| 1. |
- Dahlström, Marcus, et al.
(författare)
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Atomic and macroscopic measurements of attosecond pulse trains
- 2009
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 80:3
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Tidskriftsartikel (refereegranskat)abstract
- We characterize attosecond pulses in a train using both the well established "reconstruction of attosecond beating by interference of two-photon transitions" (RABITT) technique and the recently demonstrated in situ method, which is based on a weak perturbation of the harmonic generation process by the second harmonic of the laser field. The latter technique determines the characteristics of the single atom emission, while RABITT allows one to measure attosecond pulses "on target." By comparing the results of the two methods, the influence of propagation and filtering on the attosecond pulses can be extracted.
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| 2. |
- Gisselbrecht, Mathieu, et al.
(författare)
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Exploring single-photon ionization on the attosecond time scale
- 2012
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Ingår i: XXVII International Conference on Photonic, Electronic and Atomic Collisions (Icpeac 2011), Pts 1-15. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 388, s. 032025-032025
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Konferensbidrag (refereegranskat)abstract
- One of the fundamental processes in nature is the photoelectric effect in which an electron is ripped away from its atom via the interaction with a photon. This process was long believed to be instantaneous but with the development of attosecond pulses (1 as 10(-18) s) we can finally get an insight into its dynamic. Here we measure a delay in ionization time between two differently bound electrons. The outgoing electrons are created via ionization with a train of attosecond pulses and we probe their relative delay with a synchronized infrared laser. We demonstrate how this probe field influences the measured delays and show that this contribution can be estimated with a universal formula, which allows us to extract field free atomic data..
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| 3. |
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| 4. |
- 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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| 5. |
- Klünder, Kathrin, et al.
(författare)
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Probing Single-Photon Ionization on the Attosecond Time Scale
- 2011
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Ingår i: Physical Review Letters. - 1079-7114. ; 106:14
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Tidskriftsartikel (refereegranskat)abstract
- We study photoionization of argon atoms excited by attosecond pulses using an interferometric measurement technique. We measure the difference in time delays between electrons emitted from the 3s(2) and from the 3p(6) shell, at different excitation energies ranging from 32 to 42 eV. The determination of photoemission time delays requires taking into account the measurement process, involving the interaction with a probing infrared field. This contribution can be estimated using a universal formula and is found to account for a substantial fraction of the measured delay.
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| 6. |
- Mansten, Erik, et al.
(författare)
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Broadband attosecond pulse shaping
- 2007
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Ingår i: Optics Letters. - 0146-9592. ; 32:11, s. 1353-1355
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Tidskriftsartikel (refereegranskat)abstract
- We use semiconductor (Si) and metallic (Al, Zr) transmission filters to shape, in amplitude and phase, high-order harmonics generated from the interaction of an intense titanium sapphire laser field with a pulsed neon gas target. Depending on the properties of the filter, the emitted attosecond pulses can be optimized in bandwidth and/or pulse length. We demonstrate the generation of attosecond pulses centered at energies from 50 to 80 eV, with bandwidths as large as 45 eV and with pulse durations compressed to 130 as. (c) 2007 Optical Society of America.
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| 7. |
- Mansten, Erik, et al.
(författare)
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Spectral shaping of attosecond pulses using two-colour laser fields
- 2008
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- We use a strong two-colour laser field composed of the fundamental (800 nm) and the second harmonic (400 nm) of an infrared (IR) laser field to generate attosecond pulses with controlled spectral and temporal properties. With a second-harmonic intensity equal to 15% of the IR intensity the second-harmonic field is strong enough to significantly alter and control the electron trajectories in the generation process. This enables us to tune the central photon energy of the attosecond pulses by changing the phase difference between the IR and the second-harmonic fields. In the time domain the radiation is emitted as a sequence of pulses separated by a full IR cycle. We also perform calculations showing that the effect of even stronger second-harmonic fields leads to an extended tunable range under conditions that are experimentally feasible.
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| 8. |
- Mauritsson, Johan, et al.
(författare)
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Attosecond electron interferometry
- 2013
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Ingår i: Attosecond Physics : Attosecond Measurements and Control of Physical Systems - Attosecond Measurements and Control of Physical Systems. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1556-1534 .- 0342-4111. - 9783642376221 - 9783642376238 ; 177, s. 121-134
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Bokkapitel (refereegranskat)abstract
- Attosecond extreme ultraviolet light pulses have the potential to resolve the ultrafast electron dynamics that govern basic properties of atoms, molecules, and solids. Here we present three different interferometric pump-probe methods aiming to access not only the temporal dynamics, but also state specific phase information after excitation/ionization using attosecond pulses.
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| 9. |
- 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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| 10. |
- Mauritsson, Johan, et al.
(författare)
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Coherent electron scattering captured by an attosecond quantum stroboscope.
- 2008
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Ingår i: Physical Review Letters. - 1079-7114. ; 100:7
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a quantum stroboscope based on a sequence of identical attosecond pulses that are used to release electrons into a strong infrared (IR) laser field exactly once per laser cycle. The resulting electron momentum distributions are recorded as a function of time delay between the IR laser and the attosecond pulse train using a velocity map imaging spectrometer. Because our train of attosecond pulses creates a train of identical electron wave packets, a single ionization event can be studied stroboscopically. This technique has enabled us to image the coherent electron scattering that takes place when the IR field is sufficiently strong to reverse the initial direction of the electron motion causing it to rescatter from its parent ion.
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