| 1. |
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| 2. |
- Felicissimo, V.C., et al.
(författare)
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Proton transfer mediated by the vibronic coupling in oxygen core ionized states of glyoxalmonoxime studied by infrared-X-ray pump-probe spectroscopy.
- 2006
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 110:47, s. 12805-12813
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Tidskriftsartikel (refereegranskat)abstract
- The theory of IR-X-ray pump-probe spectroscopy beyond the Born-Oppenheimer approximation is developed and applied to the study of the dynamics of intramolecular proton transfer in glyoxalmonoxime leading to the formation of the tautomer 2-nitrosoethenol. Due to the IR pump pulses the molecule gains sufficient energy to promote a proton to a weakly bound well. A femtosecond X-ray pulse snapshots the wave packet route and, hence, the dynamics of the proton transfer. The glyoxalmonoxime molecule contains two chemically nonequivalent oxygen atoms that possess distinct roles in the hydrogen bond, a hydrogen donor and an acceptor. Core ionizations of these form two intersecting core-ionized states, the vibronic coupling between which along the OH stretching mode partially delocalizes the core hole, resulting in a hopping of the core hole from one site to another. This, in turn, affects the dynamics of the proton transfer in the core-ionized state. The quantum dynamical simulations of X-ray photoelectron spectra of glyoxalmonoxime driven by strong IR pulses demonstrate the general applicability of the technique for studies of intramolecular proton transfer in systems with vibronic coupling.
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| 3. |
- Sałek, P., et al.
(författare)
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Resonant X-ray Raman scattering involving avoided crossings in the final-state potential-energy curves
- 2000
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 1050-2947. ; 62:6, s. 62501-62506
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Tidskriftsartikel (refereegranskat)abstract
- The effect of avoided crossings on the spectral profiles of resonant X-ray Raman scattering was investigated. The theory was also applied to nitrogen molecule in the core-excited level to analyze the electron decay process. The dependence of internuclear distance on electron transition amplitude was considered important with respect to the breakdown process of the transition. The correlation between the nuclear and electronic degrees of freedom was also reported.
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| 4. |
- AGREN, H, et al.
(författare)
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SYMMETRY SELECTIVE RESONANT INELASTIC X-RAY-SCATTERING
- 1995
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Ingår i: PHYSICA B. - : ELSEVIER SCIENCE BV. - 0921-4526. ; 209:1-4, s. 105-107
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We use two species with high point group symmetry, fullerene and benzene, to discuss important features of symmetry selective resonant inelastic X-ray scattering spectroscopy.
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| 5. |
- Bjorneholm, O, et al.
(författare)
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Femtosecond dissociation of core-excited HCl monitored by frequency detuning
- 1997
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Ingår i: PHYSICAL REVIEW LETTERS. - : AMER INST PHYSICS. - 0031-9007. ; 79:17, s. 3150-3153
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Core excitation of gaseous HCl to the dissociative sigma* state leads to a deexcitation spectrum with two qualitatively different contributions-a broad molecular background and narrow atomic lines. The experiment demonstrates that the ratio of integrated
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| 6. |
- C. Couto, Rafael, 1987-, et al.
(författare)
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Selective gating to vibrational modes through resonant X-ray scattering
- 2017
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Ingår i: Nature Communications. - : Macmillan Publishers Ltd.. - 2041-1723. ; 8, s. 14165-1-14165-7
-
Tidskriftsartikel (refereegranskat)abstract
- The dynamics of fragmentation and vibration of molecular systems with a large number of coupled degrees of freedom are key aspects for understanding chemical reactivity and properties. Here we present a resonant inelastic X-ray scattering (RIXS) study to show how it is possible to break down such a complex multidimensional problem into elementary components. Local multimode nuclear wave packets created by X-ray excitation to different core-excited potential energy surfaces (PESs) will act as spatial gates to selectively probe the particular ground-state vibrational modes and, hence, the PES along these modes. We demonstrate this principle by combining ultra-high resolution RIXS measurements for gas-phase water with state-of-the-art simulations.
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| 7. |
- Cesar, A, et al.
