Diffusion on surfaces Surface Science Course 2006 Achim Schnadt TR Linderoth et al. Phys. Rev. Lett....
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Transcript of Diffusion on surfaces Surface Science Course 2006 Achim Schnadt TR Linderoth et al. Phys. Rev. Lett....
![Page 1: Diffusion on surfaces Surface Science Course 2006 Achim Schnadt TR Linderoth et al. Phys. Rev. Lett. 82 (1999) 1494 Aarhus Universitet.](https://reader036.fdocuments.in/reader036/viewer/2022062518/56649f3d5503460f94c5cc31/html5/thumbnails/1.jpg)
Diffusion on surfaces
Surface Science Course 2006 Achim Schnadt
TR Linderoth et al.Phys. Rev. Lett. 82 (1999) 1494Aarhus Universitet
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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
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Image fromJ. V. Barth, Surf. Sci. Rep. 40 (2000) 75
Chemisorption, physisorption, and precurors
Which particles do diffuse on surfaces?
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T. Ala-Nissila, R. Ferrando, S. C. YingAdv. Phys. 51 (2002) 949
Tekniska Högskolan, HelsingforsBrown University, Rhode Island
Università di Genova
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T. Ala-Nissila, R. Ferrando, S. C. YingAdv. Phys. 51 (2002) 949
Tekniska Högskolan, HelsingforsBrown University, Rhode Island
Università di Genova
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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
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Some theory ...
Following the treatment inA. Groß,Theoretical Surface Science,Springer-Verlag
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A. Zangwill, Physics at Surfaces,Cambridge University Press
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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.
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What would you expect for the diffusion on a stepped surface?
(take into account what you’ve just learned about transition states)
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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
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Single (nearest neighbour)jumps
Image fromT. Ala-Nissila, R. Ferrando, S. C. YingAdv. Phys. 51 (2002) 949
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Single (nearest neighbour)jumps Long jumps
Image fromT. Ala-Nissila, R. Ferrando, S. C. YingAdv. Phys. 51 (2002) 949
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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
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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
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A different view on downward diffusion at steps
Image fromT. Ala-Nissila, R. Ferrando, S. C. YingAdv. Phys. 51 (2002) 949
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T.R. Linderoth et al.Phys. Rev. Lett. 82 (1999) 1494Aarhus Universitet
Island diffusion on Pt(110) (2x1)
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T.R. Linderoth et al.Phys. Rev. Lett. 82 (1999) 1494Aarhus Universitet
Island diffusion on Pt(110) (2x1)
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Single-particle diffusion coefficient and chemical diffusion coefficient
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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
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Laser-induced thermal desorption
Integrating methods
Experimental techniques for studying surface diffusion
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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
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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
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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