Diffusion on surfaces
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Diffusion on surfaces. 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.

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Diffusion on surfaces

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Diffusion on surfaces

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


Classical movement

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!


Some theory ...

Following the treatment in

A. Groß,

Theoretical Surface Science,

Springer-Verlag


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)

jumps

Image from

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

Adv. Phys. 51 (2002) 949


Single (nearest neighbour)

jumps

Long jumps

Image from

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

Adv. Phys. 51 (2002) 949


Single (nearest neighbour)

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

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

Image from

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

Adv. Phys. 51 (2002) 949


Island diffusion on Pt(110) (2x1)

T.R. Linderoth et al.

Phys. Rev. Lett. 82 (1999) 1494

Aarhus Universitet


Island diffusion on Pt(110) (2x1)

T.R. Linderoth et al.

Phys. Rev. Lett. 82 (1999) 1494

Aarhus Universitet


Single-particle diffusion coefficient and chemical diffusion coefficient


Experimental techniques for studying surface diffusion

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

Integrating methods

Laser-induced thermal desorption


Experimental techniques for studying surface diffusion

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

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?

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


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