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Henning Schmidt

About me

In 1994, I took my PhD from Aarhus University, Denmark (having included a six-months guest PhD work at the Max-Planck Institute in Heidelberg. In December 1995, I moved to Stockholm for a postdoc, became an assistant professor in 1998, moved to a permanent position in 2006 and was promoted to Professor in 2011.

Most of my current research is performed at the Swedish National Research Infrastructure, DESIREE, for which I am the director:

A popular science description of (some of) the research at DESIREE is found here.


Research projects


A selection from Stockholm University publication database

  • Spontaneous Electron Emission from Hot Silver Dimer Anions

    2020. Emma K. Anderson (et al.). Physical Review Letters 124 (17)


    We report the first experimental evidence of spontaneous electron emission from a homonuclear dimer anion through direct measurements of Ag-2(-) -> Ag-2 + e(-) decays on milliseconds and seconds timescales. This observation is very surprising as there is no avoided crossing between adiabatic energy curves to mediate such a process. The process is weak, yet dominates the decay signal after 100 ms when ensembles of internally hot Ag-2(-) ions are stored in the cryogenic ion-beam storage ring, DESIREE, for 10 s. The electron emission process is associated with an instantaneous, very large reduction of the vibrational energy of the dimer system. This represents a dramatic deviation from a Born-Oppenheimer description of dimer dynamics.

    Read more about Spontaneous Electron Emission from Hot Silver Dimer Anions
  • Rotationally Cold OH- Ions in the Cryogenic Electrostatic Ion-Beam Storage Ring DESIREE

    2017. Henning T. Schmidt (et al.). Physical Review Letters 119 (7)


    We apply near-threshold laser photodetachment to characterize the rotational quantum level distribution of OH- ions stored in the cryogenic ion-beam storage ring DESIREE at Stockholm University. We find that the stored ions relax to a rotational temperature of 13.4 +/- 0.2 K with 94.9 +/- 0.3% of the ions in the rotational ground state. This is consistent with the storage ring temperature of 13.5 +/- 0.5 K as measured with eight silicon diodes but in contrast to all earlier studies in cryogenic traps and rings where the rotational temperatures were always much higher than those of the storage devices at their lowest temperatures. Furthermore, we actively modify the rotational distribution through selective photodetachment to produce an OH- beam where 99.1 +/- 0.1% of approximately one million stored ions are in the J = 0 rotational ground state. We measure the intrinsic lifetime of the J = 1 rotational level to be 145 +/- 28 s.

    Read more about Rotationally Cold OH- Ions in the Cryogenic Electrostatic Ion-Beam Storage Ring DESIREE
  • Electrostatic storage rings for atomic and molecular physics

    2015. Henning T. Schmidt. Physica Scripta T166


    A significant number of electrostatic ion-storage rings have been built since the late 1990s or are currently in their construction or commisioning phases. In this short contribution, we attempt to supply an overview of these different facilities, while we also mention a selection of the electrostatic ion-beam traps that has been developed through the same time period and by some of the same research groups.

    Read more about Electrostatic storage rings for atomic and molecular physics
  • Storing keV negative ions for an hour

    2015. Erik Bäckström (et al.). Physical Review Letters 114 (14)


    We use a novel electrostatic ion storage ring to measure the radiative lifetime of the upper level in the 3p 5  P 2  o 1/2 →3p 5  P 2  o 3/2   spontaneous radiative decay in S −  32   to be 503±54  sec . This is by orders of magnitude the longest lifetime ever measured in a negatively charged ion. Cryogenic cooling of the storage ring gives a residual-gas pressure of a few times 10 −14   mbar at 13 K and storage of 10 keV sulfur anions for more than an hour. Our experimental results differ by 1.3σ  from the only available theoretical prediction.

    Read more about Storing keV negative ions for an hour

Show all publications by Henning Schmidt at Stockholm University