ABSTRACT
There are two distinctive channels in the dissociation reaction of O2 on Si(001)-(2 x 1): a trapping-mediated channel and a direct-activated channel. Externally applied tensile strain along the <110> direction on the (001) surface is found to suppress the dissociation via a direct-activated channel and to enhance that via a trapping-mediated channel in the temperature range between 200 and 300 K. It has been demonstrated that the dissociation dynamics involving elementary processes such as inelastic scattering and trapping, desorption and/or dissociation from a trapping precursor, and direct dissociation are sensitively influenced by the strain to change the branching ratio of the dissociation reaction.
ABSTRACT
In exploring the dynamics of dissociative chemisorption of O2 on clean and O-covered Cu(001), we demonstrate that the chemisorption is very sensitive to uniaxial tensile stress within an elastic limit. The stress enhances the dissociative chemisorption on clean Cu(001) when the translational energy of incident O2 is below 250 meV, and suppresses it when the energy is above 250 meV. In the case of an oxygen-covered Cu(001)- (2squareroot2 x squareroot2) surface, the dissociative adsorption probability of O2 decreases as the stress increases. The effect of external stress on the O2 dissociation dynamics is different between clean and O-covered surfaces.
