Ab Initio Description of Vibronic Emission Bands in Noncentrosymmetric Lanthanide Complexes

Understanding the effect of coupling between the electronic and vibrational states is important for interpretation of the emission spectra of lanthanide-based materials. We present an approach for predicting vibronic bands in the luminescent noncentrosymmetric lanthanide complexes based on ab initio electronic structure calculations. We apply this approach to the complex vibronic structure of the ⁴S_3/2 → ⁴I_15/2 green emission in the erbium trensal complex, analyze the positions and intensities of vibronic peaks, and identify the key molecular vibrations contributing to the vibronic bands. The introduced approach is highly complementary to the experimental studies of lanthanide luminescence and can be used to gain valuable insight into electron-vibrational coupling in lanthanide-based materials.