(författare)
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Resonant x-ray scattering beyond the Born-Oppenheimer approximation: Symmetry breaking in the oxygen resonant x-ray emission spectrum of carbon dioxide
- 1997
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Ingår i: Journal of Chemical Physics. - 0021-9606. ; 106:9, s. 3439-3456
-
Tidskriftsartikel (refereegranskat)abstract
- Although resonant x-ray scattering of molecules fulfills strict electronic symmetry selection rules, as now firmly proven by. spectra of diatomic molecules, the accumulated body of data for polyatomic molecules indicates that an apparent breaking of these rules represents the common situation rather than the exception. The CO2 molecule provides a good example of symmetry breaking, with the. oxygen x-ray emission spectra showing strong intensity for transitions that are forbidden by the parity selection rule. We present time-independent and time-dependent theories for frequency-dependent resonant x-ray scattering beyond, the Born-Oppenheimer approximation in order to explore under what circumstances one can anticipate symmetry breaking in the spectra of polyatomic molecules. The theory starts out from the Kramers-Heisenberg dispersion relation and is generalized for vibrational degrees of freedom and for nonadiabatic coupling of the electronic (vibronic) states, including the frequency dependency of, the scattering cross section. Different Limiting cases and few-level models are considered. The symmetry breaking is proven to be the result of pseudo-Jahn-Teller-Like vibronic coupling between near-degenerate core-excited states. Thus vibromic interaction over the antisymmetric vibrational mode between the ''bright'' 1 sigma(g)(-1)2 pi(u)(-1) and ''dark'' 1 sigma(u)(-1)2 pi(u)(-1) intermediate states of CO2 allows transitions otherwise forbidden. The measurements and theory demonstrate that the symmetry-selective character of the resonant x-ray emission is strongly frequency dependent. The strong intensity of ''dipole-forbidden'' transitions in the pi* oxygen K spectrum at resonance is reduced monotonically with the detuning of the excitation energy from resonance, and the spectra become ''symmetry purified.'' Simulations with full vibronic coupling predict this feature of the x-ray scattering experiment and a few-level model explains the energy dependence of the symmetry selection and the symmetry purification at large detuning energies in the limit of narrowband photon excitation.
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| 8. |
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| 9. |
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| 10. |
- Couto, Rafael C., et al.
(författare)
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Anomalously strong two-electron one-photon X-ray decay transitions in CO caused by avoided crossing
- 2016
-
Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- The unique opportunity to study and control electron-nuclear quantum dynamics in coupled potentials offered by the resonant inelastic X-ray scattering (RIXS) technique is utilized to unravel an anomalously strong two-electron one-photon transition from core-excited to Rydberg final states in the CO molecule. High-resolution RIXS measurements of CO in the energy region of 12-14 eV are presented and analyzed by means of quantum simulations using the wave packet propagation formalism and ab initio calculations of potential energy curves and transition dipole moments. The very good overall agreement between the experimental results and the theoretical predictions allows an in-depth interpretation of the salient spectral features in terms of Coulomb mixing of "dark" with "bright" final states leading to an effective two-electron one-photon transition. The present work illustrates that the improved spectral resolution of RIXS spectra achievable today may call for more advanced theories than what has been used in the past.
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| 11. |
- Couto, Rafael C., et al.
(författare)
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Coupled electron-nuclear dynamics in resonant 1 sigma -> 2 pi x-ray Raman scattering of CO molecules
- 2016
-
Ingår i: Physical Review A. - : American Physical Society. - 2469-9926. ; 93:3
-
Tidskriftsartikel (refereegranskat)abstract
- We present a detailed experimental-theoretical analysis of O K-edge resonant 1 sigma-2 pi inelastic x-ray scattering (RIXS) from carbon monoxide with unprecedented energy resolution. We employ high-level ab initio calculations to compute the potential energy curves of the states involved in the RIXS process and simulate the measured RIXS spectra using the wave-packet-propagation formalism, including Coulomb coupling in the final-state manifold. The theoretical analysis allows us to explain all the key features of the experimental spectra, including some that were not seen before. First, we clearly show the interference effect between different RIXS channels corresponding to the transition via orthogonal (1)Pi(x) and (1)Pi(y) core-excited states of CO. Second, the RIXS region of 13 eV energy loss presents a triple structure, revealed only by the high-resolution measurement. In previous studies, this region was attributed solely to a valence state. Here we show a strong Coulomb mixing of the Rydberg and valence final states, which opens the forbidden RIXS channels to the "dark" final Rydberg states and drastically changes the RIXS profile. Third, using a combination of high-resolution experiment and high-level theory, we improve the vertical bar 4 sigma(-1)2 pi(1)> final-state potential-energy curve by fitting its bottom part with the experiment. Also, the coupling constants between Rydberg and valence states were refined via comparison with the experiment. Our results illustrate the large potential of the RIXS technique for advanced studies of highly excited states of neutral molecules.
