| 1. |
- Bowen, K. P., et al.
(författare)
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Nondipole Effects in Chiral Molecules Measured with Linearly Polarized Light
- 2015
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 635
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Tidskriftsartikel (refereegranskat)abstract
- We present the first-ever measurement of nondipole chiral angular distribution parameters for C 1s photoemission from each enantiomer of camphor in the photon energy range 296-343eV using linearly polarized light. The angular distribution parameters are determined to be enantiomer-specific, suggesting a new form of linear dichroism.
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| 2. |
- Bowen, K. P., et al.
(författare)
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Partial-ion-yield studies of SOCl 2 following x-ray absorption around the S and Cl K edges
- 2012
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 137:20, s. 204313-
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Tidskriftsartikel (refereegranskat)abstract
- We present a series of photoabsorption and partial-ion-yield experiments on thionyl chloride, SOCl2, at both the sulfur and chlorine K edges. The photoabsorption results exhibit better resolution than previously published data, leading to alternate spectral assignments for some of the features, particularly in the Rydberg-series region. Based on measured fragmentation patterns, we suggest the LUMO, of a' character, is delocalized over the entire molecular skeleton. Unusual behavior of the S2+ fragment hints at a relatively localized bond rupture (the S-O bond below the S K edge and the S-Cl bonds below the Cl K edge) following excitation to some of the higher lying intermediate states.
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| 3. |
- Carniato, S., et al.
(författare)
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A new method to derive electronegativity from resonant inelastic x-ray scattering
- 2012
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 137:14, s. 144303-
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Tidskriftsartikel (refereegranskat)abstract
- Electronegativity is a well-known property of atoms and substituent groups. Because there is no direct way to measure it, establishing a useful scale for electronegativity often entails correlating it to another chemical parameter; a wide variety of methods have been proposed over the past 80 years to do just that. This work reports a new approach that connects electronegativity to a spectroscopic parameter derived from resonant inelastic x-ray scattering. The new method is demonstrated using a series of chlorine-containing compounds, focusing on the Cl 2p(-1)LUMO(1) electronic states reached after Cl 1s -> LUMO core excitation and subsequent KL radiative decay. Based on an electron-density analysis of the LUMOs, the relative weights of the Cl 2p(z) atomic orbital contributing to the Cl 2p(3/2) molecular spin-orbit components are shown to yield a linear electronegativity scale consistent with previous approaches.
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| 4. |
- Carniato, S., et al.
(författare)
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Thomson-resonant interference effects in elastic x-ray scattering near the Cl K edge of HCl
- 2012
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 137:9, s. 094311-
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Tidskriftsartikel (refereegranskat)abstract
- We experimentally observed interference effects in elastic x-ray scattering from gas-phase HCl in the vicinity of the Cl Kedge. Comparison to theory identifies these effects as interference effects between non-resonant elastic Thomson scattering and resonant Raman scattering. The results indicate the non-resonant Thomson and resonant Raman contributions are of comparable strength. The measurements also exhibit strong polarization dependence, allowing an easy identification of the resonant and non-resonant contributions.
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| 5. |
- Ceolin, Denis, et al.
(författare)
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Fragmentation of methyl chloride studied by partial positive and negative ion-yield spectroscopy
- 2007
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 126:8, s. 084309-
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Tidskriftsartikel (refereegranskat)abstract
- The authors present partial-ion-yield experiments on the methyl chloride molecule excited in the vicinity of the C12p and C1s inner shells. A large number of fragments, cations produced by dissociation or recombination processes, as well as anionic species, have been detected. Although the spectra exhibit different intensity distributions depending on the core-excited atom, general observations include strong site-selective fragmentation along the C-Cl bond axis and a strong intensity dependence of transitions involving Rydberg series on fragment size.
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| 6. |
- Céolin, D, et al.
