Dokument: Coulomb Crystal Studies, Sympathetic Cooling, and Mass Spectrometry Using Laser-Cooled Be+ Ions

Titel:	Coulomb Crystal Studies, Sympathetic Cooling, and Mass Spectrometry Using Laser-Cooled Be+ Ions
URL für Lesezeichen:	https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=10396
URN (NBN):	urn:nbn:de:hbz:061-20090303-104450-1
Kollektion:	Dissertationen
Sprache:	Englisch
Dokumententyp:	Wissenschaftliche Abschlussarbeiten » Dissertation
Medientyp:	Text
Autor:	Fröhlich, Ulf [Autor]
Dateien:	[Dateien anzeigen] Adobe PDF [Details] 3,86 MB in einer Datei [ZIP-Datei erzeugen] Dateien vom 11.02.2009 / geändert 11.02.2009
Beitragende:	Prof. Dr. Schiller, Stephan [Betreuer/Doktorvater] Prof. Dr. Görlitz, Axel [Gutachter]
Dewey Dezimal-Klassifikation:	500 Naturwissenschaften und Mathematik » 530 Physik
Beschreibung:	In this work, the setup of an experiment aimed at high-precision laser spectroscopy of ultracold molecular hydrogen ions, started at the University of Konstanz in 1999 [1,2], was continued and first results were obtained. In particular, a new linear rf trap and a new trap supply electronics were built, the latter being capable of driving the linear rf trap with a maximum rf amplitude of > 1000V at a frequency of 14.2MHz. This made possible the simultaneous trapping of a large mass range (2u <= m/z <= 15u) with a trap potential depth of several eV over the whole mass range. Furthermore, a fluorescence detection system was added to the experimental setup, including a photomultiplier tube (PMT) and a CCD camera. For laser cooling of Be+ ions, doubly resonant sum-frequency generation (DR-SFG) of 313nm laser light was performed between a resonantly frequency-doubled monolithic Nd:Yag laser and a Ti:sapphire laser, emitting at 532 and 760nm wavelength, respectively. An output power of P_UV > 100mW was achieved at 313nm wavelength, with a high spectral purity (rms short-term frequency fluctuations < 160kHz) and a wide continuous tuning range of more than 15GHz. The DR-SFG setup was added by an absolute frequency stabilization and an optical frequency shifter for the 532nm master laser, thus obtaining absolutely frequency stabilized 313nm laser light (frequency drift < 1MHz/h), tunable by up to 340MHz. With this experimental setup, sympathetic cooling of N+, BeD+, BeH+, 4He+, HD+, and D+ ions by the laser-cooled Be+ ions was demonstrated, using laser-cooled fluorescence mass spectrometry (LCF-MS) to detect the sympathetically cooled species. Accordingly, sympathetic cooling at a minimum mass ratio of m(H2+)/m(Be+) = 0.22 was shown to be possible with both the sympathetically and laser-cooled ions in a cloud-like state. This points out the incorrectness of the theoretical lower limit m_SC/m_LC = 0.53 which was predicted in Ref.[3]. Here, the subscripts SC and LC denote the sympathetically and the laser-cooled species, respectively. In a further experiment, almost pure Be+ ion plasmas were laser-cooled down to temperatures in the milli-Kelvin range, leading to the crystallization of the Be+ ion plasmas. The outer shapes of different-sized Be+ ion crystals in a fully anisotropic trap potential were compared with the charged fluid predictions, showing good agreement at sufficiently large numbers of Be+ ions. By fitting Voigt profiles to the measured fluorescence signal, a typical temperature T(Be+) of 30mK was estimated for the Be+ ions. Finally, an ultracold sample of 4He+ ions [T(He+) approximately 40mK] was produced for the first time by sympathetic crystallization of the 4He+ ions. This may open up perspectives for the high-precision laser spectroscopy of 4He+ (and 3He+). [1] T.K.W. Boley, Diplomarbeit, Universität Konstanz (1999) [2] H. Schnitzler, Dissertation, Universität Konstanz (2001) [3] T. Baba and I. Waki, Appl.Phys.B, 74, 375-382 (2002)
Lizenz:	Urheberrechtsschutz
Fachbereich / Einrichtung:	Mathematisch- Naturwissenschaftliche Fakultät » WE Physik » Experimentalphysik
Dokument erstellt am:	03.03.2009
Dateien geändert am:	11.02.2009
Promotionsantrag am:	06.05.2008
Datum der Promotion:	24.06.2008