Angular-resolved uv photoemission and the band structure of GeS

Angular-resolved photoelectron spectra (ARPES) are presented for GeS using 21-eV excitation energy. From the measurements that cover a wide range of angles along the two principal directions in the basal plane of the orthorhombic layered compound GeS E vs →k_∥ curves were constructed. The band structure of GeS was calculated utilizing the empirical pseudopotential method. The E vs →k_∥ curves can almost completely be understood in terms of this band structure under the assumption that only peaks in the one-dimensional density of states along k_⊥ contribute significantly to the ARPES spectrum.