Hannover 2003 – scientific programme

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MO: Molekülphysik

MO 12: Poster II

MO 12.20: Poster

Thursday, March 27, 2003, 16:00–18:30, Lichthof

Laser Spectroscopy of Ultracold Molecular Hydrogen Ions in a Linear RF-Trap — •Ulf Fröhlich, Claus Lämmerzahl, Bernhard Roth, and Stephan Schiller — Heinrich-Heine Universität Düsseldorf, D-40225 Düsseldorf

We present an experiment aimed at high-resolution spectroscopy of the ro-vibrational level structure of HD⁺. As one of the simplest molecules, HD⁺ is particularly suitable to test theories of molecular structure. Furthermore, once theory and experiment both achieve an accuracy better than 2*10⁻⁹, the spectroscopic values of the ro-vibrational transition frequencies of HD⁺ can be used to obtain a more accurate value of the fundamental constant m_e/m_p.

The HD⁺ molecular ions will be confined in a linear rf-trap and cooled by Coulomb interaction with laser cooled Be⁺ atomic ions stored in the same trap. To check the applicability of this method, called sympathetic cooling, for the special case of HD⁺ and Be⁺ ions, we performed several numerical simulations, which showed the gradual cooling and final crystallization of the HD⁺ molecular ions.

To avoid the small 1st order Doppler-broadening, we plan to perform 2-photon spectroscopy of the (ν=0, N=4) - (ν=4, N=4) ro-vibrational transition of the HD⁺ molecular ions at 2.8 µm.

Currently we are in the process of embedding HD⁺ molecular ions in a Be⁺ ionic crystal, obtained by laser cooling the Be⁺ atomic ions at 313 nm. The next step will be the direct excitation of the (ν=0, N=4) - (ν=4, N=4) transition at 1.4 µm, as an intermediate step before the final 2-photon spectroscopy at 2.8 µm.