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MO: Fachverband Molekülphysik

MO 11: Kalte Moleküle 2

MO 11.6: Vortrag

Dienstag, 3. März 2009, 15:15–15:30, VMP 6 HS-G

Translational cooling and storage of protonated proteins in an ion trap at subkelvin temperatures — •David Offenberg, Chaobo Zhang, Christian Wellers, Bernhard Roth, and Stephan Schiller — Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany

The remarkable advances in the development of techniques for producing cold molecules (< 1 K) enabled studies of light-molecule, atom-molecule, and molecule-molecule interactions in a temperature regime that has not been accessible previously. So far, complex molecules, like biomolecules or anorganic clusters, have been studied in ion traps using buffer gas cooling, with lowest temperatures of ≃ 10 K. Recently we have reported on a technique for translationally cooling polyatomic molecular ions of mass 410 Da produced by electrospray ionization (ESI) to less than 140 mK via their mutual Coulomb interaction with laser-cooled ¹³⁸Ba⁺ ions in a linear quadrupole trap [1]. We have extended this approach to proteins. In one case, an ensemble of 53 cytochrome c molecules (mass ≃ 12390 amu, protonation charge +17 e) was cooled by ≃ 160 laser-cooled barium ions to less than 0.75 K secular temperature [2]. The temperature was determined by comparing experimentally acquired images of the Ba⁺/cytochrome⁺¹⁷ ion ensembles with those from molecular dynamics simulations. Storage times of more than 20 minutes have been observed. This technique is applicable to a wide variety of complex molecules.

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

[2] D. Offenberg et al., Phys. Rev. A 78, 061401(R) (2008)