Orientation ofN2O molecules adsorbed on Grafoil

The nuclear resonance scattering of 6324-keV photons from ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ was used to study the tilt angles of ${\mathrm{N}}_2$O molecules adsorbed on graphite. It is shown that for a coverage n=0.8 and 1.3 commensurate √3 × √3 monolayers, at T=12 K, the ${\mathrm{N}}_2$O tilt angles are φ=4°±4° and φ=16°±2°, respectively, with respect to the graphite planes. The orientation angle remains nearly the same between 12 K and ∼150 K, while the ${\mathrm{N}}_2$O film passes from a solid to a liquid and then to a gaseous phase.