Kink site position residence time

What happens to an atom in the kink site position This may be determined by the time interval in which the atom stays in the kink site position. This time is called residence time in the kink site position (in German Verweilzeit )- The residence time is the statistical average of the time between the arrival of the atom in the kink site position and its separation from the kink site position. During the residence time the process of separation from the kink site position competes with the arrival of new atoms. The residence time t in a kink site position is given by the reciprocal value of the rate constant of separation. 

In the following section, a statistical description of the surface processes will be presented. This is based on the definition of a residence time of an atom in a kink site position. 

Comparison of the dynamic of some metals with cep and hep structures rate constants of separation from kink site positions (calculated with the assumption that the activation energy is proportional to the cleavage of one bond nd residence time t... 

With Avogadro s number and F the Faraday constant. The density of kink site positions at the equilibrium potential [ksp] is given by the product of exchange current density and residence time. This equation will be discussed in the next section. 

The residence time provides a measure of how long an atom can stay in a kink site position. The next atom accumulated in the kink site position determines its future. Therefore one has to compare residence time and rate of deposition. 

Dividing Eq. (7.35) through the density of kink site positions [A p], the number of atoms arriving during the residence time per kink site position is obtained... 

A special situation that can cause stationary conditions is at the electrochemical equilibrium potential (Nemst potential). The current density at the Nemst potential is the exchange current density The density of kink site positions [fopJo is therefore proportional to the product of exchange current density Iq and residence time, as was already shown in Eq. (7.34). 

Exchange current densities have been determined for many metals. Using ig values from the literature and the values for the residence times presented in Table 7.1 a rough estimation of the order of magnitude of the density of kink site positions at the Nemst potential is possible. Examples are presented in Table 7.2. 

Density of kink site positions at the Nemst potential calculated with Eq. (7.34) for some metals, residence times taken from Table 7.1, and exchange current densities from the literature ... 

A residence time can be defined for each atom newly added to a kink site position. 

Selectivity constants and residence times in kink site positions... 

Residence time of atom A in kink site position AA Residence time of atom B in kink site position AB Residence time of ad-atoms... 

Residence time of atom A in kink site position BA ... 

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