2. Spectroscopic and dynamic characteristics – Optical processes involved

Basically, luminescent materials are characterized by their spectral and dynamic properties. Their spectral properties are determined by the position, profile and intensity of their absorption and emission spectra. Their dynamic properties are determined by the relaxation dynamics (time evolution) of optical excitations between the energy levels that characterize each type of emitting center (including fluorescence lifetime), and by the quantum efficiency of the emitting level in question. These properties may derive from the characteristics of the emitting center and its interactions with the vibrations of its solid environment; they may also result from more complex mechanisms involving direct and indirect absorption/excitation, relaxation and emission processes, involving couplings with the host lattice as well as with other absorbing or radiation-emitting centers. These different situations...