SPECTROSCOPIC STUDY ON SUPERCONDUCTOR YBa_2Cu_3O_x~*

The structure of energy levels is the most important factor to determine the characteris-tic of solid. Single phase of high T_c superconductor YBa_2Cu_3O_x is investigated by the spec-troscopic method. The reflection-absorption spectra, Raman spectra and fluorescence spectraof high T_c samples have been measured. The absorption bands of 350 and 500 nm and emis-sion bands of 390 and 560 nm are assigned to the transition between ~1A_(1g)(3d^(10)) to ~1E_g and^3E_g(3d^94s^1) of the emission center of Cu^+. The emission bands of 720 and 860 nm come fromthe emission center of Cu^(2+), which is considered to be the transition between five splittingenergy levels of the spectral term ~2D of free ions in octahedra and rhombic crystal fields. Inaddition, there are some bands that may come from the emission center of Cu^(3+) in the crystallattice. The presence of phonon pairs of 481 and 551 cm^(-1) indicates the strong coupling be-tween tbe phonon pair of 312 cm^(-1) and electron system.