X-RAY MAGNETIC CIRCULAR DICHROISM AT TEMPERATURES LESS-THAN-1K - DEMONSTRATION WITH THE BLUE COPPER SITE IN PLASTOCYANIN

摘要

We have demonstrated the first XMCD to be taken at ultra-low temperatures (<1 K) using a He-3 cryostat. By measuring the XMCD at a fixed temperature and varying fields, we have been able to plot a magnetization curve for the S=1/2 Cu site in the protein plastocyanin. This magnetization curve allows us to definitively calculate the temperature at the surface of the sample and remove any ambiguity related to the system thermometry. These experiments at low temperature open the door to further study of more complicated systems by optimizing the observable XMCD effect and allowing us to reach a wide range of field and temperature combinations. [References: 28]