| 1. |
- Kuepper, Jochen, et al.
(författare)
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X-Ray Diffraction from Isolated and Strongly Aligned Gas-Phase Molecules with a Free-Electron Laser
- 2014
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 112:8, s. 083002-
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Tidskriftsartikel (refereegranskat)abstract
- We report experimental results on x-ray diffraction of quantum-state-selected and strongly aligned ensembles of the prototypical asymmetric rotor molecule 2,5-diiodobenzonitrile using the Linac Coherent Light Source. The experiments demonstrate first steps toward a new approach to diffractive imaging of distinct structures of individual, isolated gas-phase molecules. We confirm several key ingredients of single molecule diffraction experiments: the abilities to detect and count individual scattered x-ray photons in single shot diffraction data, to deliver state-selected, e.g., structural-isomer-selected, ensembles of molecules to the x-ray interaction volume, and to strongly align the scattering molecules. Our approach, using ultrashort x-ray pulses, is suitable to study ultrafast dynamics of isolated molecules.
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| 2. |
- 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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| 3. |
- Hickstein, Daniel D., et al.
(författare)
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Direct Visualization of Laser-Driven Electron Multiple Scattering and Tunneling Distance in Strong-Field Ionization
- 2012
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Ingår i: Physical Review Letters. - 1079-7114. ; 109:7
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Tidskriftsartikel (refereegranskat)abstract
- Using a simple model of strong-field ionization of atoms that generalizes the well-known 3-step model from 1D to 3D, we show that the experimental photoelectron angular distributions resulting from laser ionization of xenon and argon display prominent structures that correspond to electrons that pass by their parent ion more than once before strongly scattering. The shape of these structures can be associated with the specific number of times the electron is driven past its parent ion in the laser field before scattering. Furthermore, a careful analysis of the cutoff energy of the structures allows us to experimentally measure the distance between the electron and ion at the moment of tunnel ionization. This work provides new physical insight into how atoms ionize in strong laser fields and has implications for further efforts to extract atomic and molecular dynamics from strong-field physics.
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| 4. |
- Rouzée, Arnaud, et al.
(författare)
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Molecular Movies from Molecular Frame Photoelectron Angular Distribution (MF-PAD) Measurements
- 2014
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Ingår i: Ultrafast Phenomena in Molecular Sciences : Femtosecond Physics and Chemistry - Femtosecond Physics and Chemistry. - Cham : Springer International Publishing. - 0172-6218. - 9783319020501 ; 107, s. 1-24
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Bokkapitel (refereegranskat)abstract
- We discuss recent and on-going experiments, where molecular frame photoelectron angular distributions (MFPADs) of high kinetic energy photoelectrons are measured in order to determine the time evolution of molecular structures in the course of a photochemical event. These experiments include, on the one hand, measurements where single XUV/X-ray photons, obtained from a free electron laser (FEL) or by means of high-harmonic generation (HHG), are used to eject a high energy photoelectron, and, on the other hand, measurements where a large number of mid-infrared photons are absorbed in the course of strong-field ionization. In the former case, first results indicate a manifestation of the both the electronic orbital and the molecular structure in the angle-resolved photoelectron distributions, while in the latter case novel holographic structures are measured that suggest that both the molecular structure and ultrafast electronic rearrangement processes can be studied with a time-resolution that reaches down into the attosecond and few-femtosecond domain.
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| 5. |
- Schütte, Bernd, et al.
(författare)
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Autoionization following nanoplasma formation in atomic and molecular clusters
- 2016
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Ingår i: European Physical Journal D. Atomic, Molecular, Optical and Plasma Physics. - : Springer Science and Business Media LLC. - 1434-6060. ; 70:5
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: Nanoplasmas resulting from the ionization of nano-scale particles by intense laser pulses are typically described by quasiclassical models, where electron emission is understood to take place via thermal processes. Recently, we discovered that, following the interaction of intense near-infrared (NIR) laser pulses with molecular oxygen clusters, electron emission from nanoplasmas can also occur from atomic bound states via autoionization [Schütte et al., Phys. Rev. Lett. 114, 123002 (2015)]. Here we extend these studies and demonstrate that the formation and decay of doubly-excited atoms and ions is a very common phenomenon in nanoplasmas. We report on the observation of autoionization involving spin-orbit excited states in molecular oxygen and carbon dioxide clusters as well as in atomic krypton and xenon clusters ionized by intense NIR pulses, for which we find clear bound-state signatures in the electron kinetic energy spectra. By applying terahertz (THz) streaking, we show that the observed autoionization processes take place on a picosecond to nanosecond timescale after the interaction of the NIR laser pulse with the clusters. Graphical abstract: [Figure not available: see fulltext.]
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