| This talk will focus on forbidden transitions and novel dynamics in Rydberg rubidium atoms excited in a MOT. When a transform-limited pulsed laser is used to directly excite the Rydberg spectrum from the 5s ground state, "pair photoassociation" resonances are observed to weakly bound pairs of Rydberg atoms. In addition, we observe direct excitation of dipole-forbidden atomic states due to electric quadrupole transitions, a purely single-atom effect. We have studied 5s-nd excitation for high n, as well as the 5p-8p transition, for which we show that prior reports of measureable magnetic dipole transition amplitudes are incorrect. At present, we are searching for states with predominantly ion-pair character near the energy of the Rb+ + Rb- separated-atom limit. Proposed schemes for enhanced coupling with ion pair states, including bound "heavy Rydberg" atoms, are discussed. |
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