| 1. |
- Maroju, P. K., et al.
(författare)
-
Analysis of two-color photoelectron spectroscopy for attosecond metrology at seeded free-electron lasers
- 2021
-
Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 23:4
-
Tidskriftsartikel (refereegranskat)abstract
- The generation of attosecond pulse trains at free-electron lasers opens new opportunities in ultrafast science, as it gives access, for the first time, to reproducible, programmable, extreme ultraviolet (XUV) waveforms with high intensity. In this work, we present a detailed analysis of the theoretical model underlying the temporal characterization of the attosecond pulse trains recently generated at the free-electron laser FERMI. In particular, the validity of the approximations used for the correlated analysis of the photoelectron spectra generated in the two-color photoionization experiments are thoroughly discussed. The ranges of validity of the assumptions, in connection with the main experimental parameters, are derived.
|
|
| 2. |
- Gryzlova, E. V., et al.
(författare)
-
Influence of an atomic resonance on the coherent control of the photoionization process
- 2022
-
Ingår i: Physical Review Research. - 2643-1564. ; 4:3
-
Tidskriftsartikel (refereegranskat)abstract
- In coherent control schemes, pathways connecting an initial and a final state can be independently controlled by manipulating the complex amplitudes of their transition matrix elements. For paths characterized by the absorption of multiple photons, these quantities depend on the magnitude and phase between the intermediate steps, and are expected to be strongly affected by the presence of resonances. We investigate the coherent control of the photoemission process in neon using a phase-controlled two-color extreme ultraviolet pulse with frequency in proximity of an excited energy state. Using helium as a reference, we show that the presence of such a resonance in neon modifies the amplitude and phase of the asymmetric emission of photoelectrons. Theoretical simulations based on perturbation theory are in fair agreement with the experimental observations.
|
|
| 3. |
- Mazza, T., et al.
(författare)
-
Mapping Resonance Structures in Transient Core-Ionized Atoms
- 2020
-
Ingår i: Physical Review X. - 2160-3308. ; 10:4
-
Tidskriftsartikel (refereegranskat)abstract
- The nature of transient electronic states created by photoabsorption critically determines the dynamics of the subsequently evolving system. Here, we investigate K-shell photoionized atomic neon by absorbing a second photon within the Auger-decay lifetime of 2.4 fs using the European XFEL, a unique high-repetition-rate, wavelength-tunable x-ray free-electron laser. By high-resolution electron spectroscopy, we map out the transient Rydberg resonances unraveling the details of the subsequent decay of the hollow atom. So far, ultra-short-lived electronic transients, which are often inaccessible by experiments, were mainly inferred from theory but are now addressed by nonlinear x-ray absorption. The successful characterization of these resonances with femtosecond lifetimes provides the basis for a novel class of site-specific, nonlinear, and time-resolved studies with strong impact for a wide range of topics in physics and chemistry.
|
|
| 4. |
- Ilchen, M., et al.
(författare)
-
X-ray spectroscopy on ultrafast-decaying core-excited atomic ions
- 2020
-
Ingår i: Charge-exchange. - : IOP Publishing. - 1742-6588. ; 1412
-
Konferensbidrag (refereegranskat)abstract
- Results from the first soft X-ray user experiment at the European XFEL on nonlinear photon-matter interaction will be presented. Angle-resolved electron time-of-flight spectroscopy employed at the AQS (Atomic- like Quantum Systems) endstation of the SQS (Small Quantum Systems) instrument reveals insight into the character of resonances in highly transient, core ionized neon ions, i.e. Ne:+ 1s12s22p6 → Ne+&∗ 1s02s22p6np, together with their respective relaxation dynamics. Enabled by the unique properties of the European XFEL, novel perspectives on efficient nonlinear spectroscopy will be discussed.
|
|
