for this structure is θ
= 1/2 (θ =
The coverage can be determined simply by counting atoms within a given area of surface, but the area chosen must be representative of the surface as a whole.
If we take the adsorbate unit cell then
θ = (No. of adsorbate species/ No. of substrate atoms) = (4 x ¼ + 1) / (4 x ¼ + 4 x ½ + 1) = 2/4
i.e. θ = 1/2
The coverage can also be obtained by comparing the areas of the unit cells of the adsorbate and substrate, with additional allowance for the number of atoms per unit cell.
|where :||NADS = Number of atoms in the adsorbate unit cell.|
|AADS = Area of adsorbate unit cell|
|ASUB = Area of the primitive unit cell of the substrate|
In this instance
Hence, θ = (1/4) x 2 = 1/2