The Bloch beamline is dedicated to high resolution angle-resolved photoelectron spectroscopy (ARPES) for studying the electronic structure of surfaces and 2D materials. Bloch is optimized for a photon energy range of 10-200eV, and features a spot size down to 10μm x  10μm. Both linear and circular polarized light can be provided, and with substantially reduced flux the beamline can source photon energies up to 1000eV, enabling core level spectroscopy of most elements.

Branchline 1 has an endstation comprehensively configured for ‘standard’ ARPES experiments. Six ultra-high vacuum coupled chambers provide ample opportunities for sample preparation and offline characterization with LEED and STM. The analysis chamber is equipped with a fully motorized six-axis manipulator, with a closed-cycle cryostat capable of arbitrary sample temperatures down to 20K. The electron analyzer is a high performance DA30 hemispherical analyzer from ScientaOmicron. Here the electronic deflection mode enables Fermi surface mapping without needing to rotate the sample, which combined with the small spot size is highly advantageous for studying small or inhomogeneous samples.

The branchline 2 endstation is currently in the installation and commissioning stage, and is expected to be available to general users by early 2022. This branchline will be dedicated to spin-resolved ARPES measurements, using a high efficiency VLEED detector and spin rotator from SPECS capable of resolving all three spin components.

2021-06-04

Unusual electronic properties taking shape at the Bloch beamline

In a recent study, an international team led by researchers from The Pennsylvania State University in the US investigated the one-dimensional (1D) material tantalum selenide iodide (TaSe4 )2I. Its electronic properties had been theoretically predicted but not observed experimentally before the study conducted at the Bloch beamline. Evaporating iodine atoms turn out to drive unforeseen