Heidelberg 1999 – wissenschaftliches Programm

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MO: Molekülphysik

MO 7: Poster I: Stoßprozesse und Photodissoziation

MO 7.1: Poster

Dienstag, 16. März 1999, 16:00–19:00, PA

Negative ion formation by electron transfer in Rydberg atom – sodium dimer interactions — •Ch. Gebauer-Rochholz, O. Kaufmann, M. Keil, K. Kalogerakis, and K. Bergmann — Fachbereich Physik der Universit"at Kaiserslautern, Postfach 3049, D-67653 Kaiserslautern

Interaction of Rydberg states of sodium atoms with vibrationally excited

sodium dimers can lead to a dissociative charge transfer (DCT) from the Rydberg atom to the dimer: Na₂ (v″)+ Na^**(n,l) → (Na₃^**) → Na⁻ +Na+Na⁺. This process depends on the initial atomic and molecular quantum states of the interaction partners. As DCT intrinsically involves three-body interaction, it is also necessary to obtain information about the energy

distribution in the output channels. In this work a new experimental setup for the detection of Na⁻ ions is presented, which constitutes a modified implementation of the ion-imaging method now widely employed in photodissociation experiments [1]. The fragments from the dissociative charge transfer interaction are projected onto a position sensitive output anode. The spatial pattern, visualized by a CCD video camera, resembles the velocity distribution of the negative ions after the dissociation. Due to the implementation of an ion optics that provides velocity-mapping [2] properties, it is possible to achieve high energy resolution even when taking advantage of a large interaction region.

[1] e.g. see K. Tonokura, et al. J. Phys. Chem. A 101, 7754 (1997)

[2] A. T. J. B. Eppink and D. H. Parker, Rev. Sci. Inst. 68, 3477 (1997).