Key points are not available for this paper at this time.
uv-photoemission spectra (h=21. 2 eV) of single-crystal specimens of the high-T₂ superconductor Bi₂Sr₂CaCu₂O₈ have been measured with a resolution of 20 meV in the normal state at 105 K and in the superconducting state at 15 K. In a narrow energy range of 120 meV below the Fermi energy, the low-temperature spectra reveal unambiguously the low-lying quasiparticle excitations reflecting the superconducting state. A straightforward analysis of these spectra provides strong evidence for the existence of a superconducting gap with a reduced value 2{k₁T₂}8.
Imer et al. (1989) studied this question.