Beamline overview

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The Materials Science Beamline was designed as a multipurpose beamline for surface science using photoemission and absorption spectroscopies, with a photon energy ranging from vacuum ultraviolet to soft X-ray radiation (22-1000 eV). It is based on a bending magnet radiation source and grazing-incidence reflective optics. All optical surfaces are gold coated.The resulting beam size is 150-400 μm. Photoelectrons from the sample are analyzed by hemispherical electron energy analyzer.
 beamline layout


Photon source

The Materials Science Beamline (6.1L) uses radiation from bending magnet of the Elettra storage ring, which we share with the SYRMEP beamline (6.1R). It provides to the beamline with polychromatic light in a wide energy range from visible to hard X-ray. The bending magnet radiation is mostly linearly polarized in the horizontal direction, with only a minor part of the radiation above and below the orbit having circular polarization. The Elettra storage ring parameters can be found here.

Prefocusing mirror

The first optical element is a toroidal prefocusing mirror that bends the beam by approx. 8° in the horizontal direction and focuses the divergent photon beam from the bending magnet sagittally onto the entrance slit and tangentially onto the exit slit. It also absorbs all hard X-ray radiation and is water-cooled. Because of the radiation safety the mirror is locked in the radioprotection hutch and its position is remotely controlled by the MSB-SLAVE computer via servomotors. Setting the prefocusing mirror position allows for compensating of the variation of the position of the synchrotron beam in the storage ring. For details see Setting the beam position.

Entrance and exit slits

The slits adjust the energy resolution of the photon beam. Their apertures are set manually by micrometers. Closing the slits improves the resolution but at the cost of beam intensity. The beamline provides the best results with exit slit aperture = 2 × entrance slit. The entrance slit is water-cooled. For details see Setting the photon energy resolution.

Monochromator

The energy of photons is selected by a plane grating monochromator (PGM) of the SX-700 concept. The monochromator consists of water-cooled plane mirror (PM) and plane grating (PG) with variable angles set by stepping motors controlled by the MSB-MONO computer, and of the fixed spherical mirror (SM). The monochromator is supposed to be calibrated so the software sets the correct PM and PG angles in order to provide the desired photon energy of the beam. Miscalibration due to thermal and mechanical drift is more visible at higher photon energies (above 100 eV) and it can reach several eVs at 1000 eV. For details see Setting the photon energy.
Manual in PDF PDF

Refocusing mirror

Refocusing mirror is intended for refocalization of the divergent beam coming from the exit slit. Moreover, the micrometers allow for manual setting of the beam position on the sample. For details see Setting the beam position.

Gold mesh

Immediately after the refocusing mirror there is a fine gold mesh placed in the beam line. It is connected to the current amplifier and A/D converter and it provides a measure of the photon flux. For details see Mesh Monitor.

After passing through the gold mesh the beam enters the end station analysis chamber.


Last Updated on Thursday, 19 October 2023 09:00