(författare)
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Partial ion yield spectroscopy around the Cl 2p and C 1s ionization thresholds in CF3Cl
- 2009
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 131:24, s. 244301-
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Tidskriftsartikel (refereegranskat)abstract
- We present a partial ion yield experiment on freon 13, CF3Cl, excited in the vicinity of the C 1s and Cl 2p ionization thresholds. We have collected a large amount of cationic fragments and a few anionic fragments at both edges. We have observed a strong intensity dependence of Rydberg transitions with ion fragment size for the CFnCl+ and CFn+/F+ (n=0-3) series at both the Cl 2p and C 1s ionization edges. Selectivity in the fragmentation processes involving the C-Cl and C-F bonds are highlighted by the intensities of the C 1s to lowest unoccupied molecular orbital (LUMO) and LUMO+1 transitions measured on the CFnCl+ and CFn+ yields. Equally, by comparison with their cation counterpart, we discuss possible bond-length dependence for the anion formation at the carbon 1s edge.
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| 7. |
- Derevianko, A, et al.
(författare)
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Electric-octupole and pure-electric-quadrupole effects in soft-X-ray photoemission
- 2000
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Ingår i: Physical Review Letters. - 0031-9007. ; 84:10, s. 2116-2119
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Tidskriftsartikel (refereegranskat)abstract
- Second-order [O(k(2)), k = omega/c] nondipole effects in soft-x-ray photoemission are demonstrated via an experimental and a theoretical study of angular distributions of neon valence photoelectrons in the 100-1200 eV photon-energy range. A newly derived theoretical expression for nondipolar angular distributions characterizes the second-order effects using four new parameters with primary contributions from pure-quadrupole and octupole-dipole interference terms;Independent-particle calculations of these parameters account for a significant portion of the existing discrepancy between experiment and theory for Ne 2p first-order nondipole parameters.
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| 8. |
- Dias, E.W.B, et al.
(författare)
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Breakdown of the independent particle approximation in high-energy photoionization
- 1997
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Ingår i: Physical Review Letters. - 0031-9007. ; 78:24, s. 4553-4556
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Tidskriftsartikel (refereegranskat)abstract
- The independent particle approximation is shown to break down for the photoionization of both inner and outer nl (l > 0) electrons of all atoms, at high enough energy, owing to interchannel interactions with the nearby ns photoionization channels. The effect is illustrated for Ne 2p in the 1 keV photon energy range through a comparison of theory and experiment. The implications for x-ray photoelectron spectroscopy of molecules and condensed matter are discussed.
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| 9. |
- Guillemin, R., et al.
(författare)
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Selecting core-hole localization or delocalization in CS2 by photofragmentation dynamics
- 2015
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Electronic core levels in molecules are highly localized around one atomic site. However, in single-photon ionization of symmetric molecules, the question of core-hole localization versus delocalization over two equivalent atoms has long been debated as the answer lies at the heart of quantum mechanics. Here, using a joint experimental and theoretical study of core-ionized carbon disulfide (CS2), we demonstrate that it is possible to experimentally select distinct molecular-fragmentation pathways in which the core hole can be considered as either localized on one sulfur atom or delocalized between two indistinguishable sulfur atoms. This feat is accomplished by measuring photoelectron angular distributions within the frame of the molecule, directly probing entanglement or disentanglement of quantum pathways as a function of how the molecule dissociates.
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| 10. |
- Hemmers, O, et al.
(författare)
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Beyond the dipole approximation: angular-distribution effects in valence photoemission
- 1997
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - 0953-4075. ; 30:21, s. L727-L733
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Tidskriftsartikel (refereegranskat)abstract
- Angular distributions of valence photoelectrons showing effects due to highermultipole photon interactions have been measured for the first time. Neon 2s and 2p photoemission exhibits effects beyond the dipole approximation throughout the 250 to 1200 eV photon-energy range studied. The results suggest that any photoemission experiment, on any sample, can be affected at relatively low photon energies, pointing to a general need for caution in interpreting angle-resolved-photoemission measurements.
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