Showing papers by "Till Jahnke published in 2015"
TL;DR: Experimental observation of this long-predicted but experimentally elusive Efimov state of 4He3 by means of Coulomb explosion imaging confirms the predicted size and a typical structure where two atoms are close to each other while the third is far away and sheds light on three-body physics more broadly.
Abstract: Quantum theory dictates that upon weakening the two-body interaction in a three-body system, an infinite number of three-body bound states of a huge spatial extent emerge just before these three-body states become unbound. Three helium (He) atoms have been predicted to form a molecular system that manifests this peculiarity under natural conditions without artificial tuning of the attraction between particles by an external field. Here we report experimental observation of this long-predicted but experimentally elusive Efimov state of 4 He 3 by means of Coulomb explosion imaging. We show spatial images of an Efimov state, confirming the predicted size and a typical structure where two atoms are close to each other while the third is far away.
182 citations
TL;DR: In this paper, Cederbaum et al. showed that ICD is a very general and common feature occurring after a manifold of excitation schemes and in numerous weakly bound systems, as revealed by more than 200 publications.
Abstract: In pioneering work by Cederbaum et al an excitation mechanism was proposed that occurs only in loosely bound matter (Cederbaum et al 1997 Phys Rev Lett 79 4778): it turned out, that (in particular) in cases where a local Auger decay is energetically forbidden, an excited atom or molecule is able to decay in a scheme which was termed ‘interatomic Coulombic decay’ (or ‘intermolecular Coulombic decay’) (ICD) As ICD occurs, the excitation energy is released by transferring it to an atomic or molecular neighbor of the initially excited particle As a consequence the neighboring atom or molecule is ionized as it receives the energy A few years later the existence of ICD was confirmed experimentally (Marburger et al 2003 Phys Rev Lett 90 203401; Jahnke et al 2004 Phys Rev Lett 93 163401; Ohrwall et al 2004 Phys Rev Lett 93 173401) by different techniques Since this time it has been found that ICD is not (as initially suspected) an exotic feature of van der Waals or hydrogen bonded systems, but that ICD is a very general and common feature occurring after a manifold of excitation schemes and in numerous weakly bound systems, as revealed by more than 200 publications It was even demonstrated, that ICD can become more efficient than a local Auger decay in some system This review will concentrate on recent experimental investigations on ICD It will briefly introduce the phenomenon and give a short summary of the ‘early years’ of ICD (a detailed view on this episode of investigations can be found in the review article by U Hergenhahn with the same title (Hergenhahn 2011 J Electron Spectrosc Relat Phenom 184 78)) More recent articles will be presented that investigate the relevance of ICD in biological systems and possible radiation damage of such systems due to ICD The occurrence of ICD and ICD-like processes after different excitation schemes and in different systems is covered in the middle section: in that context the helium dimer (He2) is a particularly interesting (and exotic) system in which ICD was detected It was employed in several publications to elucidate the strong impact of nuclear motion on ICD and its longrange-character The review will present these findings and their initial theoretical predictions and give insight into most recent time-resolved measurements of ICD
162 citations
TL;DR: In this article, the authors reported experimental observation of this long predicted but experimentally elusive Efimov state by means of Coulomb explosion imaging, confirming the predicted size and a typical structure where two atoms are close to each other while the third is far away.
Abstract: Quantum theory dictates that upon weakening the two-body interaction in a three-body system, an infinite number of three-body bound states of a huge spatial extent emerge just before these three-body states become unbound. Three helium atoms have been predicted to form a molecular system that manifests this peculiarity under natural conditions without artificial tuning of the attraction between particles by an external field. Here we report experimental observation of this long predicted but experimentally elusive Efimov state of $^{4}$He$_{3}$ by means of Coulomb explosion imaging. We show spatial images of an Efimov state, confirming the predicted size and a typical structure where two atoms are close to each other while the third is far away.
97 citations
TL;DR: Investigation of electron momentum distributions from single ionization of Ar by two orthogonally polarized laser pulses of different color shows that the visibility of the interference fringes depends on the degree of the which-way information determined by the controllable phase between the two pulses.
Abstract: We investigate electron momentum distributions from single ionization of Ar by two orthogonally polarized laser pulses of different color. The two-color scheme is used to experimentally control the interference between electron wave packets released at different times within one laser cycle. This intracycle interference pattern is typically hard to resolve in an experiment. With the two-color control scheme, these features become the dominant contribution to the electron momentum distribution. Furthermore, the second color can be used for streaking of the otherwise interfering wave packets establishing a which-way marker. Our investigation shows that the visibility of the interference fringes depends on the degree of the which-way information determined by the controllable phase between the two pulses.
79 citations
07 Sep 2015
TL;DR: In this article, the authors reported experimental observation of the long predicted but experimentally elusive Efimov state of 4He trimer by means of Coulomb explosion imaging, confirming the predicted size and a typical structure where two atoms are close to each other while the third is far away.
Abstract: We report experimental observation of the long predicted but experimentally elusive Efimov state of 4He trimer by means of Coulomb explosion imaging. We show spatial images of an Efimov state, confirming the predicted size and a typical structure where two atoms are close to each other while the third is far away.
25 citations
TL;DR: The progress of examining the time-domain aspects of interatomic Coulombic decay is summarized in this short topical review with a special emphasis on experiments that are now feasible due to the developments of free-electron lasers as mentioned in this paper.
