Trapping-mediated and direct chemisorption of N2 on

Data obtained by Rettner [12] also show that the sticking probability had negligible dependence on the incidence angle for the precursor-mediated chemisorption regime and a very weak dependence on incidence angle in the direct chemisorption region. Rettner et al. postulate that this could possibly be due to the effective corrugation of the surface potential or multiple interactions of the molecule with the surface. 

Several important studies have been conducted by various research groups regarding the chemisorption of various saturated hydrocarbons on the Ir(l 1 0) and Pt(l 11) surfaces, providing much insight into the dynamics of alkane activation on transitional metal surfaces. 

The dissociative adsorption of alkanes on Ir(l 1 0) surface was investigated in a series of studies performed by the Madix group [13, 32, 33]. A study performed by Hamza et al. [32] probed the dynamics of the dissociative chemisorption of methane, ethane, propane, and n-butane on the Ir(l 1 0)-(l x 2) surface. These investigations were complemented by a later study of propane dissociation on the Ir(l 1 0)-(l x 2) surface by Soulen and Madix [13]. Shown in Figs 6 and 7 are plots of S0 vs. E obtained for propane at various surface temperatures [32] and a plot of experimental and theoretical values of S0 for propane (at an incident translational energy of 50kcal/mol) on Ir(l 1 0)-(l x 2) as a function of surface temperature [13]. 

Hamza et al. argue that the data shown in Fig. 6 supports the existence of two distinct regions of chemisorption. At low kinetic energies a trapping-mediated mechanism appears to be the dominant 

The direct contribution to chemisorption also shows an apparent dependence on carbon chain length as the length of the hydrocarbon increases, the energy required to produce the same chemisorption 

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