| 1. |
- Ballan, M., et al.
(författare)
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Nuclear physics midterm plan at Legnaro National Laboratories (LNL)
- 2023
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Ingår i: European Physical Journal Plus. - 2190-5444. ; 138:8, s. 3-26
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Tidskriftsartikel (refereegranskat)abstract
- The next years will see the completion of the radioactive ion beam facility SPES (Selective Production of Exotic Species) and the upgrade of the accelerators complex at Istituto Nazionale di Fisica Nucleare – Legnaro National Laboratories (LNL) opening up new possibilities in the fields of nuclear structure, nuclear dynamics, nuclear astrophysics, and applications. The nuclear physics community has organised a workshop to discuss the new physics opportunities that will be possible in the near future by employing state-of-the-art detection systems. A detailed discussion of the outcome from the workshop is presented in this report.
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| 2. |
- Sansone, G., et al.
(författare)
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Electron localization following attosecond molecular photoionization
- 2010
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 465:7299, s. 3-763
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Tidskriftsartikel (refereegranskat)abstract
- For the past several decades, we have been able to directly probe the motion of atoms that is associated with chemical transformations and which occurs on the femtosecond (10(-15)-s) timescale. However, studying the inner workings of atoms and molecules on the electronic timescale(1-4) has become possible only with the recent development of isolated attosecond (10(-18)-s) laser pulses(5). Such pulses have been used to investigate atomic photoexcitation and photoionization(6,7) and electron dynamics in solids(8), and in molecules could help explore the prompt charge redistribution and localization that accompany photoexcitation processes. In recent work, the dissociative ionization of H-2 and D-2 was monitored on femtosecond timescales(9) and controlled using few-cycle near-infrared laser pulses(10). Here we report a molecular attosecond pump-probe experiment based on that work: H-2 and D-2 are dissociatively ionized by a sequence comprising an isolated attosecond ultraviolet pulse and an intense few-cycle infrared pulse, and a localization of the electronic charge distribution within the molecule is measured that depends-with attosecond time resolution-on the delay between the pump and probe pulses. The localization occurs by means of two mechanisms, where the infrared laser influences the photoionization or the dissociation of the molecular ion. In the first case, charge localization arises from quantum mechanical interference involving autoionizing states and the laser-altered wavefunction of the departing electron. In the second case, charge localization arises owing to laser-driven population transfer between different electronic states of the molecular ion. These results establish attosecond pump-probe strategies as a powerful tool for investigating the complex molecular dynamics that result from the coupling between electronic and nuclear motions beyond the usual Born-Oppenheimer approximation.
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| 3. |
- Kelkensberg, F., et al.
(författare)
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Molecular Dissociative Ionization and Wave-Packet Dynamics Studied Using Two-Color XUV and IR Pump-Probe Spectroscopy
- 2009
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Ingår i: Physical Review Letters. - 1079-7114. ; 103:12
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Tidskriftsartikel (refereegranskat)abstract
- We present a combined theoretical and experimental study of ultrafast wave-packet dynamics in the dissociative ionization of H-2 molecules as a result of irradiation with an extreme-ultraviolet (XUV) pulse followed by an infrared (IR) pulse. In experiments where the duration of both the XUV and IR pulses are shorter than the vibrational period of H-2+, dephasing and rephasing of the vibrational wave packet that is formed in H-2+ upon ionization of the neutral molecule by the XUV pulse is observed. In experiments where the duration of the IR pulse exceeds the vibrational period of H-2+ (15 fs), a pronounced dependence of the H+ kinetic energy distribution on XUV-IR delay is observed that can be explained in terms of the adiabatic propagation of the H-2+ wave packet on field-dressed potential energy curves.
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| 4. |
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| 5. |
- Mauritsson, Johan, et al.
(författare)
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Attosecond Electron Spectroscopy Using a Novel Interferometric Pump-Probe Technique
- 2010
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Ingår i: Physical Review Letters. - 1079-7114. ; 105:5
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Tidskriftsartikel (refereegranskat)abstract
- We present an interferometric pump-probe technique for the characterization of attosecond electron wave packets (WPs) that uses a free WP as a reference to measure a bound WP. We demonstrate our method by exciting helium atoms using an attosecond pulse (AP) with a bandwidth centered near the ionization threshold, thus creating both a bound and a free WP simultaneously. After a variable delay, the bound WP is ionized by a few-cycle infrared laser precisely synchronized to the original AP. By measuring the delay-dependent photoelectron spectrum we obtain an interferogram that contains both quantum beats as well as multipath interference. Analysis of the interferogram allows us to determine the bound WP components with a spectral resolution much better than the inverse of the AP duration.
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| 6. |
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| 7. |
- Sansone, G., et al.
(författare)
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Attosecond excitation of electron wavepackets
- 2008
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Ingår i: Quantum Electronics and Laser Science Conference, QELS 2008. - 9781557528599
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Konferensbidrag (refereegranskat)abstract
- We present experiments, supported by time-dependent Schrödinger simulations, on the dynamics of Helium bound states after an attosecond excitation in the presence of a strong infrared laser field.
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| 8. |
- Lepine, F., et al.
(författare)
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Short XUV pulses to characterize field-free molecular alignment
- 2007
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Ingår i: Journal of Modern Optics. - : Informa UK Limited. - 0950-0340 .- 1362-3044. ; 54:7, s. 953-966
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Tidskriftsartikel (refereegranskat)abstract
- We present experiments on field-free molecular alignment of N-2 and CO2 probed with short XUV pulses that are obtained via high-harmonic generation. The XUV pulses induce a dissociative ionization or a Coulomb explosion of the molecule, where the fragment ion recoil (measured using the velocity map imaging technique) provides information on the alignment of the parent molecule at the time of ionization. We discuss how photoelectron detection may in future allow the determination of molecular-frame photoelectron angular distributions and molecular structure.
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| 9. |
- Siu, W., et al.
(författare)
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Attosecond control of dissociative ionization of O(2) molecules
- 2011
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 84:6
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate that dissociative ionization of O(2) can be controlled by the relative delay between an attosecond pulse train (APT) and a copropagating infrared (IR) field. Our experiments reveal a dependence of both the branching ratios between a range of electronic states and the fragment angular distributions on the extreme ultraviolet (XUV) to IR time delay. The observations go beyond adiabatic propagation of dissociative wave packets on IR-induced quasistatic potential energy curves and are understood in terms of an IR-induced coupling between electronic states in the molecular ion.
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| 10. |
- Johnsson, Per, et al.
(författare)
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Characterization of a two-color pump-probe setup at FLASH using a velocity map imaging spectrometer
- 2010
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Ingår i: Optics Letters. - 0146-9592. ; 35:24, s. 4163-4165
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Tidskriftsartikel (refereegranskat)abstract
- We report on the implementation of a high-count-rate charged particle imaging detector for two-color pump-probe experiments at the free electron laser in Hamburg (FLASH). In doing so, we have developed a procedure for finding the spatial and temporal overlap between the extreme UV free electron laser (FEL) pulses and the IR pulses, which allows for complete alignment of the setup in situations where the region of overlap between the FEL and the IR is not easily accessible by means of imaging optics. (C) 2010 Optical Society of America
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