Since the first attempts to calculate the helium ground state in the early days of Bohr-
Sommerfeld quantization, two-electron atoms have posed a series of unexpected …

Recent experimental work using photons to study double excitation, double escape and
related processes near their respective thresholds is reviewed. These processes are of …

The fluorescence yield spectrum of the double excitations in helium has been measured. All
three Rydberg series converging to the N= 2 threshold are resolved, and the intensity of the …

We have observed, for the first time, LS-forbidden triplet doubly excited states, in single
photon excitation of ground state helium, below the second ionization threshold. These …

The radiative decay of P o 1 doubly excited states in helium has been investigated using a
novel apparatus in which metastable atoms and vacuum ultraviolet photons are detected …

We have made an investigation on the 2 s 2 p P o 1, 3 resonance states of helium
embedded in dense plasma environments. A screened Coulomb potential obtained from the …

A theoretical study of the radiative decay of low-lying doubly excited 1 P o states of Helium in
the energy region below the He+(N= 2) threshold is presented. We calculated the oscillator …

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 …

The molecular beam scattering of a K atom beam off a zirconia surface at 1100 K is studied
with four different detection techniques: field ionization, which is sensitive only to field …

We have investigated the doubly excited 1, 3 P o resonance states of helium embedded in
weakly coupled plasmas. A screened Coulomb potential obtained from the Debye model is …