There are two main areas of research being conducted in the Spangler group. The first involves investigation of optical materials and the mechanisms by which they function. In materials such as laser materials, optical power limiters (materials with non-linear absorption which can protect against lasers) and photorefractives, complicated energy transfer and charge transfer processes can occur after the initial photoexcitation. These processes can occur on timescales ranging from 10-13 sec to minutes and can cause spectral changes anywhere in the optical range (UV to IR). For this reason, we are developing new, multi-dimensional spectroscopic techniques for the investigation of optical materials that yield high information content in a relatively short experiment time.