Spin correlation in O(2) chemisorption on Ni(111).

Molecular oxygen (O(2)) is a paramagnetic linear molecule, yet how its electron spin affects the chemisorption probability remains unclear. We here present the first spin- and alignment-resolved O(2) chemisorption experiment conducted with a single spin-rotational state-selected O(2) beam and a magnetized Ni(111) surface. The results show that the O(2) sticking probability is higher when its spin is oriented antiparallel to the majority spin direction of the Ni substrate. The spin dependence becomes more significant at low translational energy, and amounts to over 40% at thermal energy. This strong spin effect suggests that incident O(2) molecules keep high spin polarizations even at the position of the dissociation barrier.