diffusion on surfaces surface science course 2006 achim schnadt tr linderoth et al. phys. rev. lett....

Diffusion on surfaces

Surface Science Course 2006 Achim Schnadt

TR Linderoth et al.Phys. Rev. Lett. 82 (1999) 1494Aarhus Universitet

Surface diffusion is important for ...

G. Ertl, Lecture at Nobel SymposiumEnergy in Cosmos, Molecules and Life, July 2005

... growth processes

... surface reactions

A. Groß, Theoretical Surface Science, Springer-Verlag

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

Chemisorption, physisorption, and precurors

Which particles do diffuse on surfaces?

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

Tekniska Högskolan, HelsingforsBrown University, Rhode Island

Università di Genova

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

Tekniska Högskolan, HelsingforsBrown University, Rhode Island

Università di Genova

Quantum tunnelling

only for hydrogen!

Classical movement

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

Tekniska Högskolan, HelsingforsBrown University, Rhode Island

Università di Genova

Some theory ...

Following the treatment inA. 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. YingAdv. 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) 1039R. K. Schwoebel, J. Appl. Phys. 40 (1969) 614

Single (nearest neighbour)jumps

Image fromT. Ala-Nissila, R. Ferrando, S. C. YingAdv. Phys. 51 (2002) 949

Single (nearest neighbour)jumps Long jumps

Image fromT. Ala-Nissila, R. Ferrando, S. C. YingAdv. Phys. 51 (2002) 949

Single (nearest neighbour)jumps Long jumps

Depends on the energy dissipation rateand the temperature!

Image fromT. Ala-Nissila, R. Ferrando, S. C. YingAdv. Phys. 51 (2002) 949

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

Another mechanism for diffusion: Exchange diffusion

Initial state Transition state Final state

A different view on downward diffusion at steps

Image fromT. Ala-Nissila, R. Ferrando, S. C. YingAdv. Phys. 51 (2002) 949

T.R. Linderoth et al.Phys. Rev. Lett. 82 (1999) 1494Aarhus Universitet

Island diffusion on Pt(110) (2x1)

T.R. Linderoth et al.Phys. Rev. Lett. 82 (1999) 1494Aarhus Universitet

Island diffusion on Pt(110) (2x1)

Single-particle diffusion coefficient and chemical diffusion coefficient

Experimental techniques for studying surface diffusion

Local probe techniques

Field ion microscopy

Image fromA. Zangwill, Physics at Surfaces. Cambridge University PressOriginally from G. Ehrlich,CRC Crit. Rev. Sol. State Mat. Sci. 10 (1982) 391

Scanning tunnelling microscopy

M. Schunack et al., University of AarhusMore STM movies on http://www.ifa.au.dk/spm

Laser-induced thermal desorption

Integrating methods

Experimental techniques for studying surface diffusion

Integrating methods

Experimental techniques for studying surface diffusion

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

Quasielastic helium scattering

Photoelectron emission microscopy

Integrating methods

Experimental techniques for studying surface diffusion

O/Pt(110)50 m x 190 m

Time between images: 120 s

[1-10]

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

Want to know more?

Theory review (easy to read!):

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

Experiment review (plus some theory):

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