Production and Decay of Atomic Inner-Shell Vacancy States Thomas Gorczyca   Department of Physics Western Michigan University 1903 West Michigan Avenue Kalamazoo, MI 49008-5252 Our recent investigations on the accuracy of the existing1s-vacancy fluorescence and Auger data base, which is crucial for the interpretation of spectra from X-ray photoionized plasmas and for supernova remnants under conditions of non-equilibrium ionization, will be reviewed. In particular, effects such as non-hydrogenic scaling, correct initial state averaging, configuration interaction (CI), and spin-orbit mixing, which were not included in the earlier calculations but sometimes affect profoundly our computed fluorescence yields, will be discussed. Furthermore, the production of1s-vacancy states through photoabsorption will be reviewed, with emphasis on orbital relaxation and spectator Auger broadening of the resonance edge. How our recent oxygen photoabsorption data contribute to elemental abundance studies of the inter-stellar medium will also be discussed.