The two-dimensional energy-band structure of the layer compound InSe has been determined directly from the polar-angle dependence of its photoemission spectra. The measurements were performed using synchrotron radiation in the photon energy range 15-29 eV. The measuring system consisted of two miniature plane-mirror analyzers which could be moved separately so as to sample electrons in two orthogonal planes, one of which was the plane of incidence. It is demonstrated that the requirements of repeated zone symmetry are rigorously observed. Normal photoemission spectra and effects due to the polarization of the synchrotron radiation are reported and discussed. The experimental energy bands of InSe are found to be in very good agreement with recent pseudopotential calculations on GaSe.

• Received 22 October 1976

DOI:https://doi.org/10.1103/PhysRevB.15.3200