolines have been determined by measuring the vapor and solid state spectra simultaneously in similar experimental conditions applying synchrotron radiation excited photoelectron spectroscopy. This method has the important benefit that the work function is not needed to correct for different reference energy levels, therefore much more accurate values for binding energy shifts are obtained. (C) 2011 Elsevier B.V. All rights reserved.
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| 6. |
- Patanen, M., et al.
(författare)
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High-resolution study of K 3p photoabsorption and resonant Auger decay in KF
- 2009
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 80:1
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution (K3p sigma and pi)->sigma absorption spectrum of KF in the photon energy range of 18.2-19.4 eV was measured at the new FINEST beamline branch on the I3 beamline on MAX III. The experimental spectrum is presented and interpreted using nonrelativistic ab initio molecular calculations corrected with perturbation theory treatment to account for spin-orbit interaction. Resonant Auger decay recorded at the strongest resonances is also presented and reproduced by theoretical calculations. Also a brief introduction to the FINEST beamline branch is presented.
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| 7. |
- Patanen, M., et al.
(författare)
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Laboratory-frame electron angular distributions : Probing the chemical environment through intramolecular electron scattering
- 2013
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 87:6, s. 063420-
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Tidskriftsartikel (refereegranskat)abstract
- Carbon 1s photoelectron asymmetry parameters beta for the chlorinated and the methyl carbon atom of CH3CH2Cl, CH3CHCl2, and CH3CCl3 have been measured using synchrotron radiation in the 340-600 eV energy range. We provide experimental evidence that the intramolecular scattering strongly affects beta values, even far from the ionization threshold. The results are in agreement with B-spline density functional theory calculations, making it possible to single out the behavior of the various continuum partial waves. We conclude that the intramolecular scattering makes electron angular distributions sensitive to the chemical environment, even in isolated gas phase molecules.
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| 8. |
- Patanen, M., et al.
(författare)
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Strong molecular field effects in Auger decay of the potassium 2p core-hole state in molecular KCl, KBr and KI
- 2008
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 41:21
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Tidskriftsartikel (refereegranskat)abstract
- The K 2p photoionization and subsequent LMM Auger decay have been studied for molecular gas-phase KCl, KBr and KI. The detected manifold spectral structure of the Auger electron spectrum of KCl has been interpreted to originate from strong molecular field effects. This indicates that Auger decay on potassium side of originally very ionic molecules creates inner-shell hole states with a strong molecular character.
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| 9. |
- Patanen, M., et al.
(författare)
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Valence photoionization and photoelectron-photoion coincidence (PEPICO) study of molecular LiCl and Li2Cl2
- 2012
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 185:8-9, s. 285-293
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Tidskriftsartikel (refereegranskat)abstract
- Molecular LiCl and Li2Cl2 have been studied in the vapor phase with valence photoelectron and photoelectron-photoion coincidence spectroscopies. These two techniques determine the binding energies in fundamentally different ways. Binding energies obtained from photoelectron spectra are usually taken as the vertical ionization energies of the corresponding electronic states. In cases with several overlapping bands, corresponding to different electronic states, the coincidence measurement can separate the bands if the respective final states fragment differently. This applies well to the monomer case. To facilitate the determination of state-specific ionization energies in the dimeric molecule, a theoretical Franck-Condon analysis has been carried out. Moreover, ab initio coupled-cluster and density-functional-theory calculations have been used to analyze the fragmentation pattern based on asymptotic dissociation energies. The fragmentation pattern is largely common to all the accessible valence-ionized states of the chiller, consistent with rapid conversion to the ionic ground state before fragmentation. However, the highest-lying state of Li2Cl2+, (2)A(g). shows enhanced propensity for Li+ as dissociation product. (C) 2012 Elsevier B.V. All rights reserved.
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| 10. |
- Patanen, M., et al.
(författare)
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Valence shell photoelectron angular distributions and vibrationally resolved spectra of imidazole : A combined experimental-theoretical study
- 2021
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 155:5
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Tidskriftsartikel (refereegranskat)abstract
- Linearly polarized synchrotron radiation has been used to record polarization dependent valence shell photoelectron spectra of imidazole in the photon energy range 21–100 eV. These have allowed the photoelectron angular distributions, as characterized by the anisotropy parameter β, and the electronic state intensity branching ratios to be determined. Complementing these experimental data, theoretical photoionization partial cross sections and β-parameters have been calculated for the outer valence shell orbitals. The assignment of the structure appearing in the experimental photoelectron spectra has been guided by vertical ionization energies and spectral intensities calculated by various theoretical methods that incorporate electron correlation and orbital relaxation. Strong orbital relaxation effects have been found for the 15a′, nitrogen lone-pair orbital. The calculations also predict that configuration mixing leads to the formation of several low-lying satellite states. The vibrational structure associated with ionization out of a particular orbital has been simulated within the Franck–Condon model using harmonic vibrational modes. The adiabatic approximation appears to be valid for the X 2A″ state, with the β-parameter for this state being independent of the level of vibrational excitation. However, for all the other outer valence ionic states, a disparity occurs between the observed and the simulated vibrational structure, and the measured β-parameters are at variance with the behavior expected at the level of the Franck–Condon approximation. These inconsistencies suggest that the excited electronic states may be interacting vibronically such that the nuclear dynamics occur over coupled potential energy surfaces.
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