Electronic structure of alkali halide–metal interface: LiCl(0 0 1)/Cu(0 0 1)

Electronic structure of the heteroepitaxial LiCl thin film grown on Cu(0 0 1) was studied using electron energy loss spectroscopy (EELS) and ultraviolet photoelectron spectroscopy (UPS), as a model system of the insulator/metal interface. The EELS results did not show any change in the band gap of the LiCl film, though the Anderson’s prediction indicated that the band gap of an insulator decreased at the insulator/metal interface. The change in the band gap of the LiCl film is discussed by considering Madelung potential and many body effects. The UPS results, on the other hand, showed an upward shift of the Cl 3p with an increasing film thickness.