Darmstadt 2008 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 26: Spektroskopie in He-Tröpfchen
MO 26.2: Poster
Donnerstag, 13. März 2008, 16:30–19:00, Poster C1
Localisation of Calcium in 3He, 4He and mixed 3He/ 4He Nanodroplets — •Matthieu Dvorak, Oliver Bünermann, and Frank Stienkemeier — Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg-im-Breisgau
Electronic spectroscopy of atomic impurities in helium nanodroplets is a sensitive method for determining the localisation of the impurity in the droplet. The important observables are the shift as well as the width of electronic transitions. Atomic impurities located inside the droplet show large blue shifts identical to measurements made in bulk helium. Atomic impurities located on the surface, for example alkali metal atoms, only show small blue shifts.
We present new results of the 4s2 1S0 ← 4s4p 1P0 transition of calcium atoms bound to droplets formed of both helium isotopes. The results are directly compared to those obtained in bulk helium. For 4He the shift is much smaller in the droplet than in bulk but for helium 3He shifts are the same in both cases. The interpretation that calcium is located in the centre of the 3He droplet and on the surface of 4He droplets agrees with the prediction of theoretical calculations and is consistent with results obtained for strontium[1].
Calcium in 3He-4He mixed droplets have also been studied. The aim of this experiment is to map out a situation where calcium is located at the interface of 4He and 3He.
[1] A. Hernando, R. Mayol, M. Pi, M. Barranco, F. Ancilotto, O. Bünermann and F. Stienkemeier, J. Phys. Chem. A, 2007, 111, 7303-7308