Mainz 2017 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 9: Posters 1: Dichroism, VUV and Xray, Clusters, and Cold Molecules
MO 9.15: Poster
Dienstag, 7. März 2017, 17:00–19:00, P OG1
Dissociative electron attachment in small clusters of ammonia and formic acid — •Marvin Weyland1, Alexander Dorn1, Xueguang Ren1, Hans Rabus2, and Woon Yong Baek2 — 1Max Planck Institute for Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany — 2Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
Dissociative electron attachment (DEA) has been identified as a possible process for radiation damage. In short, DEA is a resonant two-step process in which first a low-energetic electron is captured by a molecule. The created negative ion can subsequently dissociate while the captured electron stays attached to one of the fragments. Most experiments however have been carried out on isolated gas phase molecules. We show the influence of clustering on the dissociation resonance energies and the fragmentation channels, thereby recreating effects which occur in the liquid phase.
Our experiments are carried out in a COLTRIMS type negative ion spectrometer and the electron beam is created using a photo-emission electron source, yielding a good combination of energy resolution and current. In ammonia cluster fragments of up to 17 molecules we observe an increase of the dissociation energy of up to 0.3 eV compared to the isolated molecule. In formic acid dimers and trimers on the other hand the impact energy for the highest dissociation yield is lowered with increasing fragment size, with impact energy for production of the fragments differing by up to 1 eV. We propose different effects which influence the dissociation path to explain our observations.