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Diffusion on surfaces

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TR Linderoth et al.

Phys. Rev. Lett. 82 (1999) 1494

Aarhus Universitet

Surface Science Course 2006 Achim Schnadt

Surface diffusion is important for ...

... growth processes

A. Groß, Theoretical Surface Science, Springer-Verlag

... surface reactions

G. Ertl, Lecture at Nobel Symposium

Energy in Cosmos, Molecules and Life, July 2005

Which particles do diffuse on surfaces?

Chemisorption, physisorption, and precurors

Image from

J. V. Barth, Surf. Sci. Rep. 40 (2000) 75

T. Ala-Nissila, R. Ferrando, S. C. Ying

Adv. Phys. 51 (2002) 949

Tekniska Högskolan, Helsingfors

Brown University, Rhode Island

Università di Genova

T. Ala-Nissila, R. Ferrando, S. C. Ying

Adv. Phys. 51 (2002) 949

Tekniska Högskolan, Helsingfors

Brown University, Rhode Island

Università di Genova

Quantum tunnelling

T. Ala-Nissila, R. Ferrando, S. C. Ying

Adv. Phys. 51 (2002) 949

Tekniska Högskolan, Helsingfors

Brown University, Rhode Island

Università di Genova

only for hydrogen!

A. Zangwill, Physics at Surfaces,

Cambridge University Press

Initial state – transition state – final state

T. Ala-Nissila, R. Ferrando, S. C. Ying

Adv. Phys. 51 (2002) 949

Single jump diffusion on a fcc(100) metal surface. A. Groß, Theoretical Surface Science, Springer-Verlag.

What would you expect for the diffusion on a stepped surface?

(take into account what you’ve just learned about transition states)

What would you expect for the diffusion on a stepped surface?

(take into account what you’ve just learnt about transition states)

”Ehrlich-Schwoebel-barrier”

G. Ehrlich, F. G Hudda, J. Chem. Phys. 44 (1966) 1039

R. K. Schwoebel, J. Appl. Phys. 40 (1969) 614

Single (nearest neighbour) surface?

jumps

Image from

T. Ala-Nissila, R. Ferrando, S. C. Ying

Adv. Phys. 51 (2002) 949

Single (nearest neighbour) surface?

jumps

Long jumps

Image from

T. Ala-Nissila, R. Ferrando, S. C. Ying

Adv. Phys. 51 (2002) 949

Single (nearest neighbour) surface?

jumps

Long jumps

Depends on the energy dissipation rate

and the temperature!

Image from

T. Ala-Nissila, R. Ferrando, S. C. Ying

Adv. Phys. 51 (2002) 949

Another mechanism for diffusion: Exchange diffusion surface?

Transition state

Final state

Initial state

Exchange diffusion on a fcc(100) metal surface. A. Groß, Theoretical Surface Science, Springer-Verlag.

A different view on downward diffusion at steps surface?

Image from

T. Ala-Nissila, R. Ferrando, S. C. Ying

Adv. Phys. 51 (2002) 949

Island diffusion on Pt(110) (2x1) surface?

T.R. Linderoth et al.

Phys. Rev. Lett. 82 (1999) 1494

Aarhus Universitet

Island diffusion on Pt(110) (2x1) surface?

T.R. Linderoth et al.

Phys. Rev. Lett. 82 (1999) 1494

Aarhus Universitet

Experimental techniques for studying surface diffusion coefficient

Local probe techniques

Field ion microscopy

Image from

A. Zangwill, Physics at Surfaces. Cambridge University Press

Originally from G. Ehrlich,

CRC Crit. Rev. Sol. State Mat. Sci. 10 (1982) 391

Scanning tunnelling microscopy

M. Schunack et al., University of Aarhus

More STM movies on http://www.ifa.au.dk/spm

Experimental techniques for studying surface diffusion coefficient

Integrating methods

Laser-induced thermal desorption

Experimental techniques for studying surface diffusion coefficient

Integrating methods

Quasielastic helium scattering

Graphs from A.P. Graham, A. Menzel, J.P. Toennies, J. Chem. Phys. 111 (1999) 1676

Experimental techniques for studying surface diffusion coefficient

Integrating methods

Photoelectron emission microscopy

[1-10]

O/Pt(110)

50 mm x 190 mm

Time between images: 120 s

A. von Oertzen, H. H. Rotermund, S. Nettesheim, Surf. Sci. 311 (1994) 322

Want to know more? coefficient

Experiment review (plus some theory):

J. V. Barth, Surf. Sci. Rep. 40 (2000) 75

Theory review (easy to read!):

T. Ala-Nissila, R. Ferrando, S. C. Ying, Adv. Phys. 51 (2002) 949