Interatomic Coulombic Decay Mediated by Ultrafast Superexchange Energy Transfer

Abstract

Inner-valence ionized states of atoms and molecules live shorter if these species are embedded in an environment due to the possibility for ultrafast deexcitation known as interatomic Coulombic decay (ICD). In this Letter we show that the lifetime of these ICD active states decreases further when a bridge atom is in proximity to the two interacting monomers. This novel mechanism, termed superexchange ICD, is an electronic correlation effect driven by the efficient energy transfer via virtual states of the bridge atom. The superexchange ICD is discussed in detail on the example of the NeHeNe trimer. We demonstrate that the decay width of the Ne^{+}(2s^{-1}) ^{2}Σ_{g}^{+} resonance increases 6 times in the presence of the He atom at a distance of 4 Å between the two Ne atoms. Using a simple model, we provide a qualitative explanation of the superexchange ICD and we derive analytical expressions for the dependence of the decay width on the distance between the neon atoms.

Virtual Photon Approximation for Three-Body Interatomic Coulombic Decay

“…This expression is often used as a consistency check for the large-distance behaviour of a particular quantum chemical calculation. Furthermore, an analytical formula for the ICD rate provides a simple means to investigate large systems based on the decomposition of the clusters into pairs [7,8].Recently, a type of three-body ICD mechanism known as superexchange was proposed [9]. Based on extensive ab initio calculations, it was shown that the rate of energy transfer can be substantially enhanced in the presence of a third ICD-inactive mediating atom.…”

“…Recently, a type of three-body ICD mechanism known as superexchange was proposed [9]. Based on extensive ab initio calculations, it was shown that the rate of energy transfer can be substantially enhanced in the presence of a third ICD-inactive mediating atom.…”

“…Then; where u NR = αρ 3 AD /(ρ 3 DM ρ 3 MA ) is a dimensionless number indicating the strength of the interaction with the mediator, which must be less than unity for our perturbative approach to be applicable. For comparison with recent ab initio work [9], we further assume that the mediator is halfway between the donor and acceptor (ρ DM = ρ MA = ρ AD /2), giving a very simple result;…”

“…3 is the comparison between the ICD widths given in our new approach by Eq. (7), and the calculated with the ab initio Fano-algebraic diagrammatic construction (ADC)-Stieltjes method [6,17] (see [9] for details of the calculations). As seen in the upper panel, the results deviate significantly from the ab initio data if ρ AD 7Å.…”

“…ICD rate vs donor-acceptor distance, with the mediator placed at the midpoint, C6 = 3.6eV and α = αHe = 0.205Å 3 . NeNe denotes the situation when the mediator is removed entirely, NeHeNe in the upper plot represents the same data as presented in [9], while the lower plot contains new high-resolution data calculated for this work. The error bars on the ab initio data are 3%, which comes from the standard deviation of the decay widths calculated by Fano-ADC-Stieltjes method.…”