Two-Dimensional First-Order Melting Transition and Polymorphism in a Monolayer of Nitric Oxide Adsorbed on Graphite

Abstract
Neutron diffraction has shown evidence for a two-dimensional first-order melting transition in the first layer of NO adsorbed on graphite (0001). Two different incommensurate solid phases β and γ have been observed. The data suggest that N2 O2 dimers are standing up on the graphite surface in the β phase and lying down in the γ phase.