Effective protocol for realizing contamination-free X-ray reflective optics.

The surface contamination of reflective X-ray optics has long been a serious problem that degrades beam quality. We evaluated the total organic content at the surface by gas chromatography to clarify the source of contamination. We found that various materials that can become contamination sources are used around the optical elements. After covering the optics with cleaned materials and applying synchrotron radiation cleaning during commissioning, the observed reflected intensity at the beamline has not reduced for 2.5 years.