VIBRATIONAL STRUCTURE IN THE INFRARED REFLECTANCE SPECTRA OF THE HIGH-TEMPERATURE SUPERCONDUCTOR BI2SR2CACU2O8

Pressed ceramic pellets of the high-temperature superconductor Bi2Sr2CaCu2O8 (T(c) = 85 K) were investigated by reflectance spectroscopy in the infrared and visible regions at several temperatures both below and above the superconducting transition. In the process of identifying and analyzing vibrational lines in these samples, two problems arise: diffuse scattering connected with the grainy surface and a non-conventional baseline caused by intense absorption of the electronic background present in the infrared region. After eliminating the effects due to these processes, the temperature dependence of the vibrational lines can be extracted. It is concluded that none of the lines behaves in an anomalous way, i.e., no vibration strongly coupled to the electronic system was found.