Angle-resolved photoelectron spectroscopy and band-structure calculations of CdI2

The electronic structure of the 4H polytype of the layered compound CdI2 was investigated using angle-resolved ultraviolet photoelectron spectroscopy (ARUPS). The spectra are compared with results of self-consistent relativistic band-structure calculations of the 2H- and 4H-CdI2 polytypes. It is shown that a detailed analysis of the spectra is possible by using calculated band dispersions. The calculated band structures are compared with the complete spectra and not only to the peak positions. The spectra can be explained by assuming indirect transitions. The wave-function symmetries were determined from the variation of peak intensities with the photon angle of incidence. The agreement between the calculated band structure and the experimental spectra is good; no significant differences between the calculated valence-band structure and the ARUPS spectra in excess of 0.3 eV are found.