  New results from tunneling spectroscopies on near optimally-doped single
crystals of Tl_{2}Ba_{2}CuO_{6} (Tl-2201) junctions are presented. The
superconductor-insulator-normal metal (SIN) tunnel junctions are obtained using
the point-contact technique with a Au tip. The tunneling conductances
reproducibly show a sharp cusp-like subgap, prominent quasiparticle peaks with
a consistent asymmetry, and weakly decreasing backgrounds. A rigorous analysis
of the SIN tunneling data is performed using two different models for the
$d_{x^{2}-y^{2}}$ (d-wave) density of states (DOS). Based on these and earlier
results, the tunneling DOS of Tl-2201 have exhibited the most reproducible data
that are consistent with a d-wave gap symmetry. We show that the dip feature at
$2\Delta$ that is clearly seen in SIN tunneling data of
Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta} is also present in Tl-2201, but at a weaker
level. The gap values for crystals with a bulk T_c = 86 K are in the range of
19-25 meV.
