Mechanism of Work-Function Reduction by Oxygen Adsorption

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Abstract
A model is proposed to explain the reduction in work function of an Na‐covered W (112) surface by oxygen adsorption. It is proposed that oxygen atoms are adsorbed directly to the W (112) substrate, forcing the Na atoms to the second layer. Since the dipole moment of an O–Na bond is much larger than that of a W–Na bond, it is believed that the W–O–Na bonding has larger dipole moment than that of the W–Na bond thus causing a decrease in work function. LEED results consistent with the proposed model is presented.