Berlin 2001 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 16: Poster: Dynamics of Molecular Systems, Polymer Dynamics, Glass Transition, Crystallization, Electronic Properties of Polymers

CPP 16.2: Poster

Montag, 2. April 2001, 12:30–15:00, AT1

Magnetic Resonance Contributions on Investigations of Radiation Defects in LiF — •Thomas Klempt¹, Dieter Suter¹, Otmar Kanert¹, Stefan Schweizer², Uldis Rogulis², and Johann-Martin Spaeth² — ¹Universität Dortmund, Fachbereich Physik, 44221 Dortmund — ²Universität Paderborn, Fachbereich Physik, 33095 Paderborn

High energy radiation propagating through matter creates various defects, including many paramagnetic defects like F centers. Magnetic resonance is therefore a suitable tool for the investigation of such defects. We use NMR (Nuclear Magnetic Resonance) of ⁷Li and ¹⁹F spins as well as MCDA (Magnetic Circular Dichroism of Absorption) of the F centers for the measurement of defect concentrations, motional processes and annealing behavior of F centers in lithium fluoride crystals. At very low temperatures (T = 1.5 K), the relaxation behavior of the electron spin can be measured directly by MCDA. At higher temperatures, the relaxation of the nuclear spins by the paramagnetic centers provides similar information from NMR measurements. The combination of the two techniques not only allows us to follow these motional processes over a wide temperature range, it also provides an opportunity to test theories of relaxation by paramagnetic centers over a wide range of parameters.