SOFT-X-RAY MAGNETIC CIRCULAR-DICHROISM - A PROBE FOR STUDYING PARAMAGNETIC BIOINORGANIC SYSTEMS

Soft x-ray magnetic circular dichroism was used to study a paramagneti c bioinorganic system. We measured the Fe L edges of Pyrococcus furios us rubredoxin, using circularly polarized synchrotron radiation, a spl it-coil superconducting magnet, low sample temperatures, and fluoresce nce detection. The observed dichroism effect is strong (30%) and in ge neral agreement with the calculation. The method is element- and oxida tion state-specific, and the data can be interpreted by established th eoretical procedures. Soft x-ray magnetic circular dichroism demonstra tes enormous potential as a probe for studying paramagnetic systems in biology, chemistry, and material science.