Orientational correlations in liquid carbon monoxide and nitric oxide

Neutron diffraction results obtained for liquid CO and NO have been modelled by means of the reverse Monte Carlo method. Partial pair correlation functions, centre-centre pair correlation functions and the relative orientations of molecular axes as a function of distances between molecular centres have been calculated from the models. It was found that, contrary to earlier suggestions, well defined orientational correlations exist in liquid carbon monoxide, even at lower densities. For liquid nitric oxide, the existence of (NO)2 dimers has been confirmed, but the 'cis-planar' structure of the dimers, suggested earlier, could not be made consistent with available diffraction data