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