Fluorescence Linewidths In Glasses

The homogenous optical linewidth of an impurity ion in a glass is described in terms of a process which arises from thermal transitions between the statues of the 2 level systems of a glass; these give shifts in the electronic energy levels via the strain field coupling. With available values of the parameters, this contribution gives reasonably good agreement of the overall magnitude as well as for the temp and time dependences observed recently for the magnitude as well as for the "anomalous" fluorescence linewidth of Eu3+ in silicate glass for temps. up to =100k.