Single crystals of Bi2Sr2CaCu20s+£ with different oxygen concentrations were investigated by Raman scattering. Dependent on the polarizations of the incident and the scattered light, the electronic spectra measured well below T c show either zero or finite intensity at small energy transfers. In oxygenannealed crystals, the superconducting order parameter A is temperature dependent. In contrast, A is almost constant in the essentially two-dimensional argon-annealed samples. PACS numbers: 74.70.Vy, 74.30.Gn, 78.30.Er The energy gap in the quasiparticle excitation spectrum of superconductors A(k, 70 reveals important information about the superconducting ground state. In classical superconductors the gap has been found to be completely developed over the whole Fermi surface. Remaining anisotropics are small and the temperature dependence obeys the prediction of the BCS theory [1]. In the heavy-fermion superconductor UPt3 several properties indirectly suggest that the gap vanishes for certain directions of k space [2]. Metallic superconductors may be completely gapless in a certain impurity concentration range [2,3l. In the Cu-O superconductors, it is not clear whether these materials are fully gapped and which features are actually intrinsic. Contradictory results have been found for the low-temperature limiting value and for the temperature dependence of the energy gap or, more precisely, for the experimentally observable related quantities. In this Letter, results of Raman scattering experiments on Bi2Sr2CaCu208+>=[010], *' = [110], and/-[lT0]. Just before the samples were mounted into the cryostat, a thin surface layer was peeled off with an adhesive tape. In any case spot temperatures will be indicated.The samples were prepared with a self-flux method [7]

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