The coverage
for this structure is θ
= 1/3 (θ=
0.33)
The coverage
for this structure is θ
= 1/3 (θ=
0.33)
Rationale
In this instance , if we let the rhombohedral substrate unit cell
be of unit area then the (
3x3)R30
cell of the adsorbate has an area of 3 units and contains one
adsorbate atom : hence
Coverage = ( 1 / 3 ) x 1 = 0.33
Note - in this instance it is still an easy matter to determine the relative area of the adsorbate unit cell since it is has the same shape as the substrate cell. More generally, the area of the adsorbate unit cell relative to that of the substrate can be obtained from the magnitude of the determinant of the matrix required to describe the adsorbate unit cell.
i.e. Relative Area = | (m11 x m22 ) - (m12 x m21 ) |
e.g. in this instance, Relative Area = |(-2)-(1)| = |-3| = 3