19 citations
07 Sep 2015
TL;DR: In this article, the electron momentum distribution from single ionization of Ar by two orthogonally polarized laser pulses of different color was investigated, and two color schemes were used to experimentally control the interference between electron wave packets released at different times within one laser cycle.
Abstract: We investigate electron momentum distributions from single ionization of Ar by two orthogonally polarized laser pulses of different color. The two-color scheme is used to experimentally control the interference between electron wave packets released at different times within one laser cycle.
16 citations
TL;DR: In this paper, the influence of several factors on the dynamics and kinematics of the dissociation of a polyatomic molecule was studied, including propensity rules, ionization mechanisms, symmetry of the orbitals from which the Auger electrons originate, multiple scattering, conical intersections, interference, and possible core-hole localization.
Abstract: The fragmentation pathways and dynamics of ethylene molecules after core ionization are explored using coincident measurements of the Auger electron and fragment ions by employing the cold target recoil-ion momentum spectroscopy method. The influence of several factors on the dynamics and kinematics of the dissociation is studied. These include propensity rules, ionization mechanisms, symmetry of the orbitals from which the Auger electrons originate, multiple scattering, conical intersections, interference, and possible core-hole localization for the double ionization of this polyatomic molecule. Energy correlation maps allow probing the multidimensional potential energy surfaces and, in combination with our multiconfiguration self-consistent field calculations, identifying the populated electronic states of the dissociating dication. The measured angular distributions of the Auger electrons in the molecular frame further support and augment these assignments. The deprotonation and molecular hydrogen ion elimination channels show a nearly isotropic Auger electron angular distribution with a small elongation along the direction perpendicular to the molecular axis. For the symmetric breakup the angular distributions show a clear influence of multiple scattering on the outgoing electrons. The lowest kinetic energy release feature of the symmetric breakup channel displays a fingerprint of entangled Auger and photoelectron motion in the angular emission pattern identifying this transition as an excellent candidate to probe core-hole localization at a conical intersection of a polyatomic molecule.
8 citations
16 Apr 2015
TL;DR: In this paper, the validity of the Born series expansion for charge transfer reactions in the case of a proton-helium collision is studied, and the role of the electron-electron correlations in the initial helium state is discussed in detail.
Abstract: The validity of the Born series expansion for the charge transfer reactions is studied in the case of a proton-helium collision. Three dierent channels are considered, namely the charge transfer, transfer excitation and transfer ionization. The dierential cross sections and the contributions from dierent charge transfer mechanisms within various Born approximations are compared with experimental data. The role of the electron-electron correlations in the initial helium state is discussed in detail. It is shown that the rst Born approximation is valid in the case of reactions under consideration, provided very small scattering angles are involved and the proton energy is >500 keV. It is also shown that the electron-electron correlations in the initial helium state are important only in transfer excitation and transfer ionization reactions.
1 citations
07 Sep 2015
Abstract: Using intense photon beams from the XFEL free electron laser, the COLTRIMS Reaction Microscope will be a versatile tool for examination of the dynamics in small quantum systems.
07 Sep 2015
TL;DR: In this article, the authors presented a method by which the internuclear distance-dependent decay width of interatomic Coulombic decay can be obtained using a measured energy distribution and a classical nuclear dynamics model.
Abstract: We present a method by which the internuclear distance-dependent decay width ᴦ(r) of Interatomic Coulombic Decay can be obtained using a measured energy distributions and a classical nuclear dynamics model.
07 Sep 2015
TL;DR: In this paper, Coulomb explosion imaging was used to determine the exact configuration of a chiral molecule with femto-second laser pulses and X-ray synchrotron light.
Abstract: In this work, we show that the direct determination of a chiral molecule's absolute configuration can be achieved with Coulomb Explosion Imaging in a COLTRIMS reaction microscope. We compare the results after ionisation with femto-second laser pulses and with X-ray synchrotron light. Different fragmentation pathways of the prototypical chiral molecule CHBrClF are identified that carry information on the handedness. The applicabilty of the technique towards bigger molecules is discussed.
07 Sep 2015
TL;DR: In this article, the Coulombic Decay in mixed NeKr dimers has been measured and the nuclear dynamics of the decay have been investigated, and the time-resolved decay has been investigated.
Abstract: Interatomic Coulombic Decay in mixed NeKr dimers has been measured time-resolved and the nuclear dynamics of the decay have been investigated.
01 Jul 2015
TL;DR: The role of electron-electron correlations both in a trial helium ground-state wave function and in the final helium state is inspected in this article, where the FDCS for single ionization p + He → p + e + He+ at proton energy of 1 MeV is studied both experimentally and theoretically.
Abstract: The fully differential cross section (FDCS) for single ionization p + He → p + e + He+ at proton energy of 1 MeV is studied both experimentally and theoretically. The 3D angular electron distribution is presented. The role of electron-electron correlations both in a trial helium ground-state wave function and in the final helium state is inspected.
07 Sep 2015
TL;DR: In this paper, the authors demonstrate the smallest possible implementation of an antenna-receiver complex which consists of a single helium atom acting as the antenna and a second ion atom acting at the receiver.
Abstract: Here we demonstrate the smallest possible implementation of an antenna-receiver complex which consists of a single (helium) atom acting as the antenna and a second (neon) atom acting as a receiver.