Observation of four-electron Auger processes

A Müller,S Klumpp,M Martins,S Schippers,S Ricz,A Borovik,J Viefhaus,A L D Kilcoyne,T Buhr,J Hellhund,K Holste

doi:10.1088/1742-6596/635/1/012033

Abstract

Multiple ionization of ions subsequent to absorption of a single photon has been studied employing a photon-ion merged-beam setup at the PETRA III synchrotron radiation facility of DESY in Hamburg. Absolute cross sections for single, double and triple ionization of C+ ions were measured with emphasis on specific well defined terms of K-shell excited C+. In particular, the terms C+ (1s2s22p2 2D,2P) were excited from the ground level of C+. Subsequent autoionization processes resulted in the production of C2+, C3+ and C4+ ions. The associated decay mechanisms are single-Auger, double-Auger and triple-Auger decay. The observation of C4+ products arising from C+(1s2s22p2 2D,2P) unambiguously confirmed the existence of triple-Auger decay, i.e., a process in which 4 electrons interact with one another such that one fills the K-shell vacancy and the others are simultaneously ejected. The experiment yields branching ratios for the Auger decay channels as well as individual decay rates for autoionization and radiative stabilization of the C+(1s2s22p2 2D,2P) terms.

Highlights

Multi-electron processes associated with electron-electron interactions or electron correlations have always attracted broad interest since the early days of quantum mechanics
In level of complexity after the singleAuger process [1] are Auger mechanisms in which three electrons interact with one another, one filling a core hole and two electrons being promoted to excited states or to the continuum
By normalizing the signal count rate to the ion flux measured in a large Faraday Cup inside the demerger chamber, to the photon flux measured with a photodiode and to the form factor, absolute cross sections for photodisintegration of atoms or molecules can be determined

Summary

Introduction

Multi-electron processes associated with electron-electron interactions or electron correlations have always attracted broad interest since the early days of quantum mechanics. Higher-order Auger decay processes are possible and have been observed in numerous electron-ion and photon-ion interactions [2,3,4]. By normalizing the signal count rate to the ion flux measured in a large Faraday Cup inside the demerger chamber, to the photon flux measured with a photodiode and to the form factor, absolute cross sections for photodisintegration of atoms or molecules can be determined.

Results

Conclusion