The optical scheme is based on the collimated plane-grating monochromator (cPGM), astigmatic intermediate focus and switchable refocusing mirrors.

The maximum beamline acceptance is 0.62 mrad x 1.36 mrad (h x v) and corresponds to full illumination of M1. Acceptance can be reduced using movable masks in the front end and/or baffles in front of the monochromator.

Main optical components:

M1Horizontally deflecting vertically collimating side-cooled Au-coated cylindrical mirror; angle of incidence is 2°
cPGMPlane grating monochromator (Zeiss SX700 modified to work with collimated light); up to three gratings (for now only 1200 l/mm and 1800 l/mm gratings installed); both M2 and gratings are Au-coated; plane M2 is side-cooled, gratings are back-cooled
M3 (x2)A pair of switchable horizontally-deflecting Au-coated toroidal mirrors focusing onto two exit slits each (foci in the horizontal and the vertical planes are at different distances from M3); angle of incidence is 1.95°
Exit slitsA pair of precision exit slits (spatially separated H-focus and V-focus) on each branch
ChopperA retractable chopper is planned to be installed in 2019 on the gas-phase branch for Time-Of-Flight experiments (see below)
M4 (x4)Horizontally deflecting refocusing Au-coated double-striped toroidal mirrors; each stripe can focus x-rays into a specific single point (in total four focal points allow for four different experimental setups); angle of incidence is 2°

Main beamline specifications:

Photon energy resolution ΔE, meV
(for V-slit of 10 µm)
2.4 @ 40 eV, 26 @ 400 eV, 140 @ 1500 eV
Flux at sample, ph/s
(@ E/ΔE = 10000)
0.5 – 3 x 1013 (40 – 200 eV), 1 – 5 x 1012 (200 – 900 eV), down to 2 x 1011 at 1500 eV
Beam size at sample Defocused (h x v): up to 2 x 1 mm
Focused (h x v): 65 x 10 µm (UHV XPS), 100 x 20 µm (open port), 80 x 15 µm (ToF), 130 x 25 µm (LDM XPS); further reduction in size is possible with baffles (at the cost of flux)


Disc radius120 mm
Rotation speed≈ 0.8 kHz
Number of slits (two slit circles)12/120
Slit width85 µm
Opening time≤ 300 ns
Repetition rates (two slit circles)≈ 10/100 kHz
Single bunch period time320 ns
Bunch length≈0.15 ns
Projected single bunch current≈20 mA
Projected impurity<0.3%