Figure 4: Experimental and calculated FS maps.
From: Observation of a topologically non-trivial surface state in half-Heusler PtLuSb (001) thin films
(a) The observed constant binding energy surface of PtLuSb (001) with an incident photon energy of 83 eV (the bulk X point) and binding energy of 0.075 eV. The higher photon energy increases the amount of accessible reciprocal space at a cost of resolution. A threefold periodic state can be seen in addition to the TSS. The second-order 
points (kx=±k0, ky=0) have greatly increased intensity, because they project from near the bulk Γ point of the adjacent Brillouin zone enabling both surface and bulk states to be seen. (b) Low-energy electron diffraction pattern (75 eV) of the sample’s surface revealing a (1 × 3) surface reconstruction. (c) Schematic diagram highlighting kz position of the 16, 18 and 83 eV FS maps. Finally, high-resolution second-derivative FS maps near 
for an incident photon energy of (d–g) 16 and (h–k) 18 eV for various binding energies showing a complex Fermi-surface shape, overlaid with the calculated bulk structure. The theory calculation Fermi level has been shifted −0.35 eV to align with the experimental Fermi level position.
