Iridium Literature 4f7/2 Values [1]:
Ir(0) 60.8 +/- 0.2 eV (assumed to have an asymetric peak-shape)
IrO2 61.6 +/-0.5 eV
IrBrx 61.7+/-0.5 eV
IrClx 62.2+/-o.7 eV
IrIx 61.9+/-0.6 eV
4f7/2 - 5/2 douplet separation = 2.93+/-0.05 eV

From a quick look at the literature there may be some complex species possible that may complicate the fitting. A second oxide peak may be found in some instances at higher binding energies (61.9-63.7 eV) than seen for IrO2 [2]. This author also sets the oxide doublet-separation to 3.03 eV.

Also watch for overlaps with Na 2s and Ta 5s.

[1] http:/
[2] H.Y. Hall, P.M.A. Sherwood, J. Chem. Soc. Faraday Trans. 1, 1984, 80, 135-152.