Frankfurt 2006 – wissenschaftliches Programm

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A: Atomphysik

A 10: Poster I: Wechselwirkung mit Elektronen und Ionen

A 10.9: Poster

Dienstag, 14. März 2006, 16:30–18:30, Labsaal

Channel-selective electron emission spectra from fragmentation of CO₂ and H₂ by fast proton impact. — •Christina Dimopoulou¹, R. Moshammer¹, A. Dorn¹, D. Fischer¹, C. Höhr¹, J. Ullich¹, M.E. Galassi², R.D. Rivarola², and P.D. Fainstein³ — ¹MPI für Kernphysik, Heidelberg — ²Instituto de Fisica Rosario, Argentina — ³Centro Atomico Bariloche, Argentina

Dissociative ionization of H₂ and CO₂ by 6 MeV proton impact was studied in a reaction microscope. Channel-selective low-energy electron spectra were recorded, by measuring the momenta of the emitted electron and the recoil ionic fragment in coincidence. The data for CO₂ are compared with a CDW-EIS calculation for molecular orbitals. A good qualitative agreement is observed even though the model does not account for the vibrational motion. The electron energy spectra show rich structure due to molecular excitation channels which undergo radiationless decay, via autoionization and predissociation [1]. The interference patterns recently observed in electron emission from ion- impact ionization of H₂, in analogy to Young’s two-slit experiment [2], are predicted to be more pronounced if the orientation of the molecular axis could be fixed in space at the instant of the collision [3]. Experimentally, the dissociative ionization of H₂ gave access to molecular-frame angular distributions of emitted electrons.They are compared with the CDW-EIS calculation [4].
C. Dimopoulou et al., J. Phys. B 38, 3173 (2005) [2] N. Stoltherfoht et al., Phys. Rev. Lett. 87, 023201 (2001) [3] G. Laurent et al., J. Phys. B 35, L495 (2002) [4] C. Dimopoulou et al., J. Phys. B 38, 593 (2005)