Luminescence quantum yield of Tb3+‐activated yttrium compounds excited in the UV and VUV range

The energy transfer from the host to the dopant ion by capture of charge carrier gives rise to the self‐ionization (SI) state of the luminescent center. The oxido‐reduction power of the host matrix imposes on the luminescent center its self‐ionization state energy. In the configurational coordinate diagram of the luminescent center, the probability of non‐radiative relaxation from the self‐ionization state directly to the ground state increases when this former state is situated at low energy and/or when its coupling with the vibrational modes of the surrounding ions is important.