title: New approaches for cooling molecular anions to the Kelvin range
creator: Tauch, Jonas
subject: 530
subject: 530 Physics
description: This thesis presents two anion cooling techniques based on their interaction with photons or ultracold atoms, pushing the frontier of anion cooling beyond state-of-the-art experiments. A hybrid atom-ion trap (HAITrap) is presented, combining an octupole radio frequency (rf) trap and a dark spontaneous-force optical trap for rubidium. The anions and atoms are probed via photodetachment tomography, time-of-flight thermometry and saturation absorption imaging, respectively. The anion photodetachment via a focused far-threshold laser beam removes anions selectively by their energy. This thesis reports forced evaporative cooling of OH− via dynamically moving the beam, below 4 Kelvin in 2 seconds. A derived thermodynamic model describes the evolution of anion temperature and number, including the importance of ion-ion thermalization and resulting rf-heating in such traps. It shows experimental and theoretical framework to prepare any anionic specie in a vast energy range. This thesis also reports the sympathetic cooling and the collision dynamics of anions with ultracold rubidium in a HAITrap. The cooling is experimentally demonstrated to 30(2) Kelvin for O− and 135(8) Kelvin for OH−. The different cooling behavior is explained by their dissimilar loss channels, which are identified and quantified. These limitations can be overcome in future experiments, providing a tool to cool anions translationally and internally.
date: 2021
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/30105/1/Dissertation_Jonas_Tauch_heiDOK.pdf
identifier: DOI:10.11588/heidok.00030105
identifier: urn:nbn:de:bsz:16-heidok-301059
identifier:   Tauch, Jonas  (2021) New approaches for cooling molecular anions to the Kelvin range.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/30105/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng