The effect of carbon monoxide on the work function of evaporated films of titanium and erbium

Small doses of CO reduced phi by approximately 50 mV for Er films but did not reduce it for Ti films. The sign and magnitude of this reduction of phi can be accounted for by a simple geometrical model. Larger doses increased phi for both metals. Each increase of Er before saturation was followed by a slow decrease, but phi for this effect was seen only occasionally with Ti. The difference between phi for the clean film and phi for the saturated film was 0.49 +- 0.05 eV for CO/Ti and 0.71 +- 0.11 eV for CO/Er. The bulk structure of both films was found to be randomly oriented hcp. The surface cleanliness of the Ti films was checked by their Auger spectrum; this spectrum changed slowly owing to beam effects and to the reaction of Ti with residual gases. The results are compatible with the dissociative adsorption of CO, provided that there is some reconstruction of the surface. (Auth.)