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Double Photoexcitation of Helium in a Strong dc Electric Field

2003; American Physical Society; Volume: 90; Issue: 13 Linguagem: Inglês

10.1103/physrevlett.90.133002

1092-0145

James R. Harries, James P. Sullivan, James Sternberg, Satoshi Obara, Tadayuki Suzuki, P. R. Hammond, John D. Bozek, N. Berrah, M. Halka, Y. Azuma,

Quantum, superfluid, helium dynamics

We report the first experimental measurements of the effect of an applied field on the photoexcitation and autoionization of doubly excited states of helium. Ground-state photoionization spectra have been measured in the region below the He+(N=2) threshold with static electric fields of up to 84.4 kV/cm across the interaction region. The results are compared to the theoretical calculations of Chung et al. [J. Phys. B 34, 165 (2001)]], which are the only calculations available in this regime. Transitions to several states in the N=2, n=6 manifold are assigned, and a wealth of new structure is observed. Our data show that many more series are mixed in by the field than those predicted by theory.