Abundance of molecular triple ionization by double Auger decay

A Hult Roos,O Talaee,R Feifel,J H D Eland,D Koulentianos,J Andersson,R J Squibb

doi:10.1038/s41598-018-34807-8

Abstract

Systematic measurements of electron emission following formation of single 1s or 2p core holes in molecules with C, O, F, Si, S and Cl atoms show that overall triple ionization can make up as much as 20% of the decay. The proportion of triple ionization is observed to follow a linear trend correlated to the number of available valence electrons on the atom bearing the initial core hole and on closest neighbouring atoms, where the interatomic distance is assumed to play a large role. The amounts of triple ionization (double Auger decay) after 1s or 2p core hole formation follow the same linear trend, which indicates that the hole identity is not a crucial determining factor in the number of electrons emitted. The observed linear trend for the percentage of double Auger decay follows a predictive line equation of the form DA = 0.415 · Nve + 5.46.

Highlights

Formation of a core vacancy in an atom or molecule, upon photon absorption or high energy particle impact, will lead to relaxation of the system where one of the possible consequences is non-radiative secondary electron emission commonly denoted as Auger decay
This is consistent with the theory on double Auger decay in atoms reported in refs[1,2], and with our previous study[3] on the amount of double Auger decay in simple molecules
1s and 2p core hole formation events follow the same linear trend, which may indicate that the hole identity is not a crucial distinction for the proportion of double Auger decay

Summary

Introduction

Formation of a core vacancy in an atom or molecule, upon photon absorption or high energy particle impact, will lead to relaxation of the system where one of the possible consequences is non-radiative secondary electron emission commonly denoted as Auger decay. Spectra of dications from this single Auger (SA) decay in polyatomic molecules are more complex than the spectra of isolated atoms, because molecular vibrations and dissociations come into play, and the increased number of valence electrons implies an increased number of possible final double-hole states. These factors typically result in broad spectral profiles, where the intensity represents a convolution of contributions from many possible transitions. We investigate the Auger decay upon the formation of a carbon, oxygen, or fluorine 1s core hole, and upon the creation of a sulphur, chlorine, or silicon 2p core hole in a series of compounds

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Conclusion