1. Diffusion on surfaces Surface Science Course 2006 Achim Schnadt TR Linderoth et al. Phys. Rev. Lett. 82 (1999) 1494 Aarhus Universitet

2. Surface diffusion is important for... G. Ertl, Lecture at Nobel Symposium Energy in Cosmos, Molecules and Life, July 2005... growth processes... surface reactions A. Groß, Theoretical Surface Science, Springer-Verlag

3. Image from J. V. Barth, Surf. Sci. Rep. 40 (2000) 75 Chemisorption, physisorption, and precurors Which particles do diffuse on surfaces?

4. T. Ala-Nissila, R. Ferrando, S. C. Ying Adv. Phys. 51 (2002) 949 Tekniska Högskolan, Helsingfors Brown University, Rhode Island Università di Genova

5. T. Ala-Nissila, R. Ferrando, S. C. Ying Adv. Phys. 51 (2002) 949 Tekniska Högskolan, Helsingfors Brown University, Rhode Island Università di Genova

6. Quantum tunnelling only for hydrogen! Classical movement T. Ala-Nissila, R. Ferrando, S. C. Ying Adv. Phys. 51 (2002) 949 Tekniska Högskolan, Helsingfors Brown University, Rhode Island Università di Genova

7. Some theory... Following the treatment in A. Groß, Theoretical Surface Science, Springer-Verlag

9. A. Zangwill, Physics at Surfaces, Cambridge University Press

10. 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.

11. What would you expect for the diffusion on a stepped surface? (take into account what you’ve just learned about transition states)

12. 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

13. Single (nearest neighbour) jumps Image from T. Ala-Nissila, R. Ferrando, S. C. Ying Adv. Phys. 51 (2002) 949

14. Single (nearest neighbour) jumps Long jumps Image from T. Ala-Nissila, R. Ferrando, S. C. Ying Adv. Phys. 51 (2002) 949

15. 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

16. Exchange diffusion on a fcc(100) metal surface. A. Groß, Theoretical Surface Science, Springer-Verlag. Another mechanism for diffusion: Exchange diffusion Initial state Transition stateFinal state

17. A different view on downward diffusion at steps Image from T. Ala-Nissila, R. Ferrando, S. C. Ying Adv. Phys. 51 (2002) 949

18. T.R. Linderoth et al. Phys. Rev. Lett. 82 (1999) 1494 Aarhus Universitet Island diffusion on Pt(110) (2x1)

19. T.R. Linderoth et al. Phys. Rev. Lett. 82 (1999) 1494 Aarhus Universitet Island diffusion on Pt(110) (2x1)

20. Single-particle diffusion coefficient and chemical diffusion coefficient

21. 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

22. Laser-induced thermal desorption Integrating methods Experimental techniques for studying surface diffusion

23. 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

24. 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

25. 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