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Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
Double excitations of helium in weak static electric fields
Conny Såthe1, Magnus Ström, Marcus Agåker
1Physics Department, Box 530, S-751 21 Uppsala, Sweden.
Physical Review Letters
|February 21, 2006
Summary
Electric fields dramatically alter helium
Area of Science:
- Atomic physics
- Quantum mechanics
- Spectroscopy
Background:
- Doubly excited states in helium exhibit complex behavior.
- Electric field effects on atomic spectra are crucial for understanding quantum phenomena.
Purpose of the Study:
- Investigate the electric field dependence of fluorescence yield in helium's doubly excited states.
- Explain the observed spectral features, including yield tuning and enhancement of forbidden states.
Main Methods:
- Employed R-matrix multichannel quantum defect theory.
- Utilized spherical-to-parabolic frame transformation.
Main Results:
- Successfully reproduced key features of the experimental fluorescence yield spectrum.
- Observed dramatic electric field dependence below the ionization threshold.
- Tuned fluorescence yields to zero for specific states.
- Significantly enhanced dipole-forbidden states with weak electric fields (< 1 kV/cm).
Conclusions:
- Weak electric fields induce significant mixing of states in helium.
- The theoretical model accurately captures the observed spectral phenomenology.
- Provides insights into the quantum behavior of atoms under external fields.
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