COMPARISON OF FIELD IONIZATION YIELDS FROM FOIL AND GAS EXCITED RYDBERG STATES IN FAST IONS

Abstract
Recent results of an investigation of effects of external electric fields on high Rydbery states which are formed in foil and gas interactions of fast (MeV) ions are reported. Absolute field ionization yields of the excited Rydberg states are measured for a variety of beam ions. Comparison between the quantum state population for the gas and foil excitation and mode1 calculations are consistent with lhe assumption that the Rydbery states are predominantly formed in the last layers of the solid target . The effect of a variable weak static electric field applied to the Rydberg states, causes marked oscillatory structures in the ionization yield as a function of the field strength. These oscillations, observed for gas and foil excitation , are interpreted in terms or quantum interferences among Stark states coherently developing in the weak field.