Adsorption of CO on clean {100} nickel

LEED experiments on the adsorption of CO on {100} nickel have been repeated with the addition of a quadrupole mass spectrometer. The results confirm earlier observations that CO does adsorb on this clean surface and further indicate that such a surface cannot be cleaned by heating alone. CO adsorption on the surface subsequent to prolonged heat treatment is greatly reduced due to diffusion of contamination from the bulk.