Interatomic or Intermolecular Coulombic Decay (ICD)

The chemical environment places a fundamental role on the electronically excited states of atoms, molecules and solids. If the excited atom or molecules is alone, it can decay only radiatively. While putting excited atom or molecule close to the neighborhood of other particles, a new more efficient decay mechanism may occur. Such an electronic decay was first predicted in a pioneering theoretical work by Cederbaum and co-workers and called Interatomic or Intermolecular Coulombic Decay (ICD) [1]. The electronically excited atom can transfer its energy in an extremely efficient way to a neighboring atom which then releases that energy by emission of one of its own outer shell electrons (see Fig.1). Since that time, various experimental and theoretical studies have shown that ICD is a rather common decay mode, widely encountered in loosely bound matter [2]. One of the most remarkable features of ICD is its extremely short lifetime, making it a highly efficient decay process for an excited atom embedded in an environment and, thus, a strong source of low-energy electrons. Therefore ICD is of current interest in attosecond and short wavelength free electron laser sciences [3-5]. In a broader context, ICD bridges the gap between fundamental research on the correlated motion of electrons and nuclei and more applied research, for example, on the use of low kinetic energy electrons in radiation chemistry.
Figure 1. The ICD process in Ne dimer: creation of a 2s hole in a neon dimer by photoionization; successive interatomic Coulombic decay: the 2s hole is filled by a 2p electron, the excess energy is transferred to the neighboring neon atom causing the ejection of one of its 2p electrons; the final state consists of two singly charged Ne+ ions, which undergo a Coulomb explosion [6].
[1] L.S. Cederbaum, J. Zobeley, F. Tarantelli, Phys. Rev. Lett. 79, 4778 (1997).
[2] U. Hergenhahn, J. Electron Spectrosc. Relat. Phenom. 184, 78 (2011).
[3] A. Dubrouil et al., J. Phys. B. 48, 204005 (2015).
[4] D. Iablonskyi e al., Phys. Rev. Lett.117, 276806 (2016).
[5] T. Takanashi et al, Phys. Rev. Lett. 118, 033202 (2017).
[6] T. Jahnke et al., Phys. Rev. Lett. 93, 163401 (2004).


Last Updated on Thursday, 19 August 2021 16:11