Detailed band structures of Na₃Bi measured on the (100) surface. (a) Fermi surface taken on the (100) surface with a photon energy of 56 eV. (b) Fermi surface taken on the (100) surface by using He Iα (21.2 eV) light source. (c) Band structure along line in (a). (d) Band structure along the line in (b). (e)–(g) Band structures measured along the momentum cuts shown as red lines in panel (a). (e1)-(e2) Band structures measured along the e1 and e2 momentum cuts near the lower Z̃ point in the first Brillouin zone. Weak bands can be observed that are marked by red and blue dashed lines and labelled as α’ and γ’. They show resemblance to the α and γ bands in the band structure around . (e5) Band structure along a momentum cut that roughly crosses the lower node in the first Brillouin zone. (f1), (f2) Band structures along momentum cuts that are around in the first surface Brillouin zone. Four bands are observed below the Fermi level marked as α, β, γ and δ in sequence. (f3) Band structure along a cut that approximately crosses the upper node in the first surface Brillouin zone. (g1), (g2) Band structures along the cuts around the upper Z̃ point. Weak bands are observed that are marked by α’ and γ’. (g3), (g4) Band structures along cuts that roughly cross nodes in second and third surface Brillouin zones. From panels (e1)–(g2), the major period of (100) projected surface Brillouin zone along is marked by the gray rectangle with an unusual value π/c′ = π/(0.5c). Signature of the small period that is consistent with the usual value π/c as marked by the dashed blue rectangle has also been observed. (g3), (g4) confirm the major period along and provide evidence of the unchanged (100) projected surface Brillouin zone period along .