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@PHDTHESIS{Martin:211853,
      author       = {Martin, Alexander and Walter, Thomas},
      othercontributors = {Birkl, Gerhard},
      title        = {{L}aser {S}pectroscopic {I}nvestigation of {E}xotic
                      {S}tates in {N}oble {G}ases},
      school       = {TU Darmstadt},
      type         = {Dissertation},
      reportid     = {GSI-2018-00733},
      pages        = {163},
      year         = {2017},
      note         = {Die Veröffentlichung steht unter folgender Creative
                      Commons Lizenz:Namensnennung – Keine kommerzielle Nutzung
                      – Keine Bearbeitung 4.0
                      Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/;
                      Dissertation, TU Darmstadt, 2017},
      abstract     = {The focus of this thesis lies on exotic states of noble
                      gases, in particular metastable neon (Ne*) and boron-like
                      argon ions (Ar13+): the former shows extraordinary
                      collisional properties due to its high internal energy
                      compared to its low kinetic energy. On the other hand,
                      highly charged ions, such as Ar13+, can be used to verify
                      quantum electrodynamics with extremely high accuracy by
                      determining their magnetic moments. These extraordinary
                      atomic states can be probed with methods of laser
                      spectroscopy and allow for deep insights of timely physical
                      question. The magnetic moment of bound electrons in Ar13+
                      shall be determined by the energy-splitting of the Zeeman
                      sublevels of the fine structure transition 2P1/2 - 2P3/2 at
                      a wavelength of 441 nm in the magnetic field of a Penning
                      trap. For this, the transition is measured by means of
                      microwave and fluorescence laser spectroscopy. The first
                      part of this thesis presents the laser system for the
                      spectroscopy of Ar13+ and tellurium 130Te2. Using a
                      polarization stabilization scheme, a single-mode diode laser
                      with a high long-term stability of up to two days has been
                      developed. Using a Doppler-free 130Te2-spectroscopy, six
                      lines close to the expected Ar13+ transitions have been
                      characterized with an absolute frequency accuracy of 2.2
                      MHz. A first characterization of the Ar13+ fluorescence
                      spectroscopy has been conducted with a dark-measurement
                      without ions. During this process, the measured background
                      signal was reduced by three orders of magnitude by
                      optimizing the setup. Thus, a reliable laser system is
                      provided for experiments with ions, as planned for the near
                      future. The second part of this thesis investigates the
                      two-body collisional interactions of ultra-cold Ne* atoms.
                      Inelastic collisions of Ne* atoms leads to losses due to
                      Penning and associative ionization. The efficient detection
                      of the ions produced by these processes allows for
                      determining the collision rate. For the investigations, a
                      laser-cooled atom cloud is prepared in a magnetic trap at
                      350 µK. The measurement of the inelastic collision rate in
                      a regime between 20 µK and 350 µK confirms the theoretical
                      predicted temperature-independent rate for 20Ne and 22Ne of
                      mixtures of the Zeeman sublevels mJ = +2 and mJ = +1.
                      Furthermore, the dependence of the collision rate on
                      external magnetic fields has been measured. For fields up to
                      120 G, a suppression by a factor of 5.6 for 22Ne has been
                      proved. Additionally, the so called δ-kick cooling, a
                      method for manipulating the phase-space density of cold atom
                      clouds, was implemented by using the magnetic trap. This
                      allowed for a variation of the velocity distribution of the
                      cloud over a range, which corresponds to an effective
                      temperature between 10 µK and 460 µK.},
      cin          = {ATP},
      cid          = {I:(DE-Ds200)ATP-20051214OR020},
      pnm          = {6211 - Extreme States of Matter: From Cold Ions to Hot
                      Plasmas (POF3-621)},
      pid          = {G:(DE-HGF)POF3-6211},
      typ          = {PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:tuda-tuprints-66662},
      doi          = {10.15120/GSI-2018-00733},
      url          = {https://repository.gsi.de/record/211853},
}