Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 12: Posters Thursday (Ion/Atom/Molecule/Surface Scattering)
A 12.10: Poster
Donnerstag, 5. April 2001, 12:30–15:00, AT3
Electric-field anticrossings of the 1s4ℓ configurations of 3He and 4He atoms — •Marco Busch1, Ryszard Drozdowski2, Gebhard von Oppen1, and Jens Witt1 — 1Technische Universitaet Berlin, Institut fuer Atomare und Analytische Physik, Hardenbergstrasse 36, D-10623 Berlin, Germany — 2University of Gdansk, Institute of Experimental Physics, ul. Wita Stwosza 57, 80-952 Gdansk, Poland
The electric-field splitting of the 1s4ℓ configuration of 3He and 4He atoms was evaluated numerically for determining the singlet-triplet anticrossings of the 1s4ℓ Stark sublevels. These anticrossings give rise to pronounced variations of the fluorescense-light intensity when investigating collisional excitation in He+-He collisions. We measured the intensity of the λ(1snℓ−1s2p 3P)=447 nm spectral line excited by 75/100 keV-3He+-4He collisions as a function of an electric field −30 kV/cm<Fz<+30 kV/cm. The 4He anticrossing spectrum dominates at fields Fz<0, whereas the 3He spectrum was observed at fields Fz>0. Both spectra differ significantly due to the hyperfine coupling of 3He. By exploiting this difference, the influence of the nuclear symmetry on the collisional excitation of He atoms in He+-He collisions can be investigated.