Temperature derivative of the electronic work function of copper at low temperatures

The temperature derivative of the electronic work function of oxidized polycrystalline copper has been measured in the temperature range 2.9-6.2 K in search of features associated with the surface shielding effect reported by Lockhart, Witteborn, and Fairbank. No anomalies that could be associated with a transition to surface shielding were observed. The temperature derivative of the work function is found to vary from -3 to -12 \ensuremath{\mu}V/K in the temperature range covered. The limitations of these measurements with respect to the detection of the surface shielding transition are discussed.