Berlin 2014 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 22: Cold Molecules 3

MO 22.6: Vortrag

Freitag, 21. März 2014, 11:45–12:00, BEBEL SR144

Rydberg states of alkali atoms on helium nanodroplets: Screening effects of a nanosized helium dielectric — Florian Lackner, Günter Krois, and •Wolfgang E. Ernst — Institute of Experimental Physics, Graz University of Technology, Graz, Austria

Rydberg series of Rb and Cs atoms on the surface of helium nanodroplets (HeN) [1] have been studied by resonance enhanced multiphoton ionization and laser induced fluorescence spectroscopy. The recorded excitation spectra [2,3] are analyzed by using a Rydberg-Ritz approach [4]. The dependence of the quantum defects on the principal quantum number within a Rydberg series gives insight into the interaction between the alkali valence electron and the superfluid helium droplet. For higher excited states, a screening of the valence electron from the alkali atom core by the helium droplet is observed, i.e. the helium reduces the probability to find the high-n electron nearby the core [4]. For lower states, the screening effect decreases and the quantum defects are found to lie closer to free atom values. In addition, the large spin-orbit constant of the Cs-HeN P states allows a detailed study of the influence of the helium droplet on the SO splitting as function of the principal quantum number. [1] C. Callegari and W.E. Ernst, in Handbook of High-Resolution Spectroscopy, edited by M. Quack and F. Merkt (John Wiley & Sons, Chichester, 2011), Vol. 3, pp. 1551-1594 [2] F. Lackner, G. Krois, M. Theisen, M. Koch, and W. E. Ernst, Phys. Chem. Chem. Phys. 2011, 13, 18781 [3] F. Lackner, G. Krois, M. Koch, and W. E. Ernst, J. Phys. Chem. Lett. 2012, 3, 1404 [4] F. Lackner, G. Krois, and W. E. Ernst, Mol. Phys. 2013, 111, 2118