Towards a general concentration quenching model of Bi³⁺ luminescence

The vacuum referred binding energy of the electron in the Bi²⁺ ground state has been determined in 15 different compounds. This shows that the electron binding energy in the ground state of Bi²⁺ is at lower (more negative) energy compared to the electron binding energy in the excited state of Bi³⁺. This means that electron transfer from the excited state of one Bi³⁺ to a neighboring Bi³⁺, forming a Bi2+−Bi⁴⁺ pair, acts as a quenching route for the Bi³⁺ emission. Electron back transfer in the Bi2+−Bi⁴⁺ pair is then suggested to be the origin for the frequently observed pair emission. This paper shows that vacuum referred electron binding energy diagrams can provide a unique physical insight in the properties of inorganic compounds.