Orientation of molecularly intercalated ${\mathrm{N}}_2$ in ${\mathrm{C}}_{24}$K

The nuclear-resonance photon-scattering technique was used to study the tilt angle of physisorbed ${\mathrm{N}}_2$ with respect to the graphene planes of ${\mathrm{C}}_{24}$K prepared from highly oriented pyrolytic graphite. This was done by measuring the ratio of the resonantly scattered intensities from the 6324-keV level in ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ with the photon beam parallel and perpendicular to the graphene planes. In the temperature range T=10–190 K where nitrogen is molecularly intercalated into the ${\mathrm{C}}_{24}$K, a huge anisotropy, a factor ≊2.5, was observed in the scattering cross sections. This is interpreted in terms of the orientation of the molecular axes of the ${\mathrm{N}}_2$ molecules as being very nearly parallel to the graphene planes. Above 200 K, the amount of molecularly intercalated ${\mathrm{N}}_2$ was negligible.