| 1. |
- Savchenko, Viktoriia, et al.
(författare)
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Hydrogen bond effects in multimode nuclear dynamics of acetic acid observed via resonant x-ray scattering
- 2021
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 154:21
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical and experimental study of the gas phase and liquid acetic acid based on resonant inelastic x-ray scattering (RIXS) spectroscopy is presented. We combine and compare different levels of theory for an isolated molecule for a comprehensive analysis, including electronic and vibrational degrees of freedom. The excitation energy scan over the oxygen K-edge absorption reveals nuclear dynamic effects in the core-excited and final electronic states. The theoretical simulations for the monomer and two different forms of the dimer are compared against high-resolution experimental data for pure liquid acetic acid. We show that the theoretical model based on a dimer describes the hydrogen bond formation in the liquid phase well and that this bond formation sufficiently alters the RIXS spectra, allowing us to trace these effects directly from the experiment. Multimode vibrational dynamics is accounted for in our simulations by using a hybrid time-dependent stationary approach for the quantum nuclear wave packet simulations, showing the important role it plays in RIXS.
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| 2. |
- Savchenko, Viktoriia, et al.
(författare)
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Vibrational resonant inelastic X-ray scattering in liquid acetic acid : a ruler for molecular chain lengths
- 2021
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Quenching of vibrational excitations in resonant inelastic X-ray scattering (RIXS) spectra of liquid acetic acid is observed. At the oxygen core resonance associated with localized excitations at the O-H bond, the spectra lack the typical progression of vibrational excitations observed in RIXS spectra of comparable systems. We interpret this phenomenon as due to strong rehybridization of the unoccupied molecular orbitals as a result of hydrogen bonding, which however cannot be observed in x-ray absorption but only by means of RIXS. This allows us to address the molecular structure of the liquid, and to determine a lower limit for the average molecular chain length.
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| 3. |
- Söderström, Johan, et al.
(författare)
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Parity violation in resonant inelastic soft x-ray scattering at entangled core holes
- 2024
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 10:7, s. 3114-
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Tidskriftsartikel (refereegranskat)abstract
- Resonant inelastic x-ray scattering (RIXS) is a major method for investigation of electronic structure and dynamics, with applications ranging from basic atomic physics to materials science. In RIXS applied to inversion-symmetric systems, it has generally been accepted that strict parity selectivity applies in the sub-kilo-electron volt region. In contrast, we show that the parity selection rule is violated in the RIXS spectra of the free homonuclear diatomic O2 molecule. By analyzing the spectral dependence on scattering angle, we demonstrate that the violation is due to the phase difference in coherent scattering at the two atomic sites, in analogy with Young's double-slit experiment. The result also implies that the interpretation of x-ray absorption spectra for inversion symmetric molecules in this energy range must be revised.
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| 4. |
- Barreau, Lou, et al.
(författare)
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Core-excited states of Formula Presented probed with soft-x-ray femtosecond transient absorption of vibrational wave packets
- 2023
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society (APS). - 2469-9926 .- 2469-9934. ; 108:1
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Tidskriftsartikel (refereegranskat)abstract
- A vibrational wavepacket in Formula Presented is created by impulsive stimulated Raman scattering with a few-cycle infrared pulse and mapped simultaneously onto five sulfur core-excited states using table-top soft x-ray transient absorption spectroscopy between 170 to 200 eV. The femtosecond vibrations induce real-time energy shifts of the x-ray absorption, whose amplitude depend strongly on the nature of the core-excited state. The pump laser intensity is used to control the number of vibrational states in the superposition, thereby accessing core-excited levels for various extensions of the S-F stretching motion. This enables the determination of the relative core-level potential energy gradients for the symmetric stretching mode, in good agreement with TDDFT calculations. This experiment demonstrates a new means of characterizing core-excited potential energy curves.
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| 5. |
- Blinov, Svyatoslav N., et al.
(författare)
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Mapping molecular potentials using pump-probe spectroscopy of vibrational wave packets' revival
- 2023
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society (APS). - 2469-9926 .- 2469-9934. ; 108:1
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we investigate the nuclear dynamics in nitrogen monoxide after valence ionization by a pump pulse and subsequent probing with a time-delayed x-ray pulse. We calculate the development of the resulting vibrational wave packet, taking into account three different ionization mechanisms: one-photon, multiphoton, and tunneling ionization. Using a two-time propagation method, we solve the nonstationary nuclear Schrödinger equation to obtain time-resolved x-ray absorption spectra (TRXAS), considering the finite duration of the probe pulse. Our simulations show that the TRXAS profile accurately reflects the vibrational wave packets' trajectory in the cationic ground state. Additionally, we find that the TRXAS evolution is highly sensitive to small changes in the probed potential energy curve, making it a useful tool for reconstructing molecular potentials and determining anharmonicity and equilibrium bond length. This method can be applied to other polyatomic molecules and pump mechanisms.
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| 6. |
- Cui, Jun Jie, et al.
(författare)
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Proposal for Observing XUV-Induced Rabi Oscillation Using Superfluorescent Emission
- 2023
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Ingår i: Physical Review Letters. - : American Physical Society (APS). - 0031-9007 .- 1079-7114. ; 131:4
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Tidskriftsartikel (refereegranskat)abstract
- Intense x-ray and extreme ultraviolet (XUV) light sources have been available for decades, however, due to weak nonlinear interaction in the XUV photon energy range, observation of Rabi oscillation induced by XUV pulse remains a very challenging experimental task. Here we suggest a scheme where photoionization of a He medium by an intense XUV pump pulse is followed by a strong population inversion and Rabi oscillation at the He+(1s-3p) transition and is accompanied by superfluorescence (SF) of the 7.56 eV pulse at the He+(3p-2s) transition. Our numerical simulations show that the Rabi oscillation at the He+(1s-3p) transition induced by an XUV pulse with photon energy 48.36 eV results in significant signatures in the SF spectra, allowing us to identify and characterize the XUV induced Rabi-oscillatory regime. The proposed scheme provides a sensitive tool to monitor and control ultrafast nonlinear dynamics in atoms and molecules triggered by intense XUV.
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| 7. |
- Dong, Xiao Xia, et al.
(författare)
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Carrier-envelope-phase measurement of sub-cycle UV pulses using angular photofragment distributions
- 2022
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Ingår i: Communications Physics. - : Springer Nature. - 2399-3650. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- Carrier-envelope-phase (CEP) of sub-cycle ultraviolet (UV) pulse strongly influences the dynamics of quantum systems, but its characterization is not accessible experimentally. Here we investigate photodissociation of a diatomic molecule from its ground-rovibrational state in a linearly polarized weak sub-cycle UV pulse with a controlled CEP. The angular distribution of photofragments shows an asymmetric profile deviating from the well-known cos(2-) or sin(2)-like ones, which can be identified as a way to imprint CEP. We unveil that such an effect stems from the temporal neighboring rotational excitation by molecular permanent dipole interaction through the joint contributions between counter-rotating and rotating terms. This in turn, opens different pathways in photodissociation dynamics. Given that the temporal excitation between various states with close energies can be manipulated by CEP of subcycle UV pulses, our results pave ways for understanding and manipulating electron, nuclear and their joint dynamics with variation of CEP of attosecond pulses.
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| 8. |
- Gel'mukhanov, Faris, et al.
(författare)
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Dynamics of resonant x-ray and Auger scattering
- 2021
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Ingår i: Reviews of Modern Physics. - : American Physical Society (APS). - 0034-6861 .- 1539-0756. ; 93:3
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Forskningsöversikt (refereegranskat)abstract
- Anoverview of both experimental and theoretical results in the field of resonant scattering of tunable soft and hard x-ray radiation is presented, with a main focus on the closely related processes of resonant inelastic x-ray scattering (RIXS) and resonant Auger scattering (RAS). The review starts with an overview of fundamental dynamical aspects of RIXS illustrated for different systems. A detailed analysis of case studies with increasing complexity, considering both gas-phase and condensed matter (liquids and solids) applications, is given. In the review, the most important achievements in investigations of coupled electron-nuclear dynamics and structural aspects in studies of liquids and solids over the last two decades are outlined. To give a perspective on the insights from RIXS and RAS, the x-ray results are discussed against the background of complementary experimental techniques like vibrational infrared absorption and Raman spectroscopy, as well as small-angle x-ray and neutron scattering. Finally, recent achievements in time-resolved studies based on x-ray free-electron lasers are described.
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| 9. |
- Gel'mukhanov, Faris, et al.
(författare)
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Nonlocal resonant inelastic x-ray scattering
- 2023
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society (APS). - 2469-9926 .- 2469-9934. ; 108:5
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Tidskriftsartikel (refereegranskat)abstract
- In the description of resonant inelastic x-ray scattering (RIXS) from inversion-symmetric molecules the small core-level splitting is typically neglected. However, the spacing Δ between gerade and ungerade core levels in homonuclear diatomic molecules can be comparable with the lifetime broadening of the intermediate core-excited state Γ. We show that when Δ∼Γ the scattering becomes nonlocal in the sense that x-ray absorption at one atomic site is followed by emission at the other one. This is manifested in an unusual dependence of the RIXS cross section on the sum of the momenta of incoming and outgoing x-ray photons k+k′, contrary to the normal k-k′ dependence in the conventional local RIXS theory. The nonlocality of the scattering influences strongly the scattering angle and excitation energy dependence of the intensity ratio between parity forbidden and allowed RIXS channels. Numerical simulations for N2 show that this effect can readily be measured at present-day x-ray radiation facilities.
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| 10. |
- Liu, Ji Cai, et al.
(författare)
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Complementarity in which-path resonant Auger scattering
- 2024
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society (APS). - 2469-9926 .- 2469-9934. ; 109:2
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Tidskriftsartikel (refereegranskat)abstract
- Different types of Young's double-slit experiments contain a significant amount of both particle and wave information running from full-particle to full-wave knowledge depending on the experimental conditions. We study the Young's double-slit interference in resonant Auger scattering from homonuclear diatomic molecules where opposite Doppler shifts for the dissociating atomic slits provide path information. Different quantitative formulation of Bohr's complementarity principle - path information vs interference - is applied to two types of resonant Auger scattering experiments, with fixed-in-space and randomly oriented molecules. Special attention is paid to the orientational dephasing in conventional Auger experiments with randomly oriented molecules. Our quantitative formulation of the complementarity is compared with the formulation made earlier by Greenberger and Yasin [D. M. Greenberger and A. Yasin, Phys. Lett. A 128, 391 (1988)0375-960110.1016/0375-9601(88)90114-4].
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