ALSNews is a biweekly electronic newsletter to keep users and other interested parties informed about developments at the Advanced Light Source, a national user facility located at Lawrence Berkeley National Laboratory, University of California. We welcome suggestions for topics and content.
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Successful use of the phase retarder to generate circularly polarized light means that the technology can be used on any linear undulator beamline, thereby extending the range of spectroscopy and microscopy experiments possible. Circularly polarized synchrotron radiation is an increasingly useful tool for probing spin-dependent phenomena, such as the behavior of magnetic materials and transition metals in proteins. Spin information comes from the difference, or dichroism, between photoemission intensity obtained with left and right circularly polarized light. Understanding magnetic behavior at such a fundamental level is critical for controlled design of ultrathin magnetic layers and other nanoscale magnetic structures and, ultimately, devices such as sensors and storage media. A translation stage moves the linear polarizer into or out of the beam as needed, and tuning between right and left circularly polarized light is accomplished simply by rotating the retarder.