25 Tesla resistive magnet commissioned for three magnetic resonance spectroscopies

March 1998

Contact:
Janet Patten, (850) 644-9651

TALLAHASSEE, Fla. – The National High Magnetic Field Laboratory (NHMFL) recently commissioned the world's highest-field, high-resolution resistive magnet for three complementary forms of magnetic resonance spectroscopies: nuclear magnetic resonance (NMR), electronic magnetic resonance (EMR), and ion cyclotron resonance (ICR). The innovatively-designed 25 tesla (T) resistive magnet was funded in part by a grant from the W.M. Keck Foundation of Los Angeles, California, to Florida State University and the University of Florida.

The unparalleled combination of high magnetic field strength (25 T), time stability (~ 1 part per million (PPM)), and high spatial homogeneity (~ 1 ppm) in a 52 mm bore far exceeds the magnetic resonance performance capabilities of today's best superconducting magnets. The NHMFL's unique and ultra-stable 40 megawatt direct current power supply has made this technically challenging magnet feasible.

The Keck magnet offers users a host of additional experimental opportunities compared to a persistent superconducting magnet, because the field strength of a resistive magnet can be swept more easily for EMR or stepped up or down for NMR. For example, the sweepable 25 T magnet opens up a unique new possibility of measuring, by multifrequency EPR, the full tensor representing the anisotropic spin-exchange properties of systems, because the exchange-narrowed EPR peak is split into its constituent components when the resonant frequency becomes of the order of spin exchange frequency. Measurement of all of the components of the spin-exchange tensor provides a very sensitive test for arriving at the most suitable model for spin exchange and related magnetic properties of materials.

For information and procedures for using this system, check the user facilities page or contact Bruce Brandt, Director of DC Field Facility,brandt@magnet.fsu.edu or 850-644-4068.