Hannover 2003 – wissenschaftliches Programm

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MO: Molekülphysik

MO 13: Grosse molekulare Cluster und Fullerene

MO 13.1: Vortrag

Freitag, 28. März 2003, 11:30–11:45, B 305

Coulomb explosion of DNA bases — •Thomas Schlathölter, Jur de Vries, Ronnie Hoekstra, and Reinhard Morgenstern — KVI Atomic Physics, Rijksuniversiteit Groningen, NL-9747AA Groningen, Netherlands

Modeling radiation damage on a macroscopic level has reached a high level of sophistication. However, for a full understanding of the processes involved and for a realistic modeling the molecular pathways have to be investigated on a microscopic level. Within the track of the primary radiation, hyperthermal electrons as well as singly and multiply charged ions are formed. We studied the interaction of the latter with RNA/DNA bases (uracil, thymine, guanine). From the flight-time differences of two correlated fragments in coincidence with an emitted electron we obtained the kinetic energy release for particular dissociation channels. For C^q+ (q=1−6) we found surprisingly high kinetic energies of the fragment ions as well as unusual shapes of the islands in the coincidence plots. This indicates a two body Coulomb explosion of the intermediate multiply charged molecules as a first step followed by extensive fragmentation of these intermediates. To drive this processes to the extreme, electron removal and subsequent Coulomb explosion of nucleobases driven by Xe^q+ (q=5−25) was studied. Such very highly charged ions affect the molecules quite similar as strong laser fields, i.e. short interaction time ( 10fs) as well as high electric field ( 0.05 a.u.). It turns out, that the original location of the fragment within the molecule strongly affects the corresponding coincidence patterns.