Oscillation spectra and the nature of thermal broadening of light absorption bands of HTSC compounds YBa2 Cu3 O7-x

The spectrum of light absorption by YBa2 Cu3 O6.15 films in the range of energies 1.5-3 eV at temperatures from 4.2 to 300 K has been investigated. A strong relationship (∼0.1 eV) was found between electron excitation with charge transfer and optical phonons. The main contribution to electron excitation scattering is given by 330 and 150 cm-1 optical vibrations, i.e. vibrations of oxygen and copper ions in the plane of Cu-O