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MO: Molekülphysik
MO 8: Posters Thursday: Dissociation and other Collision Processes
MO 8.28: Poster
Donnerstag, 5. April 2001, 12:30–15:00, AT3
Vibrational excitation of cold HD+ ions in collisions with electrons at eV-energies — •Michael Lange1, Xavier Urbain2, Holger Kreckel1, Sven Krohn1,3, Lutz Lammich1, Dirk Schwalm1, Daniel Strasser3, Andreas Wolf1, and Daniel Zajfman3 — 1Max-Planck-Institut für Kernphysik, Heidelberg, Germany — 2Département de Physique, Université Catholique de Louvain, Louvain-la-Neuve, Belgium — 3Department of Particle Physics, Weizmann Institute of Science, Rehovot, Israel
Excitation of HD+ molecular ions from their vibrational ground state to higher vibrational levels in collisions with free electrons has been observed at the Heidelberg heavy ion storage ring TSR. Such collisions are closely related to other inelastic processes already studied at the TSR, namely dissociative excitation and recombination (DE and DR). A stored HD+ beam of 16 MeV was colinearly merged with the intense electron beam from the ring’s electron cooler device and with the beam of a pulsed dye-laser (380 nm, 5 MW/cm2, 15 ns pulse length) along the same section of the ring. After injection into the TSR, the ion beam was translationally cooled for several seconds by interaction with electrons at near-zero relative energy, while the ions also radiatively relaxed to the vibrational ground state. Then, higher relative electron energies were applied at ∼50% duty cycle and the rate of neutral photodissociation fragments in coincidence with the laser shots was monitored. This enabled sensitive detection of HD+(v≥4) ions. The excitation rate has been measured as a function of the collision energy and detailed comparisons to the energy dependence of DE and DR are in progress. Supported by DIP(BMBF).