Heidelberg 2015 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 14: Cold Molecules 2

MO 14.6: Vortrag

Mittwoch, 25. März 2015, 16:00–16:15, PH/HS1

Photo-ejection of biomolecular ions from helium droplets — •Jenny Pestel, Doo-Sik Ahn, Ana Isabel Gonzalez Florez, and Gert von Helden — Fritz-Haber-Institut der MPG, Berlin, Germany

Superfluid helium droplets are an ideal environment to investigate ions at cryogenic temperatures. By (photo-)excitation the ion can get ejected from the helium droplet. This process is not completely understood yet. Our goal is to characterize the photo-ejection process and shed more light on the underlying mechanism.

We have developed an experimental setup [1] where biomolecular ions are brought to the gas-phase via electrospray ionization. Subsequently they are mass/charge selected in the quadrupole mass filter and accumulated in a linear ion trap. A pulsed beam of helium droplets picks up the ions as they traverse the trap. From here the doped droplets can be accelerated and measurements as a function of flight time allow us to determine the ejection efficiency on size distributed droplets [2].

With this approach we can study the ion ejection for different dopants on the pre-defined helium droplet sizes. This makes it possible to analyze and report recent results using both ultraviolet as well as infrared light for photo-excitation.

[1] F. Bierau et al., Phy. Rev. Letter. 105, 133402 (2010)

[2] F. Filsinger et al., PCCP, 1-8 (2012)