Berlin 2001 – wissenschaftliches Programm

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MO: Molekülphysik

MO 8: Posters Thursday: Dissociation and other Collision Processes

MO 8.18: Poster

Donnerstag, 5. April 2001, 12:30–15:00, AT3

Dissociative Charge Transfer from Na Rydberg Atoms to Vibrationally Excited Na₂ Molecules and the Perspectives of field-free imaging — •O. Kaufmann¹, A. Ekers^1,2, and Klaas Bergmann¹ — ¹Fachbereich Physik der Universität Kaiserslautern, Postfach 3049, D-67653 Kaiserslautern — ²University of Latvia, Institute of Atomic Physics and Spectroscopy, Raina bulv. 19, LV-1586 Riga, Latvia

We report the observation of the vibrational dependence of dissociative charge transfer (DCT), Na₂(X¹Σ_g⁺, v″) + Na^**(nl) → Na⁻ + Na + Na⁺, in a single Na/Na₂ supersonic beam at low intra-beam collision energies (1.6 meV) using the STIRAP technique for selective vibrational excitation of Na₂ in the electronic ground state and time-of-flight mass analysis of the ions. The efficiency of this process increases by about an order of magnitude in the range 13 ≤ v″ ≤ 22. Some perspectives are discussed regarding the implementation of a field-free ion-imaging technique for the detection of ions, that will allow the direct determination of the kinetic energy distributions of product negative ions and thus to distinguish among different possible mechanisms of the DCT process. The results of test experiments on imaging of photodissociation products of Na₂(v″) without an extraction field are presented confirming the potential of the new detection concept.