FLUCTUATIONS IN COUPLED ELECTRON-PHONON SYSTEM AND RAMAN LIGHT-SCATTERING

Raman light scattering with excitation of electron-hole continuum and a phonon is investigated theoretically. The effects of a surface are s tudied. The screening of the electron-photon coupling and of the defor mation potential as a result of the Coulomb interaction of the electro ns is taken into account, Two limiting cases of a low and large spatia l dispersion of charge transfer fluctuation are considered. The parame ters of the 340 cm(-1) resonance line and the electron-phonon constant in superconducting YBaCuO are estimated by comparing with experimenta l data taken from the literature.