Pair configuration of maximum occurrence probability in liquid formic acid as determined from neutron scattering and proton magnetic relaxation results

Intermolecular parts of the kappa->r Fourier transform of the coherent scattering cross section of five isotopically different formic acids are presented and from these data four weighted sums of intermolecular atom-atom pair distribution functions are determined. Very limited informations about the two (equal) hydrogen-hydrogen correlation function is also given. From proton magnetic relaxation data available in the literature two possible pair configurations were proposed. From these pairs and one additional one the corresponding sets of intermolecular atomic distances were determined and examined whether these sets lead to agreement with the weighted sums of correlation functions. Agreement was found to be best for a pair with O=C vectors being close to but not exactly parallel, it was concluded that this is correct molecular pair configuration of maximum occurrence probability. (orig.)