Experimental determination of deviation from spherical electron densities of atoms in benzene molecules in the liquid state

Deviation of electron distribution around atomic nuclei from the spherical density in liquid benzene has directly been obtained through a X-rayneutron difference interference function derived from the difference between the intermolecular X-ray diffraction interference term and the linear combination of neutron intermolecular partial structure factors weighted by atomic scattering factors for the X-ray scattering. The difference distribution function exhibits a broad negative peak at around r = 3.24 corresponding to intermolecular distance in which electron density is relatively lower than that for the spherical case. Positive peaks found at r = 4.30, 5.22, and 6.20 indicate intermolecular distances with higher electron density. This experimental evidence for intermolecular electron distribution in the liquid benzene has been discussed by means of the average molecular geometry of the nearest neighbor benzene molecules which was determined from the least squares analyses of observed neutron intermolecular partial structure factors.