The dissociative adsorption of chlorobenzene and dichlorobenzene on Si(100) surface was modeled using density functional theory. A double and triple dimer cluster was used to represent the (100) face of silicon. Initial adsorption occurs by breaking one double bond on the phenyl ring and forming two new carbon- silicon bonds with the silicon dimer. For further dissociation to occur, the system must undergo a spin crossing process from the singlet electronic configuration to a higher energy triplet state. After this spin crossing event, the chlorine can then bond to the silicon surface. The possible mechanisms of dissociation are explored for both chlorobenzene and dichlorobenzene. The minimum energy crossing point for the spin crossing is found by minimizing the energy gradients between the two electronic states. The probability of spin crossing at the minimum energy crossing point is calculated, and the activation energy for the process is determined. It is found that the activation energies for the spin crossings are small in comparison to the other steps in the proposed mechanisms.

DFT study of the dissociative adsorption of chlorobenzene and 1,2-dichlorobenzene on Si(100)

249th National Meeting (2015)

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