Orientational Ordering in a Strongly Chemisorbed System: Na on Ru(001)

Abstract
This study of Na on Ru(001) at 80 K provides the first detailed examination of orientational ordering in a strongly chemisorbed monolayer. The relative orientation of a Na layer on Ru(001) varies with the Na-Ru lattice misfit in a way consistent with predictions from theoretical models that have been used to explain orientational ordering of rare gases physisorbed on graphite. The similarity between physisorbed systems and the chemisorbed Na on Ru system suggests a universal behavior of rigid overlayers on hexagonal substrates.