The measurement of circular dichroism (CD) in soft X-ray absorption at BL25SU of SPring-8 has been developed into a phase-sensitive detection using helicity modulation (HM) of circularly polarized light. The HM is performed by the light source, "twin helical undulators". A lock-in amplifier is used for the phase-sensitive detection to extract small CD signals buried in noises. The noise level of a measured magnetic CD has been reduced to less than 1/10 by using this method in comparison with a normal integration measurement.
|Number of pages||3|
|Journal||Journal of Electron Spectroscopy and Related Phenomena|
|Publication status||Published - 2005 Jun|
- Circular dichroism
- Helical undulator radiation
- Helicity modulation
- Soft X-ray absorption