The electronic structure on an ion in a low-density plasma is compared
with that of an ion in a high-density plasma. The raising of energy l
evels and pressure ionization of loosely bound levels are well known a
nd easy to estimate with reasonable accuracy. The accompanying changes
in dipole transition rates-the main point of this note-are illustrate
d by means of self-consistent field calculations of an isolated ion an
d an ion screened by free electrons.