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| 12. |
- Couto, Rafael C., et al.
(författare)
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Coupled electron-nuclear dynamics in resonant 1σ→2π x-ray Raman scattering of CO molecules
- 2016
-
Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 93:3
-
Tidskriftsartikel (refereegranskat)abstract
- We present a detailed experimental-theoretical analysis of O K-edge resonant 1σ-2π inelastic x-ray scattering (RIXS) from carbon monoxide with unprecedented energy resolution. We employ high-level ab initio calculations to compute the potential energy curves of the states involved in the RIXS process and simulate the measured RIXS spectra using the wave-packet-propagation formalism, including Coulomb coupling in the final-state manifold. The theoretical analysis allows us to explain all the key features of the experimental spectra, including some that were not seen before. First, we clearly show the interference effect between different RIXS channels corresponding to the transition via orthogonal Πx1 and Πy1 core-excited states of CO. Second, the RIXS region of 13 eV energy loss presents a triple structure, revealed only by the high-resolution measurement. In previous studies, this region was attributed solely to a valence state. Here we show a strong Coulomb mixing of the Rydberg and valence final states, which opens the forbidden RIXS channels to the "dark" final Rydberg states and drastically changes the RIXS profile. Third, using a combination of high-resolution experiment and high-level theory, we improve the |4σ-12π1) final-state potential-energy curve by fitting its bottom part with the experiment. Also, the coupling constants between Rydberg and valence states were refined via comparison with the experiment. Our results illustrate the large potential of the RIXS technique for advanced studies of highly excited states of neutral molecules.
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| 13. |
- Ekholm, V., et al.
(författare)
-
Core-hole localization and ultra-fast dissociation in SF6
- 2020
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Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 53:18
-
Tidskriftsartikel (refereegranskat)abstract
- Resonant inelastic x-ray scattering spectra excited at the fluorine K resonances of SF(6)have been recorded. While a small but significant propensity for electronically parity-allowed transitions is found, the observation of parity-forbidden electronic transitions is attributed to vibronic coupling that breaks the global inversion symmetry of the electronic wavefunction and localizes the core hole. The dependence of the scattering cross section on the polarization of the incident radiation and the scattering angle is interpreted in terms of local pi/sigma symmetry around the S-F bond. This symmetry selectivity prevails during the dissociation that occurs during the scattering process.
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| 14. |
- Feifel, Raimund, et al.
(författare)
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Generalization of the duration-time concept for interpreting state of the art high resolution resonant photoemission spectra
- 2004
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Ingår i: Physical Review A. ; 69
-
Tidskriftsartikel (refereegranskat)abstract
- The duration-time concept, vastly successful for interpreting the frequency dependence of resonant radiative and nonradiative x-ray scattering spectra, is tested for fine-scale features that can be obtained with state of the art high-resolution spectroscopy. For that purpose resonant photoelectron (RPE) spectra of the first three outermost singly ionized valence states X 2Σg+, A 2Πu, and B 2Σu+, are measured for selective excitations to different vibrational levels (up to n=13) of the N 1s→π* photoabsorption resonance in N2 and for negative photon frequency detuning relative to the adiabatic 0-0 transition of this resonance. It is found that different parts of the RPE spectrum converge to the spectral profile of direct photoionization (fast scattering) for different detunings, and that the RPE profiles are asymmetrical as a function of frequency detuning. The observed asymmetry contradicts the picture based on the simplified notation of a common scattering duration time, but is shown to agree with the here elaborated concept of partial and mean duration times. Results of the measurements and the simulations show that the duration time of the scattering process varies for different final electronic and different final vibrational states. This owes to two physical reasons: one is the competition between the fast “vertical” and the slow “resonant” scattering channels and the other is the slowing down of the scattering process near the zeros of the real part of the scattering amplitude.
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| 15. |
- Feifel, R, et al.
