Theory of vibronic optical spectra of impurity centers with violation of the Condon approximation

Phonon-Mediated Nonradiative Relaxation in Ln3+-Doped Luminescent Nanocrystals

“…Also, Binnemans emphasized that the Eu 3+ 5 D 1 → 5 D 0 relaxation was a second-order process and could only arise by admixing of the 5 D 2 state component into the 5 D 1 and 5 D 0 states, which was in line with the explanation of “ J -mixing” denoted elsewhere. , An associated view recently reported by Netzsch et al stated that the dominance of a magnetic dipole character, instead of an induced electric dipole character, of certain nonradiative transitions of Ln 3+ was the reason underlying the abnormally slow Gd 3+ 6 P 5/2 → 8 S 7/2 and Nd 3+ 4 F 5/2 → 4 F 3/2 relaxations (Δ J = 1). In addition, the constraint brought about by the site point group selection rule (which is symmetry-associated) cannot be neglected, ,,,,, and its significance has been discussed previously. ,− Given these observations, it is undeniable that the transition selection rule regulates significantly the nonradiative relaxation of Ln 3+ .…”