BL6U  Variable-Included-Angle VLS-PGM for Molecular Soft X-Ray Spectroscopy

Description

  The beamline BL6U equipped with a variable-included-angle Monk-Gillieson mounting monochromator with a varied-line-spacing plane grating was constructed for various spectroscopic investigations requiring high-brilliance soft X-rays on solid surfaces. Through a combination of undulator radiation and sophisticated monochromator design (entrance slit-less configuration and variable-included-angle mechanism), using a single grating, the monochromator can cover the photon energy ranging from 40 to 500 eV, with resolving power of greater than 10000and photon flux of more than 10¹⁰ photons/s. Figure 1 shows an example of the monochromator throughput spectra measured using a Si photodiode, with the exit-slit opening set at 30 μm, which corresponds to the theoretical resolving power of 10000 at 80 eV. A new Momentum Microscope experimental station for photoelectron spectroscopy resolved in 3D momentum space with a microscopic field of view has been built at BL6U (SPECS KREIOS 150 MM). A momentum resolution of 0.01 Å^-1 in k_x/k_y as well as k_z is achieved. A spatial resolution of 50 nm, an energy resolution of 20 meV at 9 K, and a field of view of 2 μm for ARPES are successfully demonstrated. This experimental station specializes in characterizing the electronic structure of surface atomic sites, thin films, molecular adsorbates, and bulk crystals. This method opens the door to direct observation of the Fermi surface of μm-sized crystals, which was difficult with conventional ARPES-type hemispherical analyzers.

Technical Data

BL6U in Activity Report 2024