Berlin 2001 – wissenschaftliches Programm

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A: Atomphysik

A 7: Clusters II: Non-Metal Clusters, Fullerenes, Nanotubes (joint session A and MO)

A 7.3: Vortrag

Dienstag, 3. April 2001, 16:15–16:30, H1012

Dissociation of Rare Gas Cluster ions and Dimer Ions — •Rajendra Parajuli, Sara Matt, Aleksander Stamatovic, Paul Scheier, and Tilmann Maerk — Institut fuer Ionenphysik, Universitaet Innsbruck, A-6020 Innsbruck

We have carried out measurements on metastable fragmentation of rare gas cluster ions in the second field free region of a two sector field mass spectrometer. From the shape of the fragment ion peaks one can deduce information about the kinetic energy released in the decay reaction. The peak shape of the cluster ions is Gaussian and thus we can calculate from the width of these peaks the mean kinetic energy release <KER>. The <KER> includes also information about the transition state temperature and thus one can use finite heat bath theory to calculate the binding energies of the decaying cluster ions. In addition we also analysed metastastable decay reactions of neon, argon and krypton dimer ions. In contrast to clusters which usually decay by vibrational predissociation, only tunneling or electronic predissociation are possible for diatomic systems. The MIKE peak shape of the krypton and neon fragment ion exihibits a shape consisting of three different contributions whereas the argon dimer ion decay yields peak shapes which can only be fitted with a superposition of two gaussian functions indicating two metastable decay rates in accordance with known potential energy curves. curves.