(författare)
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Observation of a continuum-continuum interference hole in ultrafast dissociating core-excited molecules
- 2000
-
Ingår i: Physical Review Letters. - : AIP Publishing. - 0031-9007 .- 1079-7114. ; 85:15, s. 3133-3136
-
Tidskriftsartikel (refereegranskat)abstract
- The femtosecond dissociation of HCl after core excitation has been studied through the resonant Auger decay. The spectra contain contributions from decay occurring at both "molecular" and "atomic" internuclear distances. We have observed a new interference mechanism in these spectra: An atomic spectral line develops into a negative spectral contribution, a "hole," when detuning the excitation energy from the maximum of the Cl 2p(-1)sigma* resonance. Resonant x-ray scattering theory quantitatively explains this behavior as due to a novel destructive continuum-Continuum interference between molecular and atomic contributions to the Auger decay.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Gelmukhanov, F, et al.
(författare)
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Collapse of vibrational structure in spectra of resonant x-ray Raman scattering
- 1997
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 56:1, s. 256-264
-
Tidskriftsartikel (refereegranskat)abstract
- Extreme narrowing, or collapse, of electron-vibrational bands is predicted as a new phenomenon in resonant radiative and nonradiative x-ray scattering (RXS) spectra. It is shown that in the inelastic scattering case, that is, when the potential surfaces of ground and final slates are different, a considerable narrowing of the vibronic RXS band results from detuning the excitation Photon frequency omega away from the absorption resonance. By fine tuning the frequency, this may under special circumstances also occur in the region of strong photoabsorption. In the case of elastic Rayleigh scattering, that is, when the potential surfaces of ground and final states are identical, the narrowing results in a total collapse to a single resonance by detuning the frequency. The theory predicts how the differencies in vibrational structure of resonant and nonresonant photoemission spectra depends on the excitation frequency. The effect of frequency detuning on complex spectral multilevel structures due to multiplet: and spin-orbit splittings is discussed qualitatively. It is shown that the notion of: duration time for the x-ray scattering process plays a crucial role in the understanding of RXS spectra.
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| 20. |
- Gelmukhanov, F, et al.
(författare)
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Restoration of selection rules in nonadiabatic resonant inelastic x-ray scattering
- 1997
-
Ingår i: Journal of Experimental and Theoretical Physics. - : Pleiades Publishing Ltd. - 1063-7761 .- 1090-6509. ; 85:1, s. 20-26
-
Tidskriftsartikel (refereegranskat)abstract
- Recently a new effect in the Raman scattering of x-ray radiation has been predicted theoretically and discovered in experiments, the effect of restoration of the selection rules for the scattering tensor under strong electron-vibrational interaction. We propose a fairly simple model for describing this effect, a model that allows for an exact solution and takes into account the real vibrational structure of the molecule and electron-vibrational interaction.
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| 21. |
- Gel'mukhanov, F, et al.
(författare)
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Soft and hard x-ray Raman scattering by oriented symmetrical molecules : Selection rules, interference, and dephasing mechanisms
- 1998
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 109:12, s. 5060-5069
-
Tidskriftsartikel (refereegranskat)abstract
- Resonant x-ray Raman scattering in chaotical, partial, and fixed oriented symmetric molecules is analyzed for x-ray photon excitation frequencies in both the soft and the hard x-ray regions. Different dephasing mechanisms and their connection with channel interference and the observation of selection rules are investigated. It is predicted that for harder x-ray energies the scattering cross sections become strongly anisotropic and oscillatory due to channel interference. The orientational dephasing is predicted to be an important coherence-blocking mechanism and can be introduced even by zero-point vibrational or librational motions. The connections between selection rules, symmetry and phase factors of the photon wave function, Bragg conditions and the channel interference show that the selection rules may operate for oriented, surface adsorbed, molecules even in the hard x-ray region. The possibility of using the interference effect for structure determination of adsorbates is discussed.
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| 22. |
- Gelmukhanov, F, et al.
(författare)
-
Theory of Auger spectra for molecular-field-split core levels
- 1996
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Ingår i: PHYSICAL REVIEW A. - : AMER INST PHYSICS. ; 53:3, s. 1379-1387
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A theory for nonradiative decay of molecular-held-split states is presented. It is shown that the relative inner-shell sublevel cross sections for Auger transitions are sensitively dependent on the matching of spin-orbit and molecular-field interactions.
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| 23. |
- Glans, Peter, et al.
