Spectroscopy between parabolic states in hydrogen: Enhancement of the Stark-induced resonances in its photoionization

We present calculations of the photoionization spectrum of excited hydrogen using polarization in the presence of a strong electric field as a function of the spherical (applicable to complex atoms) and parabolic quantum numbers of the excited state. We also present corresponding measurements of the photoionization yield from the individual parabolic states of n=2. Both the calculations and the measurements show an enhancement of the depth of the so-called Stark-induced modulation in the region E 0 when the initial excited state is a pure ml=0 blue state, and disappear almost completely when the initial state is a pure ml=0 red state. These results are understood using arguments based on the fact that the charge distribution of the Stark-induced states is tremendously extended up field. Because of the excellent signal to noise ratio of the enhanced modulations, we were able to measure the field dependence of the spacings with sufficient accuracy to confirm the (3/4) power law and rule out the recently suggested (2/3) power law.