Cationic double K-hole pre-edge states of CS2 and SF6

R Feifel,L Journel,R Guillemin,J H D Eland,A F Lago,O Travnikova,D Céolin,I Ismail,S Carniato,T Marchenko,P Selles,P Lablanquie,M N Piancastelli,D Koulentianos,R Püttner,F Penent,B Cunha De Miranda,M Simon,G Goldsztejn

doi:10.1038/s41598-017-13607-6

Abstract

Recent advances in X-ray instrumentation have made it possible to measure the spectra of an essentially unexplored class of electronic states associated with double inner-shell vacancies. Using the technique of single electron spectroscopy, spectra of states in CS2 and SF6 with a double hole in the K-shell and one electron exited to a normally unoccupied orbital have been obtained. The spectra are interpreted with the aid of a high-level theoretical model giving excellent agreement with the experiment. The results shed new light on the important distinction between direct and conjugate shake-up in a molecular context. In particular, systematic similarities and differences between pre-edge states near single core holes investigated in X-ray absorption spectra and the corresponding states near double core holes studied here are brought out.

Highlights

Hollow atoms and molecules with double vacancies in inner shells are currently a subject of much interest because of their putatively enhanced chemical sensitivity especially in the molecular cases
Detection of double core holes (DCHs) formed by single-photon ionization became possible thanks to the availability of high-brilliance third-generation synchrotron radiation sources and to the development of a highly efficient multi-electron coincidence technique based on a magnetic bottle[2,3,4,5,6,7,8,17], which is vital for the detection of electrons which can share the excess energy arbitrarily
Density Functional Theory (DFT) calculations are performed for core-hole formation on C and F atoms

Summary

Introduction

Hollow atoms and molecules with double vacancies in inner shells are currently a subject of much interest because of their putatively enhanced chemical sensitivity especially in the molecular cases (e.g. ref.[1]). It is important that in conjugate shake-up, where an unoccupied orbital is populated upon photon absorption, dipole selection rules govern the symmetries of the final states, just as in the formation of pre-edge resonances based on single core holes, whereas in direct shake-up the excitation step is a monopole process and the state formed must have the same symmetry as the initial core hole.

Results

Conclusion