(författare)
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Resonant x-ray emission spectroscopy of molecular oxygen
- 1996
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Ingår i: Physical Review Letters. - : AMER INST PHYSICS. - 0031-9007. ; 76:14, s. 2448-2451
-
Tidskriftsartikel (refereegranskat)abstract
- Resonant soft x-ray emission spectroscopy has been applied to study the issue of symmetry breaking upon core-hole excitation in molecular oxygen. The results provide direct evidence that the inversion symmetry is not broken in the core-excited states. Furthermore, the experiments themselves demonstrate a new experimental technique of broad applicability for studies of electronic structure and excitation dynamics in free atoms and molecules.
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| 24. |
- Gunnelin, K, et al.
(författare)
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Bond-length-dependent core hole localization observed in simple hydrocarbons
- 1999
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Ingår i: Physical Review Letters. - 0031-9007. ; 83:7, s. 1315-1318
-
Tidskriftsartikel (refereegranskat)abstract
- Soft x-ray-emission spectroscopy is applied to measure the amount of dynamic symmetry breaking in core-excited acetylene, ethylene, and ethane. Large variations are observed between the molecules and are rationalized in terms of the different C-C bond lengths: Shorter bond lengths give smaller symmetry breaking. The results also indicate that asymmetric modes are important for all the systems studied, in contradiction to previous assumptions in literature.
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| 25. |
- Gunnelin, K, et al.
(författare)
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Bond-length-dependent core hole localization observed in simple hydrocarbons
- 1999
-
Ingår i: PHYSICAL REVIEW LETTERS. - : AMERICAN PHYSICAL SOC. - 0031-9007. ; 83:7, s. 1315-1318
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Soft x-ray-emission spectroscopy is applied to measure the amount of dynamic symmetry breaking in core-excited acetylene, ethylene, and ethane. Large variations are observed between the molecules and are rationalized in terms of the different C-C bond len
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| 26. |
- Hennies, F., et al.
(författare)
-
Dynamic interpretation of resonant x-ray Raman scattering : ethylene and benzene
- 2007
-
Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 76:3, s. 032505-
-
Tidskriftsartikel (refereegranskat)abstract
- We present a dynamic interpretation of resonant x-ray Raman scattering where vibrationally selective excitation into molecular resonances has been employed in comparison with excitation into higher lying continuum states for condensed ethylene and benzene as molecular model systems. In order to describe the purely vibrational spectral loss features and coupled electronic and vibrational losses the one-step theory for resonant soft x-ray scattering is applied, taking multiple vibrational modes and vibronic coupling into account. The scattering profile is found to be strongly excitation energy dependent and to reflect the intermediate states dynamics of the scattering process. In particular, the purely vibrational loss features allow one to map the electronic ground state potential energy surface in light of the excited state dynamics. Our study of ethylene and benzene underlines the necessity of an explicit description of the coupled electronic and vibrational loss features for the assignment of spectral features observed in resonant x-ray Raman scattering at polyatomic systems, which can be done in both a time independent and a time dependent picture. The possibility to probe ground state vibrational properties opens a perspective to future applications of this photon-in-photon-out spectroscopy.
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| 27. |
- Hennies, F., et al.
(författare)
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Non-Adiabatic effects in Resonant Inelastic x-ray Scattering
- 2005
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 95:16, s. 163002-
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied the spectral features of resonant inelastic x-ray scattering of condensed ethylene with vibrational selectivity both experimentally and theoretically. Purely vibrational spectral loss features and coupled electronic and vibrational losses are observed. The one-step theory for resonant soft x-ray scattering is applied, taking multiple vibrational modes and vibronic coupling into account. Our investigation of ethylene underlines that the assignment of spectral features observed in resonant inelastic x-ray scattering of polyatomic systems requires an explicit description of the coupled electronic and vibrational loss features.
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| 28. |
- Ignatova, Nina, 1989-, et al.
(författare)
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Gradual collapse of nuclear wave functions regulated by frequency tuned X-ray scattering
- 2017
-
Ingår i: Scientific Reports. - London : Nature Publishing Group. - 2045-2322. ; 7:43891
-
Tidskriftsartikel (refereegranskat)abstract
- As is well established, the symmetry breaking by isotope substitution in the water molecule results in localisation of the vibrations along one of the two bonds in the ground state. In this study we find that this localisation may be broken in excited electronic states. Contrary to the ground state, the stretching vibrations of HDO are delocalised in the bound core-excited state in spite of the mass difference between hydrogen and deuterium. The reason for this effect can be traced to the narrow “canyon-like” shape of the potential of the state along the symmetric stretching mode, which dominates over the localisation mass-difference effect. In contrast, the localisation of nuclear motion to one of the HDO bonds is preserved in the dissociative core-excited state . The dynamics of the delocalisation of nuclear motion in these core-excited states is studied using resonant inelastic X-ray scattering of the vibrationally excited HDO molecule. The results shed light on the process of a wave function collapse. After core-excitation into the state of HDO the initial wave packet collapses gradually, rather than instantaneously, to a single vibrational eigenstate.
