Semiempirical studies of the spectra heavy and highly ionized atoms

Fast ion beam methods provide a convenient means for the study of very heavy and very highly ionized atoms, for which little spectroscopic data presently exist. High wavelength resolution of a fast moving source can be achieved through optical refocusing techniques, but there is a need for very accurate wavelength predictions and precisely known calibration lines. The accuracies required for spectroscopic classification often exceed the present capabilities of ab initio theoretical calculations for high relativistic many electron systems, and semiempirical data parameterizations can often provide more accurate predictions. We are carrying out a program of studies of the properties of these systems that combines experimental measurements by fast ion beam excitation with semi-empirical data parametrizations to identify and exploit regularities in their properties. Through the acquisition and systematization of empirical data, remarkably precise methods for predicting excitation energies, transition wavelengths, transition probabilities, level lifetimes, ionization potentials, core polarizabilities, and core penetrabilities are being developed and applied. Parametrized extrapolations and interpolations along isoelectronic, homologous, and Rydberg sequences are providing predictions for large classes of quantities, with a precision that is sharpened by subsequent measurements. Two examples are described