External stress-induced chemical reactivity of O2 on Si(001)

In the dissociation reaction of O-2 on the Si(001)-c(4x2) surface, a trapping-mediated reaction is accelerated by external tensile stress. This alteration of the reactivity is more than an order of magnitude greater than estimations based on the alteration of the electronic structure caused by strain of the surface lattice. It was found that on the Si(001)-c(4x2) surface, the stress destabilized the antiferromagnetic ordering of topmost Si atoms forming buckled dimer and induced the collective phason-flip motion of the dimer. The alteration of the reactivity caused by such a collective instability of the arrangement of surface atoms is discussed.