The diffusion of CO on flat and stepped (111) surfaces was measured (table 15) by monitoring linear optical diffraction from an adsorbate grating. The results for temperatures ranging from 133 to 313K, and CO coverages of between 0.1 and 0.67 of a monolayer, revealed an Arrhenius diffusion behavior; with activation energies of 3.0 to 4.7kcal/mol for flat surfaces and 7.3 to 7.9kcal/mol for stepped surfaces. These data illustrated the magnitude of defect-induced variations in measured diffusion parameters.

Diffusion of CO on Pt (111) Studied by an Optical Diffraction Method J.Ma, X.Xiao, N.J.DiNardo, M.M.T.Loy: Physical Review B, 1998, 58[8], 4977-83

 

 

 

Table 15

Arrhenius Parameters for CO Diffusion on Miscut (111)Pt Surfaces

 

CO (monolayers)

Miscut (ยบ)

Do (cm2/s)

E (kcal/mol)

0.1

<0.1

1.4 x 10-6

4.7

0.2

<0.1

6.9 x 10-7

4.6

0.3

<0.1

6.0 x 10-7

4.2

0.3

2

2.8 x 10-4

7.9

0.4

<0.1

5.3 x 10-7

4.0

0.5

<0.1

6.1 x 10-7

3.9

0.5

2

2.1 x 10-4

7.3

0.67

<0.1

4.5 x 10-7

3.0