Observation of a triangular incommensurate ‘two-out’ herringbone phase of nitrogen physisorbed on graphite

Abstract

New results of a low-energy electron-diffraction study of incommensurate nitrogen physisorbed on graphite are reported. A triangular incommensurate ‘two-out’ structure with tilt of the type predicted by theory of Harris and Berlinsky is observed. The molecular orientation is estimated on the basis of steric considerations and a kinematic approximation for the diffraction intensities. The estimated orientation and structure are found to be in reasonable agreement with the predictions of theory when the nitrogen–nitrogen and nitrogen–graphite interaction parameters currently available are used.