Siegel der Universität

Universität zu Köln
Mathematisch-Naturwissenschaftliche Fakultät
Fachgruppe Physik

I. Physikalisches Institut


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Setup of the trapping apparatus as used for laser induced reactions (LIR). The ions are generated and collected in the storage ion source, mass selected in the quadrupole mass filter 1 and then stored in the 22-pole ion trap. As shown in the enlarged inset, this trap consists of 22 small rods which confine the ions in the radial direction when suitable rf voltages (≈ 17 MHz, 50V) are applied. Control of the injection and extraction of the ion cloud is achieved by the innermost electrodes. On entrance, the ions are cooled down to the ambient cryogenic temperature by a short intense helium pulse. During the storage period of several seconds, the ions are subject to reactant gas molecules and tunable laser light (coming from the right through the axially transparent setup). The result of this interaction is detected by extracting the stored ion cloud into mass filter 2 and counting the number of product ions in the detector. By repeating this process while scanning the IR laser, an IR action spectrum of the stored parent ions is recorded.