| 1. |
- Boguslavskiy, Andrey E., et al.
(författare)
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The Multielectron Ionization Dynamics Underlying Attosecond Strong-Field Spectroscopies
- 2012
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 335:6074, s. 1336-1340
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Tidskriftsartikel (refereegranskat)abstract
- Subcycle strong-field ionization (SFI) underlies many emerging spectroscopic probes of atomic or molecular attosecond electronic dynamics. Extending methods such as attosecond high harmonic generation spectroscopy to complex polyatomic molecules requires an understanding of multielectronic excitations, already hinted at by theoretical modeling of experiments on atoms, diatomics, and triatomics. Here, we present a direct method which, independent of theory, experimentally probes the participation of multiple electronic continua in the SFI dynamics of polyatomic molecules. We use saturated (n-butane) and unsaturated (1,3-butadiene) linear hydrocarbons to show how subcycle SFI of polyatomics can be directly resolved into its distinct electronic-continuum channels by above-threshold ionization photoelectron spectroscopy. Our approach makes use of photoelectron-photofragment coincidences, suiting broad classes of polyatomic molecules.
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| 2. |
- Brasse, Felix, et al.
(författare)
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Time-resolved inner-shell photoelectron spectroscopy : From a bound molecule to an isolated atom
- 2018
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 97:4
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Tidskriftsartikel (refereegranskat)abstract
- Due to its element and site specificity, inner-shell photoelectron spectroscopy is a widely used technique to probe the chemical structure of matter. Here, we show that time-resolved inner-shell photoelectron spectroscopy can be employed to observe ultrafast chemical reactions and the electronic response to the nuclear motion with high sensitivity. The ultraviolet dissociation of iodomethane (CH3I) is investigated by ionization above the iodine 4d edge, using time-resolved inner-shell photoelectron and photoion spectroscopy. The dynamics observed in the photoelectron spectra appear earlier and are faster than those seen in the iodine fragments. The experimental results are interpreted using crystal-field and spin-orbit configuration interaction calculations, and demonstrate that time-resolved inner-shell photoelectron spectroscopy is a powerful tool to directly track ultrafast structural and electronic transformations in gas-phase molecules.
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| 3. |
- Carlström, Stefanos, et al.
(författare)
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Control of spin polarization through recollisions
- 2023
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Ingår i: Physical Review A. - 2469-9926. ; 108:4
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Tidskriftsartikel (refereegranskat)abstract
- Using only linearly polarized light, we study the possibility of generating spin-polarized photoelectrons from xenon atoms. No net spin polarization is possible, since the xenon ground state is spinless, but when the photoelectrons are measured in coincidence with the residual ion, spin polarization emerges. Furthermore, we show that ultrafast dynamics of the recolliding photoelectrons contribute to an apparent flipping of the spin of the photoelectron, a process that has been completely neglected so far in all analyses of recollision-based processes. We link this phenomenon to the "spin-orbit clock"of the remaining ion. These effects arise already in dipole approximation.
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| 4. |
- Carlström, Stefanos, et al.
(författare)
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General time-dependent configuration-interaction singles. I. Molecular case
- 2022
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Ingår i: Physical Review A. - 2469-9926. ; 106:4
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Tidskriftsartikel (refereegranskat)abstract
- We present a grid-based implementation of the time-dependent configuration-interaction singles method suitable for computing the strong-field ionization of small gas-phase molecules. After outlining the general equations of motion used in our treatment of this method, we present example calculations of strong-field ionization of He, LiH, H2O, and C2H4 that demonstrate the utility of our implementation. The following paper [S. Carlström et al., following paper, Phys. Rev. A 106, 042806 (2022)10.1103/PhysRevA.106.042806] specializes to the case of spherical symmetry, which is applied to various atoms.
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| 5. |
- Carlström, Stefanos, et al.
(författare)
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General time-dependent configuration-interaction singles. II. Atomic case
- 2022
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Ingår i: Physical Review A. - 2469-9926. ; 106:4
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Tidskriftsartikel (refereegranskat)abstract
- We present a specialization of the grid-based implementation of the time-dependent configuration-interaction singles described in the preceding paper [S. Carlström et al., preceding paper, Phys. Rev. A 106, 043104 (2022)]10.1103/PhysRevA.106.043104. to the case of spherical symmetry. We describe the intricate time propagator in detail and conclude with a few example calculations. Among these, of note are high-resolution photoelectron spectra in the vicinity of the Fano resonances in photoionization of neon and spin-polarized photoelectrons from xenon, in agreement with recent experiments.
