  The electronic structure of the cleaved perovskite (CH3NH3PbBr3) single
crystal was studied in an ultra-high vacuum (UHV) system by angle-resolved
photoemission spectroscopy (ARPES) and inverse photoelectron spectroscopy
(IPES). Highly reproducible dispersive features of the valence bands were
observed with nice symmetry about the Brillouin zone center and boundaries. The
largest dispersion width was found to be ~0.73 eV and ~0.98 eV along the
{\Gamma}X and {\Gamma}M directions, respectively. The effective mass of the
holes was estimated to be ~0.59 m0. The quality of the surface was verified by
atomic force microscopy (AFM) and scanning electron microscope (SEM). The
elemental composition was investigated by high resolution x-ray photoelectron
spectroscopy (XPS). The experimental electronic structure shows a good
agreement with the theoretical calculation.
