A method to stabilize the incident X-ray energy for anomalous diffraction measurements.

A method to calibrate and stabilize the incident X-ray energy for anomalous diffraction data collection is provided and has been successfully used at the single-crystal diffraction beamline 1W2B at the Beijing Synchrotron Radiation Facilities. Employing a feedback loop to control the movement of the double-crystal monochromator, this new method enables the incident X-ray energy to be kept within a 0.2 eV range at the inflection point of the absorption edge.