  We show how optical spectra in dense plasmas are determined by the shift of
energy levels as well as the broadening owing to collisions with the plasma
particles. In lowest approximation, the interaction with the plasma particles
is described by the RPA dielectric function, leading to the Debye shift of the
continuum edge. The bound states remain nearly un-shifted, their broadening is
calculated in Born approximation. The role of ionization potential depression
as well as the Inglis-Teller effect are shown. The model calculations have to
be improved going beyond the lowest (RPA) approximation when applying to WDM
spectra.
