Electronic Raman scattering in Bi2Sr2CaCu2O8+delta excited with c-axis polarized light

We report on the electronic Raman spectra ex:cited and detected with photon polarization directions along the c-axis in Bi2Sr2CaCu2O8+delta single crystals. In the normal state, a resonant electronic continuum extends to 1.5 eV and gains significant intensity as the incoming photon energy increases. Below T-c, there is a low-frequency redistribution of the electronic continuum and the formation of a 2 Delta peak in the superconducting state. The monotonic increase of 2 Delta and 2 Delta /k(B)T(c) with decreasing doping is unusual. In particular, this 2 Delta feature, which has A(1g) symmetry, is found at higher frequencies than those seen in the planar symmetries for all doping levels studied.