Alignment of the photoelectron spectroscopy beamline at NSRL

• Published in: Chinese physics C Vol. 37; no. 11; pp. 104 - 107
• Main Authors: Li, Chao-Yang, Pan, Hai-Bin, Wei, Shen, Pan, Cong-Yuan, An, Ning, Du, Xue-Wei, Zhu, Jun-Fa, Wang, Qiu-Ping
• Format: Journal Article
• Language: English
• Published: 01.11.2013
• Subjects: Alignment; Diffraction gratings; Flux; Gratings (spectra); Monochromators; Particle physics; Photons; Resolution; 光学元件; 光束线; 光栅单色器; 光电子能谱; 光谱分辨率; 原子力显微镜; 国家同步辐射实验室; 性能改进
• ISSN: 1674-1137; 0254-3052
• DOI: 10.1088/1674-1137/37/11/118002

Tile photoelectron spectroscopy beamline at National Synchrotron Radiation Laboratory （NSRL） is equipped with a spherical grating monochromator with the included angle of 174. Three gratings with line density of 200, 700 and 1200 lines/mm are used to cover the energy region from 60 eV to 1000 eV. After several years＇ operation, the spectral resolution and flux throughput were deteriorated, and realignment was necessary to improve the performance. First, the wavelength scanning mechanism, the optical components position and the exit slit guide direction are aligned according to tile design value. Second, the gratings are checked by Atomic Force Microscopy （AFM） and then the gas absorption spectrum is measured to optimize the focusing condition of the monoehromator. The spectral resolving power E/AE is recovered to the designed value of 1000@244 eV. The flux at the end station for the 200 lines/ram grating is about 1010 photons/sec/200 mA, which is in accordance with the design. The photon flux for the 700 lines/mm grating is about 5 108 photons/sec/200mA, which is lower than expected. This poor flux throughput may be caused by carbon contamination on the optical components. The 1200 lines/ram grating has roughness much higher than expected so the diffraction efficiency is too low to detect any signal. A new grating would be ordered. After the alignment, the beamline has significant performance improvements in both the resolving power aim the flux throughput for 200 and 700 lines/ram gratings and is provided to users.