Highly excited electronic states of molecular clusters and their decay

Abstract

Highly excited electronic states of molecular clusters with intermediate-shell vacancies are calculated and analyzed using large scale ab initio Green's function calculations. In sharp contrast to molecules, an intermolecular Coulombic mechanism has been found to lead to an ultrafast decay of singly and doubly ionized states with vacancies in the inner-valence region. Small hydrogen-bonded ͑HF͒ n clusters (nϭ2-4͒ have been selected as explicit examples to illustrate the proposed decay process, which does not occur in the HF monomer. The decay mechanism and the main factors that exercise an influence on it are discussed. The corresponding decay widths are estimated in selected cases, showing that the lifetimes of the states are of the order of few femtoseconds.

Impact of interatomic electronic decay processes on Xe 4d hole decay in the xenon fluorides

“…Owing to the discrete basis set used, the appearance of a decaying state mimics a discretized Lorentzian curve. 25 As can be seen in Fig. 3, such curves may indeed be identified for XeF n above 50 eV.…”

“…We mention that the decay processes discussed in the following for singly ionized systems can be generalized to describe the decay of inner-valence vacancies of multiply ionized clusters. 25,34 Intra-atomic electronic decay (IAED) is usually the most prominent electronic decay process of core-ionized atoms embedded in molecules or clusters. IAED is, of course, the only Auger process that can take place in an isolated atom.…”

“…This allows us to identify various interatomic decay processes and to distinguish them from the intra-atomic one. In particular, the purely interatomic/intermolecular electronic decay mechanisms that govern the inner-valence physics in weakly bound clusters of atoms or molecules 23,24,25,26,27,28,29 provide a conceptual framework for our analysis. Therefore, a short summary of these processes is given in Sec.…”

Ionization of the xenon fluorides

“…2 an increasing loss of main-line intensity and the emergence of dense line bundles. This is the signature in our finite-basis-set calculations of enhanced electronic decay, 40 as pointed out previously.…”

“…40 In particular, the final state of the electronic decay of an ionized molecule can be approximated in terms of two-hole-one-particle configurations describing the emitted electron (the particle) and the residual dication (the two holes). 41 The shape of each decaying state can be identified as a thin bundle of lines, which mimic a discretized Lorentzian curve.…”