Low-temperature structures of Xe on graphite in the one- to two-layer regime

We have investigated the low-temperature structures of xenon overlayers on graphite with coverages ranging from 0.8 to 1.7 ({}3 ×{} {}3 ) monolayers. We find that below 60 K the full monolayer has an incommensurate structure which appears to correspond to a rectangular striped phase rather than the {}3 ×{} {}3 commensurate structure inferred from previous electron-diffraction studies. With increasing coverage there is a first-order transition from the monolayer striped phase to a bilayer hexagonal structure close to that of bulk xenon.