Berlin 2014 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 19: Photoionization
A 19.3: Vortrag
Dienstag, 18. März 2014, 14:45–15:00, BEBEL E42
Angular distribution of photoelectrons emitted from a laser-cooled and polarised lithium target — •Renate Hubele, Johannes Goullon, Elisabeth Brühl, Michael Schuricke, Hannes Lindenblatt, and Daniel Fischer — Max-Planck-Institut für Kernphysik, Heidelberg, Germany
With a magneto optical trap (MOT) a polarised atomic target for ionisation experiments can be realised. In the MOT the atoms are cooled to very low temperatures exploiting the principle of Doppler cooling, where the continuous absorption of photons from three pairs of counter-propagating red detuned laser beams is used to slow down the atoms. In our setup, the cooling takes place in a homogeneous magnetic field that leads to an energetic splitting of the atomic states into different Zeeman-sublevels according to their quantum number m. Due to the red-detuning of the cooling laser beams, a predominant population of the 2P3/2, mL=−1 (i.e. mj=−3/2) excited state is achieved.
In the experiments presented here, laser light in the UV wavelength range with linear polarisation both parallel and perpendicular to the direction of the external magnetic field is used to ionise the excited lithium atoms and the angular emission pattern of the photoelectrons is recorded with a Reaction Microscope. The emission pattern corresponds to the angular probability densities of the wave function of the final state of the reaction. Due to selection rules, the different polarisations of the UV laser lead to different final states and therefore to distinct electron angular emission patterns.