Measurements of the singlet-triplet mix ratio in He(41,3F)

Odd-parity barium Rydberg states have been populated by stepwise excitation via M1-E1 and E2-E1 transitions, starting from the 6s2 1S0 ground state. Using two cw dye ring lasers and employing thermionic detection, Doppler-free spectra of 6snp 1,3P and 6snf 1,3F Rydberg states have been recorded with excellent signal/noise ratios. A systematic study of the hyperfine structure of 6snp 1P1 Rydberg states has been carried out. Between n=20 and n=23 a resonance in singlet-triplet mixing occurs caused by configuration interaction with the 5d8p 1P1 perturbing state, located close to the first ionization limit. Our results are in disagreement with an existing multichannel quantum defect analysis of this series. The singlet-triplet mixing of 6snp 1P1 and 6snd 1D2 Rydberg series is compared.Odd-parity barium Rydberg states have been populated by stepwise excitation via M1-E1 and E2-E1 transitions, starting from the 6s2 1S0 ground state. Using two cw dye ring lasers and employing thermionic detection, Doppler-free spectra of 6snp 1,3P and 6snf 1,3F Rydberg states have been recorded with excellent signal/noise ratios. A systematic study of the hyperfine structure of 6snp 1P1 Rydberg states has been carried out. Between n=20 and n=23 a resonance in singlet-triplet mixing occurs caused by configuration interaction with the 5d8p 1P1 perturbing state, located close to the first ionization limit. Our results are in disagreement with an existing multichannel quantum defect analysis of this series. The singlet-triplet mixing of 6snp 1P1 and 6snd 1D2 Rydberg series is compared.

Le Journal de Physique ColloquesNov 1, 19836 citations

Coherent excitation of the singlet-triplet mixed 1s4f state of helium

Jingbo B. Wang, Jim Williams, A. T. Stelbovics +2 more

In this paper, we present a detailed theoretical description for the coherent electron-impact excitation, the subsequent time evolution, and the cascading decay process of the singlet-triplet mixed $1s4f$ state of helium. The excitation amplitude and phase of each sublevel of this state are related to measurable coincidence intensities and polarizations of the emitted photons. It is found that the intensity and polarization of the emitted photons are time modulated due to the singlet and triplet mixing in the $1s4f$ state.In this paper, we present a detailed theoretical description for the coherent electron-impact excitation, the subsequent time evolution, and the cascading decay process of the singlet-triplet mixed $1s4f$ state of helium. The excitation amplitude and phase of each sublevel of this state are related to measurable coincidence intensities and polarizations of the emitted photons. It is found that the intensity and polarization of the emitted photons are time modulated due to the singlet and triplet mixing in the $1s4f$ state.

Physical Review AOct 1, 199515 citations

In this paper, we present a detailed theoretical description for the coherent electron-impact excitation, the subsequent time evolution, and the cascading decay process of the singlet-triplet mixed

1s4f

state of helium. The excitation amplitude and phase of each sublevel of this state are related to measurable coincidence intensities and polarizations of the emitted photons. It is found that the intensity and polarization of the emitted photons are time modulated due to the singlet and triplet mixing in the

1s4f

state.