Rotation and alignment of molecules solvated in superfluid helium nanodroplets

PhD defence, Friday 3 February 2017. Anders A. Søndergaard

2017.02.03 | Karen Konradi

Anders A. Søndergaard

Anyone who has ever walked in a pool of water knows about the viscous drag forces that impedes movement through the water. In cold (0.37K), superfluid helium, these drag forces are usually absent, even on the molecular scale. During his studies, Anders Aspegren Søndergaard researched laser-induced rotation and alignment of molecules solvated inside nanometer-sized droplets of superfluid helium. Alignment of molecules means confining one or more molecular axes along axes defined in the laboratory. The alignment is obtained through coherent rotation of the molecules, and it is induced by an intense femtosecond laser pulse. By using aligned molecules, the orientational dependence of chemical reactions can be studied, and the molecular coordinate system can be accessed. New theoretical and experimental findings improves the understanding of how rotating molecules interact with superfluid helium. This opens for new, unique opportunities for studying molecular alignment and rotation, also in more general dissipative environments.

The PhD degree was completed at the Physics and Astronomy, Science and Technology, Aarhus University. This résumé was prepared by the PhD student.

Time: Friday, February 3 at 13.15

Place: Building 1525 room 626

Title of dissertation: “Understanding Laser-Induced Alignment and Rotation of Molecules Embedded in Helium Nanodroplets”

Contact information: Anders A. Søndergaard, e-mail:, tel.: +45 20721929

Members of the assessment committee:

Professor Ilya Averbukh, Department of Chemical Physics The Weizmann Institute of Science, Israel.

Professor Andrew M. Ellis, Department of Chemistry, University of Leicester, United Kingdom.

Professor Lars Bojer Madsen, Department of Physics and Astronomy, Aarhus University (chair)

Main supervisor: Henrik Stapelfeldt, Department of Chemistry, Aarhus University.

Language: The PhD dissertation will be defended in English


The defence is public.

The dissertation is available for reading at the Graduate School of Science and Technology/GSST, Ny Munkegade 120, building 1520, rooms 128-134, 8000 Aarhus C.



PhD defence
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Revised 25.09.2017