| 1. |
- Céolin, D., et al.
(author)
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Far-Zone Resonant Energy Transfer in X-ray Photoemission as a Structure Determination Tool
- 2017
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In: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 8:12, s. 2730-2734
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Journal article (peer-reviewed)abstract
- Near-zone Förster resonant energy transfer is the main effect responsible for excitation energy flow in the optical region and is frequently used to obtain structural information. In the hard X-ray region, the Förster law is inadequate because the wavelength is generally shorter than the distance between donors and acceptors; hence, far-zone resonant energy transfer (FZRET) becomes dominant. We demonstrate the characteristics of X-ray FZRET and its fundamental differences with the ordinary near-zone resonant energy-transfer process in the optical region by recording and analyzing two qualitatively different systems: high-density CuO polycrystalline powder and SF6 diluted gas. We suggest a method to estimate geometrical structure using X-ray FZRET employing as a ruler the distance-dependent shift of the acceptor core ionization potential induced by the Coulomb field of the core-ionized donor.
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| 2. |
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| 3. |
- Blinov, Svyatoslav N., et al.
(author)
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Mapping molecular potentials using pump-probe spectroscopy of vibrational wave packets' revival
- 2023
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In: 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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Journal article (peer-reviewed)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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| 4. |
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| 5. |
- Gel'mukhanov, Faris, et al.
(author)
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Dynamics of resonant x-ray and Auger scattering
- 2021
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In: Reviews of Modern Physics. - : American Physical Society (APS). - 0034-6861 .- 1539-0756. ; 93:3
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Research review (peer-reviewed)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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| 6. |
- Liu, J. -C, et al.
(author)
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Time-resolved study of recoil-induced rotation by X-ray pump - X-ray probe spectroscopy
- 2022
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In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 24:11, s. 6627-6638
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Journal article (peer-reviewed)abstract
- Modern stationary X-ray spectroscopy is unable to resolve rotational structure. In the present paper, we propose to use time-resolved two color X-ray pump-probe spectroscopy with picosecond resolution for real-time monitoring of the rotational dynamics induced by the recoil effect. The proposed technique consists of two steps. The first short pump X-ray pulse ionizes the valence electron, which transfers angular momentum to the molecule. The second time-delayed short probe X-ray pulse resonantly excites a 1s electron to the created valence hole. Due to the recoil-induced angular momentum the molecule rotates and changes the orientation of transition dipole moment of core-excitation with respect to the transition dipole moment of the valence ionization, which results in a temporal modulation of the probe X-ray absorption as a function of the delay time between the pulses. We developed an accurate theory of the X-ray pump-probe spectroscopy of the recoil-induced rotation and study how the energy of the photoelectron and thermal dephasing affect the structure of the time-dependent X-ray absorption using the CO molecule as a case-study. We also discuss the feasibility of experimental observation of our theoretical findings, opening new perspectives in studies of molecular rotational dynamics.
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| 7. |
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| 8. |
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| 9. |
- Savchenko, Viktoriia, et al.
(author)
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Dynamical phase shift in x-ray absorption and ionization spectra by two delayed x-ray laser fields
- 2021
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In: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society (APS). - 2469-9926 .- 2469-9934. ; 104:1
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Journal article (peer-reviewed)abstract
- We study theoretically x-ray absorption and ionization spectra of an atom or molecule by two coherent x-ray pulses that show a relative phase shift resulting in a time delay of the pulse envelopes. We demonstrate that the phase modulation of the spectra is shifted with respect to the phase oscillation comb of the x-ray double pulse. The reason for this shift is the dynamics of the process defined by the interplay of the delay time, the pulse width, the detuning, and the lifetime of the core-excited state.
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| 10. |
- Savchenko, Viktoriia, et al.
(author)
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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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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 154:21
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Journal article (peer-reviewed)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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| 11. |
- Savchenko, Viktoriia, et al.
(author)
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Size-dependent blinking of molecular aggregate total emission
- 2017
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In: 4th International School and Conference "Saint Petersburg OPEN 2017" on Optoelectronics, Photonics, Engineering and Nanostructures. - : Institute of Physics Publishing (IOPP).
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Conference paper (peer-reviewed)abstract
- Molecular aggregates are well known for their customizable optical properties. Vibronic coupling in monomers forming such aggregates offers rich opportunities for property tuning. We study generic molecular aggregate models of growing complexity (from a dimer up to a decamer) and report how vibronic coupling affects aggregate fluorescence intensity. The total aggregate fluorescence intensity is a measure sensitive to both vibronic coupling and Coulomb coupling between monomer transition densities. Using an exact diagonalization approach in the two-particle basis set, we show how the interplay between Coulomb and vibronic coupling affects aggregate fluorescence. Moreover, for H-aggregates we predict a periodic variation of the fluorescence intensity with aggregate size and show that vibronic interaction decreases the effect.
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| 12. |
- Savchenko, Viktoriia, et al.
(author)
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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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In: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
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Journal article (peer-reviewed)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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