align="justify"> Electronic band structure E (k) is a fundamental description which determines the most physical properties of solids (for example , phenomenon of transmission, optical and photoemission (PE) properties). Band structure (namely the electronic states around the Fermi level E f ) is also one of the main factors which determine functioning of solid electronics devices. Not only the location of the electronic states for energies is important (predetermining, for example, a band gap) but also the location of these states in a k-space. The traditional methods of the unfilled highly lying states research are: the x-ray absorption spectroscopy (XAS), the x-ray radiate transitions spectroscopy, the electron-energy loss spectroscopy (EELS), the reverse PE-spectroscopy, the spectroscopy of diffraction low energy electrons, the low energy repeatedly-electronic emission spectroscopy, the x-ray emission spectroscopy (XES), the low energy total current spectroscopy (TCS) and its variety - the spectroscopy of passing low energy electrons. Last two methods, differing in high surface sensitivity and absence of destroying influence on the investigated sample, with the application for the analysis of elementary violations and surface states in this time used for control of surface purity in the process of cleaning from admixtures, determination of exit work etc. It should be mentioned that the experimental simplicity of these two methods allows to apply them for control of E (k) parameters directly in the process of semiconductor devices manufacture. Although measureable highly lying states directly do not behave to the states nearly E f , changes of these states are interdependent.
Basic experimental information about the electronic structure of solids in this time is received with spectroscopy methods: by the x-ray electronic and photoelectronic spectroscopy, the reverse photoemission spectroscopy, the x-ray emission spectroscopy of internal and valency levels, the x-ray absorption spectroscopy and the spectroscopy in an optical range.
