Regensburg 2004 – scientific programme
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MA: Magnetismus
MA 21: Bio- und molekularer Magnetismus
MA 21.7: Talk
Thursday, March 11, 2004, 11:45–12:00, H22
1H-NMR on Fe2(hpdta), Fe4(hpdta)2 and Fe6(hpdta)3 clusters — •Roland Leppin and Bernd Pilawa — Physikalisches Institut, Universität Karlsruhe (TH)
1H-NMR measurements on cyclic Fe6 clusters have shown the importance of the energy level scheme for the nuclear relaxation. The investigation of the Fe2(hpdta) dimer is an interesting approach for a better understanding of the spindynamics, as it can be used as a building block for more complex clusters like the Fe4(hpdta)2 and Fe6(hpdta)3 systems, where the metal ions form a square and roof-like structure, respectively.
The 1H T1−1 rate measurements at 52 MHz in a magnetic field of 1.2 T show differences between the systems. For the Fe2 dimer, the T1−1 rate increases monotonously. For Fe4 it starts at a comparatively high value at low temperatures, goes down to a minimum around 15 K and increases again with increasing temperature. For the Fe6 sample there is a broad maximum around 30 K which reminds the results obtained for the cyclic Fe6(tea)6 samples.