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| 29. |
- Ignatova, Nina, 1989-, et al.
(författare)
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Infrared-pump–x-ray-probe spectroscopy of vibrationally excited molecules
- 2017
-
Ingår i: Physical Review A. - 2469-9926 .- 2469-9934. ; 95:4
-
Tidskriftsartikel (refereegranskat)abstract
- We develop a theory of infrared (IR)-pump–x-ray-probe spectroscopy for molecular studies. We illustrate advantages of the proposed scheme by means of numerical simulations employing a vibrational wave packet technique applied to x-ray absorption and resonant inelastic x-ray scattering (RIXS) spectra of the water molecule vibrationally excited by a preceding IR field. The promotion of the vibrationally excited molecule to the dissociative 1a−114a1 and bound 1a−112b2 core-excited states with qualitatively different shapes of the potential energy surfaces creates nuclear wave packets localized along and between the OH bonds, respectively. The projection of these wave packets on the final vibrational states, governed by selection and propensity rules, results in spatial selectivity of RIXS sensitive to the initial vibrationally excited state, which makes it possible to probe selectively the ground state properties along different modes. In addition, we propose to use RIXS as a tool to study x-ray absorption from a selected vibrational level of the ground state when the spectral resolution is sufficiently high to resolve vibrational overtones. The proposed technique has potential applications for advanced mapping of multidimensional potential energy surfaces of ground and core-excited molecular states, for symmetry-resolved spectroscopy, and for steering chemical reactions.
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| 30. |
- Kukk, E, et al.
(författare)
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Raman versus non-Raman behavior in resonant auger spectra of HCl
- 1996
-
Ingår i: PHYSICAL REVIEW LETTERS. - : AMER INST PHYSICS. ; 76:17, s. 3100-3103
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Two different types of Anger processes are shown to constitute the resonant Anger spectra of HCl: one which does and one which does not show Raman narrowing with the decrease of the spectral width of the exciting radiation. An analytical explanation for t
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| 31. |
- Marchenko, T., et al.
(författare)
-
Electron Dynamics in the Core-Excited CS2 Molecule Revealed through Resonant Inelastic X-Ray Scattering Spectroscopy
- 2015
-
Ingår i: Physical Review X. - 2160-3308. ; 5:3
-
Tidskriftsartikel (refereegranskat)abstract
- We present an experimental and theoretical study of resonant inelastic x-ray scattering (RIXS) in the carbon disulphide CS 2 molecule near the sulfur K-absorption edge. We observe a strong evolution of the RIXS spectral profile with the excitation energy tuned below the lowest unoccupied molecular orbital (LUMO) absorption resonance. The reason for this is twofold. Reducing the photon energy in the vicinity of the LUMO absorption resonance leads to a relative suppression of the LUMO contribution with respect to the emission signal from the higher unoccupied molecular orbitals, which results in the modulation of the total RIXS profile. At even larger negative photon-energy detuning from the resonance, the excitation-energy dependence of the RIXS profile is dominated by the onset of electron dynamics triggered by a coherent excitation of multiple electronic states. Furthermore, our study demonstrates that in the hard x-ray regime, localization of the S 1s core hole occurs in CS2 during the RIXS process because of the orientational dephasing of interference between the waves scattering on the two sulfur atoms. Core-hole localization leads to violation of the symmetry selection rules for the electron transitions observed in the spectra.
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| 32. |
- Marchenko, T., et al.
(författare)
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Potential Energy Surface Reconstruction and Lifetime Determination of Molecular Double-Core-Hole States in the Hard X-Ray Regime
- 2017
-
Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 119:13
-
Tidskriftsartikel (refereegranskat)abstract
- A combination of resonant inelastic x-ray scattering and resonant Auger spectroscopy provides complementary information on the dynamic response of resonantly excited molecules. This is exemplified for CH3I, for which we reconstruct the potential energy surface of the dissociative I 3d(-2) double-core-hole state and determine its lifetime. The proposed method holds a strong potential for monitoring the hard x-ray induced electron and nuclear dynamic response of core-excited molecules containing heavy elements, where ab initio calculations of potential energy surfaces and lifetimes remain challenging.
