[en] Several studies involving the development and use of high spectral brightness rare gas halogen sources are presented. At 248 nm, a source whose spectral width and beam divergence approach the fundamental limits of physical optics is described. This device is clearly scalable to terawatt power levels. Such high brightness devices can be readily utilized to examine a broad range of atomic and molecular phenomena pertinent to laser development. These studies include state specific kinetic processes, excited state photoionization, electron collisional mechanisms, and a variety of multiquantum processes