Is Auger-free luminescence present in CeF3?

Abstract

It is well known that Auger-free luminescence (AFL) is observable when the condition E g  E VC is satisfied, where E g is the band-gap energy between the lowest unoccupied band and the highest occupied band and E VC the energy difference between the top of the highest occupied band and the top of the next lower occupied band. From measurements of reflection and x-ray photoelectron spectra, CeF 3 is demonstrated to really satisfy this condition. No evidence for AFL is found, nevertheless. The absence of AFL in CeF 3 is related to a characteristic nature of its highest and next lower occupied bands, which are quite different from those of previously studied AFL-materials.

Investigation of cross luminescence in lanthanum fluoride as a potential fast-response scintillator

“…8. 47,48) Firstly, the energy between the valence and conduction bands (band gap, E g ) should be greater than the energy between the outermost core band maximum and the valence band maximum (E CV ), i.e. E g > E CV to prevent re-absorption of the CL photon.…”