6 process can be described by , where φ k i and φ k f are the initial and final state wave- functions respectively [29]. In our experimental setup, the momentum of the final-state photoelectron is in the mirror plane, and φ k f can be approximated by a plane wave. Therefore, φ k f is always even with respect to the mirror plane. In the π geometry, ( ˆ ε · r ) is even, to give a finite photoemission matrix element, | φ k i 〉 must be even with respect to the mirror plane. Thus only even state is probed in the π experimental geometry. On the other hand, one could similarly deduce that only odd state is observed in the σ geometry. In contrast to the data measured with circularly polar- ized light in Figs. 2(i) and (j), only the β band is observed in the σ geometry [Figs. 8(b) and (d)], while just the α and γ bands are observed in the π geometry [Figs. 8(c) and (e)]. Based on the symmetry of different orbitals il- lustrated in Fig. 8(a), the β band is odd with respect to the mirror plane, while the α and γ bands are even along the $_{Γ}$-X direction. Therefore, the β band has to be made of d$_{xy}$ and/or d$_{yz}$ orbitals, while the α and γ bands may be consisted of d$_{x}$ $^{2}$$_{−}$y2 , d$_{z}$ 2 , and/or d$_{xz}$ . These experimental findings of the symmetry proper- ties of the band structure are well captured by the band structure calculation. In Fig. 9, the orbital characters of the bands are shown by the false color plot. Near the Fermi energy, the α band is mainly consisted of d$_{xz}$ / d$_{yz}$ orbitals, which should be purely d$_{xz}$ along the Γ − X direction. The β band is consisted of mainly d$_{xz}$ and d$_{yz}$ orbitals, and some d$_{xy}$ orbitals; while the γ band is consisted of d$_{x}$ $^{2}$$_{−}$y2 orbital. Along the Γ − Z direction, the band structure near E$_{F}$ has some contributions from the p$_{z}$ orbital and small contributions from the d$_{z}$ 2 or- bital. They all have even symmetry and thus can be observed in the π experimental geometry. The small el- lipsoidal Fermi surface near zone center is mainly con- tributed by the d$_{z}$ 2 orbital for FeAs-based compounds, while for Fe(Te 0 . 66 Se 0 . 34 ), Te/Se p$_{z}$ orbital plays an im- portant role. To have a more quantitative picture, we have listed the contributions of various orbitals to the states at E$_{F}$ in Table. I, which are the coefficients of the calculated corresponding Bloch wavefunctions projected into the orbitals. Although the chalcogen ions contribute little spectral to the density-of-states (DOS) near the Fermi energy, the Fe 3 d related band structure in iron-chalcogenides does show significant difference compared with that of iron- pnictides. Recently, it is even proposed that the polar- ization of the As p orbitals might be the cause of the unconventional superconductivity in FeAs-based super- conductors [11]. Therefore in this regard, the electronic consequences related to the chalcogen or pnicogen anions in the iron-based superconductors are particularly inter- esting to explore. In general, Fe 1 . 04 (Te 0 . 66 Se 0 . 34 ) has similar Fermi sur- face and band structure as the iron-pnictides [22, 30]. However, there are some important differences. For ex- ample, the three bands near Γ are well separated in this iron-chalcogenides, each with distinct symmetry. On the other hand in recent polarization dependence studies of the BaFe 1 . 82 Co 0 . 18 As 2 , only two features around Γ were observed [22]. Moreover, the inner feature is a mixture of orbitals of both even and odd symmetries, while the outer feature is even in symmetry. Moreover, our calculations show that the Te 5 p orbitals contribute to the density of states near the Fermi energy, while Fe 3 d$_{z}$ 2 orbital contributes very little in this iron-chalcogenide. Fur- thermore, there is a small ellipsoidal Fermi surface near the zone center of Fe 1 . 04 (Te 0 . 66 Se 0 . 34 ), while for iron- pnictides, such a small Fermi pocket has not been un- ambiguously observed in the paramagnetic normal state. Compared with the electronic structure of Fe 1+ $_{y}$Te obtained earlier [31], the Fe 1 . 04 (Te 0 . 66 Se 0 . 34 ) electronic structure behaves differently in the following two aspects. First, three bands α , β , and γ , are clearly observed around$_{Γ}$ for Fe 1 . 04 (Te 0 . 66 Se 0 . 34 ), whereas only two bands were distinguished in Fe 1+ $_{y}$Te. Secondly, a weak Fermi surface was observed around X-point in Fe 1+ $_{y}$Te, which was argued to be a folded Fermi surface by the spin den- sity wave. For Fe 1 . 04 (Te 0 . 66 Se 0 . 34 ), neutron scattering ex- Figure 9: (color online) Contributions of various Fe 3 d and Te/Se p orbitals to the calculated band structure of Fe(Te 0 . 66 Se 0 . 34 ). VI. DISCUSSION | M k $_{f,i}$|  ∝ |〈 φ k $_{f}$| ˆ ε · r | φ k i 〉| 2