Pseudo-gap and superconducting condensate energies in the infrared spectraof Pr-doped YBa2Cu3O7

The(a,b)-plane infrared and visible conductivity (30-30000 cm(-1)) of a 40% praseodymium-substituting yttrium YBa2Cu3O7 film displays a loss of spectr al weight over two separate energy ranges when lowering the temperature. A rst loss of spectral weight is present in the range 300-800 cm(-1) from roo m temperature down to 40 K (T-c=35 K). A further distinct spectral weight d iminution appears in the superconducting phase at frequencies below 200 cm( -1). This diminution can be observed due to the high signal-to-noise ratio allowed by the large area of the thin lm. We propose that the lower energy loss of spectral weight reflects the formation and the properties of the su perconducting condensate.