In this work we demonstrate that the interatomic Coulombic decay (ICD), an ultrafast electron relaxation process known for atoms and molecules, is possible in general binding potentials. We used the multiconfiguration time-dependent Hartree method for fermions to study ICD in real time in a two-electron model system of two potential wells. Two decay channels were identified and analyzed by using the box stabilization analysis as well as by evaluating the autocorrelation function and measuring the outgoing electron flux during time-propagations. The total and partial ICD widths of an excited state localized in one potential well as a function of the distance between the two potentials was obtained. Finally, we discuss the results with a view to a possible application of ICD in quantum dot technology.

Since its discovery in 1997 [1], the ICD has been successfully investigated in a variety of systems [2]. It usually proceeds on a femtosecond timescale and becomes faster the more neighbors are present, dominating most of the competing relaxation processes. Experimental investigation of ICD in water dimers [3] found the rate of this process to be so large as to completely suppress the proton transfer in the inner-valence ionized water molecules.As a result of ICD, two intact water cations are produced by the consecutive Coulomb 1

Interatomic or intermolecular Coulombic decay (ICD) is a nonlocal electronic decay mechanism occurring in weakly bound matter. In an ICD process, energy released by electronic relaxation of an excited atom or molecule leads to ionization of a neighboring one via Coulombic electron interactions. ICD has been predicted theoretically in the mid nineties of the last century, and its existence has been confirmed experimentally approximately ten years later. Since then, a number of fundamental and applied aspects have been studied in this quickly growing field of research. This review provides an introduction to ICD and draws the connection to related energy transfer and ionization processes. The theoretical approaches for the description of ICD as well as the experimental techniques developed and employed for its investigation are described. The existing body of literature on experimental and theoretical studies of ICD processes in different atomic and molecular systems is reviewed.

Metal ions play numerous important roles in biological systems being central to the function of biomolecules. In this letter we show that the absorption of X-rays by these ions leads to a complicated chain of ultrafast relaxation steps resulting in the complete degradation of their nearest environment. We conducted high quality ab initio studies on microsolvated Mg 2+ clusters demonstrating that ionisation of an 1s-electron of Mg leads to a complicated electronic cascade comprising both intra-and intermolecular steps and lasting only a few hundreds femtoseconds.The metal cation reverts to its original charge state at the end of the cascade, while the nearest solvation shell becomes multiply ionised and large concentrations of radical and slow electron species build up in the metal's vicinity. We conclude that such cascades involving metal ions are essential for understanding the radiation chemistry of solutions and radiation damage to metal containing biomolecules.

An ultrafast mechanism belonging to the family of interatomic Coulombic decay (ICD) phenomena is proposed. When two excited species are present, an ultrafast energy transfer can take place bringing one of them to its ground state and ionizing the other one. It is shown that if large homoatomic clusters are exposed to an ultrashort and intense laser pulse whose photon energy is in resonance with an excitation transition of the cluster constituents, the large majority of ions will be produced by this ICD mechanism rather than by two-photon ionization. A related collective-ICD process that is operative in heteroatomic systems is also discussed.PACS numbers: 31.70. Hq, 32.80.Rm, 32.80.Wr The rapid development during the last decades of very intense light sources with extreme short pulse duration opened a new era in the study of radiation-matter interaction. Studying the interaction of intense fields with matter brought to the discovery of a whole plethora of new physical phenomena, like high-harmonic generation, above-threshold ionization, or tunneling ionization, to name only a few. In the same time, the progress in generating extremely short pulses gave the scientific community a powerful tool to monitor and control the electron dynamics in atomic and molecular systems and to study processes that take place on a time scale in which the electronic motion is still disentangled from the slower nuclear dynamics (for recent reviews see, e.g., Refs. [1, 2]). A number of free-electron lasers are in operation today providing extremely bright, coherent, and ultrashort pulses in the VUV regime. Exposed to such highly intense pulses, atomic and molecular systems will absorb a large amount of photons triggering various dynamical effects. In this letter we will restrict ourselves to situations where the single-photon energy in the pulse is not high enough to directly ionize the system. It is well known that even in this case the system can be ionized by a multiphoton ionization mechanism. The multiphoton ionization (MPI) results from the ability of quantum systems to absorb several and even many photons, whose individual energies are insufficient to ionize the system. The combined energy of the absorbed photons, though, suffices to eventually eject one or many electrons from the system. During the last decade the MPI has been intensively studied also in composite systems, like clusters, employing the new powerful laser sources (for a review see, e.g. Ref.[3]). However, little attention was paid to other mechanisms that can lead to a multiple ionization in an atomic or molecular cluster irradiated by an intense laser pulse.In this letter we aim at discussing a hitherto unrecognized mechanism for producing ionized species in homoatomic or homomolecular clusters exposed to an intense laser pulse, which in many cases can be by far One of the constituents of the system de-excites transferring the energy to the neighbor which uses it to emit its excited electron.the dominating one. For simplicity we will consider an atomic cluste...