Düsseldorf 2007 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 63: Spectroscopy in He-droplets / Ultracold Molecules I (gemeinsam mit Q)

MO 63.7: Vortrag

Freitag, 23. März 2007, 12:15–12:30, 6B

UV photodissociation studies of polyatomic molecular ions at milli-Kelvin temperatures — •David Offenberg, Chaobo Zhang, Bernhard Roth, and Stephan Schiller — Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf

Photodissociation spectroscopy is a commonly used tool to investigate molecular properties. The spectral resolution can be enhanced by reducing the molecules’ thermal energy [1], as recently demonstrated on diatomic molecular ions [2]. Here, we present our initial advances towards photodissociation spectroscopy of polyatomic molecules.

As a first model system we use translationally cooled, singly protonated molecules of Glycyrrhetinic Acid (GA) − a biomolecule of mass 471 amu consisting of 80 atoms. In our apparatus, the molecular ions are generated by an electrospray ionization source, transferred to and stored in a radio-frequency trap together with laser-cooled barium ions. Due to their Coulomb interaction with the atomic coolant, they cool down from ambient temperature to the hundred milli-Kelvin range and can be kept and investigated under these low-temperature and nearly collisionless conditions for more than one hour [3]. We have measured the photodissociation rate of GA ions using a single-frequency cw-laser at 266 nm. In further studies we plan to investigate the feasibility of resonance enhanced two-photon dissociation with additional tunable IR lasers.

[1] O. Boyarkin et al., J. Am. Chem. Soc. 128, 2816 − 2817 (2006)

[2] B. Roth et al., Phys. Rev. A 74, 040501(R) (2006)

[3] A. Ostendorf et al., Phys. Rev. Lett. 97, 243005 (2006)