For detailed description of the HIPPIE optical design and performance, please see the beamline publication:

HIPPIE: a new platform for ambient pressure X-ray photoelectron spectroscopy at the MAX IV Laboratory
Zhu, S., Scardamaglia, M., Kundsen, J., Sankari, R., Tarawneh, H., Temperton, R., Pickworth, L., Cavalca, F., Wang, C., Tissot, et al. (2021). J. Synchrotron Rad. 28, DOI: https://doi.org/10.1107/S160057752100103X

Hippie is a soft X-ray beamline designed to deliver high-intensity photon flux (>1012 ph/s) with exceptional resolution by fully utilising the very low emittance of the 3 GeV ring. The beamline consists of two branches optimised for different energy ranges.

Branch A (Solid-Gas endstation)Branch B* (Solid-Liquid endstation)
Energy Range260 eV – 2000 eV1000 eV – 2400 eV
PolarisationHorizontalHorizontal
Resolutionup to 35 000up to 8000
Photon Flux> 1012 ph/s (260 – 2000 eV, R=10 000)>1012 ph/s (1000 – 2200 eV, R=1000)
Spot Size60 µm (h) x 25 µm (v). Slit-independent10 µm (h) x 5-25 µm (v). Vertical size is slit-dependent
* Branch B is under construction. Performance parameters are from the optical design report

X-ray Source

TypeAPPLE II with permanent magnets
Period Length53 mm
Physical Length4 m (placed inside 5m straight section)
Accessible PolarisationsLinear (inc. Horizontal), Elliptical, Circular

Beamline Optics

The beamline shares a Collimated Plane Grating Monochromator (cPGM) between two branchlines. Hence only one endstation can be used at the time. Switching between branchlines is done by laterally mowing M3 chamber vessel

The first optical element (M1) in the beamline is a toroidal mirror, which collimates the beam vertically and focuses the beam horizontally onto the exit slit. The cPGM consists of a plane mirror and one or more plane gratings. At the moment one grating (1200 l/mm) in installed covering the entire energy range of the beamline.

The dispersed radiation from the grating is focused horizontally onto the exit slit by the cylindrical (for branch A) or toroid (for branch B) focusing mirror (M3). The focusing mirror at the branch B is of toroid shape to compensate for the manufacturing error in the M1 radius.

The refocusing for both branches is accomplished by a single toroidal mirror (M4). At the branch A the mirror does not image the vertical opening of the exit slit directly, but the vertical image size at the sample plane (2 m from M4) is dictated by the vertical divergence of the beam, which can be controlled by the monochromator. At the Branch B the vertical beam size is dependent on the exit slit opening.

All the mirrors, except for the plane mirror in the monochromator, deflect horizontally – hence, all slope errors and heat load deformations on these mirrors are diminished in the dispersion plane in a well-known manner.

Optical element M1
common
M2
common
PG
common
M3
Branch A
Exit slit
Branch A
M4
Branch A
M3
Branch B
Exit slit
Branch B
M4
Branch B
ShapeToroidPlanePlaneCylinderRectangleToroidToroidrectangle Toroid
Deflection / azimuthal angleHorizontal /90°Vertical /0°Vertical /180°Horizontal 90°‘narrow’ opening in vertical 0-100 µmHorizontal 90°Horizontal 90°‘narrow’ opening in vertical 20-160 µmHorizontal 90°
Position to proceeding element (mm)(sample BL at mono E = 867 eV )47001788.89212.059
Vertical offset: 20 mm
1000120008000100080008500
Distance (m)(along BL)24variable26270003900047000273543.5
Incidence Angle0°- 9°0°- 12°1.5°1.5°1.5° 1.5°
Opt.size (mm), substraite320 x 10370 x 10130 x 10120 x 28130×20120x28120x20
Geometrical size370×60420×60140×25140×40150×40140×40140×40
Coating  MaterialAuAuAuAuAuRhRh
Substrate MaterialSiSiSiSiSiSiSi
Roughness (Å)2.532.13333
Slope error
Sag./Merid. (arcsec)
0.17/0.430.03/0.070.02/0.040.3/0.30.3/2.5
Entrance arm (mm)24000  -/∞8000-16037/∞ 8500
Exit arm (mm)15000/∞  -/120002000/20258000 1500
ParametersR=1216580 mmρ=837.6 mm  Blaze angle1.01°
N=1200 l/mm
Cff=2.25
Aspect angle=172.8°
R=
ρ=
R=
ρ=
R=1.220 km
ρ=418.8 mm 
  R= 97410 mm 
ρ=66.75 mm  

Performance

The HIPPIE beamline can achieve 25000-35000 resolving power at 5-10 µ exit slit size. The beamline flux is higher

than 1012 ph/s up to 2000 eV with 50 micron exit slits, typical for AP-XPS measurements, where the resolving power is ~10000.