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Universität zu Köln
Mathematisch-Naturwissenschaftliche Fakultät
Fachgruppe Physik

I. Physikalisches Institut

Research Projects

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  • asvany
  • toepfer
  • schlemmer


The ion H3+ and its isotopologues are of astrophysical interest, because they transport deuterium from HD into larger molecules, starting with the exothermic reactions:
  • H3+ + HD ⇌ H2D+ + H + E
  • H2D+ + HD ⇌ D2H+ + H + E
  • D2H+ + HD ⇌ D3+ + H + E
As ions are very reactive and it is energetically preferable to have deuterium in the larger one of two reaction partners, deuterium is easily transferred to heavier molecules from the H3+ isotopologues. For this reason, the H3+ isotopologues have been investigated spectroscopically. H2D+ and D2H+ have been detected in space by their fundamental transitions of both nuclear spin species (ortho and para). ...more


Laser induced reactions (LIR)
Laser induced reactions (LIR) belong to the family of "action spectroscopy" methods. In the special case of LIR, changes of the rate coefficient of an endothermic ion-molecule reaction serve to detect the excitation of the parent ionic species. This offers not only the possibility of performing very high sensitivity spectroscopy on transient ions (a number of only 1000 ions per trapping period is enough), but LIR can yield information on state-selected reaction rate coefficients and lifetimes of excited states.
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The 22-pole ion trap apparatus LIRTrap is used both for kinetic and spectroscopic characterization of ions.
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COLTRAP and FELion are two new generation 22-pole ion trap instruments developed and built in our laboratory. Both instruments offer unique possibilities to study the kinetics of ion-molecule reactions at low temperatures, and to use highly sensitive methods for spectroscopic studies of molecular ions. Whereas the COLTRAP instrument is located in the Cologne laboratories, FELion has been installed in October 2014 at the FELIX Laboratory (Radboud University Nijmegen, Netherlands).
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Recent Results

Fundamental rotational transition of p-H2D+ at 1.37 THz observed with the method of laser induced reactions.
Ro-vibrational transitions of H3+ measured with a frequency comb system
211 - 212 rotational transition of H2D+ observed with an IR-THz double resonance scheme. Cover figure of Journal of Molecular Spectroscopy Volume 332.


External Links


  • Funding by DFG SFB 956 project B2