SCALED ENERGY-SPECTRA OF NONHYDROGENIC RYDBERG ATOMS IN A MAGNETIC-FIELD

We present a new method for computing the spectrum of one-electron Ryd berg states of non-hydrogenic atoms in a magnetic field, at constant s caled energy. It is based on a variant of the R-matrix method allowing the computation of many energy levels in a single diagonalization. Th e results are compared with recently obtained high-resolution experime ntal spectra of the helium atom. The relation between peaks observed i n the Fourier transform of scaled spectra and classical closed orbits is discussed. We show the existence of 'ghost' peaks not corresponding to any closed orbit, and also of peaks existing only in non-hydrogeni c spectra, due the scattering of the electron by the ionic core.