X-ray Study of Kr, Xe, and N₂ Monolayers on Boron Nitride

X-ray scattering has been used to investigate the structures of Kr, Xe, and N 2 monolayers adsorbed on the basal plane of boron nitride. The results indicate that all three monolayers form a 2D solid of the simple triangular structure. Both Kr and N 2 monolayers are commensurate with respect to the substrate only in very limited regions of coverage and temperature, while Xe monolayers are always incommensurate within the temperature and coverage regions examined here. The occurrence of an abnormal liquid phase in the Xe monolayer is suggested.