Abstract
A nuclear resonance photon scattering (NRPS) study of the out-of-plane orientation of nitric oxide (NO) physisorbed onto basal planes of graphite was made as a function of temperature T and the coverage n. At T = 12 K and n ⩽ 1, no configuration was observed in which all the NO molecules are oriented parallel to the graphite surface. Oblique or rectangular dimers, and monomers in which the average tilt angle of the NO molecular axes is at least 21° were found to yield a good agreement with the measured data. The precise nature of the configurations or the arrangement of the adsorbed NO molecules remain unknown.