We investigate the dissociation of H_{2}^{+} into a proton and a H^{0} after single ionization with photons of an energy close to the threshold. We find that the p^{+} and the H^{0} do not emerge symmetrically in the case of the H_{2}^{+} dissociating along the 1sσ_{g} ground state. Instead, a preference for the ejection of the p^{+} in the direction of the escaping photoelectron can be observed. This symmetry breaking is strongest for very small electron energies. Our experiment is consistent with a recent prediction by Serov and Kheifets [Phys. Rev. A 89, 031402 (2014)]. In their model, which treats the photoelectron classically, the symmetry breaking is induced by the retroaction of the long-range Coulomb potential onto the dissociating H_{2}^{+}.

Almost ten years ago, energetic neutral hydrogen atoms were detected after a strong-field double ionization of H2. This process, called 'frustrated tunneling ionization', occurs when an ionized electron is recaptured after being driven back to its parent ion by the electric field of a femtosecond laser. In the present study we demonstrate that a related process naturally occurs in clusters without the need of an external field: we observe a charge hopping that occurs during a Coulomb explosion of a small helium cluster, which leads to an energetic neutral helium atom. This claim is supported by theoretical evidence. As an analog to 'frustrated tunneling ionization', we term this process 'frustrated Coulomb explosion'.

We suggest that low energy electrons, released by resonant decay processes, experience substantial scattering on the electron density of excited electrons, which remain a spectator during the decay. As a result, the angular emission distribution is altered significantly. This effect is expected to be a common feature of low energy secondary electron emission. In this letter, we exemplify our idea by examining the spectator resonant interatomic Coulombic decay (sRICD) of Ne dimers. Our theoretical predictions are confirmed by a corresponding coincidence experiment. 32.80.Hd, 33.60.+q The emission of secondary electrons after ionization or excitation of atoms and molecules has been vastly investigated since its discovery in 1905 by Pierre Auger. Such electronic decay processes provide unique information on electron-electron (configuration) interaction effects in matter. Auger decays can be grouped into two classes: so-called participator decays are cases, where the initially excited electron is actively participating in the decay by either being emitted or being the electron that fills a vacancy in an inner shell. In contrast, in spectator decays the initially excited electron does not participate in the decay but remains in its excited state acting simply as a spectator to the decay. It is commonly accepted that an electronic decay of an ionized or excited atom or molecule can be described in good approximation independently of the initial excitation step. As a consequence, for instance, an electron emitted by an Auger decay after photoionization, does not depend on the polarization properties of the absorbed photon [1]. This approximation is commonly known as the two-step model [2]. For a resonant Auger decay [3,4], this approximation is particularly valid if the excited electron is only witnessing the decay process as a spectator. However, several works have shown, that in special cases, the twostep approximation can break down [5][6][7][8].In the present article we discuss a scenario of a breakdown of the two-step model which is not connected to specific, rare cases in nature, but is expected to occur very generally as soon as the electron emitted by the decay is of low kinetic energy. In this case, the Coulomb repulsion between the outgoing free electron and the excited bound electron may influence the emission direction of the former. Accordingly, for low energy electrons even a spectator electron is expected to influence the emission dynamics, as the wave packet of the slow secondary electron will be scattered by the density of that spectator electron when escaping the system. Such final-state scattering effects, in general, should depend on the spatial symmetry of the excited electron, and information on the polarization of the exciting photon, which is imprinted in the symmetry of the spectator electron, is (in contrast to expectations from the two-step model) transferred to the secondary electron. Please note, that the effect discussed here is very different from the so-called post collision interacti...

This corrects the article DOI: 10.1103/PhysRevLett.116.043001.

Synopsis The spectator resonant interatomic Coulombic decay (SRICD) following the 2s →5p excitation of Ne dimers has been examined experimentally and theoretically. The molecular frame angular distributions (MFADs) of the SRICD electrons depend strongly on the direction of the polarization vector of the exciting photon with respect to the molecular axis. We demonstrate that this effect is caused by the scattering of the low-energy SRICD electron on the density of the spectator electron.