Berlin 2014 – scientific programme
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A: Fachverband Atomphysik
A 38: Atomic clusters (with MO)
A 38.6: Talk
Thursday, March 20, 2014, 12:00–12:15, BEBEL E44/46
Laser-induced delayed electron emission of metal cluster anions — •Christian Breitenfeldt1, Klaus Blaum2, Sebastian George2, Michael Lange2, Sebastian Menk2, Christian Meyer2, Lutz Schweikhard1, and Andreas Wolf2 — 1Institut für Physik, Ernst-Moritz-Arndt Universität, 17487 Greifswald, Germany — 2Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
Radiative cooling is a fundamental process that determines the internal temperature of vibrationally excited ions as a function of time, eventually bringing them into thermal equilibrium with their environment. We have investigated the cooling of Cun− (n=4,5,6,7) and Con−(n=3,4) anions in a crygenic electrostatic trap. The cluster ions were produced in a Cs sputter ion source, with a vibrational excitation corresponding to temperatures of several thousand Kelvins. They were then size-selected and transferred to the Cryogenic Trap for Fast ion beams CTF located at the Max-Planck-Institut fr Kernphysik within 120 µ s. They were stored at a kinetic energy of 6 keV. This electrostatic ion beam trap can be operated at a temperature below 15 K by a closed-cycle helium refrigeration system. The extremely low pressure (few 10−12mbar) achieved by cryopumping resulted in a very low background of collision-induced ion loss and thus a beam lifetime of several minutes. We have studied vibrational autodetachment (also called delayed detachment) by recording the rate of neutral particles escaping from the trap as a function of the delay after the pulses from a laser emitting at wavelengths of 600 to 1300 nm.