Showing papers by "Till Jahnke published in 2007"
TL;DR: It is shown that a photoelectron and two protons form a minimum particle/slit system and that a single additional electron constitutes a minimum environment and that interference fringes observed in the angular distribution of a single electron are lost through its Coulomb interaction with a second electron.
Abstract: The wave nature of particles is rarely observed, in part because of their very short de Broglie wavelengths in most situations. However, even with wavelengths close to the size of their surroundings, the particles couple to their environment (for example, by gravity, Coulomb interaction, or thermal radiation). These couplings shift the wave phases, often in an uncontrolled way, and the resulting decoherence, or loss of phase integrity, is thought to be a main cause of the transition from quantum to classical behavior. How much interaction is needed to induce this transition? Here we show that a photoelectron and two protons form a minimum particle/slit system and that a single additional electron constitutes a minimum environment. Interference fringes observed in the angular distribution of a single electron are lost through its Coulomb interaction with a second electron, though the correlated momenta of the entangled electron pair continue to exhibit quantum interference.
198 citations
TL;DR: In this article, it was shown that the inversion symmetry can be broken by absorption of a linearly polarized photon, which itself has inversion symmetrized ground state, and the mechanisms behind this symmetry breaking are general for all molecules.
Abstract: H2, the smallest and most abundant molecule in the universe, has a perfectly symmetric ground state. What does it take to break this symmetry? We found that the inversion symmetry can be broken by absorption of a linearly polarized photon, which itself has inversion symmetry. In particular, the emission of a photoelectron with subsequent dissociation of the remaining H +2 fragment shows no symmetry with respect to the ionic H+ and neutral H atomic fragments. This lack of symmetry results from the entanglement between symmetric and antisymmetric H +2 states that is caused by autoionization. The mechanisms behind this symmetry breaking are general for all molecules.
146 citations
TL;DR: Ne2+ recoil-ion-momentum distributions suggest that two electrons absorbing "instantaneously" two photons are ejected most likely into opposite hemispheres with similar energies.
Abstract: Few-photon multiple ionization of Ne and Ar atoms by strong vacuum ultraviolet laser pulses from the free-electron laser at Hamburg was investigated differentially with the Heidelberg reaction microscope. The light-intensity dependence of ${\mathrm{Ne}}^{2+}$ production reveals the dominance of nonsequential two-photon double ionization at intensities of $Il6\ifmmode\times\else\texttimes\fi{}{10}^{12}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$ and significant contributions of three-photon ionization as $I$ increases. ${\mathrm{Ne}}^{2+}$ recoil-ion-momentum distributions suggest that two electrons absorbing ``instantaneously'' two photons are ejected most likely into opposite hemispheres with similar energies.
121 citations
TL;DR: By solving the two-level time-dependent Schrödinger equation, it is shown that an interference between the net-two-photon and the one- photon transition creates localized electrons which subsequently ionize.
Abstract: Using H2+ and D2+, we observe two-surface population dynamics by measuring the kinetic energy of the correlated ions that are created when H2+ (D2+) ionize in short (40-140 fs) and intense (10(14) W/cm2) infrared laser pulses. Experimentally, we find a modulation of the kinetic energy spectrum of the correlated fragments. The spectral progression arises from a hitherto unexpected spatial modulation on the excited state population, revealed by Coulomb explosion. By solving the two-level time-dependent Schrodinger equation, we show that an interference between the net-two-photon and the one-photon transition creates localized electrons which subsequently ionize.
100 citations
TL;DR: It is found that, depending on the parity of the excited state, which determines whether ICD takes place via virtual dipole photon emission or overlap of the wave functions, the decay happens at different internuclear distances, illustrating that nuclear dynamics heavily influence the electronic decay in the neon dimer.
Abstract: We investigate the interatomic Coulombic decay (ICD) of neon dimers following photoionization with simultaneous excitation of the ionized atom (shakeup) in a multiparticle coincidence experiment We find that, depending on the parity of the excited state, which determines whether ICD takes place via virtual dipole photon emission or overlap of the wave functions, the decay happens at different internuclear distances, illustrating that nuclear dynamics heavily influence the electronic decay in the neon dimer
50 citations
TL;DR: In this article, the molecular frame angular distribution of 2s photoelectrons and electrons emitted by interatomic Coulombic decay from neon dimers was investigated. And the experimental results were in excellent agreement with frozen core Hartree-Fock calculations.
Abstract: We report on molecular frame angular distributions of 2s photoelectrons and electrons emitted by interatomic Coulombic decay from neon dimers. We found that the measured angular distribution of the photoelectron strongly depends on the environment of the cluster. The experimental results are in excellent agreement with frozen core Hartree–Fock calculations. The ICD electrons show slight variations in their angular distribution for different kinetic energies.
24 citations