Physical Review A
Frequency-resolved observations of heavy Rydberg states in molecular hydrogen are reported in the ungerade manifold of states. Double-resonance spectroscopy via the E, F (1) Sigma(+)(g), v' = 6 state has been used to probe the energy region above the H(1s) + H(3l) dissociation threshold. Resonances are observed by ionizing H(3l) to produce H(+), which is then detected by using a time-of-flight mass spectrometer. The kinetic energy of the H(+) ion confirms that the observed signal is due to the photoionization of neutral H(3l) atoms, indicating that dissociation is a significant decay channel for the ion-pair states. The pattern of energies of the resonances agree well with the predictions of a mass-scaled Rydberg formula for bound quantum states of the H(+)H(-) ion pair. Energies and quantum defects have been determined for principal quantum numbers in the range of n = 130 to 207.
© 2011 by the American Physical Society. The publisher's version of the article can be found at http://link.aps.org/doi/10.1103/PhysRevA.84.020501.
R.C. Ekey, Jr., and E.F. McCormack, Phys. Rev. A 84, 20501 (2011).