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A: Fachverband Atomphysik
A 27: Poster: Photoionization
A 27.10: Poster
Dienstag, 18. März 2014, 16:30–18:30, Spree-Palais
Photoionization of the beryllium atom — •Sita Nagina Eberle1, Oscar O. Versolato1, Lisa Schmöger1, Matthias Kohnen2, Maria Schwarz1, Piet O. Schmidt2,3, Joachim Ullrich1,2, and José R. Crespo López Urrutia1 — 1Max-Planck-Institut für Kernphysik, Heidelberg, Germany — 2Physikalisch-Technische Bundesanstalt, Braunschweig, Germany — 3Institut für Quantenoptik, Leibniz Universität Hannover, Hannover, Germany
A source of beryllium photoions was built in order to sympathetically cool highly charged ions in a cryogenic Paul trap with them. A suitable process for this purpose is the two-photon ionization of neutral beryllium atoms that is achieved by a resonant excitation of the 1s22s2 a1S0→1s22s2pa1P1 transition at 235 nm of the atom followed by the non-resonant transfer of an electron to the continuum. The laser system used for the excitation and consecutive ionization of the atom is based on frequency doubling twice an amplified diode laser system at 940 nm. Ion and fluorescence spectral lines were measured and compared to simple models that describe the data quite well, at least qualitatively. Regarding the two-photon ionization cross sections, it should be noted that neither our simple estimates nor more sophisticated theoretical models reproduce the present experimental results. Most probably the assumptions underlying those calculations (e.g., weak coupling of the excited state to the continuum) are not realistic for our experimental settings. However, the setup fulfills the required specifications, including beryllium safety measures, and has been implemented in the main experiment CryPTEx.