Beamline Description

A schematic picture of the BaDElPh end station is reported in figure 1. It consists of three independent ultra-high vacuum (UHV) chambers and a load-lock. There are valves between the analysis chamber and the beamline, between the analysis chamber and the preparation chamber, between the preparation chamber and the heater chamber, and between the heater chamber and load lock. All these chambers are pumped by turbo pumps.

The Analysis Chamber

Since April 2024, a new mu-metal experimental chamber has been installed. It houses a 4^th-generation high-resolution (1 meV / 0.1°) and -transmission (200 mm mean radius) hemispherical electron energy analyzer MBS A-1 with lens scanning and wide acceptance angle, a fast 2D-CMOS detector for ARPES, and the MBS Spin Manipulator and a VLEED (FOCUS Ferrum) detector for 3D Spin-ARPES (under commissioning). The analyzer is mounted on a fixed geometry with an angle of 50° relative to the synchrotron radiation direction. The angular dispersive plane of the analyzer coincides with the polarization plane of the synchrotron light in first harmonic (horizontal plane). The use of a 2D-CCD detector combined with the lens scanning offers the possibility of simultaneous acquisition of the energy as well as the in-plane angular distributions of the photoelectrons. The span of (k_x,k_y) vectors simultaneously probed by the analyzer is defined by the angular acceptance of the particular lens mode and by the photon energy. Three different angular resolved modes of the L4 lens operation have been designed for ARPES measurements reaching a maximum angular acceptance of more than 30°; moreover, an ultimate angular resolution of about 0.1° can be achieved. On-site measurements have so far demonstrated an ultimate energy resolution of less than 3 meV from the gas phase (Xe line at about 9 eV).
The chamber also hosts a low-energy electron diffraction (LEED) optics and a residual gas analyzer (RGA). The base pressure in the analysis chamber is in 10^-11 mbar range.

The Prepartion and Heater Chambers

The preparation chamber is normally equipped with an ion sputter gun and a silver evaporator while in the heater chamber is present a 7-slot sample flag parking device and an electron bombardment heater stage for high-temperature (up to about 2400 K) annealing of the sample. Both these chambers have several free flanges to mount the needed tools for the required sample preparation (cleavage, scraping, gas treatment) and for UHV in-situ growth of thin films. The base pressure in the preparation chamber is in 10^-10-10^-11 mbar range while in the heater chamber the base pressure is in the 10^-10 mbar range.
The heater chamber is equipped with a load-lock that allows to transfer samples in about 60 minutes from air to a vacuum of better than 10^-7 mbar.

                Figure 1: BaDElPh end station