Berlin 2001 – scientific programme
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MO: Molekülphysik
MO 12: Posters Friday: Spectroscopy
MO 12.35: Poster
Friday, April 6, 2001, 12:30–15:00, AT3
Experimental evidence for a virtual state in a cold collision: Electrons and carbon dioxide — •David Field1, Stuart L. Lunt2, Jean Pierre Ziesel3, and Nykola C. Jones1 — 1Institute of Physics and Astronomy University of Aarhus, Denmark — 2ISA, University of Aarhus, Denmark — 3LCAR, University Paul Sabatier, Toulouse, France
Experimental data are presented for the scattering of cold electrons by carbon dioxide, for both integral and backward scattering, down to energies of a few meV with an energy resolution of 0.95 to 1.5 meV (full-width-half-maximum) in the electron beam. These are the first experimental data which show clear evidence for the phenomenon of virtual state scattering, a subject of extensive theoretical study. The measured scattering cross-sections rise rapidly at low energy, to a limiting value in integral scattering in excess of 100 Å2. In addition, analysis shows that scattering is s-wave dominated and that the s-wave scattering length is negative. All features are characteristic of virtual state scattering.