Surfaces scanning tunnehng microscope

The atomic force microscope (Figure 25.18) is a cousin of the scanning tunnehng microscope, which we discussed in an essay at the end of Section 7.4. Both microscopes use a probe to scan a surface but, whereas the scanning tunneling microscope measures an electric current between the... 

Rasmussen PB, Hendriksen BLM, Zeijlemaker H, Ficke HG, Frenken JWM (1998) The reactor STM a scanning tunnehng microscope for investigation of catalytic surfaces at semiindustrial reaction conditions. Rev Sd Instrum 69(11) 3879-3884. doi 10.1063/1.1149193... 

The last section will concentrate on the lateral distribution of the respective metals in a surface alloy. We will exemplarily show how the atom distribution in a disordered surface alloy can be quantitatively characterized based on scanning tunnehng microscopic (STM) data and how such a distribution can be predicted by Monte Carlo (MC) simulations. This will include the description of a simplified pairwise interaction model and how the energy parameters for such a model can be derived from both experiments and ab initio calculations. We will show that even a very basic energy model is capable of accurately predicting the atom distribution in a surface alloy via the MC simulations. The MC simulations also allow prediction of the (hypothetic) surface structure at temperatures where sluggish kinetics suppresses reorganization of the atoms in an experiment A key parameter to be derived from such simulations is the temperature of the order-disorder transition of the respective system. 

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