Study of Dipolar Interaction in Liquid Pyridine by X‐Ray and Neutron Diffraction

X‐ray and neutron diffraction experiments on liquid pyridine are reported. After data reduction and evaluation the intramolecular contribution was separated from the total intensity and the intramolecular geometry in the liquid phase was determined. The combination of X‐ray and neutron intermolecular differential cross sections permits an assignment of intermolecular distances to specific atom pairs. Based on these identifications a two‐dimensional model of the local order existing in liquid pyridine is deduced. A quantitative calculation leads to a refined model, reproducing simultaneously the X‐ray and neutron data. Most probable is an antiparallel “side‐side” for the nearest and a “head‐on‐tail” configuration for the next molecule respectively. This means, that the dipolar interaction is the structure determining factor.