Inner valence molecular orbitals of compounds and structure of X-ray photoelectron spectra

Results of the X-ray photoelectron spectroscopy (XPS) studies and theoretical calculation show that under certain conditions inner valence molecular orbitals (IVMOs) form within the binding energy range of similar to 15-50 eV in various compounds. It induces appearance of a fine structure in their XPS spectra. A correlation of the structure of XPS spectra attributed to the inner valence molecular orbitals (IVMOs) with contributions of filled atomic orbitals (AOs) to the IVMO formation and structure of compounds is established. In certain instances, the total contribution of the inner valence electrons to the bond strength is comparable to that of the outer valence electrons. This phenomenon is novel and extremely important for chemistry.