New Photoemission Studies of thedBands of Nickel and Copper

New photoemission studies of the optical density of states of nickel and copper are reported. In contrast to other earlier measurements, both Ni and Cu have a sharp maximum at the top of the $d$ band. The $d$-band optical density of states of Ni and Cu are consistent with a simple rigid-band model: The exchange splitting of Ni is estimated as $\delta E_{\mathrm{ex}}\simeq 0.4\pm 0.2$ eV.