  We report angle-resolved photoemission spectra both above and below T_c in
the single-plane cuprate superconductor Bi_2Sr_{2-x}La_xCuO_{6+d}. The
superconducting state measurements show a highly anisotropic excitation gap
with a maximum magnitude smaller than that of the bilayer compound
Bi_2Sr_2CaCu_2O_8 by a factor of 3. For a range of doping, the gap persists
well above T_c, behavior previously associated with underdoped bilayer
cuprates. The anisotropy and magnitude of the normal-state gap are very similar
to the superconducting state gap, indicating that the two gaps may have a
common origin in a pairing interaction.
