Experimental Study and Analysis of the Lithium Atom in the Presence of Parallel Electric and Magnetic Fields

The structure of the $n=30$, $M=0$ manifold of lithium has been investigated experimentally in the presence of weak parallel electric and magnetic fields. The main properties of the spectra and their evolution with increasing field strengths are interpreted from the analysis of the approximate integral of motion obtained for hydrogen. The lithium spectra exhibit additional alterations which are typical of the short-range core effects.