Hamburg 2009 – scientific programme

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MO: Fachverband Molekülphysik

MO 13: Molekülphysik Poster 1

MO 13.19: Poster

Tuesday, March 3, 2009, 16:30–19:00, VMP 8 Foyer

Trapping and cooling of single molecular ions for time resolved vibrational spectroscopy — •Günther Leschhorn, Steffen Kahra, Hsiang-Tai Dou, Wolfram Schmid, Werner Fuß, and Tobias Schaetz — Max-Planck-Institut für Quantenoptik, Garching

We report the preparation of externally cold and well localized molecular ions (spacial resolution of a micrometer). By exploiting numerous techniques like ion-trapping, sympathetic laser cooling and light pressure separation we are able to provide and trap a selectable amount of molecular ions (from a few hundred down to a single one). The trapped molecular ions can serve as targets for time resolved diffraction experiments with a resolution of a few fs and below to observe fast sturctural changes. As a first step towards this goal we propose vibrational spectroscopy on a single magnesium hydride ion (MgH⁺), using a UV-pump UV-probe (300 nJ, pulse duration below 4 fs) scheme. A coherent oszillating wave packet of an exited bound state with a period of 30.9 fs is mapped on a dissociative channel. The intramolecular distance at a given time delay between pump and probe pulse defines the required wavelength to dissociate the MgH⁺. If this wavelength lies within the spectrum of the UV-probe pulse, the molecular ion dissociates with higher probability compared to the case when the wavelength lies significantly outside the spectrum. The oszillation period of the wave packet can thus be measured by observing the variation of the loss rate (dissociation) of molecular ions. This project is part of the excellence initiative of the DFG (MAP) and financial support of MPG and IMPRS-APS is acknowledged.