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E. REINHOLD, W. HOGERVORST, W. UBACHS, Laser Centre, Department of Physics and Astronomy, Vrije Universiteit, Amsterdam, Netherlands.
In an experiment combining 1XUV + 1UV double resonance laser excitation in the presence of a small electric field with pulsed field ionization, bound states in the 1/r potential just below the H+H- ionization (or dissociation) limit were observed. About 10 cm-1 below the limit the level density is so high that even for narrowband excitation (
laser=300 MHz) about 150 n-states are coherently excited. Experimentally, signal recurrences were observed as a function of delay of the field ionization pulse, that match the splittings between Stark states. A theoretical interpretation of the phenomena is presented fully based on the analysis of Rydberg states in the hydrogen atom, in which the electron is replaced by the heavier H- particle.