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| 33. |
- Piancastelli, M. N., et al.
(författare)
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Bond-distance-dependent decay probability of the N 1s -> pi* core-excited state in N-2
- 2000
-
Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 33:9, s. 1819-1826
-
Tidskriftsartikel (refereegranskat)abstract
- We report the observation of the unusually weak decay of the N 1s --> pi* core-excited N-2 molecule to the (B) over tilde (2)Sigma(u)(+) final state of N-2(+), which is only detectable in an experiment with high sensitivity. The resonant Auger spectra exhibit an unexpected dependence on the selected vibrational level of the intermediate state. Theoretical calculations show that the interference between direct and resonant photoemission as well as a strong geometry dependence of the decay probability on the bond distance give rise to the observed features.
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| 34. |
- Salek, P, et al.
(författare)
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Generalized Franck-Condon principle for resonant photoemission
- 1999
-
Ingår i: PHYSICAL REVIEW A. - : AMERICAN PHYSICAL SOC. - 1050-2947. ; 60:4, s. 2786-2791
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A generalized Franck-Condon (GFC) principle for resonant x-ray Raman scattering and for resonant photoemission in particular is derived and numerically investigated. The GFC amplitudes differ from ordinary FC amplitudes by the presence of photon and photo
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| 35. |
- Salek, Pawel, et al.
(författare)
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Resonant x-ray Raman scattering involving avoided crossings in the final-state potential-energy curves
- 2000
-
Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : Elsevier BV. - 1050-2947 .- 1094-1622. ; 62:6
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Tidskriftsartikel (refereegranskat)abstract
- The role of avoided crossings for resonant x-ray Raman scattering is explored. The strong dependence of the electronic transition amplitudes on internuclear distance at avoided crossings causes new, and even anomalous, spectral features, and can bring about a breakdown of the generally accepted participator or spectator classification of the transitions. We report, and apply the theory on, an experimental observation of the electron decay of the N 1s-->pi* core-excited level in N-2 the B(2)Sigma (+)(u) final state with peculiar, non-Franck-Condon, vibrational intensity distributions.
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| 36. |
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| 37. |
- Santos, A. C. F., et al.
(författare)
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Resonant Auger decay induced by the symmetry-forbidden 1a(1g)? 6a(1g) transition of the SF6 molecule
- 2022
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Ingår i: Journal of Vacuum Science & Technology A. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 40:4
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Tidskriftsartikel (refereegranskat)abstract
- Resonant Auger electron spectroscopic study at the symmetry-forbidden 1 a 1 g -> 6 a 1 g excitation below the S K-shell threshold of SF 6 is reported. Partial electron yield and resonant K L L Auger spectra have been measured by using monochromatized undulator synchrotron radiation. By changing the photon energy in small steps, a so-called 2D map is produced. In this map, the dipole-forbidden transition exhibits spectral features (e.g., an S-shaped dispersion relation), which are well known and understood for dipole-allowed transitions. We validate by a theory that for the case of dipole-forbidden transitions, these spectral features can be analyzed in the same way as previously established for the dipole-allowed ones. This approach grants information on the nuclear dynamics in the K-shell core-excited states of SF 6 on the femtosecond (fs) timescale. In particular, for the potential-energy curves of the states S 1 s(-1) 6(a1g) and S 2p(-2)6a(1g), the slopes at the equilibrium distance of the ground state are derived. Symmetry breaking as a result of ultrafast vibronic coupling is revealed by the population of the electronically forbidden excited state. Published under an exclusive license by the AVS.
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| 38. |
- Skytt, P, et al.
