Adsorption and desorption with interactions

The above analysis makes the implicit assumption that molecules of P adsorbed on the surface do not interact with each other in any attractive or 

The stationary-state relationship between the partial pressure p and the extent of coverage is then 

For larger attractive interactions, however, the stationary-state locus becomes S-shaped with a hysteresis loop (Fig. 12.2(b)). The critical value of a at which the hysteresis loop first appears can be determined using the singularity theory equations of 7.3.1. The appropriate form of the stationary-state condition F is 

We then find the derivatives Fgp and Fe and equate these to zero along with F. These requirements are satisfied for 

multiple stationary-state solutions are a feature of this model with a 4. The turning points in the locus can be located from the condition dp/d0p = 0 from eqn (12.16), which gives 

---