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| 6. |
- Carlström, Stefanos, et al.
(författare)
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Rydberg atomic antenna in strongly driven multielectron atoms
- 2022
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Ingår i: Physical Review A. - 2469-9926. ; 106:4
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Tidskriftsartikel (refereegranskat)abstract
- We study the role of intermediate excitations of Rydberg states as an example of Kuchiev's "atomic antenna"in above-threshold ionization of xenon, in particular their effect on the coherence between the spin-orbit-split states of the ion. We focus on the case of a laser frequency close to resonant with the spin-orbit splitting, where a symmetry (parity) argument would preclude any coherence being directly generated by strong-field ionization. Using ab initio simulations of coupled multielectron spin-orbit dynamics in strong laser fields, we show how field-driven rescattering of the trapped Rydberg electrons introduces efficient coupling between the spin-orbit-split channels, leading to substantial coherences, exceeding 10% for some photon energies.
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| 7. |
- Ertel, Dominik, et al.
(författare)
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Anisotropy Parameters for Two-Color Photoionization Phases in Randomly Oriented Molecules : Theory and Experiment in Methane and Deuteromethane
- 2024
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Ingår i: Journal of Physical Chemistry A. - 1089-5639 .- 1520-5215. ; 128:9, s. 1685-1697
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Tidskriftsartikel (refereegranskat)abstract
- We present combined theoretical and experimental work investigating the angle-resolved phases of the photoionization process driven by a two-color field consisting of an attosecond pulse train and an infrared pulse in an ensemble of randomly oriented molecules. We derive a general form for the two-color photoelectron (and time-delay) angular distribution valid also in the case of chiral molecules and when relative polarizations of the photons contributing to the attosecond photoelectron interferometer differ. We show a comparison between the experimental data and theoretical predictions in an ensemble of methane and deuteromethane molecules, discussing the effect of nuclear dynamics on the photoionization phases. Finally, we demonstrate that the oscillating component and the phase of the two-color signal can be fitted by using complex asymmetry parameters, in perfect analogy to the atomic case.
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| 8. |
- Ertel, Dominik, et al.
(författare)
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Influence of nuclear dynamics on molecular attosecond photoelectron interferometry
- 2023
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Ingår i: Science Advances. - 2375-2548. ; 9:35
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Tidskriftsartikel (refereegranskat)abstract
- In extreme ultraviolet spectroscopy, the photoionization process occurring in a molecule due to the absorption of a single photon can trigger an ultrafast nuclear motion in the cation. Taking advantage of attosecond photoelectron interferometry, where the absorption of the extreme ultraviolet photon is accompanied by the exchange of an additional infrared quantum of light, one can investigate the influence of nuclear dynamics by monitoring the characteristics of the photoelectron spectra generated by the two-color field. Here, we show that attosecond photoelectron interferometry is sensitive to the nuclear response by measuring the two-color photoionization spectra in a mixture of methane (CH4) and deuteromethane (CD4). The effect of the different nuclear evolution in the two isotopologues manifests itself in the modification of the amplitude and contrast of the oscillations of the photoelectron peaks. Our work indicates that nuclear dynamics can affect the coherence properties of the electronic wave packet emitted by photoionization on a time scale as short as a few femtoseconds.
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| 9. |
- Patchkovskii, Serguei, et al.
(författare)
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Theory of nuclear motion in RABBITT spectra
- 2023
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Ingår i: Physical Review A. - 2469-9926. ; 107:4
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Tidskriftsartikel (refereegranskat)abstract
- Reconstruction of attosecond beating by interference of two-photon transitions (RABBITT) is a powerful photoelectron spectroscopy, offering direct access to internal dynamics of the target. It is being increasingly applied to molecular systems, but a general, computationally tractable theory of RABBITT spectra in molecules has so far been lacking. We show that under quite general assumptions, RABBITT spectra in molecules can be expressed as a convolution of the vibronic cross-correlation functions and two-electron photoionization matrix elements. We specialize the general expressions to the commonly encountered special cases. We expect our theory to enable accurate modeling and interpretation of molecular RABBITT spectra in most medium-sized molecules.
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