Regensburg 2016 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 73: Surface Dynamics: Reactions and Elementary Processes
O 73.14: Poster
Mittwoch, 9. März 2016, 18:15–20:30, Poster A
Photon Induced Processes in CH4:D2O Interstellar Ice Mimics Initiated by Femtosecond XUV Pulses — •John Thrower, Tushar Suhasaria, Robert Frigge, Sebastian Roling, and Helmut Zacharias — Physikalisches Insitut, Westfälische Wilhelms-Universität Münster, Münster, Germany
Solid state physical and chemical processes on dust grain surfaces play an important role in the chemical evolution of the interstellar medium. In dense molecular clouds, these grains are coated with layers of H2O dominated molecular ices doped with carbon containing species including CO, CH3OH and CH4. Star formation can lead to these ices being bathed in a flux of XUV and soft X-ray photons, providing a non-thermal energetic input that can lead to the production of more complex species as well as providing a low temperature desorption route for returning molecules to the gas phase. We have used femtosecond XUV (λ=30.4 nm) pulses generated by the Free-Electron Laser in Hamburg (FLASH) to irradiate interstellar ice mimics consisting of D2O and CH4 deposited on an HOPG substrate at 15 K. Time-of-flight mass spectrometry, combined with multiphoton ionisation, reveals a rich variety of neutral and ionic desorption products including ejected ionic clusters. The ion desorption yield is found to be non-linear with respect to the photon flux, permitting the probing of reaction dynamics using two correlated pulses, temporally separated by 0.5-6 ps.