Fermi surface and band structures taken by the photon energy of 21.2 eV around the K̅ points on the (001) surface of Na₃Bi. (a) Observation of features around the K̅ points. The upper-right inset image is the projection view of the (001) surface atomic structure. The blue rhombus and the orange rhombus show the repetition unit cells of the surface, where the length of the unit vector of the orange rhombus is times that of the red one. While the small blue rhombus corresponds to a large surface Brillouin zone as a gray hexagon, the expanded orange rhombus corresponds to the smaller surface Brillouin zone marked as a red hexagon. The possible surface reconstruction makes the original six K̅ points equivalent to the point. This gives rise to a possible band folding of the bands near point to the K̅ points. (b) Band structure measured along as indicated by a orange line in panel (a). It is obtained by second derivative of the original data with respect to momentum direction. The band slope near the Fermi level at both and K̅, which are fitted with red dashed linear lines, are similar with an estimated value around 3.0 eV·Å.