Interatomic coulombic decay: a short review

Abstract

The transition process of the interatomic Coulombic decay (ICD), is an electronic radiationless transition process, driving molecular complexes or clusters to a doubly ionized final state. This process differs from the Auger effect, because it takes place from a neutral monomer after the absorption of a released amount energy of the neighboring monomer in the weakly bound molecule. This process has been theoretically studied and the most recent experimental evidence was observed with neon dimer. This work presents a description of the process and a detailed revision of the derivation for the distribution kinetic energy equation to the emitted electrons by ICD decay, with a small variation in the wave packet form of the transition for the final states , with non-Hermitian time-dependent theory.Keywords: decay, ICD, transition THE PROCESS DESCRIPTIONThe ICD process was predicted by Cederbaum and coworkers [1] and experimental evidence was observed in the recent work of Jahnke et al. [2]. This new type of transition, not accompanied by emission of radiation, starts from the ionization of a monomer in the neon dimer, for the inner valence (i.v.) at 2s orbital. Initially the system is in the state ϕ 0 = ϕ n ϕ i , which is a nuclear vibrational and an electronic state, within the Born-Oppenheimer approximation. Following, one 2p electron of the outer valence (o.v.) shells of the same monomer, occupies the hole in the 2s orbital releasing a certain amount of energy that is not sufficient to ionize the same monomer. However, this energy released is sufficient to cause the emission of another 2p electron from the closest neighboring monomer, which the dimer is composed of, producing two Ne + (2p −1 ) ions, which repel each other in a so-called Coulombic explosion. A discussion of the energies involved in process can be seen in Dias [3]. The energy transfer between monomers is strongly connected with the nuclear separation [4]. The process can be described by the sets: KINETIC ENERGY DISTRIBUTION EQUATIONConsider the ICD process [5] as a transition in two times: i → k, k → f . Here, the (k) state is a intermediate decay state; (i) is the vibrational initial state and (f) is the vibrational final state. The initial state (i), it is governed by the wave packet ϕ 0 , eigenstate of the Hermitian operatorĤ 0 .The system is ionized by the inner valence (i.v.) of one of his monomers , leading to a electronic decay state (k), with a wave function ϕ k n (t) = e −iE k tD ϕ 0 , eigenstate of the nonHermitian operatorĤ k , governed by a complex potential according to Moiseyev [6]. The operatorD(R) is the ionization * Electronic address: alexandre.dias@unifenas.br or dipole operator. Gradually, this wave packet decays to the final state. To each time interval dt, part of the packet decays to the final state following the emission of an electron with the E Kin kinetic energy. Fig. 1 illustrates the decay process described. FIG. 1: The ICD transition processConsider that the decaying wave packet to the final (f) state, has the following...

Interatomic and Intermolecular Coulombic Decay

“… 12 An early summary on theoretical aspects of ICD has been provided by Santra and Cederbaum in 2002, 7 and in 2011, Averbukh et al reviewed more recent theoretical research on ICD. 13 In addition, in 2009, Dias gave a very brief review on the topic, 14 two short reviews on coincident particle detection in the gas phase covered several experiments on ICD as well, 15 , 16 and a review 17 and a book 18 on core-level spectroscopy of free clusters discuss ICD with respect to this topic. Time domain-aspects of ICD were reviewed in a short article by Frühling et al in 2015.…”