ABSTRACT
To develop efficient electronic state lasers, one must be able to populate selectively a small number of excited electronic states. This requirement demands that either highly selective excitation mechanisms be operative or that schemes for concentrating the excitation energy into the selected states can be applied. A variety of optical, electrical and chemical pumping techniques which allow for the efficient population of excited electronic states are described. These schemes coupled with collisional processes and molecular dynamics which favour specific energy channelling routes lead to inversions in a number of molecular and atomic systems. Diagnostic techniques, as well as information gained from infrared laser studies, are shown to provide valuable tools for selecting and evaluating candidate laser systems.
