Beamline optics and overview

 Key Performance

The beamline is sourced by an elliptically polarizing undulator (EPU120). A cylindrical mirror M1 collects the diverging beam from the undulator and horizontal focus the beam to the exist slit-H. The monochromator is Plane Grating Monochromator type, consisting a plane mirror M2 and two different variable line spacing (VLS) gratings. The monochromator energy-disperses VUV-light, which is then focused vertically to the exist slit-V by the VLS gratings. Monochromatized X-ray beam is switchable into two branches by the plane mirror M5. At Branch A, VUV-beam light is refocused by a KB mirror set to a sub-micro size. 

ARPES Endstation

Branch A is a VUV-ARPES endstation with the VUV beam light energy ranging from 6 eV to 135 eV. Equipped with a DFS30 analyzer from Scientia Omicron, this endstation is designed to measure both the electronic structure of quantum materials. 

Analyser chamber: measurement       

Up chamber: preprocessing

RDC: Radial Distribution                      

Load Lock: load sample

Suitcase: vacuum sample transfer      

MBE: sputter- annealing  and film growth

Key Performance

Science

Scientific Scope 1 ：Traditional high flux ARPES usually can reach a beam spot around 20~50um, which is limited by the beam source size and divergence of the third generation synchrotron. By further reducing the beam spot size to sub microns ,new emergent quantum phenomenon can be visualized.  

Scientific Scope 2 ：High-temperature superconductivity and charge density waves, are dictated by very small energy scales. For instance, a 1 meV resolution enables the direct observation and precise measurement of superconducting gaps, which are often only a few meV in size. Resolving the exact size and momentum dependence of this gap is crucial for understanding the mechanism behind superconductivity.

Scientific Scope 3:  VUV light, with lower photon energy (typically < 11 eV), offers very high momentum resolution and is highly bulk -sensitive. In contrast, higher-energy EUV light (tens to hundreds of eV) can eject electrons from shallower within the material, making it more surface-sensitive. It also allows access to a much wider range of electron momenta, enabling the mapping of electronic bands across the entire Brillouin zone for a more complete, three-dimensional picture.

Useful Link:

Related beamlines:

https://www.diamond.ac.uk/Instruments/Structures-and-Surfaces/I05.html

https://www.maxiv.lu.se/beamlines-accelerators/beamlines/bloch/

http://e-ssrf.sari.ac.cn/beamlines_2024/sr_72267/beamline_maps/bl03u/xzjs/

More:

Synchrotron Radiation News: Vol 37, No 4