(författare)
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Quenching of symmetry breaking in resonant inelastic X-ray scattering by detuned excitation
- 1996
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Ingår i: Physical Review Letters. - 0031-9007. ; 77:25, s. 5035-5038
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Tidskriftsartikel (refereegranskat)abstract
- Observations made in oxygen K emission of CO2 show that the symmetry selective character of resonant x-ray emission is excitation energy dependent. Electronically dipole forbidden O K emission lines are observed for excitation at the O 1s --> pi* resonance, and they are gradually reduced upon detuning the excitation energy below threshold. The occurrence of forbidden transitions is explained in terms of dynamical symmetry breaking due to vibronic coupling, and the observation of quenching of the symmetry breaking upon detuning as due to an effective quenching of this vibronic coupling. Scattering theory applied to a few-level system is shown to account for the energy dependence of the symmetry selection in the limit of narrow bandpass photon excitation.
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| 39. |
- Travnikova, O., et al.
(författare)
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Ultrafast dissociation of ammonia : Auger Doppler effect and redistribution of the internal energy
- 2022
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 24:10, s. 5842-5854
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Tidskriftsartikel (refereegranskat)abstract
- We study vibrationally-resolved resonant Auger (RAS) spectra of ammonia recorded in coincidence with the NH2+ fragment, which is produced in the course of dissociation either in the core-excited 1s−14a11 intermediate state or the first spectator 3a−24a11 final state. Correlation of the NH2+ ion flight times with electron kinetic energies allows directly observing the Auger-Doppler dispersion for each vibrational state of the fragment. The median distribution of the kinetic energy release EKER, derived from the coincidence data, shows three distinct branches as a function of Auger electron kinetic energy Ee: Ee + 1.75EKER = const for the molecular band; EKER = const for the fragment band; and Ee + EKER = const for the region preceding the fragment band. The deviation of the molecular band dispersion from Ee + EKER = const is attributed to the redistribution of the available energy to the dissociation energy and excitation of the internal degrees of freedom in the molecular fragment. We found that for each vibrational line the dispersive behavior of EKERvs. Ee is very sensitive to the instrumental uncertainty in the determination of EKER causing the competition between the Raman (EKER + Ee = const) and Auger (Ee = const) dispersions: increase in the broadening of the finite kinetic energy release resolution leads to a change of the dispersion from the Raman to the Auger one.
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| 40. |
- Vaz da Cruz, Vinicius, 1987-, et al.
(författare)
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A study of the water molecule using frequency control over nuclear dynamics in resonant X-ray scattering
- 2017
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 19:30, s. 19573-19589
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Tidskriftsartikel (refereegranskat)abstract
- In this combined theoretical and experimental study we report a full analysis of the resonant inelastic X-ray scattering (RIXS) spectra of H2O, D2O and HDO. We demonstrate that electronically-elastic RIXS has an inherent capability to map the potential energy surface and to perform vibrational analysis of the electronic ground state in multimode systems. We show that the control and selection of vibrational excitation can be performed by tuning the X-ray frequency across core-excited molecular bands and that this is clearly reflected in the RIXS spectra. Using high level ab initio electronic structure and quantum nuclear wave packet calculations together with high resolution RIXS measurements, we discuss in detail the mode coupling, mode localization and anharmonicity in the studied systems.
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| 41. |
- Vaz da Cruz, Vinicius, et al.
(författare)
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A study of the water molecule using frequency control over nuclear dynamics in resonant X-ray scattering
- 2017
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 19:30, s. 19573-19589
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Tidskriftsartikel (refereegranskat)abstract
- In this combined theoretical and experimental study we report a full analysis of the resonant inelastic X-ray scattering (RIXS) spectra of H2O, D2O and HDO. We demonstrate that electronically-elastic RIXS has an inherent capability to map the potential energy surface and to perform vibrational analysis of the electronic ground state in multimode systems. We show that the control and selection of vibrational excitation can be performed by tuning the X-ray frequency across core-excited molecular bands and that this is clearly reflected in the RIXS spectra. Using high level ab initio electronic structure and quantum nuclear wave packet calculations together with high resolution RIXS measurements, we discuss in detail the mode coupling, mode localization and anharmonicity in the studied systems.
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| 42. |
- YI, L, et al.
(författare)
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SYMMETRY-SELECTIVE RESONANT INELASTIC X-RAY-SCATTERING OF C-60
- 1995
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Ingår i: PHYSICAL REVIEW B-CONDENSED MATTER. - : AMER INST PHYSICS. - 0163-1829. ; 52:20, s. 14479-14496
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The resonantly excited x-ray emission spectra of the C-60 molecule are presented and analyzed in terms of symmetry- and polarization-selective resonant inelastic scattering processes (RIXS). The theoretical analysis implements recently derived formalisms
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