Oxygen, monolayer structure defined

The suggested nomenclature that is most nearly complete is then as follows. The name of the substrate surface is followed by the Park-Madden symbol, which is then followed by the name of the adsorbate, and last by the coverage of adsorbate in square brackets. Thus the complete names for the oxygen structures on Ni(llO) shown in Fig. 8 read Ni(110)-( )-O-[i], Ni(110)-( )-O-[J], and Ni(110)-( )-O-[f]. In these arrays of symbols, 0 refers to oxygen atoms and the final fractions in square brackets to fractions of a monolayer. One monolayer is defined as the number of atoms in a single plane of the substrate. When the unit mesh vectors dg and 5g are, respectively, parallel to d and 5, the shorthand Lander notation is convenient. Thus the three structures of Fig. 8 can also be called (3 X 1), (2 x 1), and (3 X 1), respectively, where the first number in each set of brackets refers to the magnitude of dg in units of a, and the second to the magnitude of 5g in units of 6. When a centered mesh is chosen, the symbol C is written prior to the shorthand symbol. Thus the structure of Fig. 28a (p. 223) is written (2 X 2) and that of Fig. 28b, C(2 X 2). 

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