Since their theoretical prediction in 1997, interatomic (intermolecular) Coulombic decay (ICD) and related processes have been in the focus of intensive theoretical and experimental research. The ...spectacular progress in this direction has been stimulated both by the fundamental importance of the discovered electronic decay phenomena and by the exciting possibility of their practical application, for example in spectroscopy of interfaces. Interatomic decay phenomena take place in inner-shell-ionized clusters due to electronic correlation between two or more cluster constituents. These processes lead to the decay of inner-shell vacancies by electron emission and often also to disintegration of the resulting multiply ionized cluster. Here we review the recent progress in the study of interatomic decay phenomena in singly and multiply ionized clusters.
Electronically excited states of atoms and molecules in an environment may decay in interatomic processes by transferring excess energy to neighboring species and ionizing them. The corresponding ...interatomic decay width is the most important characteristic of the decay allowing to calculate its efficiency and the final states' distribution. In this paper we present calculations of interatomic widths by the Fano-Stieltjes method applied to Lanczos pseudospectra, which has been previously shown to provide accurate autoionization widths in atoms and molecules. The use of Lanczos pseudospectra allows one to avoid the full diagonalization bottleneck and makes the method applicable to larger systems. We apply the present method to the calculation of interatomic decay widths in NeMg, NeAr and HCNmiddle dotMg(n), n = 1, 2 clusters. The results are compared with widths obtained analytically and by other ab initio methods where available.
The pattern of interspecific associations of three stem-galling sawfly species (Euura atra, E. elaeagnos, E. purpureae) and three stem-galling gallmidge species (Rabdophaga sp. 3-5) was investigated ...on five willow taxa (Salix alba, S. fragilis, S. x rubens, S. elaeagnos, S. purpurea) at five natural sites in Central Europe. The willow species harboured specific species associations of two stem gallers, each pair consisting of one Euura and one Rabdophaga species. The stem gallers were patchily distributed and their densities varied significantly among willow host plant species, host plant individuals, and host plant sexes. Four of the six species showed a significant increase in galling rate with shoot length. The other two species were the sawfly and cecidomyiid pair that induce galls on S. purpurea. The preference of stem gallers to longer shoots was generally not related to higher larval performance in terms of survival. Only one species, Rabdophaga sp. 5, was found to be more abundant on male plants. The correlation of densities of the species pairs of stem gallers was independent of willow sexes. Species pairs of stem gallers co-occurring on the same willow species tended to attack different shoots within the same host plant individual. When species pairs co-occurred on shoots they were usually found in similar densities as when occurring alone on shoots. The stem-galling sawflies usually formed galls at the basal part of a shoot, whereas the gallmidge R. sp. 5 (R. sp. 3 and R. sp. 4 showed no clear tendency) preferred the middle or distal part of a shoot. This is interpreted with differences of their phenology and oviposition period.
In this article, we investigate the dependence of interatomic Coulombic decay widths on the symmetry of the decaying state. In this type of decay, excited, ionized, and doubly ionized states of an ...atom or molecule can efficiently relax by ionizing their environment. We concentrate on an atom A and a neighboring atom B and consider such excited, ionized, or doubly ionized states of A that decay by emitting a single photon if A were an isolated atom. Analytical expressions for the various widths are derived for large interatomic distances R. A pronounced dependence of the widths on the symmetry properties of the decaying state is found. This dependence at large R is related to the dependence of the interaction energy of two classical dipoles on their mutual orientation. Comparison with precise ab initio calculations shows that the analytical results hold well at large R, while they deviate from the ab initio values at smaller R due to the effect of orbital overlap.
Excitation of two identical species in a cluster by the absorption of two photons of the same energy is strongly suppressed since the excitation of one subunit blocks the excitation of the other one ...due to the binding Coulomb interaction. Here, we propose a very efficient way to overcome this blockade in producing doubly-excited homoatomic clusters by a single intense laser pulse. For Ne\(_2\) it is explicitly demonstrated that the optimal carrier frequency of the pulse is given by half of the energy of the target state, which allows one to doubly excite more than half of the dimers at moderate field intensities. These dimers then undergo ultrafast interatomic decay bringing one Ne to its ground state and ionizing the other one. The reported \emph{ab initio} electron spectra present reliable predictions for future experiments by strong laser pulses.
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