Seminar of Physics - Sebastian Vielhauer (20.11.2017)
Monday 20.11.2017 at 15:00, Lecture room F2/272
By: Peter Markoš
Sebastian Vielhauer (Laboratory of Physics of Ionic Crystals, Institute of Physics University of Tartu, Estonia):
Energy transfer processes in wide band gap materials and their impact on the development of novel phosphors and scintillators
The non-linearity of the light yield in tungstate crystals under high excitation density with free electron lasers and conventional fs UV lasers was studied using time-resolved photoluminescence spectroscopy. This method allows to investigate the dynamics of the energy transfer from the excited to the emitting states. For the case of high excitation density, a model for the self-quenching of excitons was developed which is applicable to a wide range of scintillators.
Another important application field is the development of phosphors for white light emitting LEDs. In these materials, doping with rare earth or transition metal ions is used to create the desired spectral composition of luminescence. The efficiency of energy transfer to the emitting states of the dopant and the influence of the host on the emission characteristics of the dopant ions are key parameters in the design and characterization of new phosphors for white LEDs.