| 2. |
- Pickworth, Louisa A., et al.
(författare)
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Distributed focusing reduces mirror error sensitivity on x-ray beamlines
- 2023
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Ingår i: Applied Optics. - 1559-128X. ; 62:16, s. 4327-4333
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Tidskriftsartikel (refereegranskat)abstract
- The appearance of very low emittance, high-power synchrotron sources has resulted in ever longer beamlines, often requiring a very weak curvature on the mirrors that transport the beam to the experiment, where the radius of curvature is on the order of kilometers. Manufacturing weakly curved, low figure error grazing incidence mirrors is difficult as the mirrors must be manufactured to an accuracy comparable to the wavelength of the transmitted light. Often the delivered mirrors have figure errors at various length scales (general shape, slope errors, roughness), which compromise image quality. An error in general shape, like the radii of a toroidal mirror, results in longsighted or short-sighted imaging that is not so simply corrected by changing the distances and incidence angles as the mirror controls the beam focus in both vertical and horizontal directions; for a toroidal mirror, the tangential and sagittal radii need to match correctly for the desired focusing effect. Adaptive downstream optics can compensate for this. In this paper, an alternative method to reduce the sensitivity to a large radius error outside the specified tolerance range in the first mirror of a plane grating monochromator beamline at MAX IV is presented. It is found that distributed focusing by two passive, fixed radius mirrors reduces greatly the sensitivity to the radius errors in both mirrors. The radius tolerance of a mirror initially found to be unacceptable for single stage focusing is easily accommodated on both mirrors in distributed focusing, without compromising the imaging capability.
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| 3. |
- Zhu, Suyun, et al.
(författare)
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HIPPIE : a new platform for ambient-pressure X-ray photoelectron spectroscopy at the MAX IV Laboratory
- 2021
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Ingår i: Journal of Synchrotron Radiation. - : INT UNION CRYSTALLOGRAPHY. - 1600-5775 .- 0909-0495. ; 28, s. 624-636
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Tidskriftsartikel (refereegranskat)abstract
- HIPPIE is a soft X-ray beamline on the 3 GeV electron storage ring of the MAX IV Laboratory, equipped with a novel ambient-pressure X-ray photoelectron spectroscopy (APXPS) instrument. The endstation is dedicated to performing in situ and operando X-ray photoelectron spectroscopy experiments in the presence of a controlled gaseous atmosphere at pressures up to 30 mbar [1 mbar = 100 Pa] as well as under ultra-high-vacuum conditions. The photon energy range is 250 to 2200 eV in planar polarization and with photon fluxes >1012 photons s-1 (500 mA ring current) at a resolving power of greater than 10000 and up to a maximum of 32000. The endstation currently provides two sample environments: a catalysis cell and an electrochemical/liquid cell. The former allows APXPS measurements of solid samples in the presence of a gaseous atmosphere (with a mixture of up to eight gases and a vapour of a liquid) and simultaneous analysis of the inlet/outlet gas composition by online mass spectrometry. The latter is a more versatile setup primarily designed for APXPS at the solid-liquid (dip-and-pull setup) or liquid-gas (liquid microjet) interfaces under full electrochemical control, and it can also be used as an open port for ad hoc-designed non-standard APXPS experiments with different sample environments. The catalysis cell can be further equipped with an IR reflection-absorption spectrometer, allowing for simultaneous APXPS and IR spectroscopy of the samples. The endstation is set up to easily accommodate further sample environments.
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